Engine Reving- Clutch Engaged

S

Shredocity

New Member
Hello All,

So i have read several post focused on adjusting the idle control screw on the side of my 80cc 2 stroke carb. My idle, (not twisting the throttle while riding the bike, clutch disengaged) is great, however, when i engage my clutch to roll in nuetral (while at a stop) my engine revs really loud. Any ideas? Thanks much. A noobie.
 

Attachments

  • Cruiser.jpg
    Cruiser.jpg
    50.7 KB · Views: 696
You have an air leak somewhere between the carb and the cylinder. To find leaks I spray carb cleaner around the area and when the engine slows down or starts to die then I know I found the spot it is leaking at.
 
Thanks! this engine is brand new, ran less than 2 hours... ill check for leaks tomorrow, I was hoping it could be from my throttle cable being too taught. Appreciate the help!
 
That is possible too. It is difficult to troubleshoot something without seeing it for yourself. Usually when a motor revs hard seemingly all on its own it is an air leak. Often the carbs leak where they connect to the intake pipe. Myself and others use an O ring there to prevent that. SBP's sells the O rings. It is possible to have a leak at cylinder as well.
 
maybe you just need to turn your idle down some. with engine idling and clutch disengaged in your driveway turn screw counter clockwise until engine almost stops.

the screw is only for idling at a stop,not for riding,thats why it runs fine when riding and when you stop ,it idles high,adjust your idle lower.
 
Thanks guys, i'm still having an issue and my checked my carb and its connection, its sealed up tight. As for the exhaust im not positive, i will check tonight and get back to you.

As for the idle adjust screw... I'm frustrated to all ends with that thing, I have sat in my driveway, motor on, clutch engaged, (Motor Revving uncontrolably) and screwed that thing the entire way out till it fell in my hand and no adjustment to the idle was made.... Am i missing something here? I know this is basic small engine mechanics.. ive never been so stumped! Thanks all for the help!!!
 
take your air cleaner off and look inside at the throttle slide will it go completely closed?(it should) Then start screwing in the idle screw and watch the throttle slide . With the throttle slide all the way closed start screwing in the idle screw it should make the throttle slide start opening but only a tiny bit.
sometimes the throttle slide will bind causing a run away or high rpms . The cap on the carb if over tightened will cause the slide to stick.
Is you throttle cable tie wrapped to the frame or the handle bars? another cause of high rpms at idle. You need the cable to be able to move freely. move handle bars side to side and watch the throttle slide see if it moves.
Throttle cable too short not allowing throttle slide to go completely closed? need to redo the throttle cable by shortening the outer housing only or replacing the throttle cable.
this is just some of the things to look at.
The last item would be the twist grip when you open it up and let go of the throttle it should snap shut by itself. Paint on the handle bars will cause the twist grip to stick. Sand off the paint under the twist grip do not oil or grease that area either.
Let me know how its going.
Norman
 
You might check the cable housing at the carburetor. Mine sometimes jumps out of place and causes the engine to rev uncontrollably. Fixed it with some duct tape, wrapped arount the cable housing were it meets up with the carb.
 
Last edited:
hi norm -glenz here, hey, do you know where to get a pull start for an 80cc-jet? also,where do you get the aftermarket paper air filters? thanx. i've got the same revving problem with mine,seems like it started after i changed the fuel line to reg. auto line. i have a bear of a time trying to get a clamp on it at the carb. is a clamp really needed there?
 
Problem Solved!!! Thanks everyone for the suggestions. Turned out my throttle cable was too taught, had to shave the stopping block/point inside the twist grip to allow for more slack. I was able to diagnose this issue thanks to Norman's suggestion to take the air filter off and look at the throttle bodys position. When i looked i noticed it was suspended in a half open position (no wonder my idle adjust screw wasnt doing anything!!!) Once i allowed for more slack the throttle bottomed out inside the carb and i was able to actually use the idle adjust screw. Thanks agian i really appreciate it!
 
Last edited:
Glenz
I don't know where you would get the pull starter you might try looking at the vendors here on the side of the forum lot to look at same for the filters.
I still run the cheap vinyl fuel line and use .031 safety wire as hose clamps if the line leaks. I change out the line as it becomes brittle.
Norman
 
You must log in or register to reply here.
Back
Top