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Author Topic: Jetting Advice (Ballpark Starting Point)  (Read 1947 times)

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Re: Jetting Advice (Ballpark Starting Point)
« Reply #25 on: April 22, 2014, 02:55:57 pm »
Well motorgeek then it is time to develop an adjustable main jet on the handlebars ....
 and  be a millionaire $ $ $ $ $ $ ;-)




Mike Tollett had an adjustable main at the handlebars when he raced pikes peak.

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Re: Jetting Advice (Ballpark Starting Point)
« Reply #26 on: April 22, 2014, 09:01:09 pm »
how did he do that? under the carburetor of the Zilla is still plenty of room for an adjustable main jet?
under-steers is when you see the tree the goes in. overrides is when you hear the tree which you were going on.
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Re: Jetting Advice (Ballpark Starting Point)
« Reply #27 on: April 22, 2014, 09:21:49 pm »
Well motorgeek then it is time to develop an adjustable main jet on the handlebars ....
 and  be a millionaire $ $ $ $ $ $ ;-)




I could become a millionaire by making an adjustable main jet on the handle bars if I also owned a piston company.  I would make my millions selling pistons not the adjustable main jet apparatus. 

The majority of the riders would not have any more success tuning with an adjustable main jet than the guys that are using tools to change jets.  You need  turning experience and a way to gage performance when optimizing your jetting. 

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Re: Jetting Advice (Ballpark Starting Point)
« Reply #28 on: April 23, 2014, 01:16:20 pm »
The way I jetted my wife's 86 lt250r was run and if it flattened out on the top end I would go up a size on the main and would ruin it again and did this until it started to bog then backed it down one size.would that be the correct way or at least a good way to get the right jetting.

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Re: Jetting Advice (Ballpark Starting Point)
« Reply #29 on: April 23, 2014, 05:09:56 pm »
The way I jetted my wife's 86 lt250r was run and if it flattened out on the top end I would go up a size on the main and would ruin it again and did this until it started to bog then backed it down one size.would that be the correct way or at least a good way to get the right jetting.

Jetting is a trial and error routine.  I would have started with it so rich that it misses near the peak Rpm in the first few gears.  Then lean it down a main jet size at a time until it starts pulling through the first few gears without any miss-fire.

If you stop at the point where one jet miss-fires and the next leaner jet does not miss-fire you will not be at peak performance but will be at a safe main jet size. 

If you want to tune it for max power you will need to find a way to gauge your acceleration by comparing it to another bike with similar power and do some roll on side by side acceleration runs with different main jets.  Or you could use a dyno that can put enough load on the engine so that it takes 5 to 10 seconds for it to pull through the RPM range.  You can also use a stop watch, drag strip etc. to gauge your performance with different main jets. 

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Re: Jetting Advice (Ballpark Starting Point)
« Reply #30 on: April 28, 2014, 12:38:17 am »
I think i'm on the right page now. Your talking about issues using a rear tire dyno (atv dyno) and setting up the perfect A/F ratios with air & fuel meters. Not a engine dyno that you can set parameters like step and hold rpm..

 

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