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Old 08-01-2009, 06:01 PM   #1
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Default jammin .21 shimming

i heard and read in the manuel that the JPX .21 is shimmed for 20%. i was wondering what shim i would use for 30%. i saw a .1 and a .2..i was thinking it was the .1
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Old 08-01-2009, 06:09 PM   #2
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i heard and read in the manuel that the JPX .21 is shimmed for 20%. i was wondering what shim i would use for 30%. i saw a .1 and a .2..i was thinking it was the .1

For 30% you need to add another .1
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Old 08-01-2009, 06:12 PM   #3
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what pipe are you running with this motor?
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Old 08-01-2009, 06:13 PM   #4
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Does having it shimmed wrong do any damage? I have a couple of used motors that may be shimmed for 20% but previous owner ran 30.

That's only a guess, as I think a lot of guys just get motor and 30% fuel and don't reshim and just run it. Is that possible or it wouldn't run right?
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Old 08-01-2009, 06:44 PM   #5
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Last year I ran the Jammin' 21 with 30% Byrons fuel and never had any issue with tuning or temps.
I think your engine is fine as long as it has good compression. From my experience, the JP-4 is the best possible pipe for this engine.
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Old 08-01-2009, 07:00 PM   #6
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Last year I ran the Jammin' 21 with 30% Byrons fuel and never had any issue with tuning or temps.
I think your engine is fine as long as it has good compression. From my experience, the JP-4 is the best possible pipe for this engine.
what kind of time were you getting per tank? im getting this engine in a couple weeks so.
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Old 08-01-2009, 07:05 PM   #7
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For 30% you need to add another .1

I run them (ran) them box stock, 30% they run! If you add the shim, they tend to lose some power and eat fuel. But the mill will last alot longer. Depends on what you wanna do.
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Old 08-01-2009, 07:23 PM   #8
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i'm running 20% and the thing is hardly controllable, i tried softer springs, bigger bell and even teflon shoes, my inside tire still comes off the ground mid-turn. i'm thinking of selling it and going back to just smooth controllable go based motors. i ran 30% a couple tanks and it had no problems, with a little over a gallon it still sticks at the top once in a while. if adding shims takes away performance and increases engine life i might try that then, but increased fuel consumption, hmmm. what happens if we take off shimms, would it get better run times?
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Old 08-01-2009, 07:37 PM   #9
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alright cool thanks everyone. from the sounds of it i want to stick with the stock shims because i run it stock shimming and run 30% but i was just wanting to know if there were any advantages but it doesnt seem like there are any. im running a dynamite 053 pipe but that pipe is a gas guzzler! i get on average 7 minutes a tank. how much do you get with your jp-4?
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Old 08-01-2009, 08:13 PM   #10
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alright cool thanks everyone. from the sounds of it i want to stick with the stock shims because i run it stock shimming and run 30% but i was just wanting to know if there were any advantages but it doesnt seem like there are any. im running a dynamite 053 pipe but that pipe is a gas guzzler! i get on average 7 minutes a tank. how much do you get with your jp-4?
I run the Jammin' in a truggy. Last year I was getting almost 10 minutes. That was 30% and the JP-4. I am in the process of breaking a new one in and will run it next week in a D8T.
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Old 08-01-2009, 08:16 PM   #11
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I run the Jammin' in a truggy. Last year I was getting almost 10 minutes. That was 30% and the JP-4. I am in the process of breaking a new one in and will run it next week in a D8T.
sweet let us know how it does!
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Old 08-01-2009, 08:26 PM   #12
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in truggy it would be VERY difficult if not near impossible to get the JPX to do 10 min stops in a race.....modified...sure it can...but stock they suffer from poor run time.
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Old 08-01-2009, 10:47 PM   #13
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I did 9:45 one time in buggy with this motor & actually was not trying to finish the race just kill the motor but that was with a JP-3 pipe & I know from switching that a 086 will go more just loose bottom end but at that kind of tune not much room for error. I dont think the average club guy can do 20 min in 1 stop without sweating bullets in buggy or truggy.Anythin more than 8:30 min will increase your stress level beyond a fun day.
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Old 08-02-2009, 08:48 AM   #14
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in truggy it would be VERY difficult if not near impossible to get the JPX to do 10 min stops in a race.....modified...sure it can...but stock they suffer from poor run time.
It all depends on the layout of the track and how you drive. Last year, our track wasn't as fast. This year is different and will consume more fuel. I am not saying the Jammin' is the best engine made but performance for the buck it can't be beat.
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Old 08-02-2009, 10:21 AM   #15
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does anyone know the warrenty plan on the jammin .21?
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