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Post by breezer on Dec 22, 2007 13:15:07 GMT
Been at chis this morning talking to Martin about the engine I'm building. I was gonna put a 2.56 primary on it, but he reckons that's too tall for a polini 130 with matched cases and no REAL tuning. Whats everyone think - I'm sure he knows his stuff, but I just want to avoid having a bike that revs its tits off. He also said that the 2.56 primary on my primmy may be the reason its not getting past 55mph, and jumping out of 3rd & 4th when the power band kicks in. Been looking at SIP and they reccommend a 2.56 for 105 - 130cc engines  My other options for prim and project engines are 2.86 primarys Gentlemen, your thoughts pur-lease? |
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Post by tony on Dec 22, 2007 15:33:04 GMT
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Post by breezer on Dec 22, 2007 15:47:12 GMT
Yeah seen that Tony, cheers
Same one is on ET3.it - however I'm not convinced that a standard Primmy / ET3 ratio is higher than a 2.56 upgear kit!!!!
According to that standard 125 is 2.54!
Even taking it into consideration, it doesn't really say how much tuning work is required to be able to pull which ratio
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Post by adspeed on Dec 22, 2007 16:50:30 GMT
I too run the 2.61 - 23/60 Polini on my Parmakit.
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Post by breezer on Dec 22, 2007 17:13:04 GMT
Right so 2.56 probably IS too tall on my polini 130 (primmy)  and will probably be too tall on this one. Ad, you've got zirri short 4th though havent you which will raise the gearing again? It just feels like I should have something in between - maybe a 22/60 Tony what spec is your road bike? |
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Post by tony on Dec 22, 2007 18:03:53 GMT
hi breezer..my road bike is played with.. t5 cyl,wiseco, crankcase reed etc. it does rev-10,000 peak power-over rev to nearly 11.
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Post by breezer on Dec 22, 2007 18:05:30 GMT
large frame?
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Post by tony on Dec 22, 2007 18:10:17 GMT
large frame  NO! defnately not.. it below mate...  |
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Post by breezer on Dec 22, 2007 18:13:25 GMT
Was what made me ask  |
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Post by breezer on Dec 22, 2007 18:14:09 GMT
What exhaust is that - and what is it painted / covered with?
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Post by tony on Dec 22, 2007 18:16:31 GMT
its actually a few! the body is a taffy proto blown by john howe but is cobbled to a kegra downpipe. Graham at kegra made it for me.
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Post by tony on Dec 22, 2007 18:17:16 GMT
oh and its bare metal lacquered.
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Post by hank on Dec 22, 2007 18:26:25 GMT
all very confusing.......  so whats the std primmy/pk125 gearing - 2.56? just got a pk125 primary drive/cluch basket which i was going to put in my pk80 engine (upgraded to either 125 ets or maybe polini/malossi). maybe i should keep the 80 gearing? |
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Post by breezer on Dec 22, 2007 18:32:56 GMT
how many teeth are on the basket and the cog? You divide the basket by the cog to get the ratio. According to the www 125 gearing is 2.54? ? 2.56 is an upgear so I don't think so. I would have thought it would have been very similar to 80/90/100 gearing |
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Post by hank on Dec 22, 2007 18:44:15 GMT
2.54 is the std pk125 gearing then
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Post by breezer on Dec 22, 2007 19:09:44 GMT
Just checked in my Norrie Kerr book and he lists 2.54 as primmy ratio. How does a standard primmy pull that? ?? |
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Post by tony on Dec 22, 2007 19:16:19 GMT
well they dont rev very high mate. so seems about right..62mph at 7000 rpm.
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Post by adspeed on Dec 22, 2007 19:17:35 GMT
Breezer, I had the Malossi before the Parmakit without the Zirri 4th. The barrel was fairly well tuned but 4th was always a cruising gear it wouldn't pull at all, this was with the same Polini setup 23/60.
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Post by breezer on Dec 22, 2007 19:18:22 GMT
But then why would a polini 130 struggle to pull a 2.56?
I would have thought a polini 130 had more torque than a std primmy?
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Post by breezer on Dec 22, 2007 19:20:40 GMT
I think come the better weather I will bring the primmy for you to have a look at Ad. It needs taking in hand. I have a spare 2.86 so it may be worth trying that. I also think the cruciform / spring / shimming needs a review. Fuckinbastardmopeds |
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so whats the std primmy/pk125 gearing - 2.56?