Good point FN, but 4k rpm is towards midrange. Could be that the charge of the plugs/wires/alternator cannot handle the load.

 

Tuning an engine is isn't easy. In the days when we had points and condensers, I used to either tune my engine for either forfast acceleration, or economy of fuel. When it was set up for speed it never was happy when cruising and used to backfire when throttling down
I don't know if your running with a power commander, but I have been told that those can help.
Si

 

I have finally figured it out. Six months later and after listening to every possible expanation for what it could be. It was the PILOT JETS, the god damn pilot jets needed to be drilled out just one size bigger and bam, this thing runs like perfect now, at all rpms. I should also mention that I added a dynatech computer and removed the stock one and that alone made a huge difference. It was $400 but worth every penny. Six advance and six retard curves and fully programmable using a laptop interface. Anyway, thanks to everyone who replied. Time for a ride.

 

You added the dynatech before or after getting larger pilot jets?

 

I added the Dynatech before drilling out the pilots.

 

I would not mind more info on the history then. Would the dynatech solve the issue you had or was it just the pilot jet issue.

 

Mario66, can you give me a web address for Dynatech - I've looked for them but can't find them, and they're a make I've not heard of in the uk..... I'd be interested in having a look though...

 

Not bagging but why does it seem that people always forget to check and clean the pilot jets. Why! Everyone wants to clean the mains that are only really open when you are at higher RPM's.

Glad you got her figured out and I guess it is lesson learned, Clean the pilots too!

Ha, I should talk though I think I remember learning the same way after removing, re-cleaning and re-installing carbs 10 times

 

NS, thought he drilled out the pilots one size bigger? And added the Dynatech.

 

Yes he did but if he or others had started with the pilot jets the problem would have been solved much quicker.

I personally would have gone up in size instead of drilling the pilots jets also, can't imagine drilling to be very precise unless your doing it at a machine shop. Jets or pretty cheap by themselves.

I too have made this mistake to where I am removing and cleaning and paying more attention to the mains and then after the 5th removal finding that it was a couple of the pilot jets that were dirty and clogged. Cleaned them and all was good.

Like I said, not bagging on him and glad it got worked out but I see this a lot and 90% of the time it is clogged pilot jets. So don't forget to check the Pilot Jets!

What color are you going to paint that glass on your bike?