125 stroker backfiring at top end.

[arnada]

any clues or suggestions would be greatly appreciated, thnx

[kingkamehameha]

Must be the signal fluid

[Bear45-70]

I have never seen a WOT backfire NOT caused by being lean. To rich just makes the motor go flat.

[paulpauly7]

Possibly 4 strokeing at max rpm

[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?

[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?)

[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.

[bakaracer]

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.

[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!

[kingkamehameha]

Before you rip everything apart pressure test the motor

[bakaracer]

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.

[CNI Dawg]

Off Topic....

Possibly 4 strokeing at max rpm

What is 4 stroking?

[Bear45-70]

Off Topic....

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.

[CNI Dawg]

thanks

[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!