Jerking/ bucking at idle? By catrell92 (Read 1,210 times)

[catrell92]

I have a chrome storm 250 with te 244cc Honda clone motor, I've had this scoot since 2010 and man is this thing fast I've done a number of custom mods to it, uni filter/ main jet upgrading ect trunk lights, chopper handle bars. But for the life of me I can't figure out the problem when it's idling. It jerks and bucks but there isn't ANY hesitation or bogging in any part of the throttle band. I JUST put on a new intake and braced the crb with a custom hanger mount to prevent per-mature failure this time around. Valves are adjusted correctly. I bought a new carb back in early December to rule out that. I've removed the entire vacuum fuel peacock, just have gravity fed fuel line with filter, so manifold vacuum is right at the carb. I tightened all hoses clamps ect. I've been thought thick and thin with this thing but this issue comes and goes. Most people like. I did would initally think it's a intake leak but the intake is brand new and the intake o ring,! I have no cold start issues and the bike is started atleast 2-3 times a week since its cold, I go for a ride when it's warm out in these winter months, help me out please. It's like it's surging or something but it runs really good other than that! I've also adjusted the idle, bike doesn't have a tach so I don't know what it's exactly idling @

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[cruiser]

Welcome to the forum, catrell92. Once the engine is at full operating temp, set the idle speed so that the rear wheel is almost starting to spin when on the center stand. You may be setting the idle speed too low and since you don't have a tach, the above method is the only way to set the idle speed.

[Luke]

two words:
sea foam

[alleyoop]

If what you say jerking and bucking DO YOU MEAN the IDLE is going up and going down BOUNCEING?
If it is doing that it is LEAN.
Alleyoop

[catrell92]

Yup, I found a hose on my "new" carb that looked deteriorated from the cold, hard to explain but you know what I mean, if you bend a ac line and see rips in it, I put a new American good quality hose on, it's the hose that s under the air bypass hose it connects from the front of the carb to the bck on the throttle side, I haven't started it yet but I'll be going for a ride 2mrw because it's suppose to be in the 50s but yeah alley when I start it initally it idles normal, when it warms up it starts bucking violently which it's like the clutch engaging/ disengaging, it seemed. As if the mixture screw maybe any to no change at all but only if you turned it a great amount to the left or right, this is before what I've done tonight so 2mrw will tell

[alleyoop]

Yea, if after the ENRICHER(CHOKE) cuts off the extra fuel the IDLE starts bounceing Turn that Fuel Ratio Screw Counter Clockwise to feed it more fuel and the Idle should settle down. If it is idleing to high after the adjustment then lower the idle using the IDLE SPEED screw to stop the rear wheel from spinning.
Alleyoop

[imnts2]

I would start by checking for a leak in the intake. There are several ways. I like the propane torch best. With the engine idleing, turn a propane torch on without lighting it and move around the pipe and hoses and check for leaks. Engine speed will pick up if you find one.
If not leak, try turning the idle mixture screw out a bit. What you are describing is typical of a lean mixture.

cheers
Spring is on the way
lefty2

[Ernie]

Not sound like a parts replacer but when I had that same problem, I replaced the carburetor and that cured it.

I have the old new one if anybody would like to try to rebuild it, come and get it. Free to a good home.

Ernie

[speedracer]

Since you have found one cracked Chinese hose then you need to change every vacuum and fuel line hoses. You may need to take the carb out and clean it as it sounds like a partially blocked pilot jet.