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Main Area => General GS500 Discussion => Topic started by: Rema1000 on August 19, 2005, 03:26:10 PM

Title: flat spot at 6k rpm
Post by: Rema1000 on August 19, 2005, 03:26:10 PM
I had been having problems with the bike killing at idle, so I reamed-out the pilot jets, I now have a major flat spot just under 6k RPM.

It's mostly noticabe in 6th, once in a blue moon in 5th, and never in 4th or below.  If I'm on the highway at (say) 5500rpm, and just slightly add throttle, sometimes the bike will bog; today, it even chugged once, like it does when you're running out of gas.  If I hold steady throttle once it bogs, it just keeps bogging, slowing down.  If I roll-on harder, then it spins-up again and starts to accelerate.

Very odd.  Think I might put in fresh pilot jets, just to start with a clean slate.  These have been drilled-out a couple of times.
Title: flat spot at 6k rpm
Post by: davipu on August 19, 2005, 03:49:38 PM
interesting, you thing it may have anything to do with your choice of fuel?
Title: flat spot at 6k rpm
Post by: scratch on August 19, 2005, 05:05:14 PM
Shim up the needle.
Title: flat spot at 6k rpm
Post by: Rema1000 on August 19, 2005, 05:44:24 PM
Yes, the fuel could have something to do with it: because the jets are oversized by 40% an 30%, but the needle is stock.   It's always had a bit of a flat spot at 6k, but since I reopened the pilots and sync'ed recently, it got much worse.  

I thought that the needle shimming mostly helped richness "off the line", not when doing mild acceleration at 55mph in 6th.
Title: flat spot at 6k rpm
Post by: mjm on August 20, 2005, 09:16:00 AM
[quote="Rema1000"I thought that the needle shimming mostly helped richness "off the line", not when doing mild acceleration at 55mph in 6th.[/quote]

Raising the needle richens the mixture as the slide rises out of the emulsion tube - almost no effect just off idle - it mainly has an effect on the transition from part to full throttle,