Montesa 315R Carburetor Swap

[tjcarr]

I recently purchased a 1998 315R with the Dellorto PHBH carburetor.   The bike was pretty much a stock unit and I've been updating over the past year.   She now runs well with a new clutch, rebuilt F&R suspension, recent piston, good gas, a fresh plug and a clean air filter.   A new reed is on the short list.   No performance complaints however I hear that a carburetor upgrade will take the bike from good to better.   There are several opinions scattered across the forum as to which is the best upgrade.   Some offer the later PHBL as the best choice while OKO, Keilin and Mikuni are also tossed about.   So my question is three-fold:

1. Was the PHBH never a really a good carburetor and should be replaced ?

2. If the PHBH should be replaced, will the PHBL be sufficient or is the OKO, Keilin or Mikuni the best investment of time and money ?

3. Will there be a noticeable return for the upgrade effort ?

Thanks in advance for your thoughts and comments,

tj carr

Edited April 28 by tjcarr

[lineaway]

Phbl is probably the easiest. And it is actually better in some ways than the PWK. Otherwise you will need different connections. Air box to carb and maybe intake. Hopefully someone that has done it will chime in. We are talkining a 3 decades old design.

[sherpa325]

The PHBH is a larger version of the PHBL. The PHBL is a small body carb used on trials bikes to save space, with a maximum bore size of 26mm whereas the PHBH goes from 26mm to 30mm and I think your cota would be a 26mm. I wouldn't think there would be any gain going from 26 PHBH to a 26 PHBL. The Keihin is a Flatslide 28mm and will give you more topend power if that is what you are chasing and they are pretty much standard on most newer bikes, but there is nothing wrong with a Dellorto.

[tjcarr]

Thank you both for your input.   Very helpful in sorting this out.