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Hey, I have a 1985 Suzuki LT250R that I have recently rebuilt the engine on. It has recently had the cylinder bored 40 over to 71 mm and new rings and piston. I completely tore it all down and cleaned it. I am running it at a 32:1 fuel ratio. The spark plug is still good. It has a K&N Universal Coned Air Filter. I took it out for a ride and after about 30 mins of riding, it poped and blew white smoke out the airfilter and wanted to quit. Everytime I tried to rev it up it would pop and try to die. Then when we got it back to the shop I would start it up and let it idle and it would pur like it was brand new for about 30 secs to a minute then just abruptly die. The exhaust smelt different. The smell resembled the smell of starter fluid. (Of course it wasn't that. That was just a description of what it smelt like.) If anyone knows what could possibly be wrong or have any ideas, ur feedback is well appreciated. Thank you.
 

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I just put new Wiseco gaskets on so it shouldnt be doing that. Could it possibly be overheating? If so what should I do?
 

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1985-1986 Lt250r Genius
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What did the old plug look like?
 

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it wasnt a dark black as if it had fouled from too rich of a mixture, but it was by no means clean. Everything was still sharp...it wasn't rounded off
 

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flotek...... do u mean a compression test? no we did not do one. the compression was so bad before the rebuild that it was easy to tell that we had ALOT better compression.
 

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just put a new plug in today. the heat range wasnt exactly factory specs but it still ran the same way. i ran it for about 10 mins and it did the same thing with the poping in carb and missing out. pulled the plug and it wasnt burnt at all but there is still wet liquid on the seet of the plug. that was very dark like used motor oil.
 

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what is a leak down test and how do i preform it?
Testing your crankcase for leaks.
bad crank seals, base gasket, or actual case leakage will make your engine doo a variety of strange things

Do some thread searching as it has already been spelled out in detail (like how to build one

But simply:
Remove carb and exhaust
Plug exhaust opening on cylinder w/ expandable plug
Insert your "tester" into intake boot
your cylinder & crankase will now be isolated

charge with low PSI compressed air
watch the leakage rate



UHHH, this reminds me I have to do another one myself
 

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nevermind i found how to build it. but would it run fine for 10 minutes and then all of a sudden shit out like that? wouldnt it just not run right to begin with?
 

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if your plug is black and wet i would check the carb. whats the jetting set at? it could possibly be leaky needle and seat or too high floats. seems like it just loads up on fuel and floods out from what i am reading. start simple and work your way deeper into the job.
 

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i have a 45 pilot and 210 main. have a KN filter and a after market pipe... carb is good. plug is not black good tan color. but there is some liquid residual left around the seat of the plug (where the plug seals on the head) also some on the back of the ground tab on the plug.
 

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ok took the head and jug off. what i found was that everything inside was very sticky, im guessing that this is caused by the gas/oil mixture mixing with the coolant. between the head gasket and the cylinder there was a black sticky substance towards the front. (same substance that was found on the seat of the plug.) does not smell like fuel. crank and connecting rod also have a very clear runny liquid coating it. not think like oil should be. inside wrist pin there was a large amount of the thick black sticky liquid built up. could this be the coolant mixing with fuel? we did not use any kindof sealant on either of the top end gaskets. should we have?
 

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the 3rd pic is what was between the head and the cylinder.
the 4th pic is what was inside the wrist pin
the 5th shows a small rectangular cavity that is full of coolant which from what i can tell it shouldnt be.
the 6th pic shows the connecting rod and crank. i know u cant see much but everything appears to be very wet. (not oily wet either)
 
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