Throttle/Acceleration Problems

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crassius

Well-Known Member
Sep 30, 2012
4,032
158
63
USA
Throttle cable kept coming out here and where it does into the carb! Could that be a problem?
you should use the adjuster in that pic to give the cable less slack so it stays in the mounts

nothing looks horrible in the set of pics - if you grab the top of the motor & pull hard, does it move? - if so it needs to be tighter which may stop some vibration

maybe the float level could be raised a bit to see if that helps
 

JoshuaYoung

New Member
Dec 17, 2013
19
0
0
Moreno Valley
For the adjuster will I throw tighten the adjuster so it screws all the way into the throttle?
The engine is mounted on their very secure.
And how do I raise the float level?
 

GearNut

Active Member
Aug 19, 2009
5,104
11
38
San Diego, Kaliforgnia
To fix the cable issue you are experiencing, you want to make the outer housing longer in comparison to the inner wire. Turn the adjusters away from the carburetor top on the carburetor end and lengthen the other adjuster on the throttle hand grip. Tighten but do not crank down hard on the locking nuts to hold the adjusters in their new positions.
The threads can be damaged or the adjusters snap in half if the lock nuts are over tightened.

Rich and lean refer to the amount of fuel the carburetor adds to the incoming air.
Heavy or light ratio refers to the amount of oil you add to the gasoline to make the fuel.
If you added 2 ounces extra to the gasoline you have a heavy fuel mix.
Most all of the kit carburetors come from the factory tuned to run rich.
The good news here is your kit came with an NT carburetor, the easiest of them all to work on.
If your spark plug is black and dark it is a sign that the carburetor is tuned too rich. The spark plug color should be anywhere from a cardboard brown to a light chocolate brown color.
Lighter, nearly white color means too lean, not enough fuel. A too lean of a state of tune can do catastrophic damage in a very short time.
Care must be taken when tuning a carburetor to insure that the engine stays healthy. Do this by checking the color of the spark plug frequently while performing the tuning process. Never remove the spark plug while the engine is hot though. Doing so can ruin the threads inside the cylinder head.

Start be raising the clip on the slide needle to the second groove from the top. This will lower the needle further into the needle jet and reduce (lean out) the flow of fuel from just off idle to 3/4 throttle. If you still experience a rich condition past 3/4 throttle you will need to solder the fuel jet closed and drill a smaller fuel metering hole in it.

Just to keep things simple, remember that tuning is done by throttle position more so than engine speed.

Here is the greatest tutorial ever for your carburetor for learning what the parts are and how to care for them, shared for us all by Norman, Lord Vader.
In post #5 he shows the slide, jet needle, circlip.
http://motorbicycling.com/showthread.php?t=302
The whole post will help you out alot in properly tuning the carburetor, but does not cover all aspects of tuning.

If anything seems sketchy, do not hesitate to ask more questions.

Oh yeah, My what a large fuel filter you have there. At least you have it installed in the correct direction. Win!
 
Last edited:

CTripps

Active Member
Aug 22, 2011
1,310
1
38
Vancouver, B.C.
Also, your throttle cable could be secured a bit better. That sharp bend at the carb (and the slight kink just past it) will cause you response problems. Try to keep from having tight curves and loops in the cable, it'll bind up inside the sheath. I'd try to secure it to the crossbar above, so the cable goes straight up then makes a gentle 90° curve toward the handlebars.

(..and my 2¢ worth, get rid of the stock spark plug boot, swap out for a good one.. search the forums for how to and what to use)
 

GearNut

Active Member
Aug 19, 2009
5,104
11
38
San Diego, Kaliforgnia
So do you think lowering the needle in the carb will help my issue?
Absolutely! Tuning is necessary for any engine. Changing the clip position is a good start down the path of tuning, and could be all you need to do. You won't know until you start tuning it up.
Variables such as where you live (the altitude), gasoline quality available to you, and the preferences of your particular engine need to be addressed by tuning the carburetor. There is alot more you can do to increase the engine's performance, but let's just start with the basics first.

And what does the spark plug do in the affect of the bike performance?
The spark plug is responsible for igniting the fuel and air mixture.
The factory spark plugs are known for being cheap and unreliable.
The factory spark plug boot (the part that snaps onto the top of the spark plug)is known to fall apart all by itself.
Combining these two known faults it is wise to replace the spark plug with an NGK B6HS as well as replacing the spark plug boot and wire with a known good automotive one or a high performance one such as the one that Sick Bike Parts sells (used as an example).

Get them from where ever you can or support a vendor that supports this site and our hobby, it's your choice. :)

one page of SBP site that has lots of spark plugs

SBP spark plug wire
 

MotorBicycleRacing

Well-Known Member
Jul 28, 2010
5,844
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SoCal Baby!!!
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Okay so more gas was full inside the new carb . So I adjusted the clip on the leanest side! Should thAt stop the overflowing of gas?
No.
Moving the clip has nothing to do with it.
That is called flooding.
Either your float has a hole so it is filling up with gas causing it to be a "sink" :)
Or the needle valve shut off has debris which is allowing gas to keep flowing into the bowl.
 

BrokenVessel

New Member
Jun 11, 2018
18
0
1
40
Is your engine mounted solidly to the frame? You're not trying to use rubber or something soft in the engine mounts are you? That will cause more vibration and can result in fuel foaming. Extreme vibrations can cause the problems you're having.

Tom
I bought my bike already assembled and used and there is actually rubber square cut outs in between my engine and the frame... should I remove them?