Flat spot / Misfire below 3-4000rpm ?????

bullitt · Post by **bullitt** » Sun Jan 25, 2015 11:48 am

Howdy Folks,
I've a 1000 RU Streetfighter that rev's freely stationary but when driving off it stutters like a misfire then clears over 3-4000 rpm & rev's clean..

The exup is wired open & servo is still plugged in..

I've ran 1000's with the same set up before with no prob's....

Any idea's people??????

Post by **nuggitt** » Sun Jan 25, 2015 12:17 pm

To me that sounds like your tubes have worn. Replace them and you'll be back to normal.

Stig does a group buy every now and again at good prices.

undeadhairy · Post by **undeadhairy** » Sun Jan 25, 2015 2:21 pm

Could be a coil starting to break down. Mine was like that till I changed them

Post by **Stig** » Sun Jan 25, 2015 2:38 pm

if the servo is wired open it'll affect the back pressure when it should in fact be closed at low revs....wont help the spluttering issue

markg · Post by **markg** » Sun Jan 25, 2015 4:05 pm

Sounds like classic fully open EXUP syndrome

Mine was seized at one time but in the open position and was horrible below 4000 rpm

yzfpaul · Post by **yzfpaul** » Mon Jan 26, 2015 9:18 pm

remember checking costs nowt

emulsion tubes you can see when oval that check costs nowt

checking the coils costs nowt

did it run ok before, with the exup wired open or is this a problem that

has recently occured ?

maybe you have a leaky carb boot - we'll worry about that if the first two

things check out ok