Super Jet cylinder pics 2 tanks after fresh top end

[McDog]

This was freshly bored and honed, new pro-x pistons and rings. Two tanks of gas have been run through it. It has 185ish compression. I use 40:1 klotz r50 and 93 octane gas. The first tank I used 32:1 mix.

The motor has underperformed since I rebuilt it. It has a low end hesitation and lacks the power it should have. When I first leak tested the case after installing a new hot rods crank it went from 10 to 7psi in 10 minutes. I ran it anyway and thought that an airleak was my problem when it wouldn't act right. I just pulled the motor and now it holds 10psi forever. At six hours I depressurized it.

It looks like some rubbing on the sleeves, but the main issue is some corrosion that can be felt with a fingernail. It is freshwater only. One plug is a yellow/brown like it was lean and the other looks normal.

The cylinder is freestle ported by LPW. It has oem carbs and reeds, a b-pipe, and analog total loss.

I'm trying to brainstorm here, any opinions would be appreciated.

 

[whitca]

I had somewhat similar wear marks in my fresh Jetworks topend. My rough spots were identical in both cylinders on the intake side. I called Art and he said its common for a little different wear spot where the ring ends are. I checked the stock pistons to see where the rings were in relation to the wear on the cylinders and sure enough right where the ring ends were. Not sure about the markings over your exhaust ports though. I'm running wiseco pistons if it makes a difference.

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[tor*p*do]

piston crowns look lean to me
there should be bare piston in front of the exhaust port

 

[driftmaster]

piston crowns look lean to me
there should be bare piston in front of the exhaust port

Bend ur head down a little, think its just the pix. Also only two tanks ran so far.


Not sure bout your tuning skills but I couldn't tuned one in in two tanks.
Good luck getn her rite. Not trying to be negative dog.

 

[McDog]

Paul Lehr tuned it for me.

 

[driftmaster]

What was his thought's?

 

[driftmaster]

I couldn't tuned one in in two tanks.
Good luck getn her rite.

And be sure bout it.


Sorry to talk to myself in a public place.

 

[McDog]

He thinks it is a ignition issue. Any other ideas out there?

 

[masterblaster]

i was going to say ign also,did you change anything with it at all when you put it back together after the rebuild,what are you using?

 

[Waternut]

He's using the MSD analog total loss on that engine.

 

[McDog]

I found what I believe to be the problem. Maybe my air gap was just a little less than optimal. It goes to show how much farther a flywheel will go on the crank if it is boiled for 5 minutes. That is the only difference from when I torqued it down to check the air gap. I was switching to the EPIC anyway. I think the pickup is toast on this MSD system.

 

[Waternut]

Sucky. I wouldn't throw it out as I used a pickup that I ground down to the metal probe when the stator plate came loose for quite a while. Might make a good emergency backup. I do have an extra good pickup if you need it though.

 

[ATS_Aaron]

How could a single channel ignition that shares a coil like that be good on one cylinder and bad on another? Was timing verified with a light back when it was installed?

 

[Jr.]

How could a single channel ignition that shares a coil like that be good on one cylinder and bad on another? Was timing verified with a light back when it was installed?

one magnet is exposed as normal, the other is smeared with plastic, thus the good cyl will fire as normal...........

Glad you found your issue

 

[ATS_Aaron]

Duh, I didn't even look at the flywheel. Thanks Paul.

 

[Waternut]

one magnet is exposed as normal, the other is smeared with plastic, thus the good cyl will fire as normal...........

Glad you found your issue

True but the plastic came from the pickup in the first place so there isn't any additional material clogging up the works. Actually there is less because some of the plastic is smeared elsewhere on the flywheel. The fact that it was touching the flywheel could be causing interference in the way the pickup is getting a signal but I'm confused how plastic on the magnet would cause a problem.

 

[McDog]

Well it wasn't my airgap measuring skills that were a problem. I got her ski back together today and found out that the pickup plate for the MSD was loose and rattling around. I don't know if I didn't tighten it enough or if it just rattled loose. Red loctite is on the stator bolts now.

So that means that my timing was all over the place. That explains a lot. After close inspection the pickup I have should be fine. No metal showing or anything. Seems like just the surface was scraped a little. MSD total loss for sale! I'm going with EPIC because I'm tired of charging her battery and mine too.

 

[McDog]

Stock ignition. Fire it up before I carry it to the water to make sure it is all working.

Revs to the freaking moon!

Hit the stop button...nothing. Cover the stock flame arrestor opening with my hand....nothing. Pull the plug wires...nothing. Pull a plug and it stops.

Holy crap! 90 seconds or so of absolute hell. Is my motor shot....I don't know.

WHERE IS THE FREAKING AIRLEAK!!!!!!!!! WTF!!!!!!! It's nothing obvious I can tell you that. I'm so pissed and frazzled....and deaf (it was in my shop).

 

[sjetrider]

Dude, go through those carbs and it sounds like you may be leaning out on at least one cylinder. Take the FA's off and ride it with NO hood look at the fuels distribution closely. If you past a leak down test for 6hrs its gotta be in the intake system.

 

[McDog]

Did another leak down test. 10 psi for 10 minutes with plugs in the fpp manifold and both holes on the intake manifold. I'm still showing 195 compression in each cylinder so I don't think I melted anything.

Could it suck enough air through an open empty regular fuel line and have enough fuel in it from priming it from the reserve line to cause the motor to run away for a minute or so?

The carbs look fine. Butterflys were closed. I don't get it. The above idea is all I've got. Unless somehow it's possible for screwed up carb internals to allow this with the butterflys closed.