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thanks guys......also, being as the left cylinder is gouged really bad, would it be better to get another cylinder/jug and bore it to the size of pistons i have (obviously replacing the one that has shrapnel in it. im not sure how far you can bore a cylinder on these motors, is the only reason i ask, being as mine is already 1.5 over

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If you need a new cylinder, you might want to check out the Serval cylinders. You will need a new set of pistons. 66.5mm is the max you can bore stock cylinders, and both need to be the same. There's no point in buying one cylinder, and boring it to the max, from the start, just so it matches the bore of the other cylinder. Replace both cylinders, pistons, and so on. The cheap way now, will cost you a lot more, in the long run.

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If you need a new cylinder, you might want to check out the Serval cylinders. You will need a new set of pistons. 66.5mm is the max you can bore stock cylinders, and both need to be the same. There's no point in buying one cylinder, and boring it to the max, from the start, just so it matches the bore of the other cylinder. Replace both cylinders, pistons, and so on. The cheap way now, will cost you a lot more, in the long run.

i havent heard of the serval cylinders...what exactly are they, and why should i look into them? kinda sucks i have to rebuild the entire top end now, but oh well, it woulda been fun to ride it as a 375cc. so are you reccomending i start out with fresh standard jugs/pistons and go from there???

 

EDIT: just looked up serval cylinders on ebay. i dont have a grand just to throw at the top end. or maybe you could correct me on what im looking for

Edited by SteveCZ28
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looks like lower crank bearing blew out those look like big end pins floating around on top.

 

cranks trashed. with that much shit floating around its weakend the bearings for sure. i see this happen a lot on older motors the top end gets replaced and the crank lets go soon after the increased comp makes it rough on the already weak from age crankshaft and it goes kabloie.

the dieseling and overreving you let it do was also hard as hell on the motor. it was so lean it was detoing on its own that why even after you killed the spark it still ran continuing to try adn get it to run with a bad airleak, and probably totally plugged up carbs and possibly bad assembly may have also caused the crank bearings to nuke.

 

your gonna need a complete motor, probably cylinders, pistons, head and crankshaft, seals gaskets etc and whatever else you find in there thats screwed. if your that lost on it i'd really suggest you take it to someone to fix it OR sell it and buy one with a good documented motor and is already running.

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looks like lower crank bearing blew out those look like big end pins floating around on top.

 

cranks trashed. with that much shit floating around its weakend the bearings for sure. i see this happen a lot on older motors the top end gets replaced and the crank lets go soon after the increased comp makes it rough on the already weak from age crankshaft and it goes kabloie.

the dieseling and overreving you let it do was also hard as hell on the motor. it was so lean it was detoing on its own that why even after you killed the spark it still ran continuing to try adn get it to run with a bad airleak, and probably totally plugged up carbs and possibly bad assembly may have also caused the crank bearings to nuke.

 

your gonna need a complete motor, probably cylinders, pistons, head and crankshaft, seals gaskets etc and whatever else you find in there thats screwed. if your that lost on it i'd really suggest you take it to someone to fix it OR sell it and buy one with a good documented motor and is already running.

they arent pins in the piston. their thin and flat, like chunks of piston ring. but i do hope its not the crank ike you say it is...i completly tore apart both carbs, and thei both clean. not a spot of dirt in any of them. i pulled all the jets out and you can see lite thru them all.

it would do the dieseling, oand high revving on its own. it would often do it right off idle. i would hit the kill switch and it would keep going until i would pull the choke completly out and it would kill it then.

 

how much is it to rebuild the crank, and start fresh on it?? i knew i would need the top end but wasnt planning on doing the bottom end. im good with 2 strokes, but have never dug into the bottom ends before. but thats not stopping me tho from figuring it out

Edited by SteveCZ28
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Get a Clymers manual, keep eye out for parts on here. Trying to figure out who to trust is the hardest part. Ive seen used cranks go for 100, new start at about 350. Seen used jugs& pistons pretty cheap also. Just keep eye out and be ready to jump cause good shit don't last long banghead:cheers:

well i tore my bottom end down today. to my surprise, the crank is still good, not a spec of metal chunks/shavings in bottom end at all. although the left outter seal was good, but the right outter seal had a few cracks and look like it had spun a few times as it looked worn, but not horrible. bearings are good in the crank, and bearing seats in the case are good on both upper and lower cases.

 

but after doing some reading, im not going to use my stock crank, even though it still feels good and has no noticable movement in the rod bearings, im gonna do it right and get a wiseco, or hot rod crank, and then do a fresh top end on this, as i dont wanna put it together with a stock crank and tear it all back down again

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well i tore my bottom end down today. to my surprise, the crank is still good, not a spec of metal chunks/shavings in bottom end at all. although the left outter seal was good, but the right outter seal had a few cracks and look like it had spun a few times as it looked worn, but not horrible. bearings are good in the crank, and bearing seats in the case are good on both upper and lower cases.

 

but after doing some reading, im not going to use my stock crank, even though it still feels good and has no noticable movement in the rod bearings, im gonna do it right and get a wiseco, or hot rod crank, and then do a fresh top end on this, as i dont wanna put it together with a stock crank and tear it all back down again

 

 

Now i dont know for sure if i am correct, but i was told that the stock cranks true better than the aftermarket cranks. with that being said, you could probably send out your stock crank and have it rebuilt, trued and welded for cheaper than buying a new crank. You could even throw a set of long rods while you are at it.

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i havent heard of the serval cylinders...what exactly are they, and why should i look into them? kinda sucks i have to rebuild the entire top end now, but oh well, it woulda been fun to ride it as a 375cc. so are you reccomending i start out with fresh standard jugs/pistons and go from there???

 

EDIT: just looked up serval cylinders on ebay. i dont have a grand just to throw at the top end. or maybe you could correct me on what im looking for

let me tell you i have a 421 serval and its more than enough for playing around it has alot of bottom end and it still pulls hard off the top

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well i tore my bottom end down today. to my surprise, the crank is still good, not a spec of metal chunks/shavings in bottom end at all. although the left outter seal was good, but the right outter seal had a few cracks and look like it had spun a few times as it looked worn, but not horrible. bearings are good in the crank, and bearing seats in the case are good on both upper and lower cases.

 

but after doing some reading, im not going to use my stock crank, even though it still feels good and has no noticable movement in the rod bearings, im gonna do it right and get a wiseco, or hot rod crank, and then do a fresh top end on this, as i dont wanna put it together with a stock crank and tear it all back down again

if you buy the serval you better get the 4 mil setup cuz if you buy the regular serval and want a little more itll cost you alot to set it up for a 4 mil crank

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