Polini case matching.

magnus gustafsen /

Hey guys, I just casematched my Polini 65cc kit for my Maxi, and there's no difference before and after the casematching?

Is it just me, or shouldn't there be a difference?

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Re: Polini case matching.

Brandon Weiss (Detective brandon to you) /

Uhhh...what do you mean theres no difference? You removed material from the cases for better flow, didnt you?

That would qualify as a difference.

Re: Polini case matching.

magnus gustafsen /

Yeah, I took all material away to match Polini 100% and what wonders me is that there isn't difference is...

Re: Polini case matching.

The material you took away is the difference.

Re: Polini case matching.

It’s together and running correct?

Re: Polini case matching.

magnus gustafsen /

It's topping out at 74 km/h/46 mph because of my ignition i think. If someone did it behind my back and I rode the bike, I wouldn't be able to tell any difference. Same powerband, same speed and same sound and setup.

Re: Polini case matching.

What exhaust and carb are you using?

Re: Polini case matching.

magnus gustafsen /

I'm running a 19mm Dellorto with 90 jet and a Tecno Boss exhaust.

https://www.kgi.dk/product/15718-3169/puch-maxi-k/tecno-boss-udstoedning-sort

Re: Polini case matching.

I'd say the exhaust is the biggest problem, dont put a 30€ exhaust on a 200€ cylinder.

Re: Polini case matching.

Your not going to feel a difference between case matched and not. But it’s the difference between doing something correct and incorrect. You just helped improve the flow path.

Re: Polini case matching.

magnus gustafsen /

Alright, that's the answer I needed, thanks. I've also heard that it helps cool down the piston from the 2 holes in the top of the cylinder.

Re: Polini case matching.

I think case matching is pretty pointless on these small engines, Maybe some people are trying to shave a thousandth of a second off the quarter mile times?

As long as your having fun, your doing it right!

Re: Polini case matching.

Using that BOSS pipe is like the stock cigar pipe...Get a better pipe....

Re: Polini case matching.

NICE CASE MATCH...by the way...

Re: Polini case matching.

magnus gustafsen /

Probably, but I know some guys that run same exhaust and carb and they're going around 53-55 mph with 16-40 gearing, and mine is 17-40. But it takes 8300 rpm, and that's my main problem about running right.

I just hit 50 on it, because i was running without airfilter!

Re: Polini case matching.

magnus gustafsen /

No, it's not. It can rev very high up in rpm's when I'm doing circles in the grass, so the pipe isn't restricting the rpm's.

Re: Polini case matching.

Mikey Antonakakis /

Case matching will show a difference if your cylinder to case transfer ports step is the main restriction/limitation. With a Techno Boss, that will definitely not be the limitation. But it's the "right" way to do it, as others have said. The windows in your cylinder wall, combined with your pipe, are the most important thing. Right now your pipe can't pull strong enough to have cas matching make a difference.

Re: Polini case matching.

Not jetted/tuned correctly,

Many boss pipes have extra 2-4 inch of header sticking in chamber due to poor manufacturing.

For a boss pipe to work good the welds need to be cut and header needs to be shortened or you could extend chamber out and get a better power band suitable to your needs but you don’t know until you remove the chamber and see if you got a bogus made pipe or not, chances are you do.

I would just pitch the pipe anyway and get a derestricted estoril

Re: Polini case matching.

I've deeeefinitely noticed gains on casematching polini. and others. but it's gonna be topend in the high rpm. if you're stuck at 8k on a polini, that's a bigger problem than whether it's casematched.

basically, you're not feeling the gains because that wasn't your weakest link. It's obvious if you're getting better action sans airfilter that you've got room to improve your tuning, and timing too i'd suspect, and i'd be down to second improving your exhaust - that makes a huge gain especially when it's more inline with the powerband your cylinder's trying to push.

so yeah - you're not feeling it cuz you're not done. much optimization left, but be glad that that step's already taken care of!

Re: Polini case matching.

Jonathan Feldman /

Sorry to be the guy who has nothing interesting to say but man nice dremel work. Shit looks damn near close to perfect. Saving that pic for inspiration for when I eventually cross the puch polini bridge.

Re: Polini case matching.

Teflon/plastic stuffed crank is going to melt and spread goo all over crankcase/carter

Re: Polini case matching.

Tune better, if it runs better sans filter you are too rich. Try dropping to 15 or 16 front sprocket so you can actually get up into the pipe powerband.

Re: Polini case matching.

magnus gustafsen /

I've tried 14-40 and it would still stop at 8k rpm... But the acceleration was insane.. It lifted the front wheel when I was sitting on the carrier haha :D

Re: Polini case matching.

timothy rendall /

yep i'll go along with what Ken said, I've just taken an engine apart that had on of those cranks melt/ brake up, Messy !

Re: Polini case matching.

Joe Schuitema /

The boss pipe on an airsal 70cc, 16mm carb and 16/40 gearing got me to 48mph gps'ed. Thats about 9250rpm. I wouldn't expect much more out of the boss pipe, it just doesn't have much of any powerband. I'm sure the port timings on a polini are more radical than the airsal and it needs a different pipe to take advantage of it. Also, a few degrees in timing can make a big difference up top. Can you check your timing with the bike running? I bet its 10 or 12 degrees and not 16-18 degrees.

Re: Polini case matching.

Polini’s need low timing to keep temps down. I’m at 14 degrees on my E50 which is also as low as they go without opening the stator slots.

Re: Polini case matching.

mine's timed at 23 degrees and runs grrrrrrrrreat!

Re: Polini case matching.

Jimmy Cincinnati /

basically, you're not feeling the gains because that wasn't your weakest link.

This/\

But honestly, i think you took too much material out of your crankcase. The idea is to de-restrict the flow while saving as much material as you can. That's why they stuff cranks, too increase crank case pressure. I personally just ramp my ports rather than cutting it all the way down. The more you take out of the crank case the more crank case volume you have and the less throttle response you get.

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