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Post by wealdenwasp on Nov 28, 2015 10:29:47 GMT
Just got a PK 50. I'd like to derestrict it if possible and get as much oomph as I can out of it but I don't want to go down the big bore route ....yet.
It has a Giannelli exhaust already but has a standard 16mm carb and inlet.
I get that I need to lob a bigger carb and inlet on to derestrict it but there are a fair few on the market.
I've been advised to get a 19/19 Dell'Orto carb and the requisite Manifold/inlet.
Mine's a 1987 model and there seems to be a lot to choose from.
Two questions:
Which set up should I buy and from where? ( Manifold and carb combos on SIP seem good to me)
Will this make much difference ? ( What with the exhaust I've already got on it)
and a third question.....
Should I change the gears? ( I'd rather not, my experience with motorcycles makes me weary of splitting cases if I can avoid it.)
Many thanks and apologies if this is already covered.
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Post by Juan on Nov 29, 2015 21:20:44 GMT
Not that clued up on the later PK's so I'm not sure of the primary ratio on yours but I know certain models ran longer gearing than most of the earlier stuff.
Depending on your later plans I'd go for either an ETS/ Motovespa 20/20L carb if you were thinking of a bigger kit eventually or if keeping it with a 75 or 85 kit a 16/15 or 16/16 will be ample with the exception of the Polini 75 Race and possibley the DR 75 F1. SIP is likely your best bet if buying new, Scooter Center Cologne are also worth looking at.
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Post by Juan on Nov 29, 2015 21:35:57 GMT
Just had a look in the gearing guide and it seems you could have one of a few options. You could pop off the clutch cover and give the small cog a rough count to see what it has, if it's running a 14/69 you can drop a 16 tooth in there to lengthen things a bit.
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Post by wealdenwasp on Nov 30, 2015 7:27:13 GMT
Thanks, good advice. Are they all similar or will I run into the usual minefield finding the right one?
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Post by potatopl on Nov 30, 2015 7:35:26 GMT
My mate run 50cc for some time. After modifications it went true 60km/h:
- transfer ports opened at the cylinder and matched with casings - exhaust port slightly raised - 19.19 carb - LeoVince SecSys exhaust - Pinasco 16 tooth gear cog
If you really want to stay with 50cc you can look for the original HP4 cylinder kit, I guess it was the best kit out of the original ones/
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Post by Juan on Nov 30, 2015 16:58:40 GMT
The Pinasco ones are fine, haven't used any others but I believe DRT also does one now. If you are looking for a HP topend I have, barrel, piston, 'head, barrel studs,cowl and crank I'd let go for what it owes me.
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Post by wealdenwasp on Nov 30, 2015 18:48:13 GMT
Thanks chaps, the HP top end, does it have all the aforementioned porting and that?
Is the changing of the front cog a simple enough operation? Is it a straight swap? I can't find a video or diagram that shows the procedure.
I gather it elongates the top gear and gives a bit more top end like dropping the teeth on the rear cog of a motorcycle or upping the teeth on the primary etc.
Does it make it crawl uphill? I'm 15 stone of bricklaying glamour me.
Mine's only got a three speed box. Should it have?
I hear it's a pain in the 'arris to change them to 4 gears and is it necessary?
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Post by Juan on Nov 30, 2015 21:22:08 GMT
Yeah, the HP is in a higher state of tune taking the porting layout of the SS 50/ 50 Sprinter. Changing the cog is easy enough if fiddly. Have a look in the tech sections of smallframes.com and scooterhelp for an idea on what to do. HP's ran gearing a fair bit longer than what you're looking at so you should be safe enough.
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Post by wealdenwasp on Mar 17, 2016 22:43:48 GMT
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Post by vinrouge on Mar 17, 2016 23:50:42 GMT
Think that's for an auto with the brass oil and vacuum pipes, worth asking the question of the seller tho or if it's an easy conversion
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Post by potatopl on Mar 17, 2016 23:54:59 GMT
You can get 2 versions of this carb: rubber or clamp mount. I used the clamp mount on standard SHB 19.19 manifold + PTFE reduction. For the rubber mount you will also need to make a reduction (about 2-3mm diameter difference). If you could get a complete SHBC19 or SHBC20 carb from here it would be easier. If not your plan should also work.
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Post by potatopl on Mar 17, 2016 23:59:34 GMT
Think that's for an auto with the brass oil and vacuum pipes, worth asking the question of the seller tho or if it's an easy conversion Oil/vaccum banjos can be blanked.
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Post by henri on Mar 18, 2016 14:15:59 GMT
think thats a 4 stroke carb ,might be wrong, if it is it will need atomiser changing to a 2 stroke one . ive a zip 50cc 2 stroke carb , 19mm clamp on , but its electric choke .if you want to work with that Pm me . H
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Post by potatopl on Mar 18, 2016 18:13:41 GMT
If it's got an oil banjo it must be 2 stroke henri
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Post by wealdenwasp on Mar 19, 2016 6:57:11 GMT
From where Mr Potatopl? Help!
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Post by potatopl on Mar 19, 2016 7:33:30 GMT
"The intenets" PHBG19-21 are the most popular tuning carburators for Twist&Go scooters. You can get the genuine dellorto or copies of different quality from stage6, tec to chinese no-names. I'm not from the UK so don't know the shops you are using, but check any automatic scooter online-shop, or 'craigslist' type page for second hand ones. Ebay link
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Post by wealdenwasp on Mar 20, 2016 13:18:51 GMT
Mine's not an auto though, it's a three speed.
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Post by henri on Mar 20, 2016 14:45:33 GMT
good point about the oil feed potatopl ,i missed that one . an it doesnt matter wether your auto or geared to the carb choice . H
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Post by potatopl on Mar 20, 2016 14:46:44 GMT
I know your's not an automatic I'm saying that you check auto-scooter shops in search of a carb.
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Post by wealdenwasp on Mar 23, 2016 16:07:15 GMT
Thanks Potatopl, it's me , I'm as slow as my scooter sometimes.
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