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Post by shaunpx on Nov 18, 2012 20:25:23 GMT
I've got a px200e with electric start to which I'm fitting a Harry Barlow stage 4 207 top end T5 fourth gear and revolver exhaust. Im thinking of leaving the electric start off and have been told that the flywheel can be lightened by removing the starter gear from the back, my question is woud this be of benefit with the above mentioned set up if so how do you remove the gear from the flywheel?
Shaun
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Post by kru251 on Nov 18, 2012 21:06:27 GMT
Lightened flywheels have less rotating mass so 'spin-up' quicker with revs, but with less rotating mass this can lead to a more snatchy low RPM running as the firing strokes are less balanced. Much better on two strokes (than four strokes) but this change of mass can increase vibration harmonics and also strain gearbox components more than normal due to the snatchy 'on/off' feel with the flywheel.
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Post by sbwnik on Nov 18, 2012 22:36:38 GMT
I run this set up, TBH it doesn't make a world of difference - I think binning the weight of the starter motor had a better effect! Seriously, yes it does spin the engine up quicker, and with that engine you'll notice the difference.
I can't remember the difference in weight if you remove it, but it's there.
One thing though... A friend of mine is Oz who built the TS1 powered P range (because someone told him he couldn't do it) and the Rotax powered small frame (because someone told him it was a stupid idea!). He's been employed by a top car race team to build engines, and owned his own performance car tuning business - OAP Racing - so knows exactly what he's talking about when it comes to building fast engines. He is my first stop for advice on my own 207 reed valve engine. (IIRC Diablo Al says much the same thing and won't run them on his fast engines.) He says he'd not run a seriously lightened flywheel on a fast engine as the clutch will then have greater centrifugal force acting on it, causing it to act like a flywheel. In his experience, if you want to twist a crank then this is the best way to do it. Get the crank pin welded....
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Post by shaunpx on Nov 19, 2012 8:04:48 GMT
Thanks for the feedback fellas I've been looking online for info but sadly there's very little so I'll try it with the ring gear left on and just remove the starter motor and see how that goes ,when Harry delivered the kit he mentioned that the flywheel was already lightened I don't know if that meant with the ring gear left on though?
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Post by sbwnik on Nov 19, 2012 21:53:01 GMT
You want to see a lightened flywheel, I'll post a pic of the one for my 207. The clutch has also had some modification, but until proven, I'm not posting pics of that.
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Post by shaunpx on Nov 19, 2012 22:40:37 GMT
Yes mate i would be intrested to see what it looks like if your offering cheers, also how do you find your 207 performs compared with standard nic?
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Post by sbwnik on Nov 20, 2012 16:46:14 GMT
Not got it built yet, it's being a very slow build.
It's not quite a stock Polini 207, crank's cut to hell, ports are opened up nicely, reed valve that sits really close to the crank (more so than usual), old Mickek exhaust etc etc! I'm thinking of running a P125 gearbox as I want it as a round town sprinter rather than as a long range machine, hence having to modify the clutch. If all goes like I think it will, I'm considering taking up racing with it.
It's got the makings of a very expensive explosion coming up!
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Post by shaunpx on Nov 20, 2012 23:09:49 GMT
Your 207's different to mine then nic ive got the one with the bored out raised and tuned standard barrel and upjetted standard carb. I spoke to harry today and he said just take the ring gear off that's what he does and lightens them further without any problems the flywheels to avoid in his opinion are the hp 4's which are to light and can cause clutch damage etc.
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Post by sbwnik on Nov 21, 2012 21:32:29 GMT
Yup, it's a well documented issue. They're nice and light, but you need your crank pin welding and machining, and something doing to the clutch to balance it. If you want to REALLY cause problems for yourself, combine it with one of those cranks whose name starts with M - Mazarochi or something similar? That was the first twisted crank I ever saw, and it totally ruined the engine casings too.
I take it yours is the HB Tuning one with the packing plate? They're bloody quick machines, and are what I intend to do to the P2 one day - does he still recommend a Sito +?
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Post by shaunpx on Nov 21, 2012 22:27:55 GMT
I'm not sure what other pipes he recommends my P2 already had a stainless Revolver fitted when I bought it and he rates them. Yes its the standard barrel which is ported with the packing plate uprated piston with thin wire type rings, he mentioned a guy he done one for that used to have his 218 set up with the 60mm crank thought it was better so touch wood there'll be plenty of power on tap.
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Post by sbwnik on Nov 21, 2012 23:40:53 GMT
Wire type rings are late Cosa pistons, aren't they?
I think I have one somewhere.
Harry's making his own pipes too isn't he?
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Post by shaunpx on Nov 22, 2012 9:05:12 GMT
Sorry nic I can't answer either of those questions for you, however he told me that he had the pistons specialy made by a moto x bike company, I don't think its a cosa as its quite a substantial 208 piston with larger transfer cutouts around the side
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Post by sbwnik on Nov 22, 2012 10:59:42 GMT
Definately not then, the Cosa piston looks the same as the P2 one in all but rings. I'd not mind a look at them though, I suspect it's more likely to be an off the shelf part of unknown origin, same as you'd find in Lambrettas in the 80s. Interesting....
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Post by shaunpx on Nov 22, 2012 12:43:58 GMT
I wouldn't like to say nic all it says on the box that the pistons in is vespa and pro porting there are no other details.
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Post by sbwnik on Nov 22, 2012 14:16:32 GMT
Got any pics and measurements? I bet I know a man who could find it...
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Post by shaunpx on Nov 22, 2012 17:27:44 GMT
Sorry no pics and haven't a clue how to post em if I did. The only measurements on the box are 68mm and 1.2mm wire rings the only other detail is that it has sc stamped on the piston crown just above the arrow pointing toward the exhaust port the dims of the 2 transfers next to the gudgeon pin are 23mm at there widest point by 30mm and the transfer on opposite side to exhaust near the base of the piston is 25mm wide by 15mm high hope that helps
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Post by sbwnik on Nov 22, 2012 23:35:35 GMT
Not really, but thanks anyway!
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Post by shaunpx on Nov 23, 2012 16:21:31 GMT
I still haven't found out how to remove the starter ring?
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Post by kru251 on Nov 23, 2012 20:58:05 GMT
Took this off the VCB site (and cleaned up the spelling and grammar !) The aluminium flywheel is obviously a lot softer than the hard steel starter ring. At my first attempt with a flat lever bar I broke a small sliver off the flywheel in between 2 fins. but did not prove to be a problem; more annoying than anything. If you have some gear pullers its quite easy. The next time I stuck the flywheel in the freezer for an hour and then slowly worked my way around the cog, prying it little by little, always levering against a fin and not inbetween. This way was ok and I've done it twice like this. The starter ring is not actually that tight ! Might help you!!!!
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Post by sbwnik on Nov 23, 2012 21:23:04 GMT
Drill it off. Three holes spaced around the rim, the ring will flex at these points and come away
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Post by shaunpx on Nov 23, 2012 21:55:10 GMT
Thanks lads
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Post by sbwnik on Nov 23, 2012 22:05:48 GMT
I'm just so ghetto sometimes.
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Post by shaunpx on Nov 24, 2012 9:16:09 GMT
In that case a Ali G style "Westside!!!"
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Post by kru251 on Nov 24, 2012 9:51:32 GMT
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Post by shaunpx on Nov 24, 2012 9:57:28 GMT
Ayyyyye! ;D
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Post by kru251 on Nov 24, 2012 10:48:01 GMT
We need a laugh so .................... ;D
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Post by sbwnik on Nov 24, 2012 15:24:42 GMT
That looks worryingly like me. Replace the hat with a flat cap though
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Post by shaunpx on Nov 24, 2012 16:55:13 GMT
Respect to the Scunny massive!
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Post by sbwnik on Nov 25, 2012 21:26:21 GMT
Innit.
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Post by shaunpx on Nov 26, 2012 10:51:41 GMT
Selecta!
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