Pinasco 251 advice
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Member
Vespa T5 251, Lambretta GP200
Joined: 27 Jul 2019
Posts: 40
Location: Leeds, England
Tue Nov 17, 2020 1:29 pm quote
TIA and thanks for all your previous posts. They've helped.

I am unable to find a 30mm PHBH Sinister rubber mount type carb for sale in the UK but I have other carbs sat here that I could use. (28mm PHBH dextra, 28mm and 32mm PWK).

I was just trying to follow the advised set-up in the very limited instructions as a starting point which are:

PHBH 30mm

60 pilot
AV268
40 slide
X3 Needle
145 > 135 MJ

I'm just wondering what the equivalent jetting would be to other carbs, preferably one that I already have!

I am definitely being a bit cautious here because besides the ride for MOT I will probably not use this until next spring and if I do it will be short rides in city traffic.

Thanks guys.
Ossessionato
Joined: 26 Oct 2015
Posts: 2967

Tue Nov 17, 2020 2:34 pm quote
What size needle seat are you using?
Lurker
Px200
Joined: 02 May 2021
Posts: 3
Location: Hong Kong
Sun May 02, 2021 12:36 am quote
Hi RunLikeSlug
I have a Pinasco 251 too with PHBH 30mm

Here are my jetting I have email Pinasco and they replied me the best needle is X7 or X25 on 30mm PHBH.

Below are my jetting with air filter
Idle 58
1.5 turn out mixture screw
AV268
40 slide
X7 2.5 or 3 clips
Main jet 142
Running pinasco 251 valuable timing ignition CDI
However when I climbing hill I heart a lot of piston ring noise! On 1/3 to 2/3 throttle. But no piston ring sound on flat road. Kind of like ttttttttt…… Sound. after getting the rev over to 5000rpm the sound is gone. I also tried x13 needle from 1,1.5,2,3 clips. Clip 1 give me a good response too but piston ring noise again. I order the x7-13 needle from MB scooter will see how it goes with that.
RunsLikeSlug wrote:
TIA and thanks for all your previous posts. They've helped.

I am unable to find a 30mm PHBH Sinister rubber mount type carb for sale in the UK but I have other carbs sat here that I could use. (28mm PHBH dextra, 28mm and 32mm PWK).

I was just trying to follow the advised set-up in the very limited instructions as a starting point which are:

PHBH 30mm

60 pilot
AV268
40 slide
X3 Needle
145 > 135 MJ

I'm just wondering what the equivalent jetting would be to other carbs, preferably one that I already have!

I am definitely being a bit cautious here because besides the ride for MOT I will probably not use this until next spring and if I do it will be short rides in city traffic.

Thanks guys.
Member
Vespa T5 251, Lambretta GP200
Joined: 27 Jul 2019
Posts: 40
Location: Leeds, England
Sun May 02, 2021 10:32 am quote
As it happens I have only just started getting this set up. So far I am at:

PHBH 30mm Open
X4 needle top clip
AV268
40 degree slide
60 pilot
145 main.

It still runs rich up to half throttle stuttering and lumpy. Once past half it takes off like a rocket ship!!

I have tried X25 with 45 degree slide and 58 pilot which was much better (yesterday) but I just changed it back as changing 3 things at once did not really tell me which bit was working. So I will do it 1 thing at a time with a test between each.

I think X7 will be too weak, you describe pinking which is that high pitch tat,tat,tat. That is the result of being weak.

My needle changes from rich to weak is/will be X3 > X5 > X32 > X4 > X25 > X2 > X13 > X7. (From broadys tech site).

I feel I might end up with X2 but definitely not X7. I'll update this post once I get there! If only all the dyno's were not booked up for months!
Lurker
Px200
Joined: 02 May 2021
Posts: 3
Location: Hong Kong
Sun May 02, 2021 7:29 pm quote
Exactly sound something like this high pitch tat,tat,tat.

that why I change to X13 1.5 clip with AV268. still not really good from 1/3 to 2/3 throttle

Pinasco also recommend me to try x25 with 45 or 50 slide.

Good to see people share the 251 jetting here. I will try your latest setting on tomorrow.

funny thing tho, with x7 needle I need 142-145 main. guess main jet is helping 2/3 throttle.

unfortunately we do not have dyno in HK. will wait to see your jetting after your dyno test run.

i will also try
x2 needle 1.5 to 2 clip guess still need 45 slide to help reduce the fuel on 1/3
Lurker
Px200
Joined: 02 May 2021
Posts: 3
Location: Hong Kong
Fri May 07, 2021 2:05 am quote
Hi RunlikeSlug try your x4 top clip needle on AV268 still heard the piston ring noise! But not really noticeable! But I guess you getting there with 45 slide x25 av268 145mj. Maybe x2 with AV266 and 45slide help reduce air on 1/3 til half throttle! But still give good oil to lube the piston and ring. Will try then once part arrived
Member
Vespa T5 251, Lambretta GP200
Joined: 27 Jul 2019
Posts: 40
Location: Leeds, England
Fri May 07, 2021 11:48 am quote
I am awaiting some different atomisers (AV266 and AS268) as I am fairly happy with the Pilot and Main but still a bit rich from just off idle to three quarters. Not being an expert and very little info from other owners of our engines out there...I'm forced to tinker!!



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