81 Liquifire CDI with intigraded coils ????

[GreenGenes]

Hi guys.... I have an 81 LF that I'm having an issue with spark and performance.
Short story is that both cylinders have spark when pulling engine over.
When it starts sound like one cylinder and if I remove the mag side plug wire machine still runs and sounds the same ... If you reverse the test and pull the left side wire off machine dies... So running on left cylinder only.

So why would I see spark on both cylinders when pulling over and then none on mag side when running?? BTW plugs have been swapped and replaced with no change.

Also something that I need clarified is that the service guides / parts guide show that there is a cdi box and a coil pack... Mine has an integrated cdi/coil pack.
According to the serial # J44LK156225M it shouldn't have this.

Any ideas ? I would like to replace the cdi/coil pack but have not been able to locate one. (AM55416)

Any thoughts or suggestions...

Vintage rally next week and one cylinder just doesn't cut it.

Also read some stuff on the rev limiter .... Could this be a possibility?

Thanks

[ljm]

Some of the earlier Liquifire were retro fitted with the newer HSP (High Speed Retard) CDI like what yours is. They are almost impossible to find now.

I doubt that is what is causing it to run on one cylinder.

Have the carbs been cleaned and cleaned again and yet again? ( Dad always told me.."take a carb apart and you will have it apart 3 times before you have it right)

Does it ever fire on both cylinders?

What is the compression on both sides?

I know that seems like a lot of questions but We need some more info before we can be much help.

Lloyd

[ihengineer76]

It could also be possible that you have a bad crankshaft seal on the mag side.

[JDT]

Like Tom suggested, crank seal.
Or as Lloyd brought up very low compression.
Or one carb not doing much as far as fuel goes.

[JoeRainville]

I had a Liquifire that we could not make run right to save my life after a friend rebuilt it. We swapped carbs left to right, etc. Turns out the crank timing had slipped so bad the TDC from right to left was off about a half inch on the drive clutch diameter.

It was not too hard to check using a screw driver down the plug hole to check for top dead center of both sides. Crank seals are also a good suggestion. Typically the mag side goes out first, as the PTO side has an oil filled gear case on one side of it.

I hope this helps,
-Joe

[GreenGenes]

Hi Lloyd, Tom, Joe and Todd

Carbs have not been cleaned or rebuilt, I have 120 PSI in each side, as for firing on both sides not sure if it ever did fire on both sides, I have owned it for 2 seasons but barely used it the first season and just getting around to working out the bugs now.

Had it out today and was able to get 7000 RPM and about 60 mph. Rev limiter is unplugged.

Motor defiantly dies when I pull the plug wire off the clutch side..... Soooooooo I'm thinking that I get to put some new crank seals in.

Are there any gotchya's that I should know about ?

And thank you all for the advise.

Is there a any quick test to verify the crank seals?

[ljm]

About the best test for crankseals is to replace them. It doesn't take very long.

You can do a pressure test on the engine to check seals.

Some people suggest using either, carb cleaner etc. I have never found that very conclusive.

Lloyd

[GreenGenes]

Thanks Lloyd.

[JDT]

As for crankseals a wise man once said "when in dought, change them out."

[GreenGenes]

Just looking on New Breed..... Would you know which crank seal to order I see 2 and not sure..

[AirborneX4Special]

Perhaps you have one of those 81's that were built with the HSR engines as a pilot program for the upcoming 1982 model year. Locate your engine serial number if you can, should be on the mag housing if it's there. It would be an engine without a provision for electric start already in the casting which didn't arrive until 1983.

[GreenGenes]

I'm currently away on business and won't be back until the weekend..... I will have a look...

[That Girl Racing]

Before I did anything, I would switch the carbs around and see if the dead cylinder follows the carb.

[AirborneX4Special]

I'm currently away on business and won't be back until the weekend..... I will have a look...

Seems like the pilot 82's in the 81 chassis might have had the new TR drive system but my brain housing does not recall. That would be a dead giveaway if you had that plus an HSR motor.

[nick80lf]

The factory updated 81s were stamped with an "A".

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