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Hi everyone, I have an ex police special I have been working on. It has 65,000+ miles on it. It’s never been apart but still has 150 lbs per cylinder. I have the float levels correct and I’m working on the pilot jets now. I have stock air box and a kerker pipe with a street baffle. The carburetors have never been dirty. Stock pilots are 37.5 , I have been going up trying to get it to leave a stop sign clean. It seems to loose a cylinder right off idle. I’m at 42.5 now and it has just about gone away but still stutters a bit. I have 45s ready to go but the rest of the throttle range is great. It really rips now. Has anyone here done a similar project? I don’t want to go from poor mileage to worse. My idle screws are out 3 turns and they kind of bugs me, seems like too far out. Should I stay the course and keep pouring the coal to it?

PS. The pipe was already blue when I got it, I don’t think I was ever that lean.

I was able to borrow a set of carburetors from a friend. They were a real mess, even the main jets were plugged. I used tiny wires pulled out of a wire brush to poke out the crap in all the usual places. Also hot water and “super clean” from a parts supplier. They came out very nice. I put them on my bike with stock jetting and it ran better but still had the miss when leaving a stop. I was disappointed but at least it told me that my problem wasn’t carburetor related.
I needed to return the borrowed carbs so I went through mine one more time and found a couple of the air jets on the intake side were partially plugged so I cleaned them all up and put the stock jets back in. It was cold out so I started it up and let it build some heat to make it easier to r&r the carbs. When I got the borrowed carbs off I decided it would be a good time to do a compression test. With the plug wires removed and the engine cranking over I could see a big spark jumping from my fairly new Dyna coil around the side of the coil into the power wire feeding the coil! I switched the two wires around and put it all back together and it runs better than it ever has since I’ve owned it.

Very nice looking old P model. Is this bike for sale right now? I remember seeing it somewhere recently. Anyhoot...

I had an off idle stumble last spring that I hunted for a bit. It turned out I had a shorted stator coil assembly. I did not realize this until I did the checking for shorts outlined in the service manual. Ohming the yellow stator wires between them checked good, but ohming to engine ground while checking for shorts was a fail, although it charged the 13.5 volts, off idle as expected. While this may not be the case, it is always good to know the charging system is working as advertised.



I also added a relay to provide full battery voltage to the brown sense wire to the regulator / rectifier module, to stop overcharging. Not a lick of a problem since.

I just saw the part where you had arcing at the coil. (sorry didn't read far enough in the last post) Still ignition / electrical induced, not carb induced problem (now), from my understanding.

Arcing = not good. My 05 4.3 chevy truck had arcing at the coil.. caused mucho SES engine lights and a bunch of different codes in the computer, P0300, P0306 etc. New coil and wires was the cure, hasn't has a SES light on code since.

I maintain a fleet of trucks that run on propane and plug wires are always an issue. Heat under the hood cooks them I guess.
It was kind of a fluke that I found the problem. Under the tank you just don’t see it. I guess the added load of the plug wires being pulled off made it easier to see.
Hope this helps others with tuning problems!

Good idea with the relay! I might try that soon

Jussumguy wrote: I maintain a fleet of trucks that run on propane and plug wires are always an issue. Heat under the hood cooks them I guess.
It was kind of a fluke that I found the problem. Under the tank you just don’t see it. I guess the added load of the plug wires being pulled off made it easier to see.
Hope this helps others with tuning problems!

I owned a dual fuel propane / gasoline C-30 Chevrolet bucket truck back in the mid 80's. I got to know the conversion guys pretty good and they were adamant about using 8mm spiral core plug wires on their conversions. Low noise (spiral solid core wire) and more spark delivered. My spark problems was in a van that I have to remove the wheels and engine cover to access most anything on the engine. I used AC Delco OEM wires on this truck that is the coil wire pictured. Love the van, hate working on it.

Thank you that’s good to know. There’s less and less old school propane guys around that remember things like that. California is so concerned about clean air that they make practically impossible to do conversions anymore