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hi speed fuel starvation

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:bonk: im beating my bains out with this one, every time I hit 4th gear powerband on my mc1 the damn thing dies of fuel starvation, replaced the bowl gasket, gave the petcock a thourogh clening, checked for air leaks in fuel line, and checked vents, all passed, so what is causing this!!!!!!!!! :smirk::bonk::banana::bonk::busted::bonk::awww:

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Dies of fuel starvation? You mean stalls out? That sounds more like the stator to me.

i eliminated it to a fuel issue, rode around till it died then immediately shut the fuel off, then pulled the bowl, dry as a bone, turned the fuel back on, good flow :bonk::foul::smirk::foul::banana:

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I would think you need to adjust your float to allow more fuel in at any given time. At fourth gear pinned you are using alot of fuel fast. Not enough getting into the bowl. Check for partially clogged/dirty petcock or filter screen in the tank also.

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Could be a sticky needle valve??? Some times a good carb service can work wonders.

Thats what im thinking. Sounds like your float valve is sticking shut. Have you taken the carb apart and looked it over?

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Thats what im thinking. Sounds like your float valve is sticking shut. Have you taken the carb apart and looked it over?

yes, checked needle valve for free movement, and check float heighth, all passed, didn't check the vent it the cap, cause the mc1's didn't have one

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Sounds like a plugged vent on the gas cap. As soon as it dies, take the cap off and see if it is instantly better.

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highspeed fuel starvation is generaly caused by one of two things. your main jet or..your main jet. lol the way i understand this you pilot jet controls your 0-1/4 throttle and your 1/4-3/4 throttle is controled by the needle hight. the 3/4-full throttle is controled by the main jet. how ever these do all effect eachother.

if your main jet is too lean it will be extremely lean at WOT but the entire range will be lean. if it is your main jet as you twist the throttle it will be increasingly lean and rise exponentialy throughout the entire range.

if it is your needle you will likely think that it is your main jet too lean but you will soon know by running the bike. increase your main jet by about 5. the bike will still run lean through out the entire range but at WOT it will run great or it will seem great until you hit WOT. then it will be too rich and run a little doggy at WOT if thats the case drop your main back to the original and try dropping the clip down one slot. this will lift your needle up higher in the carb making the part plugging the orfice smaller which will let more gas pass through.

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highspeed fuel starvation is generaly caused by one of two things. your main jet or..your main jet. lol the way i understand this you pilot jet controls your 0-1/4 throttle and your 1/4-3/4 throttle is controled by the needle hight. the 3/4-full throttle is controled by the main jet. how ever these do all effect eachother.

if your main jet is too lean it will be extremely lean at WOT but the entire range will be lean. if it is your main jet as you twist the throttle it will be increasingly lean and rise exponentialy throughout the entire range.

if it is your needle you will likely think that it is your main jet too lean but you will soon know by running the bike. increase your main jet by about 5. the bike will still run lean through out the entire range but at WOT it will run great or it will seem great until you hit WOT. then it will be too rich and run a little doggy at WOT if thats the case drop your main back to the original and try dropping the clip down one slot. this will lift your needle up higher in the carb making the part plugging the orfice smaller which will let more gas pass through.

I know for a fact its not jetting, its got stock jetting,

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stock jetting is never right!!! lol

its all depending on riding conditions. cold weather needs to be richer hot is leaner.

high altitude go leaner. low altitude go richer.

not to mention that any little mod you make to your motor, exhaust, or intake will have a dramatic effect on your jetting!

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Sounds like a plugged vent on the gas cap. As soon as it dies, take the cap off and see if it is instantly better.
well, it kinda solved its self, Idk how but it did!

There must be some way that air can enter the fuel tank to replace the area the gas was taking. Its either the fuel cap or there is a vent hose somewhere. One of them must have been plugged.

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found out the fuel cap has a hidden breather system in it, took it apart, the gasket had pushed itself into the hole, problem solved, thanks to those who tried to help, greatly appreciated!!! now lets ride!!!! :bonk:

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never thought of that. must be at high speeds the bike was consuming more fuel than than the amount of air being let in by the vent

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If this was a main jet or clip position problem it would do it in every gear and in neutral, doesnt sound like it to me. If your float height is good i would say its likely a vent problem, could be tank vent or your float bowl vent too, but probly tank vent.

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