gofast5 Posted June 29, 2010 Report Share Posted June 29, 2010 So I had a set of cylinders laying around a guy gave me he put this bike together with a brand new topend and everything and put a bad crank in it and what do you know the one side lost compression but the cylinder seemed fine other then 2 scratches I could feel with my finger nail but nothing serious. So I go over to a neighbors house I bought my original shee from and what do you know he has the exact matching piston still in good condition and gave it to me. So I slap it all together thinking what the heck if it runs it runs. I start it and ride around some both sides are showing about 110psi which I know is a little low. After riding it for a little I take it through a field and it stalls 2 or 3 times the thing wont start for a damn even when warm so a buddy pulls me and I bump start it and start to head down the road to the house and baaaaaaaa all power gone. Its locked up well fun while it lasted we pull it into the garage and my friend sits their trying to kick it and slowly but hardly it turns over so he pours a drop of amsoil dominator in the plug holes and turns it over a few times and what do you know it turns over fine and still has compression and everything. We start it up and ride it some more but still doesnt start for a damn even when hot and sometimes when you start to kick it, it gets real stiff like its locking up again but after you push it through the stroke its absoloutley fine and will bump no problem??? My last bike only had 90 psi but it would atleast start without bumping it. I figure im just going to run it until it dies and when It does ill start all fresh new bore and everything. Quote Link to comment Share on other sites More sharing options...
ItOnlyTakes2Strokes Posted June 29, 2010 Report Share Posted June 29, 2010 (edited) sounds like it is already blown. Diddo... Edited June 29, 2010 by ItOnlyTakes2Strokes Quote Link to comment Share on other sites More sharing options...
#1JUANstunna Posted June 29, 2010 Report Share Posted June 29, 2010 It's FUCKED! Time for a rebuild with brand new parts this time. Quote Link to comment Share on other sites More sharing options...
gofast5 Posted June 29, 2010 Author Report Share Posted June 29, 2010 You would figure its blown but if you bump it it starts right up and runs great till i broke the kicker gear atleast. Quote Link to comment Share on other sites More sharing options...
RagunCajun Posted June 29, 2010 Report Share Posted June 29, 2010 You might wanna rebuild and figure out why it messed up. If a piston goes to pieces your gonna have to split the cases to get the metal out. Quote Link to comment Share on other sites More sharing options...
90lxsleeper Posted June 29, 2010 Report Share Posted June 29, 2010 im a lil confused on how you explained everything but....correct me if im wrong doesnt cast and forged pistons hae different wall tolerences? Quote Link to comment Share on other sites More sharing options...
gofast5 Posted June 30, 2010 Author Report Share Posted June 30, 2010 Yes they do but theyre identical pistons. I rode the bike an hour it locked up. I tryed to turn it over and it was stuck and locked good. I tryed hard to kick it over and it gave all the sudden and still had compression so we put a little oil directly into the cylinders and turned it over to lube everything well and then bumped it and it ran fine. I rode it bout an hour today like this but now it only wants to bump start even with 110 psi. Doesnt matter if its hot or cold. Quote Link to comment Share on other sites More sharing options...
gofast5 Posted June 30, 2010 Author Report Share Posted June 30, 2010 You might wanna rebuild and figure out why it messed up. If a piston goes to pieces your gonna have to split the cases to get the metal out. Ya luckily I have 2 spare sets of cases but still i'd rather not screw them up if the piston chunks. The kicker gear ended up going out of it or something and you like cant kick it and then it started having shift problems so looks like this motors going for a complete rebuild from the ground up some day. Quote Link to comment Share on other sites More sharing options...
RagunCajun Posted June 30, 2010 Report Share Posted June 30, 2010 Good luck. I know splitting cases Is never something we look forward to Quote Link to comment Share on other sites More sharing options...
gofast5 Posted June 30, 2010 Author Report Share Posted June 30, 2010 Good luck. I know splitting cases Is never something we look forward to Ya me either. How do you like your 4 mill. I've been talking to denny how was his work? Quote Link to comment Share on other sites More sharing options...
AKheathen Posted July 1, 2010 Report Share Posted July 1, 2010 sounds like you probably have an airleak, or pluged up carbs, if compression isn't the issue, but there is probable cause to tear into the clutch cover right away. start with a leak-down and inspect the pistons. how were the rings and ring lands? they weren't used rings were they? you should have also at least honed. Quote Link to comment Share on other sites More sharing options...
buster48116 Posted July 1, 2010 Report Share Posted July 1, 2010 it sounds like a bad crank bearing you cant kick it fastenough to get it to fire but bump starting will then it locks up when its warm def sounds like a crank bearing Quote Link to comment Share on other sites More sharing options...
gofast5 Posted July 2, 2010 Author Report Share Posted July 2, 2010 Well I took the jugs off topends fine. Something was in my bottem end it looks like theres big scrape marks in the case like something was rubbing in it as the crank spun. Quote Link to comment Share on other sites More sharing options...
gofast5 Posted July 2, 2010 Author Report Share Posted July 2, 2010 sounds like you probably have an airleak, or pluged up carbs, if compression isn't the issue, but there is probable cause to tear into the clutch cover right away. start with a leak-down and inspect the pistons. how were the rings and ring lands? they weren't used rings were they? you should have also at least honed. The pistons and jugs were lightly used no more then 5 hours on each. I was told not to hone it do to it will break the seat the rings are used to. Quote Link to comment Share on other sites More sharing options...
AKheathen Posted July 3, 2010 Report Share Posted July 3, 2010 The pistons and jugs were lightly used no more then 5 hours on each. I was told not to hone it do to it will break the seat the rings are used to. hmm, makes me wonder if it was broke in properly. if not, there could be binding. and are you certain the rings/pistons went back in the same jugs?. just a thought- are you warming it up before you go ride hard? Quote Link to comment Share on other sites More sharing options...
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