Topic: acceleration stumble need help

[Broseph]

Hey folks,

Got my bike running but am coming in to a few problems. Hoping there is some one here that can help.

details on bike:

4 into 1 aftermarket exhaust
pod filters (yea i know)
slow jet 40
main jet 115
air screw out 1 1/2 turns
electronic ignition which have recently been set
brand new coils

I had 120 main jets in but pulled my plugs to find them totally black so have gone down to 115
The bike starts up and idles perfectly but after a few minutes of driving my the bike starts to stumble and has no get up and go. Anything over a crawl causes the bike to stumble. once I get the bike up to about 60km/h it starts to smooth out.
Any ideas?

[flybox1]

When was the last 3000mi maintenance items completed, including a vacuum sync of the carbs?
"Get up and go" usually means mixture screw,pilot, and needle jets at work to get you going.
Your 120 might have been OK, but leave the 115 in there for now and work on tuning the A/F mixture at idle, first.
Ride your bike, get it hot, and put in a new set of D8EA plugs.  Start it and let it idle, with a fan on the engine, for 4-5 minutes.
No blipping of the throttle, no reving.  When done, pull the plugs and take ONE picture of the tips of all four plugs lined up 1-2-3-4.
Post it here.

[Broseph]

thanks for the reply flybox1,

I have yet to do a 3000mi maintenance as the engine has been rebuild recently and I have yet to put on that many km. Just been out for test runs. I have yet to vacuum sync the carbs, I have a sync tool on its way. When syncing the carbs with vacuum gauges is there a specific number it should be hitting or is more so to make sure that all are at the same number. Over the next few days Ill follow your advice and post up some photos

Thanks again

[flybox1]

Cool.  If they are gauges, calibrate them first, please.
Pick one carb, and attach each one to it one at a time, and adjust so they all read the same value.
Just make all the carbs the same vacuum level.   The NUMBER on the gauges is basically irrelevant.

[BomberMann650]

Yeah 700504 and I got a chuckle out of the service manual sync guage illustration.  It showed 25psi being the "normal range" 

Flybox is right about the numbers game.

Tho we did try to get as much "suck" thru the intakes as we could.

[alacrity]

Cool.  If they are gauges, calibrate them first, please.
Pick one carb, and attach each one to it one at a time, and adjust so they all read the same value.
Just make all the carbs the same vacuum level.   The NUMBER on the gauges is basically irrelevant.

I beg to differ.  The NUMBER on the gauges is completely irrelevant.

[flybox1]

You're completely correct