Here is a picture with the tappet removed:


Will do.

 

Could be, but I double checked and made sure everything lined up good with Marcelinos post. Only thing I didn't do was the ACR portion of it.

 

I'm not buying into the cam mods.This is a DS bike, not a orange bike! If you want a racing bike, buy one!

 

Yeah, when I figure out what's wrong with my bike I'm going to go ahead and reset the cam back to normal. Whether or not this problem was caused by the cam mod is yet to be determined. I have made a lot of mistakes from day one with modding this bike, so my word/experience isn't one to base your decision on. Hopefully there isn't any major damage done. But the cam mod is definitely going bye bye.

 

Hmm... well hopefully you just had the collet fail allowing the retainer to pop up and lose compression.

thats about the best case scenario i can think of looking at the pictures. As in the post above you need to take the head off and see if theres any carnage down inside the cylinder.

Crossing fingers for you.

 

OK just thinking aloud here...so to speak..

By adjusting the cams you are changing when the valves open and close in relation to the PISTON

SO, if a 351cc big bore kit is a higher compression piston (12.5:1?!?) does that not mean the piston is taller and/or has less valve relief?

 

I'm going to take a look. Never heard anything like a collet failing. The bike only had 5,000 miles on it when I got it.

 

I don't know, man. There are lots of mods to engines of all types and brands that do not affect reliability to any real degree yet still produce decent power gains. Remember this is an engine in a street legal dual sport that has to meet emissions and sound requirements. It's choked up and stopped up in several areas ranging from the airbox, carb, and exhaust. No, it will never be a KTM or Kawasaki KLX450R by any means, but who wants a plugged up POS?

Without having seen the assembly for the 351 or the cam timing mod, I can't be sure. However, a mistimed cam will usually result in failure the first time the engine is rotated. Now, he could have the cams in such a position that it wouldn't have been evident until a high rpm run, but he's been running this engine for a little bit. Only a teardown is going to answer this.

 

Bill says compression of the 351 is 12 to one. The valve is the exhaust valve that the compression release works on. I think piston hit the valve causing it to break and letting the lifter go up.

Can you LIFT the spring out of the head with out pulling anything else? If so, the valve would be in the cylinder. I am guessing half the valve. IF this is true, then its a train wreck.

I hope I am wrong.

David

 

I'm in the process of tearing it down right now. I hope it's something noticeable, I'll take some pics along the way and see what I find. Chances are, it's a mistake caused by me. The combination of higher compression from the 351 and the cam mod could also be a factor. This didn't just happen putting around, I was in the middle of running it through the gears. So I was at higher RPMS when it happened. But I've been running it hard like this for about 2 days now with no problems. No over heating or anything.