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Post by lardyconvert on Sept 24, 2009 22:26:55 GMT
Hi Guys, Well i took you advice and have been "ragging" my polini with excellent results. It is damn fun and i earned an all time classic quote from the policeman who pulled me over one evening as i was "riding it like i stole it"! I explained that my knee only looked close to the ground as it is such a small bike.....  Any how, i am taking the opportunity of a loose stud that is causing a little leak at the head and barrel to pull out the dremmel again while i have it apart to put in new longer studs ;D I have found myself a spare polini cylinder, got a machined (13.5:1 / 1mm squish) malossi head from Worb5, and a 5 mm packing plate and am ready to get started! Apart from getting a local machinist to lathe 3.2mm off the bottom and 1.8mm off the top, opening up the packing plate and cases so the boost port breathes a bit......what else can i do to warm things up? So, without giving away trade secrets, does any one have thoughts? Re the cylinder, photos or maps of what i can grind away would be great. I am guessing the exhaust as also a prime spot as it looks really restrictive. And the piston that came with the cylinder is a beast with skirts about 4mm thick.... should i just buy a grand sport piston? I am going to keep running this with my PM40 and rotary valve / 24mm phbh (for the moment)....and keeping my std polini barrel as a back up in case it all gets a little wild / breaks! Lots of questions but be good to get people's thoughts..... Either way i am thinking that this should be much more fun than just buying the complete kit from Worb!! Cheers Andrew |
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Post by lardyconvert on Sept 25, 2009 0:47:18 GMT
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Post by tony on Sept 25, 2009 1:04:59 GMT
Hi.. good luck on the port work. Just a note.. the pm pipe will hold you back as this is designed for a standard motor really. I personally would look at alternatives. the Vsp3 race is a nice pipe. Designed by Stoffi for 9500 rpm or so on a 130cc motor. It should suit your one pretty well.
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Post by madmax on Sept 25, 2009 6:10:11 GMT
Open up the cylinder and exhaust ports too. That is a start. ;D |
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Post by Juan on Sept 25, 2009 6:25:25 GMT
My thoughts are that when you start looking at the cost of the parts needed, especially the GS piston, then you'd be as well looking at an alloy kit to start with.
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Post by lardyconvert on Sept 25, 2009 8:14:31 GMT
Thanks for the thoughts guys. Tony, yeah i had thought that might be the case but wasn't sure how restrictive the pipe would be..... I think there was a home fettled polini / PM from the rolling road day (Last year?) with a similar set up that seemed to have a sweet spot where pipe and cylinder were working well but not sure of the red line...... but yeah, a new pipe will be needed at some stage.... Any one interested in doing a "car park pipe swap session" in london in a month or so?  And Max, i am thinking we are on the same wave length here ;D but the size of some of those transfers was just scary on the link, they looked bigger than Falcs!! And i had sort of put the alloy kits out of my mind Juan... not sure why, but mainly because the polini only cost me £30 from a mate ..... and i had sort of forgotten to do my sums! All up i think it is costing another £60 for the head, £80 for the piston if i get it. And this is a daily driver / commuter / girlfriend carrier in central london so a kit that does wheelies in 3rd and spits out clutches for breakfast is a step further than i wanted to be honest  ....... i'll just try to keep the cost of going reed valve, lip crank and flat side carb in a 6 months out of my head! Cheers Andrew |
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Post by Juan on Sept 25, 2009 17:47:32 GMT
Okay, perhaps I'm being harsh seeing as you've already got a spare barrel so we'll do some sums.
You know you've got to spend £140 on parts if buying new so we're at £170. Without knowing how much your engineers will charge for topping and tailing as needed and probably a rebore we'll say £80. Could still worth be doing @ £250. I think the last time I saw the Worb5 GS Polini on SIP ready to go you were looking at well over £300 which I'd not even consider.
I don't know how the W5 goes but I expect it needs working and therefore will but shite if you do pillion work. Could be nice to keep as a spare for high days and holidays though.
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Post by lardyconvert on Sept 27, 2009 18:55:52 GMT
Yeah it is £361 for the full worb 5 treatment from SIP so i'm also thinking it was a bit steep! But at 250, it doesn't seem to bad... I'm looking forward to seeing what it can do compared to other cylinders at the price point when fully sorted. So, i got the Worb 5 malossi head on over saturday (after stripping a DRT engine stud  ) but the squish has gone up to 1.85mm.... from what i can see on the leaflet, it is supposed to a 1mm squish and 13.5:1 compression..... i didn't think i was going to have to machine the damn thing considering how much it cost! Not happy about that, so will give worb a call tomorrow... i hope their english is better than my german  BTW, Does anyone know if there is someone in London who i can trust to machine the cylinder? I guess readspeed is the fall back option but would prefer something close. Cheers |
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Post by jonnysnatchsniffer on Sept 28, 2009 17:10:50 GMT
have you got a base gasket ? if so you dont need it and as there usually about 0.5mm thick doing away with it will get you to 1.3 wich should be ok
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Post by lardyconvert on Sept 29, 2009 10:59:07 GMT
That's a good plan, I didn't realise that i could get away without a gasket. I'll try it out this weekend.
Thanks for the tip!
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Post by nicsar on Oct 5, 2009 14:04:18 GMT
Heres a pic of a chopped polini  Heres some more pics of the same cylinder/motor. ktylife.free.fr/vespa/KTy133/Found piccies on the net, not mine, hope no one minds me linking them.. |
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Post by ttscshaggy on Oct 5, 2009 14:10:44 GMT
 hmmm take a bit off there... and there ...fuck it take that big bit out theree! ;D
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Post by eean on Oct 5, 2009 17:05:59 GMT
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Post by tony on Oct 5, 2009 23:07:33 GMT
I think KTY races either in france or germany. Seen that name somewhere.
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Post by mistere on Oct 6, 2009 1:18:11 GMT
I can fully recommend the G.S. piston if you're topping and tailing a Polini Barrell.
Definitely widen the exhaust to near 70% of the bore, and lower it to match the piston crown height.
Not too sure about modifying the transfers in the bore- could be risky if you inadvertently mess with the symmetry of the layout
I run a PM 40 with a similar setup and it is good for over 130 Kph, accelerating smoothly but just about any newer pipe would be worth trying to free up the revs at top speed.
I'll be keen to know how things go.
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Post by lardyconvert on Oct 6, 2009 12:11:53 GMT
OMG i thought the transfers on the link from last week were pretty extreme but that is just crazy looking. I am actually wondering just how far you need to take the polini transfers to get the most out of it... they do look extreme!
And the GS piston has arrived so thanks for the confirmation on that mistere. Re the exhaust i was thinking of keeping the width to about 67% as per Worb's daily driver recommendation... but how peaky do you find your bike with the PM40? Even better, do you know how much power you are getting at what revs? Be interested to hear.
And i got in touch with Worb5 and Andy is going to send some photos/diagrams of their barrel and GS piston so i know what to cut. Then going to send the barrel up to readspeed to get it topped, tailed and rebored to the first oversize for about £100.
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Post by unreliablesc on Oct 6, 2009 19:44:44 GMT
I can fully recommend the G.S. piston if you're topping and tailing a Polini Barrell. Definitely widen the exhaust to near 70% of the bore, and lower it to match the piston crown height. Not too sure about modifying the transfers in the bore- could be risky if you inadvertently mess with the symmetry of the layout I run a PM 40 with a similar setup and it is good for over 130 Kph, accelerating smoothly but just about any newer pipe would be worth trying to free up the revs at top speed. I'll be keen to know how things go. how long does the piston/rings last at 70%? If i remember right mine ended up @ 68% |
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Post by jonnysnatchsniffer on Oct 7, 2009 13:51:45 GMT
i wouldnt widen to 70% if its your road bike used everyday as the rings aint gonna last long, i did mine to 70 but im just gonna rag mine around
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Post by mistere on Oct 8, 2009 20:59:39 GMT
the rings seem fine although my scoot is not a daily rider at all.
chamfering the exhaust port edges properly helps alot.
Last time i got stuck into the engine with the dremel I thought,
"what's the worst that could happen?" and so far,
it's been pretty good
and this thread is "butcher the polini", isn't it? ;D
My engine's not very peaky-
And I never dyno'd the thing, but it kept up with a 225 lammy that made 24ish hp
I'd listen to the worb-5 guys- it's probably more important to concentrate on getting all the parts matched for size and the gasflow smooth and unobstructed as it is to worry about maximum size.
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Post by lardyconvert on Dec 21, 2009 17:37:30 GMT
OK got my Polini back from Beedspeed and it all looks pretty good..... but what diameter should the cylinder by for a 57.5mm piston? I have measured it to 57.8mm but .3mm clearance seems a lot.
Thoughts?
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....... i'll just try to keep the cost of going reed valve, lip crank and flat side carb in a 6 months out of my head!
) but the squish has gone up to 1.85mm.... from what i can see on the leaflet, it is supposed to a 1mm squish and 13.5:1 compression..... i didn't think i was going to have to machine the damn thing considering how much it cost! Not happy about that, so will give worb a call tomorrow... i hope their english is better than my german 
