Polini Evo

[mhart9df]

I am just looking for a little help in the way of a polini evo kit. I have a P125 ETS that it reliable and I use for day-to-day riding. I am looking to now build much more fun engine that I can ride at the weekends. I have a PK 100 engine with an old DR 135 kit. I was wondering whether it would be worth putting a polini evo reed valve kit on, and uprating the clutch, crank and everything else to go alongside. I am working on a budget as I am only 17, but due to the lockdown I will probably have around £1500 to spend. So was just wondering what is best? Should I reed valve or buy another type of kit? What size crank and carb etc. Any help would be gratefully received. Thanks, Matt.

[boreham]

Hi Matt, good luck with the upgrades!
The Polini Evo is a great kit, however is a high end unit and needs quite a bit of machining work and cost to get the intended performance out of it, the casings need heavily porting and machining on the flywheel face for the large transfers to avoid fouling on the casings.
The EVO also need a specific crank etc... and if set up correctly can be up to 20bhp so a good clutch and exhaust are a must, there’s £600 alone so £1500 is tight when you start adding everything up with variable timing £300, gearing £200, kit £350, crank £200 etc......

For that price you could build a good torquey road motor based on a rotary M1, there are alternatives with VMC pro cup or Pinasco, which you can reed valve on a budget without the direct intake, however a well set up rotary motor will give you the upgrade and a lot of ride ability and fun and give you change out of your budget.

Building a high end smallie is a costly project!
Do the research and ask a lot of questions, there are so many variables and mismatch parts which can end up costing you a lot of time and money and there’s probably a member who has tried the parts

[jonnysnatchsniffer]

ive had both versions of the evo so this is my tuppence worth
the evo rotary just needs the top of the flywheel seal by the gasket face chopped off, you can do this with a hacksaw or small cutting wheel in a dremmel, the transfers need to be cut to match the barrel which does have a lip around the transfers to fit on a standard case without milling, theres not much if any power to be gained by having huge transfers at the gasket face, if you have a genuine piaggio large taper crank, id say this would be ok too, i used a cut ets crank, a bgm superstrong clutch would be fine on standard 125 primarys or 27/69 i used 29/68 as i was using a drt runner tree and 300/10 tyres, the drt runner tree is essential to keep the gears nice and close together, i would use and did a franz pipe and raise the exhaust port to 185 degrees with a 0.9mm squish, i would use a keihin pwk carb 28-35mm, the inlet port needs a bit of work taking the pad out to it full size leaving a 1mm seal all around but then all rotarys should do this, cut he crank also to increase inlet timing, or if you do need to buy a crank then i suggest the bgm rotary crank 51/97

the evo reed is very similer but has a bridged exhaust port, its also designed to use a polini 53mm stroke crank but its fucking costly so i used a bgm 54 stroke with a 105 rod, you will also need a packer under the barrel, the case needs to be cut where the crank webs sit by 1mm, i am using a big bertha pipe, the clutch is a hartz 4 and i use 29/68 primarys, i had lots of trouble with the supplied 30mm inlet manifold as it was nowhere nearly working in my vma1 frame which is somewhat smaller than later v range and pk frames so i had one makde to fit a 38mm keihin pwm carb, with this motor you will need to use a drt f1 runner tree which is stronger but will then need 1st gear milling and spaces on the tree, clutch primary, kickstart etc

that obviously not the whole story but you get the jist of the amount of work that is needed with lots of expensive scooter porn to be added to that

a bolt on iron polini with polini snail and 24mm carb will give you a genuine 11-12hp at the rear wheel, thats about 3 or 4 more than the ets so around a 40% increase in power, now change the pipe for a franz do a little work on the exhaust port to raise it to say 180 degrees, cut 15 mm of the crank, open up the inlet enough just so you dont break thru the case and you will probably be loking at around 15-17 hp which is double that of the ets, new primary and bgm clutch and you are pretty much in budget, you could also tune the polini futher to around 20 -22 hp with the right parts, all the kits need work out of the box to perform properly as a lot of them are undertuned to preserve the life of it
any other midrange kit like those above in borehams post will be the same, i just chose the iron polini for its cheapness and near bulletproofness when set up well

[mhart9df]

Thanks very much for the fast replies, I have a polini iron kit sat in the box in the garage at the moment. A 7 port with the aluminium head, would that do the job? I will be able to get help and advice on both porting and cutting down things like the crank, but if I were to use the polini iron would I be better off buying a new crank, rather than using the standard piaggio one? As this will be near enough my first time kitting up an engine I feel that this is the best way for me to go. Would a dellorto 24 carb be best? Or something larger?

[henri]

wot johhny said , but a new ets/pl170 crank bout £60 from stoffis garage , cut , an top n tail the polini barrel an open transfers . if ya look on 10 pollicci a vmc ignition an short 4th tree comes in at around £220 . add in new bearings n seals , gaskets , clutch plates an polini spring , an a polini exhaust . 24mm inlet n carb . with the kit already your looking at under £500 an bout 14-15bhp .H

[rhys]

Sorry to Hijack the post.
Hi Jonny,
I have near enough the identical set up with the Polini Evo direct and was wondering what sort of power you are getting out of yours?
Just rebuilt mine with increased port timings and new clutch but haven't had a chance to put it on the dyno yet.