My good buddy Evan was in my son's FL350 and I was riding in my Fl350. We were at Little Sahara, Oklahoma pushing hard through the trails. I knew Evan's Ody is a little less torquey than my Ody through trails ,so I knew he was pushing his machine to keep up and doing a fine job, not far behind was Dennis in Ol Blue and bringing up the rear was a pack of old school three wheeler guys that glommed on to us sometime earlier in the day, good guys though. Then suddenly through my helmet intercom rings out "Houston we got a problem". Evans FL350 just lost power. Evans a seasoned atv rider, before the Ody lost power he told me than he was hearing a rattling noise coming from the rear of the machine. This particular Odyssey has been a reliable buggy so I thought he was hearing the flag post banging on the Odysseys frame as it will from time to time. I should have rode it to hear the noise for myself but that's hind sight now. Anyhow upon further investigation we found the motors output shaft locked up and could not pull the pull-start cord, of course the starter would not turn the motor (( Internal Combustion Engine ? )) over either. After a few tears I got out the tow line and hooked up my 350 to his. My machine was doing well pulling him in to camp until we came up on a 35 degree bowl, made it about 3/4 up the hill then "the little Engine that could" could not anymore. Dennis hooked up with Ol blue and pulled him into camp. THANKS DENNIS!!! Anyhow I have the exhaust pipe off and took a pic of the scarred piston. I havnt got any further yet.Heres a pic, more to come...

more pics. Rod bearing seized and caused scuffing? I dunno. Piston will not rock nor will it move up or down. More to come

Rod bearing seems ok and the crankshaft/output shaft will move freely now. The piston is stuck inside the cylinder. Now I have to figure out how to get it out.

hammer lube and another set of hands

No bfh there. Use lfh. I see no "poof" just "kabang". for a new top end the piston had a lot of scaffing even if it had 5 hrs on it. Try to save piston so you can mesure it up to see if the new top end was loose in the bore or if the bore was out of round or impropper bridge relief. I'll bet on all juddging from the pics. Sorry to see the damage hope you had fun anyway. The good news is your top end rebuild worked well on okc #2. Done post ride compressio test. You do have top end experience now. Good luck and keep on CSI ing.

Is it me or does that look like a sand siezure. Check intake boot for sand.

Used the bfh method and got the piston out. Intake boot had sand in it but I think it dropped in when I was removing the boot cause carb was clean and the boot had sand on the outside of it so i think it droppod into boot when I was removing it. Boot looked all out of round so Ill be replacing both intake boot and reed boot. I found that the exhaust bridge was not relieved ,nor were there any holes drilled in the piston for lubrication. Previous owner probably just did a quick top end rebuild. Heres some pics of jug and piston. The jug does not seem to have any deep gouges but Ill have to look at it closer.

ouch, its time for a new top end. What bore were you currently on?

Bummer man. Glad to see it did not take out rod. I hope the hyper speed indacaters had nothing to do with it. I bet when you done she will run like a champ. thaks for the CSI pics.

Yea... ouch happens right Not sure about bore yet. that's my next part of the investigation. Hey Adnoh I thought the hyper speed lights looked like a R2D2 Hey I will call that Ody R2 and mine D2, heh heh, how do I know if I need to bore. Should I let Phils try to hone and if they cant then bore?

The scarred Wiseco piston is a 533M08050 (80.5mm). I miced the bore which was also about 80.5 plus or minus .15mm. Should I do the releiving of the exhaust bridge or let Phil's cycle shop do this? Do I need to bevel the exhaust ports too. They looked like they were not beveled but the carbon build up might be covering the edges of the port. Ill do some searching here. There is a post on the home page for exhaust relief. I read it. It was a little everwelming but I might be able to make heads or tails. Also why did the piston get scarred and scraped at the side port?

stix

Glad to see that it was the top end and not the bottom as I had feared...

It sure was locked up tight...
Make sure you double check for air leaks once you get her back together...

Since it had been running for a good while before the seizure we know it was
not a warm up / Wiseco expansion issue.

Anyhow - good luck with the rebuild....

Dennis

piston

As bad as that seems, it certainly seems better than the whole bottom end you were worried it might be.

yeah, at least its not too bad, just a piston and a bore and you should be on your way again. I would get the exhaust bridge relieved for sure. looking at the piston I would guess that the port got hot and swelled causing the scoring on the piston.

Yea Jerry I was relieved. I was a LITTLE bummed when I left the dunes. But I should be runnin in no time. I found a guy here in OKC that specializes in old school Honda motors, so he will be doing the bore and bridge relief too Sunblock.

Try asking Hoser by chance?he may be willing to do the work perhaps?

Cylinder was bored for an 81mm piston. Bridge was relieved to about .007 from cylinder wall. I just need to drill the holes in the piston then put it all back together. Pin bearings will also be relaced, Ill install a mossbarger reed spacer too. I also cleaned up the castings in the transfer ports and intake, and took off some the "edge" from the exhaust manifold where is meets the cylinder. Barrel and camp was measured. See pics below.

pics

Looks good be sure to wash up good before assembly. Have'n fun yet. Post up some more pics as you go I enjoy viewing them.

I see lots of sharp edges that turn into oil scrapers.



http://www.pilotodyssey.com/PO/view ... m&start=24

Good thread, thanks hoser. Ill go back and look through it and "Hoserize" my cylinder as I see I left a few things out like transfer port roofs casting flaws, bottom of sleeve etc... I noticed you did a lot of "cleaning" and radiusing casting flaws, will this affect timing of flow?

Also see

viewtopic.php?t=3702&highlight=port+bevel

Exhaust Bridge Relief

http://pilotodyssey.com/ExhaustBridgeRelief.htm

Look at the bevel/chamfer work done on my exhaust port on my cylinder,pic number P1000454 , then look at Rick at MacDizz's TRX250R cylinder http://pilotodyssey.com/ExhaustBridgeRelief.htm or look at Hosers cylinder in the above pic. Looks like my mechanic that bored and honed my cylinder could have spent a little more time chamfering the top of the ports to a more flat surface rather than a bunch of divets as seen in my pic number P1000454 and P1000447 . This guy was highly recommended by two local bike shops as an "old school" Honda Engine rebuilder.This is the guy that "20 questioned" me when I told him to releive the exhaust bridge then thought I was crazy to drill holes in the piston. I went to three other shops, after talking with the service team at those places I knew right away I was going to get a bore and that's about it. After seeing that my guy really didnt pay much attn to the detail when chamfering the ports I will probably just send my next jug to Randy at Odyssey Salvage.