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Methanol Detonation


BigRed350x

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What plug are you running? What bore size is the motor (stock cylinder?/cub/twister?) 18cc dome doesnt mean anything without bore size so we can get some idea on the compression ratio. Also what piston are you running and what angle did you have your squish band cut at? Is it just one plug or is it both? What type of meth are you running?

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What plug are you running? What bore size is the motor (stock cylinder?/cub/twister?) 18cc dome doesnt mean anything without bore size so we can get some idea on the compression ratio. Also what piston are you running and what angle did you have your squish band cut at? Is it just one plug or is it both? What type of meth are you running?

 

 

I'll try to answer for him here.

 

66mm bore STOCK cylinder

 

br9es plugs, gapped at 18 thou I believe

 

795 wiseco pistons

 

dave at noss cut the squish on the experimental domes, and then he used a set of off the shelf 4mil domes with a huge squish clearance, like 55 thou, only 150lbs compression, still detonates.

 

methanol is the standard crap our fuel companies around here sell to the oilfields.

 

Only one plug, the left one, over and over. Seems to me like that side has a wierd vibration too, but maybe I'm just seeing things. Could be his crank?

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That's some good info...

You guys sure the squish is the same on both sides? (I mean left to right)

Leak down test it again.

Start it up with the stator cover removed...and spray carb cleaner behind the stator.

 

He said he checked for the crank being twisted or out of phase...

 

If it only, and every time deto's the left side, with different domes, different carbs, etc.

 

It's not electrical, it's mechanical...

 

It has to be crank, seal, leak, etc.

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That's some good info...

You guys sure the squish is the same on both sides? (I mean left to right)

Leak down test it again.

Start it up with the stator cover removed...and spray carb cleaner behind the stator.

 

He said he checked for the crank being twisted or out of phase...

 

If it only, and every time deto's the left side, with different domes, different carbs, etc.

 

It's not electrical, it's mechanical...

 

It has to be crank, seal, leak, etc.

 

Hey, sorry I've been busy busy at work and haven't gotton on here much this past week. Yeah the domes are about as close to identical as you can get. I will be checking everything over again this weekend if I get a chance. Thanks for the info on this one everyone. I will let you know if I find anything. I've got a lot of chores to do in the barn and on my new truck, so if I get time i will work on the banshee.

 

I'm going to snag a friends set of carbs and try them out and totally eliminate that issue right up front. Also have spare eletrical parts I can try, and I will do another leak-down test to be sure like you said dajogejr. Pretty confident the crank is good, but I've got an easy way to check that...

 

Thanks again,

- Jared

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Calvin worded it kind weird... I have a set of experimental domes that I'm trying an idea with that noss cut for me, and also have a set of 18cc off the shelf 4mil domes that are cut for a .020 thick base gasket and standard 795 pistons and were supposed to yield .045 squish clearance. My base gasket is a little bigger than a .020 on the bike right now and with those domes it was like .056 squish and it would still detonate. The experimental domes I had noss cut for me yielded a .038 or .040 squish. I can't remember which one off the top of my head. I'd have to go look at my notes. I've gone through 18cc, and 19cc domes and from .055 to .030 squish clearance and no change.

 

I just ran through all the basics I had handy at the dunes last time and everything I changed didn't affect the issue. Was hoping I just overlooked something. I'll do another leak-down test this weekend if I have some time.

 

Thanks

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