Carb and jetting help needed please

[neilt]

Hello,

Trying to jet an oko pwk carb on a ported iron cylinder sil 200. It has a sterling pipe on it. The carb size is 30mm.

The problem I have is that no matter what main jet I put in it, when I am in top gear on full throttle after about 5secs, the engine goes boggy and splutters, then dies. If I roll in to the edge and stop then it will start first kick.

This seems rich to me that is causing this, but no amount of plug chops from full load/throttle, will produce a dark plug. The plug is always White and just as if it had been put in.

I have currently a 52 pilot jet in and a 150 main jet with a jj needle, clip in the middle.

I replaced the worn Jetex carb with this one because of an idle and run on issue, the jets in the standard Jetex were 45 pilot, 50 choke and 122 main.does any one know how these translate to the pwk equivelants so I have a base to start from please. The plug was a nice dark colour with this on.

Cheers

[col68]

Now mate had the same problem on a rapido mine ran for about 4miles and did the same spiting petrol out so much it ran off back of footplate . changed it to a delly 30mm phbh . I run a sil 200 on my gp with a fresco 30mm phbh 40 slide av266 x7 3rd clip up 125 main 55 idle 70 choke air screw 3 turns out with ram air fliter nice plug brown plug . shouldnt be far off for you . col :fb:

[jason frost]

Check the flow from the tap with the carb bottom off and the float needle out.

[neilt]

Sounds like I need a new carb then, which is best?


Jason, it has the clear plastic bowl on it, it's very hard to see if it's full when flat in top gear. Apparently there is some mod about drilling out the needle valve on these? Any one know what it involves?

Have you got and good carbs in Jason?

Cheers

[jason frost]

Got some jets and needles if you want to come down Saturday and have a play

[djh66]

I had the same problem with my 24mm pwk, sounds like fuel starvation. Check the float level measurement, I think they should be set at 19mm (see scootrs website) it's very easy to unwittingly alter this when removing and re installing your float bowl. Check the flow rate from your tap, I had a faulty fast flow tap, that let air in the line, if you have air bubbles in the line this reduces the flow rate.

[neilt]

Will check the float height, cheers.



It's the needles that I am having trouble finding, will see what time I finish and pop down sat if I can Jason, cheers mate

[storkfoot]

Float height best at 21/22 in my experience. The articles that were on ScootRS website (last time I looked about 3 years ago) were just lifted from US dirtbike websites. Different beasts and atmospherics.