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421. Please help.


Killacaviar

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I just built a driveline 421 hp. It has slp, pwk35, vforce 4, 4 degrees of timing, pods 23cc domes, new plug caps.

 

Jetting is

50pilot

Cel 4th clip

Main 160.

 

Look at the plugs. One ring is thicker than the other and it’s driving me nuts.

 

Carbs are brand new. Leakdown passed,

 

I just took the cards apart today again. Checked floats resynced. I’ve switched wires.

 

The plugs look lean to me and a 160 on this already sounds rich. And the ring difference from the left to the right is off.

 

Any thoughts. I’m trying to get in contact with lane. Just thought I would approach it from all angles and see what you all think.

 

The bike juns strong. No hiccups, steady crisp idle, i am going to try a 162 but I feel like it should bed that much fuel.

 

In conclusion, can someone explain the plug ring difference? Has anyone seen mains this large on a similar set up at 400above sea level and 65f 98e1d09d08c473af2acc0c567dcb09e6.jpg

 

 

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my old setup (which is basically yours) except i was on race fuel at 180 psi and I had vf2s with an extra degree of timing,  I think the jetting we ended up at off the dyno was 50 or 52 pilot, CEL 4th and 142 main, we also used a 138 main and was safe.   I had a 160 in it when we put it on the dyno and it basically  was drowned in fuel and made like 38 hp.   Im sure lane will hit you back, but when i chopped my 7s plugs when i first built it i used a 150 and they read similar to yours, the rings weren't symmetrical.  I upped it to a 155 and it was perfect.  I run a 158 tho to be conservative. 

Edited by Ayesully810
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my old setup (which is basically yours) except i was on race fuel at 180 psi and I had vf2s with an extra degree of timing,  I think the jetting we ended up at off the dyno was 50 or 52 pilot, CEL 4th and 142 main, we also used a 138 main and was safe.   I had a 160 in it when we put it on the dyno and it basically  was drowned in fuel and made like 38 hp.   Im sure lane will hit you back, but when i chopped my 7s plugs when i first built it i used a 150 and they read similar to yours, the rings weren't symmetrical.  I upped it to a 155 and it was perfect.  I run a 158 tho to be conservative. 

Thanks sully.

I just don’t understand why this thing is taking so much fuel.

I talked to fast. And they said it could potentially be electrical. Which is where I’m at. I just would think if it wasn’t burning clean from a lack of spark it would be rich.


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hmm. I find it hard to be electric when its running fine, if it were electric it wouldnt spark well and not burn all the fuel and then you would have richer lookin plugs and subsequently run like crap.   Every motor is different i was very surprised when I was running a 138-142 main in mine.   I say throw some 165 in and chop it again.  If its revving out all the way and not choking a few sizes more wont hurt it

Edited by Ayesully810
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7 minutes ago, Ayesully810 said:

hmm. I find it hard to be electric when its running fine, if it were electric it wouldnt spark well and not burn all the fuel and then you would have richer lookin plugs and subsequently run like crap.   Every motor is different i was very surprised when I was running a 138-142 main in mine, although race fuel does jet leaner.   I say throw some 165 in and chop it again.  If its revving out all the way and not choking a few sizes more wont hurt it

 

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hmm. I find it hard to be electric when its running fine, if it were electric it wouldnt spark well and not burn all the fuel and then you would have richer lookin plugs and subsequently run like crap.   Every motor is different i was very surprised when I was running a 138-142 main in mine.   I say throw some 165 in and chop it again.  If its revving out all the way and not choking a few sizes more wont hurt it

Thanks man. I feel the same way. All the electrics were fine before I swapped the motor. The last thing I want to do is run through all the electrical components and it just needs a bigger jet.

I’m going to do a leakdown one more time just to make sure. Check my ground. Ground the motor with another wire and put a 162 in and see what happens.

Like I said bike rips. I just don’t want to blow it up over something foolish. Could very well be overthinking this.


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Swap carbs & see if it follows...
But it's possible one cyl likes more fuel , basically can be treated as 2 separate eng's


Good call. I just regrounded the motor. Switched carbs. Checked the sync in the carbs again. And upped my main to a 165. I’ll chop it tomorrow and see what the plugs look like. If there is any difference. Have you heard of people running two different mains in a banshee?

I know it’s common on snowmobile engines.


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