77 Superchief questions

[DialTone301]

I have a few questions about my new toy and hopefully you all can help me out.

What size is the fuel tank? I put 4 gallons in it and I think it must be at least a 6 gallon tank.

What is the recommended spark plug gap? It has B8ES plugs...is this correct?

How much compression should the G50b have? I haven't checked it yet but it seems to run better(more power) cold than hot so I assume it may be getting close to a top end rebuild.

I am sure I will have more questions later since this is my first 6x6.

Thanks in advance.

Jim

[Tango42]

some answers

I have a '78 superchief....congrats, its a great machine! I'll give your questions a shot.....

I believe the tank is 6 gallons, although I havent tested it.

I run B8ES with a .020 gap....runs great.

My G50B has 140 lbs in both cylinders....and it runs great hot or cold.

[George]

If you can switch to a CDI system you will find the engine runs better both warm and cold. I did this at Don's recommendation and it never has a problem.

I also run the B8ES with the gap is comes out of the box with. A trusted friend suggested running with B8ER (“R” as in Resistor) as they are designed for CDI. I have not tried that yet though.

[DialTone301]

What CDI unit did you install? I know it would be a fairly straight forward swap but would want to get a unit with the correct advance curve.

I think the ignition is working fine right now...no misses or backfires. It just seems like it is less powerful as it gets hotter. I have been away from air cooled motors for quite a while so it may be the normal power loss as an engine gets hotter.

What oil/gas ratio are you running? I am using Yamalube 2R at 32:1 and the plugs look good.

[Tango42]

I'm using yamalube 2S at between 32 and 40:1 (I mix it at 40:1, then chicken out and add a little more ). Plugs look good and it doesnt smoke much at all. Ive actually been running the same plugs for about a year now....no problem.

Ive been searching now and then for the CDI conversion parts.....I guess they turn up once in a while on ebay. Mine runs real nice (once I figured out the correct way to clean the points, but thats another story), so I havent had a need to change it over......yet.

George, you can also open up the gap considerably with CDI.....those B8ES plugs come out of the box at .020. I believe you can run up at about .035 with CDI and take full advantage of the better spark.

[George]

I got an aftermarket CDI box from a guy on Ebay. It's great but the guy who sold it is no longer on Ebay. You can still find the originals on occasion though. You'd also need a CDI coil, flywheel and stator to convert to CDI. If you're happy with the way it's running, I'd leave it.

I was running 40:1 but went down to 30:1 at the races last week.