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Intermittent miss at high rpm.


beaterbanshee3825

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Hey guys, it's my first post on the site. I recently built a new stock cylinder drag motor and I'm have it a little issue. One cylinder is cutting out under full throttle intermittently I have been playing with the carbs and timing and it's gotten better just not all the way fixed.

Specs on the motor are...

10 mil crank

72mm bore stock cylinders

39pwks on alcohol .120 dumps .115 mains 55 pilot

Tdr head

1-6 over ride

Lockup clutch.

Dyna cdi

8* timing plate

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i assume your running pods?

 

i had a bad outerwear once, that if would run fine until it got to power, then it wouldnt let enough air flow through, and would shut a cylinder down.  something stupid that took me a while to find. 

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Hey guys, it's my first post on the site. I recently built a new stock cylinder drag motor and I'm have it a little issue. One cylinder is cutting out under full throttle intermittently I have been playing with the carbs and timing and it's gotten better just not all the way fixed.

Specs on the motor are...

10 mil crank

72mm bore stock cylinders

39pwks on alcohol .120 dumps .115 mains 55 pilot

Tdr head

1-6 over ride

Lockup clutch.

Dyna cdi

8* timing plate

72mm stock cylinder uh

 

Sent from my SM-G900V using Tapatalk

Edited by controls77
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That's an old school set up. Very cool if you can get it to run. Have you tried it with less then the 8* of timing posted above?

 

Give the electronics a once over. Fresh boots. Clean all the connections and grease them with Dialectric.

Clean stator pick ups on flywheel. Gap pick up. Etc.

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Test the Pick Up per Clymer Manual Spec.

 

When using a stock CDI set timing plate to zero and work up. If you have the Dyna on, make sure that if there is a plate on as well that it is zero if the CDI is adding timing. Or take notice of what is on the plate then program the Dyna accordingly. The Dynas can be finicky if you are not 100% sure what kind of timing it's throwing.

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yea ive heard lots of mixed opinions on running a dyna + adding timing.... may be something to look into!

I friggin love my Dyna! It's nice to make it freight train through tight stuff and out of the turn, but on the 1/2 mile course you can pull timing out and really let it rev.
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Done a compression test? Wonder if head is leaking. If not its probobly electrical

This^^^ check plugs for water droplets or steam coming out of the pipe after plug removal.

 

Also, just to rule it out, try OEM CDI. Dynas are hit and miss. And you don't really know what timing is in it....and it adds more than OEM even on the "stock" setting.

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