wont rev over 7500.....80 Liquifire

liquifire1 · Post by **liquifire1** » Thu Feb 06, 2014 9:53 pm

Ok....I can't find a forum that describes all my circumstances

1980 Liquifire
when its colder (like first 10 - 15 minutes) of running it runs fine in the top end it pulls @ 8200 no prob

when the sled warms up (like 10 miles into ride) it wont rev when I give WOT it will got to a little over 7000 and "that's it" I even got one little backfire at WOT (out the pipe)

I unplugged the engine to isolate problems and it persists.....

It runs fine in the low end and I can feather it along up to about 2/3 throttle with the engine running under that 7000 mark without a burble but if I try to push beyond that it just wont go above........makes more noise but wont push past

it has the factory coil and wires (is this the problem??)
ran fine last year and "I think" the carbs are pretty clean (I gave them a good hose down with carb cleaner, like bowls off)
a plug swap will sometimes temporarily help, but sometimes not...

any help from the pros here would be appreciated

Thanks
Jon

JDT · Post by **JDT** » Thu Feb 06, 2014 9:56 pm

What do your plugs look like after it has warmed up and starts to bog down?

liquifire1 · Post by **liquifire1** » Thu Feb 06, 2014 9:57 pm

toasty brown...both of them

like a toasted marshmallow

JDT · Post by **JDT** » Thu Feb 06, 2014 10:01 pm

Could be starving for fuel.

Could be just a tad bit lean.

Could be a clutch issue.

Could be the engine temp is too high.

liquifire1 · Post by **liquifire1** » Thu Feb 06, 2014 10:08 pm

Here is pic of the plugs

liquifire1 · Post by **liquifire1** » Thu Feb 06, 2014 10:12 pm

The clutch issue...yup maybe...

But if I got a backfire when I was holding it to the bar doesn't that mean too much fuel?

temp gauge was at the bottom (and it works) so I don't think it was too hot?

AirborneX4Special · Post by **AirborneX4Special** » Thu Feb 06, 2014 10:40 pm

A faulty ignition coil can act up like you're describing. Fine at cold start up but fails after it's heated from running.

That Girl Racing · Post by **That Girl Racing** » Fri Feb 07, 2014 12:13 am

The backfire is from being lean or a late spark. I will also go with a bad coil. Could also be a crankseal

JDT · Post by **JDT** » Sun Feb 09, 2014 9:38 am

Picture looks like a lean condition to me.

liquifire1 · Post by **liquifire1** » Tue Feb 11, 2014 4:58 pm

Ok...

I put a new coil on it and just got back from a 15 mile run and it ran well the whole time, so hopefully that solves it.

I really appreciate all of your input and help!

Jon

liquifire1 · Post by **liquifire1** » Tue Feb 11, 2014 4:59 pm

JDT wrote:Picture looks like a lean condition to me.

Yeah it is a little...hmmm?

wont rev over 7500.....80 Liquifire

wont rev over 7500.....80 Liquifire

Re: wont rev over 7500.....80 Liquifire

Re: wont rev over 7500.....80 Liquifire

Re: wont rev over 7500.....80 Liquifire

Re: wont rev over 7500.....80 Liquifire

Re: wont rev over 7500.....80 Liquifire

Re: wont rev over 7500.....80 Liquifire

Re: wont rev over 7500.....80 Liquifire

Re: wont rev over 7500.....80 Liquifire

Re: wont rev over 7500.....80 Liquifire

Re: wont rev over 7500.....80 Liquifire