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Strange Throttle Behavior


KarTek

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Guys, I don't typically let the engine idle but recently, I've been idling a little to warm it up before riding. The idle seems too low and the engine stalls so I went to the TORS boxes to ramp it up a bit (TORS is going away soon). Strange thing is that the idle adjustments had no effect. I could turn them several turns in and out and no change to the speed.

 

I finally gave up and returned the screws to their original position. This makes me have to blip the throttle frequently to keep it running. I feel like this thing should be able to idle by itself. The engine has a fresh rebuild and it starts instantly and runs great.

 

Anyway, the other odd thing is that while idling low - maybe 900 RPM or less, if I touch the throttle, literally touch it like just lay my finger on it, the RPM's jump up to about 2500. When I touch the lever, I get the feeling that it's just taking the slack out of the cable.

 

I read over the manual and searched out info here but nothing is pointing to this specific problem. the manual simply says to use the screws on the TORS to adjust the idle and to keep them the same.

 

Is there a minimum throttle position adjustment on the lever that I'm missing that should be done before I adjust the idle?

 

Is there a quick step by step I can do to get this straightened out?

 

Thanks for the help!

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Thanks for the replies. I took the cover off the throttle assembly and made sure there was about 1/8" of slack in the cable. Then I snugged the carb tops down. (They were loose) After that, I screwed the TORS idle screws in all the way, warmed it up and did a few runs around the lower front yard to get it up to proper operating temp.

 

When I stopped this time, the idle was holding at about 2500 RPM so I started backing the idle screws off bit by bit until the RPM's started dropping. However, when the RPM's got to a certain point (still too high) further adjustment caused the engine to suddenly drop to a low level and stall.

 

I kind of went something like 2500, 2400, 2300, 2200, 2100, 2000, 900... And I couldn't make it fall anywhere in between.

 

I may just live with it idling at 2000 RPM until I do the TORS-ectomy. I also have a fuel leak from the bowl drain line so I'll have to address that as well as removing the vestigial Boost Bottle!

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I had an issue similar to yours with my Dirt Bike. It would not idle at all or would idle to high. I found that the carb was a little dirty from sitting for a while and the slide was sticking a little at the bottom.cleaning it solved my problem but it was a bike with one carb so might not be your issue. Just something for you to try if you didn't already do that first.

Good Luck .

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I would pull the carbs and adjust the float level to fix that float fuel leak (unless it's just a worn needle/seat), the float level also affects the tune too. I would use a light and make sure each jet is clean and perfectly circle and unonstructed, first thing that comes to mind when I hear 900rpm and 2k rpm and nothing in between I want to say a clogged jet but I'm no pro in that area but I would do that and make sure both carbs are synchronized, I've seen that make a world of a difference. Search on youtube if you need better instructions on how to do it

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