sredish Posted November 19, 2007 Report Share Posted November 19, 2007 Yep. Came out of the woods, hit the throttle pretty hard and after about 100 yards, grrrrr sound then it died. buddy behind me said it was puffing white a little when i got on it and then right before it died, one good puff of white. So, it appears that the exh. valves wanted to get a little closer / more intimate with the piston and were successful. I'm assuming that the right (brake side) valve hit first with how the seat, spring and all were raised up and loose. The right front tower bolt was loose, sitting in the head like it jammed the threads out. That picture of the piston was exactly how it looked when I pulled the head. So, now here I am with a screwed head, and in need of a new cylinder, piston and I'm going to replace the crank as well.... full rebuild. This thing was running sooooo good to, in the neighborhood of 58hp and it was a fairly fresh build. I clayed the piston 4 or 5 times with good numbers, tight but okay. The cam is a pretty high lift, long duration cam and the piston is a 14.25:1. Just sucks, I went from a killer build to nothing; starting totally over. Quote Link to comment Share on other sites More sharing options...
RIPRuck Posted November 19, 2007 Report Share Posted November 19, 2007 Damn thats ugly!! Sucks it happed.. GL on the rebuild. btw did you get my pm from yesterday? Quote Link to comment Share on other sites More sharing options...
sredish Posted November 19, 2007 Author Report Share Posted November 19, 2007 Sho Nuff and you gots a reply. Quote Link to comment Share on other sites More sharing options...
Coupelx Posted November 19, 2007 Report Share Posted November 19, 2007 what did your piston to vavle clearance look like when you put it together? Quote Link to comment Share on other sites More sharing options...
LiftdT4R Posted November 19, 2007 Report Share Posted November 19, 2007 What are these valves you speak of??? :woot: Looks shitty. I'm guessing that most of the new 450s are interference engines? (Valves come lower then the top of the piston during the stroke). I've only worked on non-intereference 4 strokes, so if you don't adjust the valves right, you get the tick and a loss of performace, but no mishaps. Quote Link to comment Share on other sites More sharing options...
spike Posted November 19, 2007 Report Share Posted November 19, 2007 damn that sucks! shoulda got a Yamaha!! Quote Link to comment Share on other sites More sharing options...
sredish Posted November 20, 2007 Author Report Share Posted November 20, 2007 clearances were on the tight end but satisfactory. time on the springs... well, they've been on there since I first started running that head, a while now. this is a bad case of valve float. just a horrible demise of a killer running head. the piston crank and all is nio big deal, I can handle it but losing that head really pisses me off. Quote Link to comment Share on other sites More sharing options...
PhilMoore Posted November 20, 2007 Report Share Posted November 20, 2007 That is freakin disgusting. Our chevy motorhome had a similar incident. One of the keepers let go or something, and the exhaust valve boinked the piston. It bent the stem, and jammed it up in the guide, so it didn't cause a major problem, except that cylinder quit running. I just took a vice grip and gave the stem an extra kink to make SURE it wouldn't fall into the cylinder. We put 2200 miles on it running on seven cylinders. Made it back home, had the head rebuilt, and she has been good to go ever since. Pretty tough to make it home with a one cylinder quad that is not running on one cylinder though. Quote Link to comment Share on other sites More sharing options...
inthemail Posted November 20, 2007 Report Share Posted November 20, 2007 goddamn 4 strokes look nasty when they fubar...... shit deal man i have another buddy who just did sorta the same thing to his honda. 'cept the piston flew loose....... Quote Link to comment Share on other sites More sharing options...
NYUK Posted November 20, 2007 Report Share Posted November 20, 2007 that`s why i like 2 strokes. them damn thumpers are too unreliable. break down to much. lol. :biggrin: Quote Link to comment Share on other sites More sharing options...
EastCoast Banshee Posted November 20, 2007 Report Share Posted November 20, 2007 sure does suck man. good luck getting it fixed. also reminds me why i like 2 strokes. :biggrin: Quote Link to comment Share on other sites More sharing options...
sredish Posted November 20, 2007 Author Report Share Posted November 20, 2007 you can fuck a 2 stroke up to... but not as many moving parts... that's what I get for running that big of a cam with that tight of clearances and not keeping a very very close eye on my valve springs.... i had $1,200 in that head and it was a serious power producer.... the crank, cylinder and piston I'm getting ready to replace don't bother me at all, what scares me is putting together another head. i've decided this time I'm going to go with a +3 stroker crank that'll give me 480cc's, the same displacement I was running except all bore. it'll cost me roughly the same cost, I'll have a strong crank, with the same displacement as before, similar power and if/when I want more, it'll be much simpler with a simple bore/piston change. long ways to go from here tho. Quote Link to comment Share on other sites More sharing options...
sredish Posted December 4, 2007 Author Report Share Posted December 4, 2007 Pictures of the cylinder, think I can hone out the imperfections?? Quote Link to comment Share on other sites More sharing options...
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