Just finished the istall on third SWM of OKO carb.The bikes were 2 1982 280s and a 1983 240. the 240 had a stock airbox and pipe and the inprovement was huge.bike pulls from idle to full revs with no flat spots.The 280s run tons better with no problems, one stock the other has a modified rear box.Also noticed after first trial the bike used less gas than before.I also am using 2 different size OKOs on one of my xc bikes.It has a 280 rotax motor and for the tight tracks i run a 30 mm carb and its a tractor .On more open tracks I install a 32 mm and it runs down 450 4 strokes.Have to thank Roger at MAVT.org for the carbs and tuning help.

Would have been interesting if you had fitted a new Dellorto to one of them to identify if the improvement was purely down to Oko' s being better, or just better than a worn Dellorto. I have a 240 with original carb and can't really fault it.

One of the 280 had a new dellorto carb and a full rebuilt motor and there`s no contest . the d slide OKO pulls better than a new Dellorto

So the OKO is a flat slide carb, then the carb would be inadmissible in classic Trials Events where I live, (These carbs are only allowed in the rule of grandfathering, when they where installed already as original part to the bike).

A flatslide carb is certainly better then a round slide carb due to better gas flow inside, Dell'Orto have one too the VHST model ...

Anyway interesting, can you write down the spec's of the jets and needle you mounted as the diameter is so much different to the original mounted Dell'Orto?

OKO used is a 28mm d slide not flat slide carb,The jetting I used was 52 slow and 112 main but that will vary bike to bike because of differences in wear and tear on motor

D slide is one side flat the other round an invention of our days sadly not back then.

OK then you use a 28mm and not a 30mm or 32mm carb as posted in # 01#?

Of course the jetting depends to the hight where you are, the season and the particular engine anyway it's good to get a clue where to start, the rest is fine balancing.

I used 28mm on trials bikes,30 and 32mm on cross country bikes.you can also find OKOs on Gilles Burgot and Charles Coutard retro SWM trialers

I admit I also have my SWM modified and have used as a "template" the SWM of Gilles he have used in 1981. So Betor legs in Marzocchi clamps, clutch with actuator of the Enduro and 12mm balls and too slightly longer shocks back but I did not cut off the rear loop of the frame or changed the original footrests as I never modify anything which i can not bring back to original status.

As stated b40rt I am too very pleased so far with the original Dell Orto- When the rubber parts like the manifolds and the curly part between airbox and carb are fresh and crack free and the engine rebuilded the combo works very well for me. But I'am too not at all a world class rider ...

What rubber is used from air filter to rear of carb when fitting an oko or keihin ?

I use the stock boot with a rubber sleeve that fits over the carb and boot od ...