yamaha chappy lb80 high comp or big bore

Does anyone know of a high comp piston/head or big bore kit that will work on a yamaha chappy? I think my compression is going, if I am going to tear it apart I would like to make it better.

Re: yamaha chappy lb80 high comp or big bore

Define 'better' .

Re: yamaha chappy lb80 high comp or big bore

Dirty30 Dillon /

You won't find an aftermarket overbore for the LB80, and you would have to cut a head for high comp.

If you are experiencing low compression, it's probably due to worn rings.

What PSI are you running?

Re: yamaha chappy lb80 high comp or big bore

Better - more power...lol

I haven't tested it yet, haven't had time.

Last couple times I rode it it wouldn't start unless bump started (last year would normally start on 1st kick)

After I push it around the yard for 40-50 ft it starts up and runs well, maybe a little low on power.

Carb is spotless, just ran it through my ultrasonic cleaner, made sure just clean etc.

Would something like this work? It lists chappy.

https://www.treatland.tv/puch-45mm-O-RING-high-compression-head-p/puch-45mm-oring-head.htm (edited)

Re: yamaha chappy lb80 high comp or big bore

Some one posted this review for it

"nstalled this head with the chappy polini 70cc kit. Stock studs are a little long so you must use spacers on the studs for yamaha chappy. Performance was noticeable on the lower end and gave my chappy a little extra punch. Almost 100 miles at this time and it has remained leak free. Cooling fins are slightly larger than stock yamaha chappy."

Re: yamaha chappy lb80 high comp or big bore

> mo pug Wrote:

> -------------------------------------------------------

> Some one posted this review for it

>

> "nstalled this head with the chappy polini 70cc kit. Stock studs are a

> little long so you must use spacers on the studs for yamaha chappy.

> Performance was noticeable on the lower end and gave my chappy a little

> extra punch. Almost 100 miles at this time and it has remained leak

> free. Cooling fins are slightly larger than stock yamaha chappy."

I read the reviews, I just didn't get that far lol. That kit would be very slightly smaller then stock (72vs70cc) correct? Just setup for more performance?

Re: yamaha chappy lb80 high comp or big bore

Dirty30 Dillon /

The Polin Kit intended for the LB50 does not work on the LB80, and even if it did I don't think you would see an improvement.

Before buying a new cylinder, there are some easy tests you can do to determine if a new cylinder will do anything for you.

Re: yamaha chappy lb80 high comp or big bore

How does the points gap look?

Re: yamaha chappy lb80 high comp or big bore

> Daniel '' Wrote:

> -------------------------------------------------------

> How does the points gap look?

Not sure, I have never messed with points on a vehicle. where/how would I check?

Re: yamaha chappy lb80 high comp or big bore

Jimmy Cincinnati /

Sounds like you need a good tune up. Then consider new piston kit and/or over bore of your cylinder if scored. And replace the freakin crank seals!

Re: yamaha chappy lb80 high comp or big bore

Go through these steps first: https://mopedarmy.com/wiki/Fred%27s_Guide

Re: yamaha chappy lb80 high comp or big bore

> Mike Boyd Wrote:

> -------------------------------------------------------

> Go through these steps first: https://mopedarmy.com/wiki/Fred%27s_Guide

I will check that out next time I get a chance.

I noticed the last time I looked at the bike that that cylinder outside/fins are dark and oiling looking. what would that be a sign of?

Re: yamaha chappy lb80 high comp or big bore

> I noticed the last time I looked at the bike that that cylinder

> outside/fins are dark and oiling looking. what would that be a sign of?

first thought, head gasket leaking. clean off the oil as best you can, and see if it reappears. if so you can localize where it's coming from.

Re: yamaha chappy lb80 high comp or big bore

Dirty30 Dillon /

Your exhaust screw joint is probably loose and spraying shit.

Re: yamaha chappy lb80 high comp or big bore

I have about 100lbs compression, here is a pic of the head.

Any idea what the compression should be?

20190614_191725.jpg
20190614_192234.jpg

Re: yamaha chappy lb80 high comp or big bore

anyone know what compression these should have?

Re: yamaha chappy lb80 high comp or big bore

iirc it's about 6.5:1

that would be about 95psi @ sea level

Re: yamaha chappy lb80 high comp or big bore

> kenneth gilbert Wrote:

> -------------------------------------------------------

> iirc it's about 6.5:1

>

> that would be about 95psi @ sea level

Thanks!

Re: yamaha chappy lb80 high comp or big bore

Eric Migliorino /

The heads Treats sell are for the LB50 and not LB80. The engine studs are wider on the LB80 so none will fit, even those that say they are for 70cc. They are meant for the Polini kit.

Re: yamaha chappy lb80 high comp or big bore

I had excellent results shaving my oem lb50 head. I would expect similar gains doing it on an 80. took off about a mm.

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