4500RPM in top, then 'WHAT THE?'

Jungle · Post by **Jungle** » Thu Mar 01, 2007 10:31 am

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

meemo_meh · Post by **meemo_meh** » Thu Mar 01, 2007 10:35 am

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!

Jungle · Post by **Jungle** » Thu Mar 01, 2007 10:41 am

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!

meemo_meh · Post by **meemo_meh** » Thu Mar 01, 2007 10:51 am

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.

Greg · Post by **Greg** » Thu Mar 01, 2007 11:28 am

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

Waz · Post by **Waz** » Thu Mar 01, 2007 11:22 pm

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.

Jungle · Post by **Jungle** » Fri Mar 02, 2007 12:46 pm

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

steve speed · Post by **steve speed** » Fri Mar 02, 2007 12:53 pm

what pipes are you running?

Post by **Max** » Fri Mar 02, 2007 1:36 pm

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.

nukes · Post by **nukes** » Sat Mar 03, 2007 9:08 am

why walk away max, let rip and share the aroma with all.

[visions of your waiting room experience here!!!!!!!!!!!!]

Post by **Jak** » Sat Mar 03, 2007 11:44 am

Why am I always eating when I read your posts nukes

there goes breakfast

nukes · Post by **nukes** » Sun Mar 04, 2007 9:07 am

we aim to please jak

Jungle · Post by **Jungle** » Mon Mar 05, 2007 10:24 am

Wow,
My first post!

A few serious replies, and then!

JUNK MAIL!!!

Post by **Jak** » Mon Mar 05, 2007 10:50 am

sorry Jungle

Post by **Max** » Mon Mar 05, 2007 2:27 pm

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.