LCGB Forums

Posted: **Mon Sep 19, 2016 10:22 pm**

Hello Brothers
After an embarrassing length of time(years :oops:

) I have finally by process of elimination found that a Mid Range lean spot of my 30ml PHBH must be my slide, I have a 40 at the moment and understand they go up & down in multiples of 5 so to go Richer do I want a 45 Slide?.... as they are pretty expensive to buy more than one
Thanks
Mark

Posted: **Mon Sep 19, 2016 11:29 pm**

I believe the number relates to the size of the cut away so higher means weaker. I'm no expert but 40 is fairly standard, I've only heard of people going leaner not richer but could be wrong.

Posted: **Tue Sep 20, 2016 12:44 am**

The cut-away on the slide (from front to back) is denoted by the number.

The higher the number, the greater the difference will be.

The greater the difference, the weaker the slide will be.

To go richer from a 40 would be a 35 or less.

It is worth mentioning that it is relatively straightforward to remove material from a 35 slide, say, & convert it to a leaner slide such as a 40 & so on.

Posted: **Tue Sep 20, 2016 8:48 am**

Mark it may not be as simple as changing the slide.

Mid range mixture is controlled by the Atomiser , slide and needle in combination.

Could you remind us what atomiser and needle you currently have fitted to the carb and which part of the throttle range you are getting a lean mixture .
It is helpful to put some masking tape around the throttle lever housing and mark the idle position and the wide open throttle position. Then mark the centre position between them. Lastly mark the midpoint of both halves and you'll have 4x equal sections which will help pinpoint exactly where your problem lies and what you'll need to change to improve the running.

Posted: **Tue Sep 20, 2016 7:13 pm**

Thanks for the interest in this matter Gents, I am running....

Classic Rapido bored to 225cc and NK Rally pipe & Li 150 box

Atomiser AV266
Needle X13

....the pinking occurs about 3 Quarters throttle when the speed of Scoot in 4th is about 50/55mph but it does clear about 60mph as I open up the throttle further, it pinks just at the point where I really need to cruise in comfort on Motorways/A roads as I say its been a long term problem and maybe I have just not got the combination right of Needle/Atomiser

I have just changed the needle to the X13 from the X7 and its accelerated so much better with the X13 and is showing a more healthy plug colour but this mid range leanness persists, did a quick check on a few set up on this forum & Scooterotica one and I did not see anyone running a 35 slide so maybe this is not the solution

Any further ideas would be very welcome

Chhers

Posted: **Tue Sep 20, 2016 8:49 pm**

Post by Wee Mark » Tue Sep 20, 2016 7:13 pm

Thanks for the interest in this matter Gents, I am running....

Classic Rapido bored to 225cc and NK Rally pipe & Li 150 box

Atomiser AV266
Needle X13

....the pinking occurs about 3 Quarters throttle when the speed of Scoot in 4th is about 50/55mph but it does clear about 60mph as I open up the throttle further, it pinks just at the point where I really need to cruise in comfort on Motorways/A roads as I say its been a long term problem and maybe I have just not got the combination right of Needle/Atomiser

I have just changed the needle to the X13 from the X7 and its accelerated so much better with the X13 and is showing a more healthy plug colour but this mid range leanness persists, did a quick check on a few set up on this forum & Scooterotica one and I did not see anyone running a 35 slide so maybe this is not the solution

Any further ideas would be very welcome

Chhers

By my reckoning, an X13 is ‘richer sooner’ than an X7, so, dependent upon whether you’ve got as far as the ‘bottom clip’, you have an X2 to fall back on as it is ‘even richer sooner’ than an X7.
You probably aren’t too far off with your settings.

As for the rest of the set-up, you should only be a nat’s away from a big bore Rapido I jetted in that utilised a 40 slide:

Pilot: 55
Mixture: 3 turns out
Main Jet: 132

I hope those 'Ball Park' figures help...

Posted: **Tue Sep 20, 2016 8:54 pm**

the problem with changing your slide is that it effects the entire rev band from idle to WOT ....Changing your slide cutaway might improve your mixture at 3/4 throttle but will probably find you then have issues at another parts of the throttle range which will require other changes

As every other aspect of the rev band is satisfactory my feeling is that the solution may lie with either changing your needle profile or your atomiser.
This thread might prove interesting http://scooterotica.co/forum/viewtopic.php?t=31950&p=236961

Posted: **Sun Sep 25, 2016 9:40 pm**

Thanks so much Gents, still struggling but got a few ideas, really appreciate your input

Posted: **Sat Nov 12, 2016 8:18 pm**

I've been trouble shooting a PHBH with exactly the opposite to you, half to three quarters it was too rich, I had an X2 and ended up on top clip. Still to rich.

Just swapped to a X7 on the third clip from the bottom and it is running fine now. No chugging through the rich spot. I didn't swap the atomiser or anything else.

I also had a 60 slide and swapped to a 40 and TBH there was no noticeable difference when riding. Maybe the 40 ticked over a bit better but you'd be hard pressed to tell for sure. The needles work as follows Lean X12 X7 X13 X2 X25 Rich

Posted: **Sun Nov 13, 2016 8:03 am**

Sounds more like an air getting in some where to me have you had it tested . . col

Posted: **Mon Nov 14, 2016 9:25 pm**

Thanks for the latest input on this thread, I did buy an X2 needle but even on the top clip it was too rich BUT when I opened the carb top to change it my X13 needle was on TOP clip too :oops:

so I do have a couple of lower clip positions to try as bottom position was too rich & it bogged, I will repost when I get to test lower clip positions as it may help others, yes Col I have done a leak down test a few times but worthwhile mentioning...
Cheers

Posted: **Mon Dec 12, 2016 12:15 am**

Hello again,
2nd Clip down on X13 Needle seems to be nearly perfect on this Scooters set up, I took it for a long awaited blast today and it went fantastic all the way through the range!!!
Cheers for all the input, I really had not realised how much work and trial /error is need to get it spot on, stick with it, is my advice to anyone else Jetting
Mark

Posted: **Mon Dec 12, 2016 2:27 am**

Thanks for making the effort to supply feed back.

I'm sure everybody appreciates it

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