April 5, 200818 yr axulsuv is very pleased with OKO flatslide carb on his twinshock Fantic (Fantic > "Carb! Swap from delorto to OKO"). Jaan, The Dellorto on the Fantic is the "large body" Dellorto (oval bore), like was used on the 96' JTR 370 GasGas (the "hot setup" for the 370 was to adapt a Keihin PWK28 off a KX80, which I soon did). I put a "small body" PHBL 26mm (common to most modern Trials bikes) on a friend's 348 and it did wonders over the Amal 900 Concentric (no more listening to the slide rattling around...... The PHBL is easy to get parts for and easy to jet. The advantage of a "flat" or "D" slide carb is that the airflow is directed over the main jet tower, rather than "around" it as a round slide does, so the carb is much more responsive due to the increased velocity of air over the tower at just about all throttle openings. Jon
April 5, 200818 yr Author Thanks JSE for info. Maybe have to try some flat slide carb too. Any ideas on which one of them is the best - OKO, Mikuni or Keihin? (OKO is obviously a copy of Keihin?)
April 5, 200818 yr Thanks JSE for info. Maybe have to try some flat slide carb too. Any ideas on which one of them is the best - OKO, Mikuni or Keihin? (OKO is obviously a copy of Keihin?) Jaan, I'm not very familiar with the OKO so I don't know if the internal circuits are as sophisticated as the PWK Keihin, inspite of the exact external copy. Of the three flatslides (four if you include the Dellorto VHST) carbs, the PWK would be my favorite due to the excellent low-speed metering circuitry. I'm sure riders have had good luck with all the carbs, when properly set up. I put a Mikuni flatslide on my son's Fantic 309 with good results and I ran a PWK on my JTR370, also with excellent results. I've found the VHST a little twitchy to jet properly for all conditions (it was only used one year on the 2003 GasGas Pros, the PHBL thereafter, except for the Raga, of course). I would think that coming off a well-worn 900 Concentric, you have no place to go but up..... Jon
April 6, 200818 yr The late model Montesa twinshocks were all fitted with MK2 Concentrics, which although differing in appearance from the MK1 were just as poorly made, and totally worn out in less than 6 months on any bike used regularly. Here in the UK the Amal carbs sell for around
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