Topic: I think I lost oil pressure...

[fmctm1sw]

What at a disappointment.  I spent every weekend for about a month and a half getting this old TRX running.  Someone had put a Wiseco high compression 1 over piston in it (it went from 8.5 to 10.25 IIRC).  I got it running great and I dragged all my ATVs up here to north GA for some riding and it looks like it overheated.  It ran perfectly most of the day and suddenly lost power.  I also heard a clacking sound.  The differential makes some noise so I was about 50/50 on whether it as the motor or the differential.

I towed it back to the trail head and about 20 minutes later it started right up.  Against better judgement, I went back riding it and it did it again.  Towed out again...  I looked at it and it looks like the Hondabond I used to seal the cylinder head cover was melted.  I pretty much let it go at that point but I did start it and ride it onto the trailer.  It makes a clacking sound that reminds me of the sound my GL650 made when my tappet adjusters worked loose and fell out (only worse, like "oh sh*t something is definitely wrong here" worse.  So now I'm down to my three wheeler to get around and it's slightly treacherous with the whole "balloon tire suspension" scheme.

I won't know what happened until I get it back home and get the top end apart.  The plug looked ok, a slight black ring around the bottom and a clear electrode and insulator. 

Some theories I have:

- My cooling fan (it has an oil cooler) always seemed to have a mind of its own.  It's possible that the cooling fan acted up and caused it to overheat.  We did tackle some pretty gnarly hills but it wasn't even 80 degrees.  I checked the oil, it had oil in it.  Perhaps when excess heat melted the hondabond, oil passages somewhere got clogged?

- When I bought a cam chain tensioner, I saw an ebay auction for a "modified" tensioner.  According to the ad, these TRXs could jump time due to issues with the tensioner (especially when ridden hard).  Hard riding and a high compression piston?  hmmmm

Anyway, I know these "engine disaster" threads are popular.  I won't be able to do anything until I get back to my garage but I'll try to post whatever damage I can find.  Sucks...  I was plowing up steep inclines in 3rd gear on this thing.

I know.... pictures or it never happened....

[links56]

Did you re jet it after the bigger piston install? Maybe it is running lean and getting too hot. Maybe the thing skipped time anyway. either way it sounds like something is way out of adjustment on the valves if its clacking around pretty good. could have jumped time and bent the rocker arm. pull the valve cover and see what it looks like. Make sure you post some pics.

[fmctm1sw]

And on that note, I ended up blowing a tire on my 3 wheeler that day.

Now for the diagnosis:  My head and cam are ruined.  Looks like I lost oil pressure.  Piston and valves looked alright.  I got it listed on CL as parts, I don't really want to go back through this motor right now...

[links56]

Ouch...That's not a good sight. A machine shop should be able to put a bearing in the head, Then you only have to buy a new aftermarket cam. They will grind the bearing surface bigger then put a 2 piece bearing in it so it will be a new surface for the cam. last time I did it it cost 30 bucks.