high rev start

P

pigdestroyer

New Member
hello :) after repairing some stuff on my bike and when i went to try, it started but like it was full throttle. it did a little wheelie and the chain snapped out. i barely touched the throttle when starting it, just that tiny stroke to get the engine running. i changed the intake manifold and got a more open air filter for the carb, i think that could have something to do. maybe airleaks? idk
does anyone have an idea of what could be? i dont feel like starting it again before doing some adjustment to fix the issue.
i have the nt speed carb and the eclip is at the center slot if that's relevant
 
Sounds like a vacume leak to me, check your gaskets and mainly your intake gaskets and carb seals might need to be on tighter than expected
 
Check the slide in the carb to make sure it is closing all the way, since you've had it apart the cable could be binding.
 
Testname111 said:
Sounds like a vacume leak to me, check your gaskets and mainly your intake gaskets and carb seals might need to be on tighter than expected
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ive read you can try for leaks on the intake with starting liquid do you have any tips on this? im not 100% sure how to do it. also i have carb cleaner not starting fluid does it work too?
 
High reving idle is caused by a leak in the intake system, head gasket will not cause it. Carb to intake, intake to cylinder and the base gasket are common leak points. You have a crank seal on both sides, the one behind the magnet is thinner and is usually the one that fails.
 
Testname111 said:
Id just lightly sand clean the old gaskets and replace them for the intake, Maby use a copper head gasket?
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it's the yd100 so no head gasket

Greg58 said:
High reving idle is caused by a leak in the intake system, head gasket will not cause it. Carb to intake, intake to cylinder and the base gasket are common leak points. You have a crank seal on both sides, the one behind the magnet is thinner and is usually the one that fails.
Click to expand...

do you know how to find where's the intake leak? and yeah im suspicious about my base gasket last time i checked it looked ok but the material was kinda low quality so ill replace it asap
 
First remove the air filter and watch the slide as you twist the throttle, it should travel to almost closed. The carb should have a oring to seal again the intake, hold pressure on the carb while tightening the carb down. A leak at the intake to cylinder or base gasket should be wet with fuel.
 
Here’s a couple of pictures of a nt carb with the brass slide and a Bofang carb with the black slide. Both are set at idle height.
 

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pigdestroyer said:
it's the yd100 so no head gasket



do you know how to find where's the intake leak? and yeah im suspicious about my base gasket last time i checked it looked ok but the material was kinda low quality so ill replace it asap
Click to expand...
I made a copper intake gasket with a dremal and have had no more random revs
 
Greg58 said:
First remove the air filter and watch the slide as you twist the throttle, it should travel to almost closed. The carb should have a oring to seal again the intake, hold pressure on the carb while tightening the carb down. A leak at the intake to cylinder or base gasket should be wet with fuel.
Click to expand...

i think i found the leak. i went to check and my base gasket now looks wet and dark lol.
the carb has its oring and yes i tightened it while applying pressure against the oring of course. honestly the intake looks fine but since the base gasket is damaged im replacing both intake and base gasket. thank you for your help bro
 
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