Polini 180 upgrade

[KyleGosling]

Hi fella's first post on the forum, I have a px 150 and am going to covert to a polini 180 kit. Already have a polini exhaust.
Of what reserch ive found ive read that its best to use an si 24 carb, but what size idle and main jet should I use, also the ideal squish if anybody has any ideas. Any other pit falls I may come across also what be great.
thanks

[goldeneye]

122 or 125 main, 55/160 pilot, BE3 middle jet, and 140 air corrector with a drilled air filter. better if you get the cases ported and the crank cut to suit, although you can fit them straight on. look out for a tight piston to bore clearance, take it to a motorcycle engineers or engine rebuild shop, and get it honed out (just give him the barrel and piston , no need to give him the rings) ask for 4 thou clearance, itll cost 10 quid or so, but that's less than a piston. use cheap oil to run it in, and leave it on high tickover as long as you can . add a little extra oil (1%) to the petrol tank (if you already mix in the tank, 3%) good kits, had a bad rep for seizing , but they are just tight from new. squish? 1.5mm.

[KyleGosling]

Thanks for the info will be a great help, just out of interest would I notice a marked difference in performance between an up jetted 20/20 and an up jetted 24/24 with the polini kit?
Thanks

[goldeneye]

I would go for the 24, cheap enough and plenty 2nd hand. put an advert up that you want one on here.

[KyleGosling]

Thanks for the help. Are the polini piston rings good enough or isit worth getting better ones?

[fastfrog]

fine enough.... don't bother with rings: You're only dealing with an iron low cost barrel....

[Muttley McLadd]

How 'on the cheap' do you want it to be?

If you're just going to bolt it on without matching the cases or matching the carb, or upgearing it, or putting a cut crank in, you're not going to get the full benefit of the kit anyway. The performance will be better, albeit not as good as it could be.
It seems like a lot of effort and expense to go to over a bolted on DR kit that is a lot cheaper.

[Richjak]

I had the polini 177 kit it was all standard except for porting the casings, nipping 20mm off the standard crank web and fitting a 24mm standard P2 carb.
For a relatively cheap kit this absoulutely flew compared to how it was as a standard 150 lump. If youre going to get a kit for your engine i would definately get the casings matched to the new cylinder and trim the crank web by 20mm It will maximise what you are getting out of the kit, overwise it will just be a waste of money fitting the kit in the first place. Rather like having a V8 engine in your car and only ever using 1st gear.

BTW i also run the polini pipe, its an excellent all round sports exhaust that coes into its own on a kitted engine.