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PostPosted: Sat Feb 03, 2018 6:03 pm 
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Joined: Sat Jun 30, 2007 7:45 am
Posts: 1040
Location: hole above ground
I will keep it simple
did you and the previous owner clean the exhaust after the rebuilds

most likely its sucking all old piston parts back it to the Engine

Speed


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PostPosted: Sat Feb 03, 2018 6:13 pm 
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Joined: Tue Jan 17, 2012 3:19 am
Posts: 7698
Location: Hope, B.C Canada
I would like to comment on jetting here.
This might be long winded but please bear with me.
In my opinion jetting has to be WAY out to cause major Engine damage. The reason I say this is because of some of my experiences with oddy's. One of my oddy's (the one I ride) is stock except for a bigger carb. The other oddy (my brothers) is highly modified, pipe, carb, port work, cylinder milled. It has 180 psi compression and mine had 150 psi. On rare occasions we swap machines for one run up the mountain. We go from just above sea level to just over 5000' on one run up the hill. We do not re-jet and they run fine top to bottom. I noticed one day that my machine had lots of power. My brother couldn't pull me on the straights. He then rode mine and commented on the power. This went on almost all summer (half a dozen rides at least). Then one day near the top of the hill my Engine made a back fire and died. To shorten this long story I will tell you that my intake had a two inch break (slash) in it. I couldn't see it because it was on the bottom side. When I stripped the Engine I found that my rod bearing let go. It blew because of the lack of oiling because of the severe lean condition. This severe condition did not melt my piston. In fact that piston would have been useable if all of the metal from the bearing coming apart didn't embed itself in the piston and smash up the ring grooves. I was running AVGAS and it ran great to the end even with that severe lean condition. My machines have homemade liquid cooled heads and cylinders also. Basically what I am getting at is even if you are out a couple of jet sizes I have to call bullshyte when ever I hear "your jetting is out". No FN way will you blow an Engine if you are out a jet size or two. No way. My experience above is why I believe that. Others will argue the point but I know what I know through experience. We all have our own pet theories and beliefs. That's why we are all different. Some like red heads others blondes, it don't matter, they both cost alimoney.


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PostPosted: Sat Feb 03, 2018 6:17 pm 
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Joined: Tue Jan 17, 2012 3:19 am
Posts: 7698
Location: Hope, B.C Canada
Specter wrote:
canadian oddy wrote:
Specter wrote:
well it only had about 4 hours on it before the meltdown the first time. Then only about 2 hours again before the second piston melted. maybe riding style? I really don't know.

1. I will definitely check the timing first.
2. will then fuel pump.
3. jetting is good, i can set it to run rich (which i did).
4. no floats (it has marine carbs on it).
5. checked for air leaks with carb cleaner.
6. gas tank look really good inside. but i will replace all the fuel lines.

I was checking around and at 150 is should be able to run on pump gas. it has to be either number 1 or 2, or both.


You were checking around and at 150 should be able to run pump gas ------ well your not getting 150. You said one cylinder was showing 180 psi. Not good for pump gas.
I am a great fan of Avgas as you probably have already noticed. The hotter your Engine runs the more dangerous it is for running pump fuel. There are endless threads on this site about melted engines -- endless. The problem with an oddy is that the Engine is behind the seat and it is air cooled. That's why almost everyone melts an oddy air cooled Engine. An oddy Engine must be in perfect condition, jetting must be perfect, fuel flow must be perfect and the weather must be perfect or poofkaboom. Way to many things that have to be perfect for a ride to be successful. You are running a rotax which is liquid cooled so that would not be an issue here, but the high compression is (180). The other issue that has happened several times on this site is that guys find out that their compression tester is crap. Are you sure your unit is good ?? It MUST be checked against another compression tester for accuracy. Trust me. I have two compression testers. One Chinese and one American. The Chinese unit is out by ten pounds. I also checked both against my compressor gauge.


I did test the compression gauge against the gauge on my compressor. it was spot on. I figured it would be way off since it was a cheap Chinese gauge.

I don't think the Engine was supposed to be at 180. no idea why it was so high. maybe it was a wrong piston. I have no idea. I assumed that the Engine was ready to go since it was a drop in.

It's simple. i have a farr-offroad Engine and carburetors. it is a drop in kit that is designed to run on pump gas. I ran pump gas and melted a piston. Had no idea why it happened. I assumed it was from running too lean. now it seems the timing was too advanced as well.

I just want to ride my pilot that has a new Engine in it. is that so much to ask.


I can hear the frustration. We have all been there.


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PostPosted: Sat Feb 03, 2018 6:35 pm 
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Joined: Sat Feb 03, 2018 3:42 pm
Posts: 31
canadian oddy wrote:
I would like to comment on jetting here.
This might be long winded but please bear with me.
In my opinion jetting has to be WAY out to cause major Engine damage. The reason I say this is because of some of my experiences with oddy's. One of my oddy's (the one I ride) is stock except for a bigger carb. The other oddy (my brothers) is highly modified, pipe, carb, port work, cylinder milled. It has 180 psi compression and mine had 150 psi. On rare occasions we swap machines for one run up the mountain. We go from just above sea level to just over 5000' on one run up the hill. We do not re-jet and they run fine top to bottom. I noticed one day that my machine had lots of power. My brother couldn't pull me on the straights. He then rode mine and commented on the power. This went on almost all summer (half a dozen rides at least). Then one day near the top of the hill my Engine made a back fire and died. To shorten this long story I will tell you that my intake had a two inch break (slash) in it. I couldn't see it because it was on the bottom side. When I stripped the Engine I found that my rod bearing let go. It blew because of the lack of oiling because of the severe lean condition. This severe condition did not melt my piston. In fact that piston would have been useable if all of the metal from the bearing coming apart didn't embed itself in the piston and smash up the ring grooves. I was running AVGAS and it ran great to the end even with that severe lean condition. My machines have homemade liquid cooled heads and cylinders also. Basically what I am getting at is even if you are out a couple of jet sizes I have to call bullshyte when ever I hear "your jetting is out". No FN way will you blow an Engine if you are out a jet size or two. No way. My experience above is why I believe that. Others will argue the point but I know what I know through experience. We all have our own pet theories and beliefs. That's why we are all different. Some like red heads others blondes, it don't matter, they both cost alimoney.


thank you sir, that has been my experience too. I used to run a bike without the air filter (too damn poor to afford the $30 for the air filter), plus the bike was about $100. ran like crap but no melt down or sudden Engine failure. good to hear it from someone else though.


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PostPosted: Sat Feb 03, 2018 6:37 pm 
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Joined: Sat Feb 03, 2018 3:42 pm
Posts: 31
Quote:
I can hear the frustration. We have all been there.


yeah, trying to stay positive though.

On the bright side, now i know the timing is probably off. I also know the 180 was an issue for sure. It gives me hope i can rebuild and not have it happen again.

I do appreciate the help.


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PostPosted: Sat Feb 03, 2018 6:56 pm 
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Joined: Tue Jan 17, 2012 3:19 am
Posts: 7698
Location: Hope, B.C Canada
One final comment for me on this thread and then I will let it go.

VERIFY fuel flow rate. Double check it.


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PostPosted: Sat Feb 03, 2018 7:04 pm 
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Joined: Fri Jan 12, 2007 2:17 pm
Posts: 3620
Location: Wichita ks
CO did you take a good look at the plugs. I do believe far rebuilds before shipping just this don't happen.
I think a call into him would be a good idea. Send him your pics. Get his opinion before doing any thing. He is the builder.
Plug reading 101


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PostPosted: Sat Feb 03, 2018 8:02 pm 
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Joined: Sat Feb 03, 2018 3:42 pm
Posts: 31
canadian oddy wrote:
One final comment for me on this thread and then I will let it go.

VERIFY fuel flow rate. Double check it.


absolutely will do that.


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PostPosted: Sat Feb 03, 2018 8:02 pm 
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Joined: Sat Feb 03, 2018 3:42 pm
Posts: 31
adnoh wrote:
CO did you take a good look at the plugs. I do believe far rebuilds before shipping just this don't happen.
I think a call into him would be a good idea. Send him your pics. Get his opinion before doing any thing. He is the builder.
Plug reading 101


I will do that. thanks.


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PostPosted: Sun Feb 04, 2018 1:25 am 
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Joined: Thu Jan 01, 2015 1:45 pm
Posts: 149
Location: cleveland oh
canadian oddy wrote:
I would like to comment on jetting here.
This might be long winded but please bear with me.
In my opinion jetting has to be WAY out to cause major Engine damage. The reason I say this is because of some of my experiences with oddy's. One of my oddy's (the one I ride) is stock except for a bigger carb. The other oddy (my brothers) is highly modified, pipe, carb, port work, cylinder milled. It has 180 psi compression and mine had 150 psi. On rare occasions we swap machines for one run up the mountain. We go from just above sea level to just over 5000' on one run up the hill. We do not re-jet and they run fine top to bottom. I noticed one day that my machine had lots of power. My brother couldn't pull me on the straights. He then rode mine and commented on the power. This went on almost all summer (half a dozen rides at least). Then one day near the top of the hill my Engine made a back fire and died. To shorten this long story I will tell you that my intake had a two inch break (slash) in it. I couldn't see it because it was on the bottom side. When I stripped the Engine I found that my rod bearing let go. It blew because of the lack of oiling because of the severe lean condition. This severe condition did not melt my piston. In fact that piston would have been useable if all of the metal from the bearing coming apart didn't embed itself in the piston and smash up the ring grooves. I was running AVGAS and it ran great to the end even with that severe lean condition. My machines have homemade liquid cooled heads and cylinders also. Basically what I am getting at is even if you are out a couple of jet sizes I have to call bullshyte when ever I hear "your jetting is out". No FN way will you blow an Engine if you are out a jet size or two. No way. My experience above is why I believe that. Others will argue the point but I know what I know through experience. We all have our own pet theories and beliefs. That's why we are all different. Some like red heads others blondes, it don't matter, they both cost alimoney.
As you said, everyone has their own ideas, and there's more than 1 way to skin a cat.

In your story here, there are things to consider.

http://www.jetsrus.com/FAQs/FAQ_rejet_e ... rature.htm


You're going up 5000'. According to this chart posted in that link, you're actually running fat or rich as you go up. I assume the temperature is dropping as you go higher as well. So that's going to need more fuel. So, in theory, you are only slightly fatter/richer than when you started at the base of the mountain. No worries with your poofkaboom there.

What do you think the chances are of you having a small pin hole leak in your intake manifold that was torn open from the Engine backfire?

Seems possible to me.



How familiar are you guys with watercraft carbs? There are no float bowls. There are no jet needles. You have a float chamber and diaphragm. Pop off pressure relates to when the needle lifts off the seat and allows fuel to flow through the carb.

It's not uncommon to have a burn down (piston melt) at only partial throttle. The reason being you have the most timing advance around 3/4 throttle. (generally the CDI (Capacitor Discharge Ignition) starts to retard timing as the RPM continues up to red line)

So, you may have sufficient fuel at idle and WOT (Wide Open Throttle), but if you're lean in between there, it's possible to have a melt down.

Since you never answered what carbs you're using, I'm going to assume you have the Mikuni Super BN's. Here's a manual that you might find useful.

http://www.mikuni.com/pdf/sbn_manual.pdf

Good luck with your buggy


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PostPosted: Sun Feb 04, 2018 1:31 am 
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Joined: Tue Jan 17, 2012 3:19 am
Posts: 7698
Location: Hope, B.C Canada
xlint89 wrote:
canadian oddy wrote:
I would like to comment on jetting here.
This might be long winded but please bear with me.
In my opinion jetting has to be WAY out to cause major Engine damage. The reason I say this is because of some of my experiences with oddy's. One of my oddy's (the one I ride) is stock except for a bigger carb. The other oddy (my brothers) is highly modified, pipe, carb, port work, cylinder milled. It has 180 psi compression and mine had 150 psi. On rare occasions we swap machines for one run up the mountain. We go from just above sea level to just over 5000' on one run up the hill. We do not re-jet and they run fine top to bottom. I noticed one day that my machine had lots of power. My brother couldn't pull me on the straights. He then rode mine and commented on the power. This went on almost all summer (half a dozen rides at least). Then one day near the top of the hill my Engine made a back fire and died. To shorten this long story I will tell you that my intake had a two inch break (slash) in it. I couldn't see it because it was on the bottom side. When I stripped the Engine I found that my rod bearing let go. It blew because of the lack of oiling because of the severe lean condition. This severe condition did not melt my piston. In fact that piston would have been useable if all of the metal from the bearing coming apart didn't embed itself in the piston and smash up the ring grooves. I was running AVGAS and it ran great to the end even with that severe lean condition. My machines have homemade liquid cooled heads and cylinders also. Basically what I am getting at is even if you are out a couple of jet sizes I have to call bullshyte when ever I hear "your jetting is out". No FN way will you blow an Engine if you are out a jet size or two. No way. My experience above is why I believe that. Others will argue the point but I know what I know through experience. We all have our own pet theories and beliefs. That's why we are all different. Some like red heads others blondes, it don't matter, they both cost alimoney.
As you said, everyone has their own ideas, and there's more than 1 way to skin a cat.

In your story here, there are things to consider.

http://www.jetsrus.com/FAQs/FAQ_rejet_e ... rature.htm


You're going up 5000'. According to this chart posted in that link, you're actually running fat or rich as you go up. I assume the temperature is dropping as you go higher as well. So that's going to need more fuel. So, in theory, you are only slightly fatter/richer than when you started at the base of the mountain. No worries with your poofkaboom there.

What do you think the chances are of you having a small pin hole leak in your intake manifold that was torn open from the Engine backfire?

Seems possible to me.



How familiar are you guys with watercraft carbs? There are no float bowls. There are no jet needles. You have a float chamber and diaphragm. Pop off pressure relates to when the needle lifts off the seat and allows fuel to flow through the carb.

It's not uncommon to have a burn down (piston melt) at only partial throttle. The reason being you have the most timing advance around 3/4 throttle. (generally the CDI (Capacitor Discharge Ignition) (Capacitor Discharge Ignition) starts to retard timing as the RPM continues up to red line)

So, you may have sufficient fuel at idle and WOT (Wide Open Throttle) (Wide Open Throttle), but if you're lean in between there, it's possible to have a melt down.

Since you never answered what carbs you're using, I'm going to assume you have the Mikuni Super BN's. Here's a manual that you might find useful.

http://www.mikuni.com/pdf/sbn_manual.pdf

Good luck with your buggy


I will be the first to admit that I know NOTHING about a rotax or the carbs it uses.
Any comments I make are based on an oddy.
Not shooting down anyone's ideas as we are all guessing based on our experiences.
It's possible that I am wrong but then you have to prove it to me.

I reject all realities and substitute my own.


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PostPosted: Sun Feb 04, 2018 7:51 am 
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Joined: Sat Nov 08, 2014 7:40 am
Posts: 916
Location: Tallahassee Florida
I feel like we're missing something.
I run a Polaris 3cyl in my jet ski so I'm familiar with the carbs but the Rotax has me thrown off though.

In my personal experience I've found three carbs set up exactly the same and one cylinder on mine runs a little richer then the other two. This is after a full rebuild with 140 compression on the two similar and 135 on the rich cylinder. All carbs were completely rebuilt with all new internals,pumps,seats,valves ect.
I never had any running issues and it doesn't foul the plug just runs a tad richer/cooler.
So I mention all of this because I spent about a week trying to make it perfect and although I didn't fix it I figured one thing. Fuel return line plays an important role in fuel pressure with these type of carbs.
I played with various solonoids and an rpm switch in an attempt to control my return fuel pressure but after a week I figured it was good enough and called it done. This was about 5 years ago and I never touched it again.
I know this is not much help but may be some food for thought

As I sit here thinking about it as I recall my fuel tank is pressurized. It has two one way valves to control the internal pressure.
It's been awhile so my mind is a little foggy.
Again I'm not familiar with the Rotax but I'm wondering if that may fit in somewhere.
Update
So reading back through this I see u did not set the pop off pressure in the carbs. I know on my set up this is a must. Pop off pressure is critical. I got to where I could pull the carbs and adjust them on the water I was doing it so often when tuning it. More pressure is richer and less is lean.

Think of pop off pressure as a main jet as it regulates the amount of fuel available to the fuel circuits. You have to have it set before u can jet or tune the fuel circuits.

If u r carbs use pop off pressure and u are not setting it you will melt the next piston too.

So my hypothesis is ur pop off pressure is low. U are compensating for it with the carb screws and main jet but this only compensates the bottom and top end not mid throttle causing a mid throttle lean condition. I set mine to have a slight bog mid throttle for this reason.
If u don't have pop off valves then I'm way off


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PostPosted: Sun Feb 04, 2018 8:52 am 
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Joined: Sat Nov 08, 2014 7:40 am
Posts: 916
Location: Tallahassee Florida
So for those who may be interested a quick run down on pop off pressure.
You attach the clear hose to you're fuel input on the carb. With the carb cover removed u pump up the pressure until a little bypass valve opens letting off excess fuel pressure. This pressure is recorded on the pump gauge. The set of pressure is adjusted with different springs and if u r like me u will trim coils from the springs to fine tune it.
There is a learning curve but easy after the first time.
A bike tire pump won't work because u need the gauge to store the pressure reading as it is impossible to read it otherwise.


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PostPosted: Sun Feb 04, 2018 4:13 pm 
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Joined: Tue Jan 17, 2012 3:19 am
Posts: 7698
Location: Hope, B.C Canada
That's cool.
Thx for the "how to" explanation.
I learn something new every day and I am 58 yrs old now. Cool.


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PostPosted: Sun Feb 04, 2018 4:28 pm 
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Joined: Sat Feb 03, 2018 3:42 pm
Posts: 31
FloridaEdd wrote:
So for those who may be interested a quick run down on pop off pressure.
You attach the clear hose to you're fuel input on the carb. With the carb cover removed u pump up the pressure until a little bypass valve opens letting off excess fuel pressure. This pressure is recorded on the pump gauge. The set of pressure is adjusted with different springs and if u r like me u will trim coils from the springs to fine tune it.
There is a learning curve but easy after the first time.
A bike tire pump won't work because u need the gauge to store the pressure reading as it is impossible to read it otherwise.


wow, been reading up on pop off pressure. never heard of it. Thanks for the info, i am going to buy a pop off tester.


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PostPosted: Sun Feb 04, 2018 4:41 pm 
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Joined: Sat Feb 03, 2018 3:42 pm
Posts: 31
xlint89 wrote:
canadian oddy wrote:
I would like to comment on jetting here.
This might be long winded but please bear with me.
In my opinion jetting has to be WAY out to cause major Engine damage. The reason I say this is because of some of my experiences with oddy's. One of my oddy's (the one I ride) is stock except for a bigger carb. The other oddy (my brothers) is highly modified, pipe, carb, port work, cylinder milled. It has 180 psi compression and mine had 150 psi. On rare occasions we swap machines for one run up the mountain. We go from just above sea level to just over 5000' on one run up the hill. We do not re-jet and they run fine top to bottom. I noticed one day that my machine had lots of power. My brother couldn't pull me on the straights. He then rode mine and commented on the power. This went on almost all summer (half a dozen rides at least). Then one day near the top of the hill my Engine made a back fire and died. To shorten this long story I will tell you that my intake had a two inch break (slash) in it. I couldn't see it because it was on the bottom side. When I stripped the Engine I found that my rod bearing let go. It blew because of the lack of oiling because of the severe lean condition. This severe condition did not melt my piston. In fact that piston would have been useable if all of the metal from the bearing coming apart didn't embed itself in the piston and smash up the ring grooves. I was running AVGAS and it ran great to the end even with that severe lean condition. My machines have homemade liquid cooled heads and cylinders also. Basically what I am getting at is even if you are out a couple of jet sizes I have to call bullshyte when ever I hear "your jetting is out". No FN way will you blow an Engine if you are out a jet size or two. No way. My experience above is why I believe that. Others will argue the point but I know what I know through experience. We all have our own pet theories and beliefs. That's why we are all different. Some like red heads others blondes, it don't matter, they both cost alimoney.
As you said, everyone has their own ideas, and there's more than 1 way to skin a cat.

In your story here, there are things to consider.

http://www.jetsrus.com/FAQs/FAQ_rejet_e ... rature.htm


You're going up 5000'. According to this chart posted in that link, you're actually running fat or rich as you go up. I assume the temperature is dropping as you go higher as well. So that's going to need more fuel. So, in theory, you are only slightly fatter/richer than when you started at the base of the mountain. No worries with your poofkaboom there.

What do you think the chances are of you having a small pin hole leak in your intake manifold that was torn open from the Engine backfire?

Seems possible to me.



How familiar are you guys with watercraft carbs? There are no float bowls. There are no jet needles. You have a float chamber and diaphragm. Pop off pressure relates to when the needle lifts off the seat and allows fuel to flow through the carb.

It's not uncommon to have a burn down (piston melt) at only partial throttle. The reason being you have the most timing advance around 3/4 throttle. (generally the CDI (Capacitor Discharge Ignition) (Capacitor Discharge Ignition) starts to retard timing as the RPM continues up to red line)

So, you may have sufficient fuel at idle and WOT (Wide Open Throttle) (Wide Open Throttle), but if you're lean in between there, it's possible to have a melt down.

Since you never answered what carbs you're using, I'm going to assume you have the Mikuni Super BN's. Here's a manual that you might find useful.

http://www.mikuni.com/pdf/sbn_manual.pdf

Good luck with your buggy


Thanks for the manual. The cars are in fact Super BN. When I rebuilt the carbs I didn't replace the springs but at the same time didn't test the pop off. It looks like you can compensate for high pop off by opening up the low fuel jet. But still, going to get a gauge and check the pop off pressure.


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PostPosted: Sun Feb 04, 2018 4:45 pm 
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Joined: Tue Jan 17, 2012 3:19 am
Posts: 7698
Location: Hope, B.C Canada
FloridaEdd wrote:
I feel like we're missing something.
I run a Polaris 3cyl in my jet ski so I'm familiar with the carbs

If u r carbs use pop off pressure and u are not setting it you will melt the next piston too.


And there is the warning.
When I was looking at the pics of those pistons I was certain it was fuel related. I just didn't know what the fuel issue was.

Also I would do what speed has suggested above, and make a few calls like were suggested. Manny don't send junk out the door. If he built that Engine it should have been good to go.
Lots of good suggestions in this thread.


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PostPosted: Sun Feb 04, 2018 5:08 pm 
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Joined: Tue Jan 17, 2012 3:19 am
Posts: 7698
Location: Hope, B.C Canada
xlint89 wrote:
How familiar are you guys with watercraft carbs? There are no float bowls. There are no jet needles. You have a float chamber and diaphragm. Pop off pressure relates to when the needle lifts off the seat and allows fuel to flow through the carb.

It's not uncommon to have a burn down (piston melt) at only partial throttle. The reason being you have the most timing advance around 3/4 throttle. (generally the CDI (Capacitor Discharge Ignition) (Capacitor Discharge Ignition) starts to retard timing as the RPM continues up to red line)

So, you may have sufficient fuel at idle and WOT (Wide Open Throttle) (Wide Open Throttle), but if you're lean in between there, it's possible to have a melt down.

Since you never answered what carbs you're using, I'm going to assume you have the Mikuni Super BN's. Here's a manual that you might find useful.

http://www.mikuni.com/pdf/sbn_manual.pdf

Good luck with your buggy


xlint89 called it I think. Just my opinion.


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PostPosted: Sun Feb 04, 2018 11:15 pm 
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Joined: Sat Feb 03, 2018 3:42 pm
Posts: 31
canadian oddy wrote:
xlint89 wrote:
How familiar are you guys with watercraft carbs? There are no float bowls. There are no jet needles. You have a float chamber and diaphragm. Pop off pressure relates to when the needle lifts off the seat and allows fuel to flow through the carb.

It's not uncommon to have a burn down (piston melt) at only partial throttle. The reason being you have the most timing advance around 3/4 throttle. (generally the CDI (Capacitor Discharge Ignition) (Capacitor Discharge Ignition) (Capacitor Discharge Ignition) starts to retard timing as the RPM continues up to red line)

So, you may have sufficient fuel at idle and WOT (Wide Open Throttle) (Wide Open Throttle) (Wide Open Throttle), but if you're lean in between there, it's possible to have a melt down.

Since you never answered what carbs you're using, I'm going to assume you have the Mikuni Super BN's. Here's a manual that you might find useful.

http://www.mikuni.com/pdf/sbn_manual.pdf

Good luck with your buggy


xlint89 called it I think. Just my opinion.


I am not sure that is the problem. In the manual for the Super BNs it says the pop off only affects throttle below 1/4 and has no effect above that. It also says that you can have a high pressure and compensate for it with the low speed jet adjustment. I had it adjusted so it was rich at idle. it was so rich I could start it without the choke.

I am leaning towards high compression pistons and/or ignition timing. so I will check the ignition timing when i have time. That will tell me if the ignition was off.


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PostPosted: Sun Feb 04, 2018 11:29 pm 
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Location: Tallahassee Florida
That was my best guess,just that a guess. I'll be interested in seeing the outcome.
Best of luck


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PostPosted: Sun Feb 04, 2018 11:47 pm 
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Location: Hope, B.C Canada
I still stand by my very first statement I made here on page 1


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PostPosted: Mon Feb 05, 2018 12:31 am 
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canadian oddy wrote:
I still stand by my very first statement I made here on page 1


it was super unleaded. fuel definitely wasn't crap. But you are right.... Detonation.

The cylinder that had 180psi melted... definitely too high compression.

But the other one only had 150 and is showing scoring on the cylinder wall, on the front and back of the cylinder. It appears that cylinder is getting too hot as well.


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PostPosted: Mon Feb 05, 2018 12:34 am 
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FloridaEdd wrote:
That was my best guess,just that a guess. I'll be interested in seeing the outcome.
Best of luck


I will keep the thread updated. I always hate when you read through 10 pages and the OP doesn't post the results.

Who knows, maybe it will help someone further down the road.


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PostPosted: Mon Feb 05, 2018 5:29 am 
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Location: Tallahassee Florida
It all a puzzle and we're just seeing what fits.
One more tid bit I have is on the scoring.
Let's assume the piston is wrong or the head has been shaved which raised the compression to unacceptable levels and caused detonation.
I think the scoring on the other cylinder could have been caused by it taking the load and resistance of the melted down piston. As the load on a Engine increases so must the fuel,the melted piston was placing great demand on the other one which made it lean by defult.

These are just thoughts. I make no claim to be right I'm just trying to give a different perspective.

Update

Not being a smart ass but why are we thinking the timing is off?
Either the timing is off causing preignition,which would effect both cylinders ...or a lean condition is causing the preignition.
This is half statement and half question. I too would check the timing I'm just wondering if I missed something.


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PostPosted: Mon Feb 05, 2018 10:59 am 
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FloridaEdd wrote:
It all a puzzle and we're just seeing what fits.
One more tid bit I have is on the scoring.
Let's assume the piston is wrong or the head has been shaved which raised the compression to unacceptable levels and caused detonation.
I think the scoring on the other cylinder could have been caused by it taking the load and resistance of the melted down piston. As the load on a Engine increases so must the fuel,the melted piston was placing great demand on the other one which made it lean by defult.

These are just thoughts. I make no claim to be right I'm just trying to give a different perspective.

Update

Not being a smart ass but why are we thinking the timing is off?
Either the timing is off causing preignition,which would effect both cylinders ...or a lean condition is causing the preignition.
This is half statement and half question. I too would check the timing I'm just wondering if I missed something.


i was leaning towards ignition timing since both cylinders were running too hot. The 180psi cylinder would be much hotter and melted. the 150psi cylinder was getting hot enough to cause scoring but not melting. Which is why both cylinders seem to be affected by the same thing.

also.. now that i am thinking about it. The cooling fan used to run nonstop. I fixed it and with a new temperature switch. It would turn on at 185 now. The first piston melted with the fan running constantly.... it took a couple hours of riding to do it (almost non stop riding). the second time it ran great for a couple of hours but it was cold out and the temp rarely got to 180. Before the final meltdown the Engine was idling for a while and got up to temperature. When it did melt the Engine was at 187 (the fan was running).

The only difference was that it sat idling for a while and the Engine was warmer.

someone on facebook said there could be an air leak at the crank seal too. I read up on it and confirmed that is also possible.


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