High rpm problem
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Joined: Jan 2000
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From: Conyers, GA
RE: High rpm problem
Ya, the connectors to the intake manifold can get old and cracked and have leaks. Usually this causes problems all over but gets worse as you go into the higher rev range and does not get better. You said yours got better after a certain point. Loose header pipes could also cause the problem. That's an easy one to check out -- blow some smoke on the headers (on a stand not while riding 
) while keeping the rpms around 6K. If you gots a leak you'll find it quick. Another way is (while it's cold) block the exhaust with rags and crank her up. Rev it a bit. You should be able to hear the clickity click of valves really well if you have a leak.
) while keeping the rpms around 6K. If you gots a leak you'll find it quick. Another way is (while it's cold) block the exhaust with rags and crank her up. Rev it a bit. You should be able to hear the clickity click of valves really well if you have a leak.
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Joined: Jan 2006
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From: Sweden
RE: High rpm problem
ORIGINAL: MarkR
I put a post up ages about a problem with my bike when it get to about 7k-7.5k rpm's, once it get passed 8k - 8.5k, its fine.
I always suspected it to be a carbie issue, but could never get to the bottom of it.
It doesn’t happen all the time, but most. The bike will rev OK with the clutch in but while under any load, the bike would cough and splutter when the rpm's get into that range (7-8.5)
I have always used premium 98, but the other day, I used 95 plus Ethanol (95+E10), the bike now run heaps better, and even though the problem is still there, now it happens only about half the time.
Any thoughts on what in the carbies would cause such a phenomena
I put a post up ages about a problem with my bike when it get to about 7k-7.5k rpm's, once it get passed 8k - 8.5k, its fine.
I always suspected it to be a carbie issue, but could never get to the bottom of it.
It doesn’t happen all the time, but most. The bike will rev OK with the clutch in but while under any load, the bike would cough and splutter when the rpm's get into that range (7-8.5)
I have always used premium 98, but the other day, I used 95 plus Ethanol (95+E10), the bike now run heaps better, and even though the problem is still there, now it happens only about half the time.
Any thoughts on what in the carbies would cause such a phenomena
If the carbs are known to be clean, I would try to raise the carb needles a few millimeters to see if that helps. You could put a washer under the needle head (if they are not adjustable). You dont need to pull the carbs, just remove the carb top cover and lift up the diafragm/throttle unit.
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Joined: Jan 2006
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From: Sweden
RE: High rpm problem
ORIGINAL: MarkR
To remove the intake boots (engine side), do I have to remove the carbies
To remove the intake boots (engine side), do I have to remove the carbies
I think so, you will probably not acess the engine side hose clamp with carbs in place and the carbs must be pulled anyway to remove the boots, if that is your plan. Just for adjusting the needle hight, the carbs and boots can be in place.
Joined: May 2006
Posts: 388
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From: Gladstone, Queensland Australia
RE: High rpm problem
My girl a 1992 1000 HATES Premium Unleaded the plugs glaze up as is a real dog to start, but when I run standard Unleaded there isnt a problem the other weekend I did 600 Ks as she fired up easy as for work on Monday morning if I had used Premium at any stage it would have been a battle to start her.
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Senior Member
Joined: Aug 2005
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From: Gold Coast, Australia
RE: High rpm problem
I have 91 unleaded in it now, but mixed with a little bit of 95 and 98 from bottom of the tank,
Still think there something wrong and I am thinking it’s on the carbie side.
I tighten the boots up once before and I reckon it made a different to my problem
It's going to be a matter of elimination.
Hopefully this weekend, I will get some time to play. though I would check my exhaust headers and inlet boots
Still think there something wrong and I am thinking it’s on the carbie side.
I tighten the boots up once before and I reckon it made a different to my problem
It's going to be a matter of elimination.
Hopefully this weekend, I will get some time to play. though I would check my exhaust headers and inlet boots
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Senior Member
Joined: Aug 2005
Posts: 976
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From: Gold Coast, Australia
RE: High rpm problem
This problem is still there and has gotten worse.
I check the coils today, 3.2ohms on the primary and 25.8(left)/24.8(right) on the secondry
I can't do the other checks cause I need a 'Peak Voltage Adaptor' -- what is that, can I make one?
I also took the breather off the top of the carbies - no change; pulling the cabbies for a clean/inspection is next.
I check the coils today, 3.2ohms on the primary and 25.8(left)/24.8(right) on the secondry
I can't do the other checks cause I need a 'Peak Voltage Adaptor' -- what is that, can I make one?
I also took the breather off the top of the carbies - no change; pulling the cabbies for a clean/inspection is next.
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Joined: Jan 2006
Posts: 1,149
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From: Sweden
RE: High rpm problem
A peak voltage instrument can e.g. be an oscilloscope where you will se the voltage curve and peak values. In case theengine still hesitates on mid range, but runs fine at low and high rpm, the problemis air/fuel related.
