I went ridding last week and My Engine sounded like it had rocks in it. I shut it down and brought it home for some Fun CSI to see if indeed they were rocks. While I pulled the head and went UM.

This is what can happen over revving the Engine and not checking the piston more frequently. I just had to laugh as I tool it apart.

The piston is ( was ) an 80 mm arts ( oem). I think this piston had seen too many new rings and I missed the fracture or fractures oops. Good new not a lot of cylinder ,head or rod damage. I will no more upon disassemble. I swore the Engine was saying " no disassemble no". Darn Johnny 5 anyway.

So lets have some fun and do a few mods while I'm at it. Time to start making a PLAN using collected data.

Enjoy the ugly.

more fun pics

OUCH! any idea how many hours were on the piston ?

UT OH

Its amazing how well they run right up until the last second... Any idea how many hours on the piston?

That piston was installed in 5-24-2002 with right around 117 documented hours total. This jug and piston has had three sets of rings, Third set being the last.

Heres is what I have recorded in my file for this Engine:

5-24-2002 to 12-09-2004 = 32 hr at 138 lb's cranking compression
New crank,(A) piston,(A) jug ect 89 stock head un cut. Cylinder casting clean stock carb and boyseen reeds stock pipe.

12-09-2004 to 1-26-06 =28 hr at 135/174 lb's cranking compression
Note : In 5-10-05, reworked head and added v- force, torgue pipe and silencer and changed ex port. 171 cranking compression( cut head 180 then reshape and rework band and change exhaut port to a corrected CR)

1-26-06 to 6-22-10 = 57 hr at 174 lbs cranking compression.
Pre ride 0n 6-29-10 yielded 174 after rejet for lower alitude. Pre ride run was logged at 64.8 mph (Dirt road), max rpm 11010 at an Engine temp of 189 degrees withan ambient of 92 degrees. Changed 195 to a 200 and raised the needle from second to third position( lowered clip one raising the neddle) the alitude change was, House at 1255 to an ridding area of 900 to 1000. The post rock in the Engine data was 55.6 mph (sand flats), max rpm 13150 at Engine temp of 205 degrees with an ambient of 102 degrees( see pics) the ride time was 2:55.08 (2 hours,55 min and 8 seconds) 11 galons of gas ( 3.67 gal an hour). The importance of therejet, ride time and fuel will come in later in the discussionon the piston damage during the reading process of plug,piston and head.

It was due for a make over just thought I would get one more ride out of her. I now know that was using bad judgment.

With that many rpms I am guessing your CDI (Capacitor Discharge Ignition) has been modded? 64.8 mph on a gravel road? Doesn't seem much faster than mine, but I bet it gets there real quick like!!! I would like to see a gps unit on these vapor units to compare, because I seen randmans set up, and I wonder if these consider tire stretch when they are programmed???
looking forward to the rebiuild!!!

When my rings are worn out I replace the piston too... Pretty much once a year remove the top end for inspection then replace the piston and rings, how ever I have saved all them old pistons so when Honda stops making them I have a bunch of used I can run if needed, I need to start buying RINGS for them before they stop production.

Turbo, the max rpm is peak over rev rpms. If my pilot ran contionus at that rpm it would have blown up a lot sooner. The vapor loggs max rpm or peak. If you watch the vidoe of the short bust off you will see the waring and danger lights flicker upon accerlation. Sever thing contribute to this. I have the warning ( shift 1) set at 7800 and the danger ( shift 2) set at 8900. I have the water temp warning set at 210 and danger at 250. Your pilot is just faster than mine. Boo Hoo for me. I see what I can do though. As far as I know my CDI (Capacitor Discharge Ignition) does not have the rev delete. My analog tach read right around 7600 to 7800 but did not read over rev like the digital. I do believe the digatal reads quicker and is more sensitive. The thottle bleep eight to wide open burst and yielded a over rev of 10,500 with a pull of 7940 and and accerlation from 17.7 to 25.3 in that short burst. I do belive the over rev is caused by simple piston accerlation and lag time on the clutch and CDI (Capacitor Discharge Ignition). Once the clutch is hooked up and tire get traction it levles out. I'll repost the video for you to view incase you did not see it. I watch it in full screen and set the play back speed to slow. In the video I ran burst at reqular speed and then added screen shots of the video frame break down. The water high temp post ride showed 205 so the Engine was not running hot when it gernaded. I touch more on that later. When I set the vapor I used the instructions and then did high speed run to chek with the gps. It did vary + or - 2 mph durnig setting. I set in in a quarter mile run. I tried to use a gps and watch the vapor but the vapor speed changed more frenquently than the gps. The max speed on gps is waht was + or - compared to the vapor So I do belive it's set real close. I use it like a compression guage, once I set a base line using my tool and then log data the result are used against the base line for comparison. I wish it was wrong I wanted the faster pilot, dang it. Heck if I remember there is a lot of odyssey's that are faster than my pilot UHHHHH. Oh well it still fun.

"H" that is great advise. I just wanted to know how long it would run at the CR and pressures I was running. I used poor judgment when I decided to go againt the rule and not check before leaving town. I did do cranking test but did not do top end inspection since the hour meter was getting up there not to mention the years. I do belive there was a few helping factores to failure and will post on them later. I did clean up the cylinder a little tonight and even after the piston gernading in there the cylinder is not that bad. Nothing a bore cain't clean up. Pics later. So I now know the limits of stupidy.

Those 25's you have are pretty big Turbo (everything's big in Texas)! Those things trow quite a bit of small debris by the way. I am wondering what kind of tire stretch a factory 24 or a smaller 22 will expand to.

You would definitely need to put a GPS on to get an accurate reading at top speed to to tire stretch and wheel spin with my set up. The Vapor does not compensate for tire stretch. With the stretch of the rear tires the reading from the Vapor will actually be slightly less than the actual speed. I got 61.1 top speed on the all out run we made down Hudson Way. Top speed could actually be right on or just slightly slower due to rear tire spin. We may not have been achieving complete traction so the rears may be spinning faster than the fronts. Like I said you were kicking up small rocks in a steady stream about 1 foot off the ground even peaked out at full throttle.

I believe Adnoh has his speed sensor set up on the front wheel and not on the rear wheel like mine so his tire stretch should be at a minimum and he will get a true rolling speed. If he has the proper numbers entered into the Vapor his speed should be dead on. Due to tire spin mine will be slightly off but as I spoke of during my installation, my vapor is more for the water temp and hour meter. My speedometer is for bragging rights only!

Rand

You know Rand I could change the number in the vapor and get mine to run fast than Turbos. Then mine will be faster. Thanks for the idea. Flawed data but good bragging rights. Yes mine is on the front tire on the trx spindle and mag pick up in place of one of the disc bolts. I find the vapor to be a usfull tool just like a compression guage. How else would I have known the after market belt was slower and allowed more over revs and a higher rpm and less speed for the same clutch setting. It soulded faster but was slower. I know I will sell Tubo those belts and I then will be faster.

This discussion made me go look at my maximum rpm for the trip Turbo and I took and found out it only registered a maximum of 6850. I think I might have to do a little tweeking on the ole Vapor. I think it's a little low. I did check my top speed pacing beside someone else but I need to check it with my GPS. So far it works great as an hour meter and temp sensor but I need to get it set up so I can use all the functions it offers.

Rand

Well I cleaned up my cylinder a little to get some numbers. I already new it needed bored but thought I would go through the process for general discussion. I also wanted to see what the damage was and wear for hours.

This set of pics is the top view X and Y

This set is X and Y bottom view

Time to remove the studs

Now for some fun time to set up the bore guage for readings.

Missed one set at 3.150 then insert bore guage and zero. Sorry

Time to get pen and paper and spec sheet and start measuring.

Oh MY, does it get any worse. It didn'nt look that bad, did it.

Since I only have the old piston numbers to compare it to ( not much left of the inthe bike) It should be real interesting and why you do not run a piston this long

The service limit on the bore is 3.1507 see spec sheet pic.
Even with the largest piston OD on the "A" of 3.1469+ service limits of piston to wall .0059 =3.1528 it would run with the bore at it largest of 3.1520

The Out of round is another matter. Service limit 0f .0004 and the base line numbers was .0005 out of spec by .0001
Now if we take the min and max it not so close. Min# was Y-4 at 3.1505 and the Max# X-5 at 3.1520 now its out by .0011. How about that taper. Need to go back and check Y-4 again just does not look right.



While I beter mole over the info and put into the dcp peed sheet for comparison. I also have another cylinder with about the same time which I will clean up and check to see if the results are compariable in the wear areas.

Well had some time to take a closer look at the head, Yuck. So I cleaned it up a little and did some testing and mesureing for a .25 over rebuild of the 80 mm cylinder.

more pics

Nice detailed documentation thanks.

So you rebuilding or going to do an Engine swap for mo power?

more pics

"H" Good question, I think I will let the board decide. I will rework this Engine for a spare if new power plant goes in. I plan on testing this Engine with a thought I had a while back using a programer. Don't know yet to many choices. What would you like to see.

More pics of the cc and plug.

Ok looks like the New DCP head is at 49cc's with the combustion chamber at 29.5 cc's and will get entered in the DCP work sheet for CR of a .25 over arts set up. I will measure the crushed thickness of the head gaset to enter into the spreed sheet as well as the internal dia for for cc's Now lets take a look at the gernaded piston plug.

Plug pics. The plug measurd up a little lean still ok but I should have correted when I noticed it a little lean and running a touch warm. The Engine temp was ok just felt lean. One should always listen to the little voice in there head. A simple one more clip would have corrected the touch lean condition. This in part with other factores contributed to the destruction. It does show I had ring seal right up to the piston breaking.

Now I have the nw head data and teh gasket data It's time to collect some .25 data for the new Cr and any correcton that need to be done. What I did was take a .25 over cylinder and old piston and installed a copper wire in the ring grove to hold it in the cylinder and install a flat bar across the cylinder to put the crown of the piston at the top of the cylinder deck. Then I put a grease seal in the land area and measured the distance from the crown edge to the top of the cylinder deck. Now I can cc and calculate a piston crown vloume and use this information in the spreed sheet for CR.

Pics