80cc V1 running hot

Pete Connolly /

Just got my v1 up and running and it is running real hot. Polini 80 cc mikuni vm20 with a 210 jet. Ev racing exhaust ported bottom end. It idles around 200 but runs in mid 300s with peaks at 420 degrees. I've checked for air leaks and can't find any. Also ive got yellow clutch springs and they seem to be working to well so that the clutch doesn't engage until about half throttle. Has anyone had this problem or know any solutions to either problem.?

Re: 80cc V1 running hot

210 main jet in a VM20 sounds way too high ; I am jetted at 165 with the same carb and cylinder set-up and my bike struggles to break 360* after longer 50+mph flat stretches.

What notch is your is your carb's needle clip at? I'm using the stock VM20 needle and have it leaned out 1 clip from stock, 2nd notch from the top.

What cylinder head and plug are you using? running a good head gasket?

Also do not run your bike past 400 to see if it'll cool down... shut the poor thing off !

Re: 80cc V1 running hot

What is the timing set at? The polini paper states 21 degree? What type of oil are you running in the clutch? What is your gearing?

<^> move this thread to performance. (edited)

Re: 80cc V1 running hot

I know I read something (i thought jennings but couldnt find it) that stated you want your head temps to max out around 420 after a 3-5 second pull at the end of the straight away. Alas, I cant find where I read that so, useless.

I did find this off of a scooter forum:

"This has been linked before and even though the focus is on oil ratios it does use head temp to define cool-down, moderate-duty, and severe-duty.

http://www.bridgestonemotorcycle.com/documents/oilpremix6.pdf

Jennings uses the following temps in the tests:

350F cool-down

390-400F moderate-duty

410-420F severe-duty."

Re: 80cc V1 running hot

this sounds like my AMF...

Running a 145 main and I think its a 20 Idle..

Just messed with the timing but still runs that hot, no problems.. Fast kit... Run some good oil give it some break in time, and get the bigger Rectangle head for the kit! I have yet to put mine on. but more larger fins=more surface to cool!?

Re: 80cc V1 running hot

did you check for air leaks? idk why else you would be jetted that high

Re: 80cc V1 running hot

the carb can have air leaks too...

Re: 80cc V1 running hot

Pete Connolly /

Im running MOTUL trans oil with a 40:1 gas mix with motul 510 oil. the gearing is stock and the Mikuni carb setup is stock, the only thing i changed was the jet. stock cylinder head with a NGK plug (shorty) not sure of the type. the head gasket is the one that came with the kit.

Re: 80cc V1 running hot

Probably Fred /

Simple retard the timing until it runs cool enough for your needs.

If you lose a little power oh well you gots to ride your bike and not blow up.

Unless you are using it for a sprint bike

Re: 80cc V1 running hot

Perfekt Timing Angel /

Triple check for airleaks, double check timing.

IMO, Those stock (small) heads hold a lot of heat. If you don't know what plug you're using, I'd pull it and check it. It could be a hot-range plug. This doesn't mean the spark is hotter, just that the spark plug is less effective at dissipating heat from the bang-bang. This would definitely spike your temps on the digital read-out.

Re: 80cc V1 running hot

that doesnt sound crazy at all as far as temps, especially breaking in. jet does sound high, so i'm feeling the triplecheck for airleaks. especially since it get so much hotter running than idle. how steady is your idle? that can indicate airleaks too.

Re: 80cc V1 running hot

Spray carb clean into your stator. Bet your crank seal is leaking.

Re: 80cc V1 running hot

Pete Connolly /

The plug that im using is a Champion L86C. I put anew head gasket in and put a gasket between intake and carb( there was just a rubber gasket on the mikuni before) and am still getting high temps. It starts off slow when idling but spikes quickly after running it for a minute or two

Re: 80cc V1 running hot

Pete Connolly /

ive double checked for any air leaks around the carb, intake and head and am getting no flutter out of the idle when spraying both carb cleaner and starting fluid. next im going to retard the timing a litttle and try to to keep the temp in the 300s. any other ideas suggestions?

Re: 80cc V1 running hot

check the timing with a timing light .. would be the best next thing to do. micrometer spark plug tool!

Re: 80cc V1 running hot

Pete Connolly Wrote:

-------------------------------------------------------

> Just got my v1 up and running and it is running

> real hot. Polini 80 cc mikuni vm20 with a 210

> jet. Ev racing exhaust ported bottom end. It idles

> around 200 but runs in mid 300s with peaks at 420

> degrees. I've checked for air leaks and can't

> find any. Also ive got yellow clutch springs and

> they seem to be working to well so that the clutch

> doesn't engage until about half throttle. Has

> anyone had this problem or know any solutions to

> either problem.?

that's not hot my kstar peaks at 460 and runs all day long

Re: 80cc V1 running hot

alloy vs cast ..

Re: 80cc V1 running hot

then my hobbit runs 470 and has peaked at 500... I really have to watch it on that bike

Re: 80cc V1 running hot

High comp head!!!!

More Metal, More fins, more cool!!!

Dropped temps significantly last night after the swap

Re: 80cc V1 running hot

I'm OK with the hobbit's getting up towards 450, but a kstar over 450, you're doing something wrong.

another simple option is gear taller to keep your rpm from screaming.

Re: 80cc V1 running hot

but im already geard so tall I can barely make it up hills

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