150 4T 22mm carb worth the $$?

[slotrod65]

Tasso has a 22mm carb offered for the 125/150 4T. What advantages might there be? Disadvantages? It runs around $50 less shipping. I am wondering if it is a worthwhile upgrade.

[Neurotic-Hapi-Snak]

Tasso has a 22mm carb offered for the 125/150 4T. What advantages might there be? Disadvantages? It runs around $50 less shipping. I am wondering if it is a worthwhile upgrade.

If you are talking about the Mikuni 22mm oval bore with the Polinin intake manifold, no real disadvantages to speak of.

The Keihin PB18 (18mm oval bore carb) is commonly supplied on clone Honda Cub based engines in the 49-80cc range, and formerly on Honda Cub based engines in that same cc range before Honda switched to FI on all motorcycle engines. It's very undersized for for a 147cc engine (the Stella 4T's true displacement), even a 22mm is on the small size for that displacement. I suspect LML used the PB18 for fuel economy/emissions and because it's a common (therefor cheap) carb.

You probably won't see any large decrease in MPG, unless your ride it hard, because the larger carb will decrease intake loss, while seeing a good bump in power.

Of course switching to a new carb will require some tuning, because a a new carb is never ever plug and play.

Plus the new intake manifold is larger than the stock one and closer, albeit larger, than the intake in the head. To see maximum gains and max mpg with the new carb will require some porting, at least to smooth the transition from the intake manifold to intake port, which can be done with the intake spacer if you are afraid of removing metal from the head.

[slotrod65]

OK, So here is the link:

http://www.tassoparts.co.uk/cgi-bin/sto ... &sku=TS009

Tasso is not giving up whose carb this is, and if it were a Mikuni or a Polini, I suspect they would be trumpeting it... and it would certainly cost more, no?

They say it is bolt on to the stock intake, for what that's worth. For some reason, I cannot get any info from anyone on the LML UK forum about this carb??

I have no problem with tuning, rejetting, etc, or even more fuel usage. I just want to tune the 150 for something other than economy.

[Neurotic-Hapi-Snak]

That's a Keihin PB22, stock on the LML Star 200. You might see some gain with it, but you really need to address the intake manifold and intake port for substantial gains. Another thing with the Keihin PB is that it uses a butterfly valve choke, rather than an enricher circuit as used on more modern carbs, which even when fully open causes restriction and turbulence in the intake stream into the carb.

The Mikuni 22mm oval bore isn't that great of a carb, it's okay, better than the Keihin PB, and actually fairly cheap on its own. The main thing about buying the Polini kit, other than a slide and needle selected for the LML 4T motor, is the intake manifold. That alone is almost worth the price of the kit, since there are no other options for a larger intake manifold, at least as I remember.

[viney266]

^^^ agreed. The manifold is worth it. I have installed several of these. Better response, they run well and pick up a few MPH on top. If you add a good pipe the 4T really runs well.

http://www.sip-scootershop.com/en/produ ... +_p1770090

I sell the GPR exhaust, and that combined with the carb kit really makes the 4T work the way it should.