lambretta rt 195 jetting

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holty
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Sun Jul 12, 2020 8:50 pm

hi ive got an rt 195 that ive fitted a piston to for a friend of mine after he holed the piston, i have a feeling it was partly to do with the ignition timing which i have adjusted, i had to enlongate the slots to get 17 degrees, it was about 21 without slotting the holes, i also had to remove a laminate from the stator to line up the pick up as there was no spark when i checked it, carb is a phbh 30bs its got a 115 main, 55 idle 266 atomiser x2 needle 40 slide and air screw was 1 turn from closed, needle was on next to bottom clip, i did a leak test before i stripped it, so air leak is not the problem neither is fuel flow, its also got a reedvalve fitted, i recomended i dyno session but he cannot afford it at the moment, any suggestions about the jetting please, cheers holty

ricalnic
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Sun Jul 12, 2020 11:04 pm

Sorry I can’t advise on specific jetting, but Dan has done a series of videos on jetting the phbh dellorto carbs, definitely worth a watch
https://youtu.be/Xc31PqvPRJg

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garry inglis
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Mon Jul 13, 2020 6:57 am

Hi Steve main 125 pilot 55 x7 needle on 2nd clip 40 slide 70 choke and 300 float

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garry inglis
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Mon Jul 13, 2020 6:59 am

And av266 atomiser

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holty
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Mon Jul 13, 2020 8:16 am

many thanks

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drunkmunkey6969
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Mon Jul 13, 2020 10:06 am

What pipe are you running?
If it's an expansion chamber, try the following, and tweak with plug chops:

125m
55p
AV266
X13 n (2nd clip)
40 slide
300 float valve

You might have to go lean it down to EITHER an AV264 atomiser OR an X7 needle if it's on a clubman, try one or the other... but not both!

Jetting help: https://www.youtube.com/watch?v=Xc31PqvPRJg

What stroke crank are you running? 58mm or 60mm?
Ignition-timing/compression-ratio help: https://www.youtube.com/watch?v=rWHoAb0xPMk

Cheers

Adam_Winstone
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Mon Jul 13, 2020 10:40 pm

I imagine that the ignition timing was probably the biggest factor in the first hole.

Grumpy225
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Wed Jul 15, 2020 2:15 am

Out of curiosity what plug is being run? I see a lot of people running B7's on tuned stuff. I run a B9 (colder) plug on everything and don't ever have any problems with fouling.

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drunkmunkey6969
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Wed Jul 15, 2020 8:51 am

Adam_Winstone wrote:
Mon Jul 13, 2020 10:40 pm
I imagine that the ignition timing was probably the biggest factor in the first hole.
I'd agree, though it all looks wrong to me...lol.

Ign was 21 degrees, running a 115 main jet (incredibly lean even for a piston port standard). OP states reed valve (so should be looking at 128+) but no info on whether that has been boost ported and piston windows added (so maybe less than 128?), no info on whether 266 is AV (rich) or AS (lean), refers to mix screw as air screw and is only 1 turn out, X2 (rich) needle on 2nd from bottom (very rich) setting, no info on plug or exhaust pipe...

Clearly he's trying to help a mate, which is admirable, but if the guy is running his setup like that.... he may be beyond help :lol:

Just kidding, hope he gets sorted :ugeek: :D

Warkton Tornado No.1
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Thu Jul 16, 2020 8:57 pm

The RT kit was designed & is marketed by somebody so renowned for expressing their opinions upon other manufacturer's products, much critical as in the case of the Rapido etc, that surely they should be the first to question about jetting to suit their kits?

I'm not saying that this Forum is not the place to ask, but perhaps the originator of the kit should be the initial person to ask?

Sorry if I am being as opinionated as the designer, but by now the income on RT kits should ensure that there is some after sales back up to the users?

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