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4500RPM in top, then 'WHAT THE?'
Posted: Thu Mar 01, 2007 10:31 am
by Jungle
Howdy, All,
Thought I'd throw ya's a curly one, just to see what ideas surface!
Top gear crusing and just getting to 4500RPM @120kmph and I get a very noticeable, constant but not regular severe misfire! If I continue to wind on the throttle and get to the 4800 - 5000RPM range it smooths out. TPS is set @ 4000
It's givving me the S^%ts! Been chasing it for weeks now.
Can anyone assist?
Cheers, Jungle
](./images/smilies/eusa_wall.gif "Brick wall")
Posted: Thu Mar 01, 2007 10:35 am
by meemo_meh
Is it just backfiring out of one exhaust? Other halfs TRX had the same problem @ 2800RPM, ended up being due to the left exhaust collapsing internally (urgently needed a re-packing). Got that re-done and also the other side and so far no problems! touchwood!
Posted: Thu Mar 01, 2007 10:41 am
by Jungle
Hi, Meemo_meh,
No, it's as if the ignition or fuel suddenly cut out. A complete dead hesitation and then back to life, but just at a very limited rev range (aroun 4500) I would suspect an electrical connection fault if it didn't disappear when I increase revs. Same with fuel but ya would expect it to continue if it was a fuel problem.
Got me stumped!
Posted: Thu Mar 01, 2007 10:51 am
by meemo_meh
Hmm, bugger! yeah just thought I'd mention it anyhoo, it is amazing how much your engine suffers when the air movement through the engine is no longer what is required. Is it only in top gear? or does it happen in other gears too? Aaah dear how frustrating for you! Best of luck.
Posted: Thu Mar 01, 2007 11:28 am
by Greg
My first thought would be with a carb blockage, gos it doesn't take much gunk t0 f@ck things up. Don't forget that fuel flow at smaller throttle openings are controlled by the pilot jet, then progressively by the needle then the main jet... Does it misfire at that RPM in all gears or just top?? Is it only at those 300 RPM it suffers??
G
Posted: Thu Mar 01, 2007 11:22 pm
by Waz
Just clutching at straws here, but have you checked the side stand cut out switch? The vib frequency at that RPM may play with the switch contact if the contact is marginal.
Posted: Fri Mar 02, 2007 12:46 pm
by Jungle
Guys,
It's good to see some one thinking 'OUTSIDE THE BOX', Waz! Good call!
Greg, your on the button! A quick dyno run showed a lean condition at transition between needle/and full main jet!
It turned out to be aggrivated by after market pipes causing exhaust gas 'REVERSION' at the problem RPM
Good advertisment for a dyno
Posted: Fri Mar 02, 2007 12:53 pm
by steve speed
what pipes are you running?
Posted: Fri Mar 02, 2007 1:36 pm
by Max
I used to have exhaust gas reversion problems. But now that I'm older and wiser, I just walk away from the crowd and let it rip.
Posted: Sat Mar 03, 2007 9:08 am
by nukes
why walk away max, let rip and share the aroma with all.
[visions of your waiting room experience here!!!!!!!!!!!!]
Posted: Sat Mar 03, 2007 11:44 am
by Jak
Why am I always eating when I read your posts nukes
there goes breakfast
Posted: Sun Mar 04, 2007 9:07 am
by nukes
we aim to please jak
Posted: Mon Mar 05, 2007 10:24 am
by Jungle
Wow,
My first post!
A few serious replies, and then!
JUNK MAIL!!!
Posted: Mon Mar 05, 2007 10:50 am
by Jak
sorry Jungle
Posted: Mon Mar 05, 2007 2:27 pm
by Max
Sorry Jungle, I figured you got it sorted... If you want, I'll delete the "Junk Mail".
We (well some of us) like to have a little fun around here at times. I suppose it can quickly get out of hand though.