whats the verdict on 24mm PWK carbs ?

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rosscla
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Thu Aug 23, 2018 6:08 pm

"Our dilemma is that we hate change and love it at the same time; what we really want is for things to remain the same but get better."

storkfoot
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Thu Aug 23, 2018 9:35 pm

Just to put up an alternative view, I wasted months and months of my life about 10 years ago trying to set up copy Keihins albeit largely on a Mugello which may have been part of the issue. Anyway, I vowed never again after that.

They are especially temperamental regards float height and their floats are not very robust.

In the intervening years I have gone back to Dellorto PHBHs and a Mikuni TM24. The Mikuni, which is the size you want, in my opinion is a much much better carb, responsive and when you get your head around the needle variations, straightforward to set up.

Oh, I also tried an original Keihin, albeit second hand. That was more responsive that the copies which required a lot of work to get running right.

Buyer beware.

johnny650
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Fri Aug 24, 2018 2:02 pm

rosscla wrote:
Thu Aug 23, 2018 6:06 pm
You need to get the right manifold for the carb and your cylinder.
:?
yes of course ..... so that is my question ..... ;) which one is the right one ?
Do you have an image or a link ?

johnny650
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Fri Aug 24, 2018 2:06 pm

sorry didn't see your second post with the link on the next page .

Thank you that would be perfect .
Unfortunately due to the ridiculously short editing time on this forum I wasn't able to amend my previous post . Thanks for your help

johnny650
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Fri Aug 24, 2018 3:16 pm

storkfoot wrote:
Thu Aug 23, 2018 9:35 pm
Just to put up an alternative view, I wasted months and months of my life about 10 years ago trying to set up copy Keihins albeit largely on a Mugello which may have been part of the issue. Anyway, I vowed never again after that.

They are especially temperamental regards float height and their floats are not very robust.

In the intervening years I have gone back to Dellorto PHBHs and a Mikuni TM24. The Mikuni, which is the size you want, in my opinion is a much much better carb, responsive and when you get your head around the needle variations, straightforward to set up.

Oh, I also tried an original Keihin, albeit second hand. That was more responsive that the copies which required a lot of work to get running right.

Buyer beware.
thank you for posting your experience its very important to have an alternative view and advice.

The only reason that I am considering this OKO Kehin carb is because its available for £15 which is less than the cost of a set of jetex jets. i figure if it doesn't work out I can sling it in the bitsnbobs box and not feel too bad about it.

Like you I suspect that it it the cylinder piston combination of the 185 kit that is causing the problems. The Jetex carbs have never given any problems setting up and rejetting on my 150cc engine . However since fitting the 185cc kit I just cannot even get a base tune on any of the jetex carbs so that I can consistently start and run the engine.

I have several sets of cv type Mikuni and kehin CV carbs on my Yam XS650 and they are fine carbs but they need meticulous cleaning and setting up . The slightest air leak and they don't work. I have never used a flat slide Tm type Mikuni/ Amal /Delorto although they are a lot less complicated I hear that the throttle response is not as sharp as a cv carb....not that that would matter on a Lambretta of course.

I was considering fitting this 185 kit onto my original pacemaker gearbox when it is rebuilt but I think now I will fit an original series 3 TV 175cc engine and crank I have stored instead . its likely to be a lot less aggravation.

I'm just guessing at the moment but I suspect that there is a porting mismatch between the SR 185 cylinder and the Indian piston I have fitted to it. The original piston had dropped a ring pin due to the rings sitting too high on the pins and catching one of the ports .

nick b
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Fri Aug 24, 2018 5:28 pm

I run a 28 polini on a bgm195 jets that i bought are all numbered i had a sh22 before and this is superior i run the choke and throttle through 2 elbows very easy to fit

johnny650
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Fri Aug 24, 2018 7:48 pm

thank you Nick . so it looks like there are no real issues about connecting choke and throttle cables .

tavspeed
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Sat Aug 25, 2018 9:54 am

i ran a 24mm pwk oko from scootrs a few years ago,standard 200 top end and a scorpion exhaust,went very well,although fuel consumption wasn't brilliant
never had a issue with carb rubber splitting,as they are small and light.
with the cheaper copies might be worth checking fuel flow thru the float valve,and because the float bowl has a small volume,was advised not to run them with bg cc motors on the 28/30mm version,cheers all

a.lo.v2
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Sat Aug 25, 2018 10:35 am

johnny650 wrote:
Fri Aug 24, 2018 7:48 pm
thank you Nick . so it looks like there are no real issues about connecting choke and throttle cables .
you might have to reduce the size of the soldered nipples on the cables a bit with a file or emery to allow them to fit in the recess of slide and choke plunger and I had to make a new choke outer (longer) from an old cable

johnny650
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Sat Aug 25, 2018 1:55 pm

tavspeed wrote:
Sat Aug 25, 2018 9:54 am
i ran a 24mm pwk oko from scootrs a few years ago,standard 200 top end and a scorpion exhaust,went very well,although fuel consumption wasn't brilliant
never had a issue with carb rubber splitting,as they are small and light.
with the cheaper copies might be worth checking fuel flow thru the float valve,and because the float bowl has a small volume,was advised not to run them with bg cc motors on the 28/30mm version,cheers all
cheers Tavspeed thanks for posting that advice and feedback.
I havn't yet ordered a 24 pwk I'm holding fire for the moment until I sort out the jetex and see how that runs.

The 22mm inlet manifold seems a little short which has meant that the 22mm Jetex is jammed up against the petrol tap shaft even though the shaft is practically at right angles . Every time I throttle up, the jetex cable pivot catches on the knuckle joint of the petrol shaft and consequently the nipple came loose last ride . :roll:

I have shoved the petrol tank over, off centre about 30mm and its still not enough clearance ? ! ....
I'll see if I can find a longer inlet manifold so that the Jetex is set further out.
Then I have got to devise a way that the choke cable and elbow are not fouling the top of the jetex all the time. No wonder chokes get stuck on or don't return fully. The whole fuel inlet thing on a Lambretta is a complete PITA like it was designed by a committee of 10, in the dark that never spoke to each other .

Needed some good old British design input in the beginning .
For a start off, simply switching the fuel and choke levers and tank outlet to opposite sides would have been 100% improvement.

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