Backfiring again.

[christoph.tamz]

So I was ripping the shee and it died. Got it home with a hell of alot of backfiring. Took the left plug out and was crushed. Right was fine. What I've done so far was.

 

Changed plugs

Cleaned the stator and pick up

Compression is at 160ish

Case holds 6psi for 6mins

Changed coils, confirmed spark

 

I did notice the pick ups on the fly wheel were flattened In The start of them.

 

She fired but won't hold an idle and heats up quick.

 

Any ideas?

 

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[christoph.tamz]

Also. Hard as hell to start.

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[booxzzy]

What about carburetors, getting fuel, jets clean?
Could be lack of fuel

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[christoph.tamz]

Carbs are getting fuel. I can take them apart to clean them. But didn't do that yet

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[Ayesully810]

What series plugs

what octane gas

good water pump bearing and impellar?

you still running the drag ported 421 with cpis? Sounds like its building heat

are the plugs backing out at all? I had some slight detonation at the dunes while back to back drag racing long pulls. plugs backed out with one plug bridge starting to collapse, i upped the main from a 155 to a 160 and it never happened again. This was also in 90+ degree heat in the sand with a 8 series plug

Edited August 7, 2018 by Ayesully810

[christoph.tamz]

Br8es. 32:1 yamalube . and yes.

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[christoph.tamz]

Br8es. 32:1 yamalube . and yes.

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Also 93 octane

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[christoph.tamz]

Also 93 octane

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I believe the pilot is 27.5

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[christoph.tamz]

Plugs are seating fine and not backing out.

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[christoph.tamz]

I'm running 162 mains.

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[Ayesully810]

you cant be running a 27.5 main. thats stock carb jet sizes.  check your pilot size and go up 2-3 sizes with air screw 1 turn out.  48-52 pilot should be about where its at. you have air stykers? or pwks

Edited August 7, 2018 by Ayesully810

[Ayesully810]

8 minutes ago, Ayesully810 said:

you cant be running a 27.5 main. thats stock carb jet sizes.  check your pilot size and go up 2-3 sizes with air screw 1 turn out.  48-52 pilot should be about where its at. you have air stykers? or pwks

hopefully you dont have a stock carb jet screwed into your carbs lol 

[christoph.tamz]

I know I don't. I just don't remember what's in there. I known I did it right tho and was running perfect. Nothing changed but a major backfire.

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[trickedcarbine]

Detonation if it's emu hint the end of the plug closed. Probably time to up the octane. Especially if it's really hot out. Any timing? 

And check your reeds if you've verified the Pistons/cylinders are in ok shape. More often then not, worn out or broken reeds are the culprit for backfiring if the rest of the set up is proper. 

[christoph.tamz]

Ooh. Ok.
I forgot to mention reeds are close to new and flow free. No spacing in the cage. Boots are near perfect. Gaskets are new. It's been close to 100 here daily. I do run an octane booster but not on this tank of gas.

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