TOPIC:

In general the engine goes really well now.
I have had one issue left, but I only provoke it on high speed (more the the limit in Norway) and inn deep hill..,

4 or 5th gear
6-7RPM
Approx. 50% throotle

If I give 70-100% throotle the bike start to accelerate and at the same time the problem disapear. Also If give lees Throotle so the RPM goes down some 4-5 the issue disapear.

If it was eletrical issue I should feel it when I acc. From 0 to Redline?

If something is unclear let me know!

What exactly is it doing?

Huh?

If you open the throttle the motorcycle will accelerate, if you close the throttle the motorcycle will decelerate.
Please describe your problem if you have one.

Sounds like your engine runs under lean condition. Whats your carb Setup?

hehe sorry for my English

It`s start to "cheat" not going even and pull constant force....

810 big bore kit

Carb VM24:
Pilot: 17,5
Main: 112,5
Needle: 4`th posistion (the clips is not on the highest point but second).

VM 24's on 650's and VM26's on 900's are standard. At 810 your probably at the upper limit of useful size with VM 24's. A bigger engine needs more air and 24mm diameter can only let so much air through them that's why bigger engines have bigger carbs.

Warren3200gt wrote: VM 24's on 650's and VM26's on 900's are standard. At 810 your probably at the upper limit of useful size with VM 24's. A bigger engine needs more air and 24mm diameter can only let so much air through them that's why bigger engines have bigger carbs.

I know my engine have "bigger" potensial when it comes to HP, but I think it`s to easy to conclude the symptom I have is related to restricted air flow. Its only in these range I have problem under or over its fine....

Its not only related to the throotle posistion, its the RPM range together with the throotle posistion.

High speed or deep hill, so you can setup the scenario where I have 6-7 RPM and around 50% throotle, maybe some more, 50-60% but not more... all scenario without these is working perfect.

Example 3-4 RPM 0-100% throotle works fine... example or 7-8 rpm with 30% throttle works fine....

what happens at 7 - 8k rpm at 100% throttle?
Lets say for arguments sake that 1k rpm = 1 cubic litre of air consumtion.
At 3-4 k rpm you are drawing into the engine 3 -4 litres of air through a hole which is 24mm
At 7-8 k rpm at 30% throttle you are drawing in 2.4 litres of air through a hole which is 24mm. So quite similar air consumption.
At 7-8 k rpm at 100% throttle you are TRYING to draw in 7 - 8 litres of air through a hole which is 24mm. ie twice as much.
Air has a specific density at a specific altitude and can only pass through a hole of a certain size at its maximum velocity which is why I asked whats happening at 7 - 8k rpm at 100% .

I suspect you can't draw enough air.

Then use the same argument for fuel. it can only draw fuel through a hole (Jet) at a certain rate. If you try to draw more air than can be supplied or more fuel than can be supplied one of three things will happen. The mixture will become too lean and it will run like shit at high revs or it will become too rich and do the same. Which of those two is happening will depend on which has the restriction air or fuel. The third thing that could happen is fuel and air are BOTH restricted which means it will bog down until the revs drop to a level where the supply is sufficient.

The way manufacturers counter act these affects is bigger jets if its a fuel deficiency or bigger carbs if its an air deficiency.

There are other factors involved but in lay mans terms those are the basics.

Warren3200gt wrote: what happens at 7 - 8k rpm at 100% throttle?
Lets say for arguments sake that 1k rpm = 1 cubic litre of air consumtion.
At 3-4 k rpm you are drawing into the engine 3 -4 litres of air through a hole which is 24mm
At 7-8 k rpm at 30% throttle you are drawing in 2.4 litres of air through a hole which is 24mm. So quite similar air consumption.
At 7-8 k rpm at 100% throttle you are TRYING to draw in 7 - 8 litres of air through a hole which is 24mm. ie twice as much.
Air has a specific density at a specific altitude and can only pass through a hole of a certain size at its maximum velocity which is why I asked whats happening at 7 - 8k rpm at 100% .

I suspect you can't draw enough air.

Then use the same argument for fuel. it can only draw fuel through a hole (Jet) at a certain rate. If you try to draw more air than can be supplied or more fuel than can be supplied one of three things will happen. The mixture will become too lean and it will run like shit at high revs or it will become too rich and do the same. Which of those two is happening will depend on which has the restriction air or fuel. The third thing that could happen is fuel and air are BOTH restricted which means it will bog down until the revs drop to a level where the supply is sufficient.

The way manufacturers counter act these affects is bigger jets if its a fuel deficiency or bigger carbs if its an air deficiency.

There are other factors involved but in lay mans terms those are the basics.

I have 7-8k RPM and have around 50% throttle (problem is present), if I give more and more throotle the bike start accelerate more and more and at the same time the issue disapear.

If I go direct from 50% to 100% the bike fly away without any issue in acceleration… hehe

Was that accurate information, or do I misunderstand something?

If I give full throttle 100% in all gear and push it to the red line in all gear, there is no issue under acceleration.

Okay, I think I have misunderstood your issue.
So, if Im reading your last post correctly
zero to 100% throttle in one QUICK action = no problem.
50% to 100% throttle in one QUICK action = no problem.
Zero to 50% throttle SLOWLY = no problem
50% to 100% throttle SLOWLY = problem.

If my reading of your issue description is accurate I can't think of anything carb related which would cause that.

The only thing I can think of which could cause that is a sticky ignition timing advancer. They work by centrifugal force. If it was "sticky" around 60 or 70% of the rev range it would cause the the timing to be retarded at that point. As the revs increased so would the centrifugal force to a point where it forced the sprung weights beyond the "sticky" point and then the ignition timing would be correct again. This "sticky" patch may not be evident when the throttle is opened quickly as the weights would have momentum to help them past the "sticky" patch.
You wouldn't notice it on deceleration because the cylinder firing at the correct time on deceleration is irrelevant.

Warren3200gt wrote: Okay, I think I have misunderstood your issue.
So, if Im reading your last post correctly
zero to 100% throttle in one QUICK action = no problem.
50% to 100% throttle in one QUICK action = no problem.
Zero to 50% throttle SLOWLY = no problem
50% to 100% throttle SLOWLY = problem.

If my reading of your issue description is accurate I can't think of anything carb related which would cause that.

The only thing I can think of which could cause that is a sticky ignition timing advancer. They work by centrifugal force. If it was "sticky" around 60 or 70% of the rev range it would cause the the timing to be retarded at that point. As the revs increased so would the centrifugal force to a point where it forced the sprung weights beyond the "sticky" point and then the ignition timing would be correct again.
You wouldn't notice it on deceleration because the cylinder firing at the correct time on deceleration is irrelevant.

Thank you, I will check up the timing advancer and report back.