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Old 09-13-2006, 06:50 PM   #1
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Default Engine Idling/Tuning Help Needed

hi all. i've searched this and other forums and i haven't seen the problem i'm having discussed anywhere else. i'm hoping you guys can point me in the right direction. i've got an O.S. vzb v-spec. broke the motor in right....tuned it right....sealed it right (i think). i sealed the back plate and the carb where it slides into the engine body. the motor cranks right up and idles fine. i can put the buggy down on the track and run a few hot laps for a couple of minutes (good smoke coming out and everything), bring the buggy in and again, it still idles fine. then i run the car in a full heat and after bringing the buggy in, it is idling very high. it does this each and every heat that i run the buggy in. i'm not quite sure what is happining or how to cure it. i've never had this happen to any of the other nitros that i've had either. any suggestions? thanks.
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Old 09-13-2006, 07:11 PM   #2
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Red face Air leak......??

Sounds like you may be having a prob with it being too lean. You will be rich when you first fire it up ad the car will lean out when you run it and bring it up to temp.

What temp are you going to the starting line with? CHeck this and then check again after a five minute run.

If you are coming off hot and idling high (after your run) but you are going on the starting line at reasonable temps and idle level, then you might have an air leak. Now if you do not leak or go hot all of the time but you do after your tank goes down to a certain level, it may be your tank.

Try fueling your tank and let the motor continue running when you think it is idling high. If the idle goes down then you know.

Pressure lines can do this as well. When in doubt....change the lines.

Let us know what you find.
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Old 09-13-2006, 09:23 PM   #3
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After you bring your car in after a run and it is idling high, if you let it sit there for a while will it come back down?
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Old 09-13-2006, 09:35 PM   #4
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Quote:
Originally Posted by SpeedBump57
After you bring your car in after a run and it is idling high, if you let it sit there for a while will it come back down?

i don't know. it's idling high enough that i didn't want to let it just sit there running at a very high idle for an extended period so i always shut it down.
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Old 09-13-2006, 10:10 PM   #5
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Here is why I asked.

It is very possible that you are running to rich on the bottom and you have the air gap on the carb slide set to far open. (That gap should be no more than 2mm at best) When tuned like this it will idle fine when cold and warm but when at racing temp the engine will lean out some and if the air gap is set to wide to compensate for your rich bottom end the idle will increase. Something you could try to find out. Get the engine up to temp on the bench. Grab a hand full of stick and get it cleaned out real good and let it idle. If idle starts out high and then drops down after 5 or so seconds you are too rich on the bottom. The high idle you here is actually your true idle until it starts to load up again! Lean it out an hour on the bottom and repeat until when you clean it out real good the idle stays high. Then re adjust the idle setting to where you like and at this point I will usually fatten up the bottom about an hour. When you are done with this the air gap will be 2mm or less.
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Old 09-17-2006, 07:57 AM   #6
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Front bearing is known to leak on the VSPEC. BOCA them.
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Old 09-17-2006, 08:03 AM   #7
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well it should idle a little high after running it hard but then the idle should drop within a few seconds im thinking its somewhere around 8 seconds
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Old 09-17-2006, 07:35 PM   #8
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Quote:
Originally Posted by Jim Hughes
well it should idle a little high after running it hard but then the idle should drop within a few seconds im thinking its somewhere around 8 seconds

Do you run an RB?
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