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125 stroker backfiring at top end.

Posted: Fri Mar 02, 2012 4:27 am
by arnada
any clues or suggestions would be greatly appreciated, thnx :)

Re: 125 stroker backfiring at top end.

Posted: Fri Mar 02, 2012 5:21 am
by kingkamehameha
Must be the signal fluid

Re: 125 stroker backfiring at top end.

Posted: Fri Mar 02, 2012 12:24 pm
by Bear45-70
I have never seen a WOT backfire NOT caused by being lean. To rich just makes the motor go flat.

Re: 125 stroker backfiring at top end.

Posted: Fri Mar 02, 2012 1:18 pm
by paulpauly7
Possibly 4 strokeing at max rpm

Re: 125 stroker backfiring at top end.

Posted: Fri Mar 02, 2012 1:24 pm
by bakaracer
What is the motor doing when it back fires? What does the temp gauge say? What does the plug look like? How fast are you going when its doing it? Are you at wot or closed throttle,partial throttle?

Re: 125 stroker backfiring at top end.

Posted: Sat Mar 03, 2012 5:32 am
by Dio89Elite
need more info, so that we can help with diagnosis.
I was thinking the same questions as bakaracer.
imo it's running lean. are you running any filter? what premix ratio are you running?
good way to find out is plug chops (what does the plug look like?)

Re: 125 stroker backfiring at top end.

Posted: Sat Mar 03, 2012 12:00 pm
by arnada
bike starts to sputter @ almost wot then backfires doing @ 60mph and temp @ 375. dont think im running lean wit a 175 main unless my carb is goin empty. was wonderin if it could be my petcock. also using a 62 pilot and uni filter. :)

Re: 125 stroker backfiring at top end.

Posted: Sat Mar 03, 2012 12:19 pm
by bakaracer
arnada wrote:bike starts to sputter @ almost wot then backfires doing @ 60mph and temp @ 375. dont think im running lean wit a 175 main unless my carb is goin empty. was wonderin if it could be my petcock. also using a 62 pilot and uni filter. :)
What kind of bike is this motor on? It could either be a leak somewhere or running out of gas. But more likely a leak due to the size jets your using.

Re: 125 stroker backfiring at top end.

Posted: Sun Mar 04, 2012 4:31 am
by arnada
wassup baka
you think a crankcase leak would do this or would it have to be an intake leak? been workin 12 hour shifts n mondays my next day off. itll be then that ill be able to look things over. ill probly take my intake apart first n check my reeds and put some sealant on the gaskets then test run. also check vacuum line and petcock. already changed carbs and last thing id wanna do is split the block and reseal with honda bond. peace! :)

Re: 125 stroker backfiring at top end.

Posted: Sun Mar 04, 2012 4:59 am
by kingkamehameha
Before you rip everything apart pressure test the motor

Re: 125 stroker backfiring at top end.

Posted: Sun Mar 04, 2012 12:32 pm
by bakaracer
arnada wrote:wassup baka
you think a crankcase leak would do this or would it have to be an intake leak? been workin 12 hour shifts n mondays my next day off. itll be then that ill be able to look things over. ill probly take my intake apart first n check my reeds and put some sealant on the gaskets then test run. also check vacuum line and petcock. already changed carbs and last thing id wanna do is split the block and reseal with honda bond. peace! :)
it could be a leak in the case. you need to check everything that leads into the case if you dont have a pressure tester. so crank seals, oil plug,case halves,gaskets,spark plug even check the carb spigot. make sure the fuel and vacuum hoses are tight.if air can seep between the nipple and hose, it can lean out too.

Re: 125 stroker backfiring at top end.

Posted: Sun Mar 04, 2012 5:02 pm
by CNI Dawg
Off Topic....
paulpauly7 wrote:Possibly 4 strokeing at max rpm
What is 4 stroking?

Re: 125 stroker backfiring at top end.

Posted: Sun Mar 04, 2012 8:02 pm
by Bear45-70
CNI Dawg wrote:Off Topic....
paulpauly7 wrote:Possibly 4 strokeing at max rpm
What is 4 stroking?
When the fuel mixture is so far off that the engine only fires on every other stroke.

Re: 125 stroker backfiring at top end.

Posted: Sun Mar 04, 2012 8:27 pm
by CNI Dawg
thanks

Re: 125 stroker backfiring at top end.

Posted: Sun Mar 11, 2012 12:15 am
by arnada
switched out the 28 carb with a 30 and used a 58 and 165 jets today and ran pretty good, guess my jets mustve been too big :)
thanks a lot guys with all the inputs!