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<  General Scootering  ~  Tuning advice for a PX200 stock Si carb?
bitbear
PostPosted: Wed Aug 22, 2007 4:31 pm  Reply with quote
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Joined: 05 May 2006
Posts: 16
Location: Saint Paul, MN

I'm running a PX200 engine with a stock carb -- and a Sito Plus -- in my Stella. I've been running a 116 main jet and it's been okay but seems a bit starved flat out.

By rights this setup should like a 118 main jet. I just dropped in the 118 and adjusted the low speed fuel screw. The idle and low end seem good -- it blips fine: no 4-stroking or racing. But when running flat out, it starts 4-stroking at the top end...

Doesn't that mean it's running too rich, and doesn't that suggest the 118 jet is too rich? Is there something else, I should try?

Thanks for any advice!

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P125 Josh
PostPosted: Wed Aug 22, 2007 5:49 pm  Reply with quote
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Joined: 23 Aug 2006
Posts: 27
Location: St Paul

http://www.scooterbbs.com/

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Matty
PostPosted: Thu Aug 23, 2007 7:31 am  Reply with quote
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Joined: 19 Jan 2005
Posts: 1323
Location: MPLS

new PX engine? Should have the 24/24 carb right? 118 should be spot on...

What speed are you at when this happens.

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bitbear
PostPosted: Tue Aug 28, 2007 3:15 pm  Reply with quote
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Joined: 05 May 2006
Posts: 16
Location: Saint Paul, MN

Matty, it's happening at the very top of fouth, flat out. I tightened (leaned) up the low speed circuit, with the understanding that it has at least a little efffect even at the top end. The idle and low speed is fine. Just starts four-stroking at the very top of fourth. I'm thinking I might try a leaner mixer, although there appears to be a huge controvery whether a BE2 or a BE4 is leaner -- the Si 24e carb comes stock with a BE3 mixer.

Anyway, any help or ideas are welcome!

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bitbear
PostPosted: Wed Sep 05, 2007 12:12 pm  Reply with quote
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Joined: 05 May 2006
Posts: 16
Location: Saint Paul, MN

Well, it is all cleared up. Research revealed an article and comments indicating that the low speed circuit has at least a little affect even at full throttle. On the basis of that I turned in (leaner) the low speed mixture screw farther, nearly all the way in. It is now between 1/4 and 1/2 out from seated -- and everything fell into place!

The low speed circuit is excellent, blipping perfectly, no 4-stroking/burbling at full out and best of all the PX200 engine and Sito+ exhaust LOVE the 118 main jet! Performance is noticibly increased -- it amazing how much stronger it is at virtually all RPM.

Thanks to all for taking the time to try to help...

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