The gear-driven pump on the intake plate.

Are you going to pre-mix or run the injector?

Well, a few people told me "run the injector" and a few people have told me "you don't need it - run pre-mix". After tearing the intake apart during the swap, I want to run it. Why? While the crank is turning, the rotary plate and the oil pump are ALWAYS rotating. I'm assuming the oil is not only lubricating the Engine via the pre-mix, but its also lubricating the rotary plate and its contact with the crankcase and the intake. And I know this pump works great, and its already set to run with this Engine & carb. Since I'm still not 100% sure I need it (more like 80%), I don't want to make any mounts for the oil tank permanent.

Found a SeaDoo box-type flame arrestor housing cheap from a guy in Michigan. This will allow me to clamp on a hose and run a filter/pre-filter wherever I want. Plus it makes the buggy forest-friendly. If I can get ahold of another high-flow / high-efficiency filter like I've got on my #1 buggy, I really won't need to run a pre-filter. But I'd really like to find/make a housing to run a FRAM CA8038 air filter. Plenty of media area for good flow and low restriction and performs at +98% initial & final efficiency. Oh...and I get them for FREE. I could also find an outer-wrap that would fit (for chunks/mud), or even hot-glue a foam-wrap for it.

Will have all weekend to work on the buggy and plan on having the Engine mounted, but will be tidying up my shop before I do anymore welding, cutting, or grinding.

The oil injection pump does not lube the rotary valve shaft bearings or gears. There is a sealed section in the crankcase that houses the gear drive and shaft in a bath of oil. It is plumbed to the oil reservior system as the low point so it is always full.
The gas/oil mix lubes the actually rotary valve plate whether you use injection or pre-mix.

To eliminate the injection pump you need to loop a hose from the bottom of the crankcase to the top to maintain this sealed oil bath.

Thanks Dave M - no one has explained it all before, only "yes, you can" or else "no, you can't". lol. It sure would be simpler running pre-mix!

So, by running the hose from the top to the bottom, the oil that's in there stays there? How often does that oil need changed?


On a different note, I ordered an 8-gal RJS fuel cell from Summit today. It should fit within the cage and will offer enough capacity to feed the twin cylinder Engine. It also has a lower sump section and anti-slosh foam. Now I can design/build around it since I know the dimensions. I dind't want anything holding me back this weekend. http://www.summitracing.com/parts/bob-1 ... atingmodel

Dave M hit it on the head, the rotary valve drive gear does not pump oil, so running a tank has no benifit on your motor (( Internal Combustion Engine ? )), because the injectiopn pump does not "pull" from the tank, its gravity fed. The pump is just pumping thru the small injection lines on the intake. The whole "heat sink" concept might work if the heat would travel thru the line to the tank, but since it dosn't pump the atvantage would be negligible. As far as pressure, its a sealed system not apart of the crankcase so pushing seals out won't happen. Not trying to be a Sh%&head just trying to help.

'Nuff said. Kiss the oil pump and tank goodbye. =) I'll make-up a block-off plate.

The coolant plumbing on the Engine and the rad/fan I'll be running will definitely be more than enough to keep this Engine's temps down. So I'm not worried about scavenging a tiny bit of heat-exchange out of the oil.

DaveM & JWHill...thank you for your help!

Wow in just a few words you completely un- engineered about 20 years of ROTAX's engineering of these engines and to think ROTAX was so stupid all these years to wastefully install a reservoir for the rotary valve drive gear, bearings and seals you should apply for a job with ROTAX you could save them millions.

don't be stupid run the reservoir that ROTAX engineered into the Engine its their for a reason and oil does circulate from the drive gear to and through the reservoir even though its not being pushed by a pump if their was no circulation the reservoir would not be warm after a short ride.

I change the oil in my drive reservoir once a year mainly because of all the heat cycles, heat cycles attract moisture since I am using my Engine and reservoir in temps above freezing where humidity is higher than its designed use no doubt its attracting more moisture.

My reservoir is also mounted at the same height as it was on the sled and uses the same length hoses to preserve the ROTAX engineering and ensure oil flow is per original design it would have been more convenient to relocate it elsewhere but I choose to preserve the factory design simply for reliability reasons..

I am finally starting to understand how all these years I have managed to avoid so many problems I see others suffer.

I also change the oil in my bath, just more often than you, about every 2 rides, and use ALOT less this way, so exsplain again how the oil circulates without a pump? I am not trying to "un-engineer" anything, I spoke with Harlan with harlans snowmobile parts who has been working with rotax engines for over 20 years and I took his advice, but I'm sure you would know more so I stand corrected. Your tank is probebly warm because of where it is not heat from the oil. Hoser, if I have wronged you in some way I apologize, that was not my intention, but I really don't understand the hostility from you directed at me.

Well, I'm gonna run the oil pump and tank. It's on there. Would be more work to remove. No more discussion needed.

Picked up a future upgrade Engine this morning. '91 SkiDoo Mach 1, 617 RAVE, twin cyl, Decker pipes, runs but I think has an air leak on mag side cylinder. Paid $100. lol

Now, onto hacking my buggy chassis...

I ASSume the oil circulates because of the heat by means of thermosiphon but it could also be circulating because of the motion of the gear spinning in the cases causes the oil to flow or a combination of both, I really don't care I know it circulates, I have seen these engines that had brass fragments in the reservoir because the gear went bad HOW THE HELL DID THE METAL MAKE IT TO THE RESERVOIR if oil does not circulate, magic brass maybe lmao why you think they spent the time and money to install a reservoir, if a resivour of oil was not required they would never have the extra oil made available, if it would not or could not circulate they would only need a single pipe and not a dual pipe system.

You have not wronged me your just not using common sense its your Engine do what you want remove the reservoir fill the hose with sand who cares I only care when you you use my site to give what I feel is really bad advice.

Removing the reservoir from your ROTAX Engine makes about as much sense as removing the cover off the rear differential on a automobile then installing foam blocks inside to consume volume so you can then use only 1/2 the gear oil in the rear axle, the mfg uses the volume inside the case as a reservoir and so the oil can carry away heat from the parts generating the heat.

I am pretty sure the oil dosn't get hot enough for thermosiphon to work because of its viscosity, and I know the spinning gear won't pump oil or you could see it. I will find out the temps for oil to use thermosiphon, have to do a little research.


Okay, this is the reason I don't run a tank, thanks for making my point, I don't trust a oil filter in this setup, because then you would be pumping this thru the injector , into the mix and into the Engine. If you don't run this it at worst would destroy the rotary shaft and associated bearings and seals. Why not just dump the "magic brass" into your mix and hope your filter gets it all. I don't have to worry about that since the brass gear is sealed in a separate compartment away from the rest of the Engine.


This is easy, the top pipe is the vent so the compartment can fill all the way up with oil. If you didn't have the top line there is a chance you could trap air in the compartment, this way it fills all the way up. And the extra oil was for the injection for the mix. I have not once said that you should not run oil in the rotary valve compartment.


Well I'm not sure where this came from as I run the same amount in the rotary valve compartment as you do, so it makes no sense unless you have a oil leak.


Could not agree more and that amount cannot change unless you change the inside of the case.

Saturday's progress...

Lookin good Money.

Spent some more time in the cold barn this morning working on the buggy.

Made up some cardstock templates for modified mounts, and cut them out on 3/16" luan. They lower the Engine 2.25" and move it back ~2" from where the original mount put my Engine. I may be able to move it backwards another 3/4" though (exhaust will need all the room it can get). And with the help of the ratchet straps, I got the Engine sitting where I want it. Only had to cut the middle section of the mag-side cage tubing to make room for the recoil starter. Never knew that stuff was double-walled, either! Giant TRA clutch is lined up with the driven clutch, and has enough clearance for removal while its in the Engine. There's enough room to get a belt on/off. Belt in the pics is too long. I'll need to find a couple shorter belt sizes in the same width to find the 'right' size.

Was hoping I wouldn't have to cut the cross-bar (for the FL air box and fuel-tank), but it will have to go. Need room for the air filter intake. I'm going to make a replacement cross-bar that's routed where I need it. I want to retain that stiffness in the rear of the chassis.

I'll either modify the Farr side-plates, or I need to go get a couple pieces of plate to make new ones.

Then I got crazy and started temporarily mounting parts with zip-ties to get an idea of where everything will go. Threw on the oil tank, radiator, overflow tank, and even threw the sled pipe on there to approximate the desired location of the pipe. Everything fits nice and there should be plenty of room for the fuel tank and air filter.

May head back out and tweak the side-plate prototypes and do more thinking...

Looking very good there.. might want to find that CVT belt that you are going to use before you go any further... I had trouble finding the right one for my conversion... I hope you get lucky with belts... I found that as I went shorter in length they also became too narrow for my primary clutch..
regards...

Ah, thank you for the tip!

Right now, I'm probably a couple belt sizes shorter than the Odyssey. But a quick look on evilBay shows there are all kinds of 1-3/16" v-drive belts slightly shorter than the stock 44-1/8" length. I'll get a sheave-to-sheave measurement and compare to the stock distance, but here's what I found on evilBay:

43.9", UniMatch 1922V433
43-5/8", Carlisle MAX1115M3
43-1/2", PU 46-0336
43-1/8", PU 46-0296
43", PU 46-0302
42-11/16", PU 46-0325
42.3", UniMatch 1922V417
41-1/2", PU LM743
41.4", UniMatch 1922V408
40-7/8", Carlisle MAX1121M2
40-3/4", Dayco GTS-718
39.6", UniMatch 1926V390
38.3", UniMatch 1930V375

...shouldn't be any smaller.

I'm pretty sure one of these will do the trick.

Looking good, that was the problem I seen with that prefabricated mount it just waste too much space I think in the long run you will be happy your modifying it.

I only want to build this rig once, so its getting done the right way. =)

Tore apart an old belt that was 43" long, and cut it down to what I think would be a good size as she sits = ~40". So that 39.6" belt would prob do the trick. But...I'm not close enough in progress to be ordering belts yet! Just good to know I didn't build myself into a bind.

47'F last night pushed shop-time to the top of the priority list.

Made some adjustments to the first Engine mount side plate re-do, and I've got her where I want her now. I could move it back even more (like 1.25"), but the oil pump is in the way and hits the right Engine/trans mount on the trans. And I think I'll be into the no-mans-land for belt selection if I go closer. So next step is to get the original plates modified.

Then I once again realized how big the new fuel tank is going to be (need to do more studying before buying, duh). It's big, but I want it to be big. I cut out a rectangle for the LxW. Then decided that Honda Civic radiator was too huge for this buggy. I threw on a Quadzilla radiator and a fan I had in my parts pile. I think I like it on the down-tubes at an angle. I know, it needs to be flipped so the plumbing points down (I got excited with the zip-ties). With this radiator and location, the fuel tank should fit along with the oil bottle, pipe, airbox, battery, and coolant overflow bottle all within the confines of the stock cage.

As for airbox, I saw what Odyknuck uses on his FL700 and I think that's a RZR/Rhino/Ranger air canister (takes a FRAM CA9248). I've got a line on a Kawasaki Mule filter canister that's a little smaller, and UNI makes a foam filter for it. Canister has an intake tube which would be routed to a pre-filter. Mule canister is for a 620cc Engine, too, so should be adequate for the 470 Engine. Hoping to located the air filter box above the recoil since I've got space over there.

I kinda' understand now why Farr build a "wall" around the recoil in his build -- not just for strength, but also because that recoil housing is designed to be under the hood of a sled, not next to a buggy tire! lol It has 'windows' around it and would allow water/mud/etc not only into the recoil, but to the flywheel and stator. I'll prob weld a strip of sheet around the OD of the recoil to close it in, plus make a gasket for where the recoil flange bolts to the block. And where there are drain/sight holes in the block, I'm going to put a vent tube or rubber plug.

Fuel tank and box-type flame-arrestor should arrive today. Stupid Presidents' Day delayed me.

Lastly, a MBN member sent me some pics of their ST3 buggy front spindles/hubs/heims...I might buy them. They're heavier-duty'er than any quad spindles/hubs I have. Just needs brake disks, calipers, and caliper stays. if cheap, will buy for my LT front end.

The 8-gal RJS fuel cell arrived from Summit, and as I realized after I ordered it, it's too big. Its already on its way back to Summit, lol. I'll get refunded for it, but lost $9.95 shipping. Ordered the 5-gal cell that's 13x13x8 and $10 cheaper. Call it a draw! lol Now I know this one will fit how/where I want.

Got a couple of pending offers/bids on small off-highway air intake housings. If I can't get one I want for under $40 shipped, I'm just going to make one to fit the FRAM CA8805 or CA9053 radial air filter (that CA9248 I mentioned earlier is WAY TOO SMALL). Can make it out of sheet or even 6"/8" PVC. I browsed our OEM air filter housing storage at work, but nothing really stood out. Automotive airboxes (and air filters) are often shaped funky b/c they're one of the last things designed to fit under the hood, so, no luck.

Arrestor arrived. It's got a 40mm opening on the bottom that mates to the carb, and a 3" hose/tube barb on the side. Will mount a tube from the 3" opening to the air filter housing. For this to fit, that cross bar is a GONE'R! I want to replace that cross-bar with a properly-located one for supporting the fuel tank. The backside of the arrestor box has a 1/4" hole that will get filled.

Gonna be 14'F tonight. Don't expect much progress the next few days!

New smaller RJS fuel cell arrived. This one will work.

Picked up a seat, foot tub, and some other misc stuff for her (see General BS).

And won a Kubota air cleaner assembly for $30 shipped on evilBay. Looks similar to the RZR/Ranger ones, but its steel.

Did some research on the air filter housing I got as well as the FRAM CAK530 air filter it takes. At first I freaked out thinking the 3.25" OD x 7" long air filter was going to be waaaay too small, and freaked some more after I read that Donaldson rated this filter at only 33 CFM (?!?!?).

But then, I remembered I was a filter engineer by trade and laid down some Filtration 101 math. ;)

CAK530 has 3.3 ft2 of media.
Use the ol' SAE J726 air flow formula and derive that the 467cc two-stroke Engine at say max 8k rpms will flow...92 CFM of air.
Face velocity (air flow per area of filter media) = 92 / 3.3 ==> 27.9 ft/min

That's actually pretty good! You want a lower FV for lower restriction, media durability, and long filter life (aka dust capacity).

Let's compare that the two most popular air filters in the USA: the CA8039 (Ford) and CA8755A (GM).

CA8039
Typical application:
Ford 4.6L N/A gasser will flow ~400 CFM at max rpm
Filter has 9.44 ft2 media
FV = 42.4 ft/min

Extreme Application:
Ford 4.6L Cobra (SC) will flow ~750 CFM at max rpm
Same filter
FV = 79.4 ft/min (which is a tad high IMO, and if I owned a Cobra I would be running a high performance air filter / intake)

CA8755A
Typical application:
Chevy 6.0L N/A gasser will flow ~500 CFM at max rpm
Filter has 23.2 ft2 media
FV = 21.6 ft/min

Extreme Application:
Chevy Duramax 6.6L diesel (TC & IC) will flow ~1350 CFM at max rpm
Same filter
FV = 58.2 ft/min

Therefore, the filter for the 467cc Rotax will be juuust fine.

Really nice thing about this filter is that its got a final efficiency (per ISO5011) of 99.9%. None of those K&N rock catchers will be lucky to be better than 90%. Initial efficiency is 97-98% (aka: how good a brand new filter filters air), whereas a K&N will have something more like 80-85%. Again, K&N is made to flow air and stop bugs from entering the intake on the clean paved track -- not for protecting your top-end & bearings for long term use!

So using this off-highway filter will not only flow fine, but will also offer serious protection for this Engine in any/all conditions. And TSC sells it (but I get them for free anyways).

Couple other important design factors:
#1. Make sure any/all upstream openings are larger than the carb ID.
#2. Make sure the pre-filter has as good or better flow than the primary filter. Generally, if you use a bigger filter you're okay.
#3. When you improve the flow of your 2-stroke's intake, do a plug chop and make sure your jetting is okay!


FYI...
FL350R 350cc two-stroke will flow 70 CFM at 8k rpm
FL400R 400cc two-stroke will flow 80 CFM at 8k rpm

Back to the Engine mounts...

Got the Farr mounts altered to where/how I wanted the Engine to sit. Again, nothing wrong with the Farr mount, just that I wanted to squeeze as much space as possible out of this Engine bay and with my downdraft carb setup. In the 1st pic you can see the before and after size comparison.

Got the alterations cut-out and welded. Only got pics of the tack-welded mounts, but the merged parts are fully welded and ground down, plus a coat of primer so they won't rust. Ran out of wire, so can't weld anything else tonight.

Put the Engine in and it is about ready for tacking the base plate in place. But wanted to add some of the other peripherals before I started welding. Bolted on the intake box, stock seat, and the y-pipe. Then started messing around with the skidoo pipe.

I'm very confident I will be able to make a few alterations to the pipe and y-pipe to make it fit behind the seat even with it slid all the way back (I'm 6'1'', all legs, and need the room). Right now, the y-pipe and 1st turn of the pipe fit in the space allowed, but its too close. And the "U" turn hangs about 2" below the frame. Planning to take 1" out of the y-pipe at the mount and adding about 6-10 deg angle. And the female end of the main pipe, I can cut it back about 1" as well. Then right after the 1st big "U", the pipe will get cut and turned. Lastly, I'll probably have to cut the back half of the main pipe and put a small wedge in to get it to point downward more in the right direction. No major changes in the tune of the pipe, really. Pipe mounts and spring hoops will get welded in last. BUT...no modifying exhuast plumbing until I have the mount plates, base plate, and 4 mount-tubes at least tacked in the right place. Still waiting on the 4th mount tube to arrive.