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Having difficulty with jetting

Posted: Wed May 21, 2014 11:55 am
by Donnie
right, since rebuilding the top end with new gaskets and rings and swapping my knackered 48mm clubby for a 42mm version and putting on an mtech I've been having niggly problems with jetting. And I have retorqued the head after 100 miles.

Actual setup is
Mugello 186 with the casings ported out to match.
42mm clubman af
30phbh with gp200hose and ram air filter with the following:

125main - boggy on full throttle so i know this has to come down a bit
av268
x7 needle
70choke
50 pilot
50 slide

Now been doing some plug chops again today and the x7 on second clip from top is lean, B8ES looks slightly grey

Changed the x7 to second clip from Bottom (richer) and it's boggy, not just rich, but boggy.

So, with googles help looking at needle charts and some of the working setups on various sites such as scooterotica, lloyds smell of death site and the bristol lambretta site I am having difficulty finding the same setup as mine.

So im thinking of either changing the needle to a x13 and leaving the av268 or leave the x7 and change to a av266

What do people think of this or is there something im missing?.

Re: Having difficulty with jetting

Posted: Wed May 21, 2014 6:58 pm
by Cereal GY
I've got a different set up but a similar problem. I've just dropped from AV268 X13 to AV266 X13 after having tried with X7. Have you ruled out any air leaks? I managed to find a leaky exhaust manifold which was throwing me off kilter a bit.

Re: Having difficulty with jetting

Posted: Thu May 22, 2014 11:08 am
by Donnie
yeah, checked all possibilities, ie head, base, exhaust gaskets etc.

After a lot of jetting yesterday ive ended up with an av266 with an x13 on the top clip and it feels spot on, next clip down still felt like 4 stroking. im a bit wary that its spot on at that setting being on the top clip but wary of going to a av264 on a 30mm carb. I'll need to do some more plug chops over the next day or 2 just to see how the plug colours up and reassure myself that it is in fact ok.

Re: Having difficulty with jetting

Posted: Thu May 22, 2014 1:38 pm
by Cereal GY
Before dropping to an AV264, I'd consider dropping your slide to a 45 or 40.

Re: Having difficulty with jetting

Posted: Thu May 22, 2014 1:52 pm
by storkfoot
I have av264/x13 on both phbh30 carbs I have fitted to a ts1 and gt186. Both have been on a dyno. Both had Ramair filters straight on carb. Both run well.

Re: Having difficulty with jetting

Posted: Thu May 22, 2014 6:09 pm
by Donnie
Yeah thinking of getting the slide to a 40 looking at many other setups i have to admit.

Surprised at the av264/x13 on a ts1, maybe im just being overcautious after all.

Re: Having difficulty with jetting

Posted: Thu May 22, 2014 7:12 pm
by Cereal GY
Mines a TS1 also.
Far too boggy on AV266 or AV268 X13 2nd clip,Good on top clip. Got a big pilot in as it runs along 60mphish on 1/8 throttle. Full setup is, Pilot 64, 50 choke, 40 slide, AV 266, X13 top clip, main 145 as a bit OTT but quenchs EGT when WOT without bogging.