MT runs forward on idle

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cub2000

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Boston, MA
Upon startup, the truck gradually moves forward without any throttle input. The throttle servo is not binding and at idle position, the throttle lever is at its lowest position. What are the usual suspects, the engine needles?

Thanks in advance.
 
Thanks for the input. This is a brand new clutch set with spring I've just put in. It had this issue before I replaced the clutch, and the problem is still there after I install a brand new clutch. Any other idea? Thanks.
 
I had the same problem.
Main culprit as Pablo said, a weak spring.
If you're on the 'normal' 6k spring, is your idle speed quite high?
You might need to check if it's binding on the clutch bell, from a weak spring, or poor alignment.
I just bought an option clutch, but 90+% of people here use the standard clutch, some with the 8k spring and say there's no problem at all. These are guys with years of experience.
Al.
 
If you have put in a new clutch & spring and still having the same problem it sounds to me like your idle screw needs tweaking. There are 3 screws on your carb, 1 marked 'H', 1 marked 'L' and a larger screw for the idle. This idle screw effectively adjusts the back stop for the throttle lever. Start the car up as it is & lift the back wheels off the ground (assuming 2wd !!) seeing as it is already trying to move off then tweak the idle screw until you hear the revs drop & the wheels will also stop turning. Note the position for reference before you make any adjustments just in case!! If you have a 6k spring fitted you should be looking for about 4k idle speed.
 
dwarfy, is the marked screw in the attach picture the "idle screw"? Turning it counter clockwise will lower the rev down, correct? Thanks.
 

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cub2000 said:
I bought this Zen clutch and a new FG clutch bell. Is it normal that a brand new Zenoah spring is weak out of the box?

http://www.davesmotors.com/s.nl/c.885035/n.1/it.A/id.2452/.f

I did double check and there's no binding on the clutch bell. I can turn the bell half way freely. After that there's resistence, but I think it's normal.

What else do I check, folks?
Click to expand...

You should be able to spin the bell freely all the way around with no resistance.

cub2000 said:
dwarfy, is the marked screw in the attach picture the "idle screw"? Turning it counter clockwise will lower the rev down, correct? Thanks.
Click to expand...

Yes.
 
id say its your idle screw mate, does it sound high revs when idle? Cuz if so it should just tick over nicely with hardly any rev.
 
Hey you guys rule. After starting the engine, I lifted up the rear wheels while they run wildly. I then kept on turning the idle screw counterclockwise when the rev was high to the point that the engine almost went to sleep, then I turned it back a bit higher. I think I have it at its best now.

Thank you so much.
 
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