357xp carb

[AKJonsereds]

I have seen Walbro 198/199 on 346xp's and even a 372 carb on one. Anyone know of a bigger carb that will bolt on a 357xp? I would try a 372 but it looks like quite a different carb....suggestions?

Any luck boring a walbro 198?

Not looking for a 395 sized carb--- little excessive

 

[AKJonsereds]

Also curious about a bigger carb for a 338xpt. They run so much better with no filter and cover. The intake on that saw is just begging for more flow

 

[David Young]

I have seen Walbro 198/199 on 346xp's and even a 372 carb on one. Anyone know of a bigger carb that will bolt on a 357xp? I would try a 372 but it looks like quite a different carb....suggestions?

Any luck boring a walbro 198?

Not looking for a 395 sized carb--- little excessive

the 357 carb is like 16.66 mm if I remember most 70-90 cc saws have 17.5mm carbs except the 372xt with a 19mm carb. my point is for such a small increase in the venturi it is likely not worth the hassle of putting another carb on it.

I would thin the shafts and screws sand in the venturi a little. Remember to go from 16.6 to 17.5mm you are only looking at an increase of .020 around the whole venturi. not much material and you want to be careful you don't ruin the carb.

338xp idk

 

[Chainsaw Jim]

You may not get enough air flow to effectively use a larger venturi.
Most of the time when people use a larger carb it isn't the venturi that gives the gain, it's the increase in fuel flow. The 357/359 carbs have a tiny metering seat hole and drilling that to match the size of the 562xp carb should suffice.
Your 338 with a larger carb will still gag on the filter/cover and leave you where you started. Drill a few nice looking holes in your cover and that should take care of that.

 

[AKJonsereds]

Thanks for the ideas---the 357 carbs have both had the screws and shafts thinned, perhaps slight grinding around the Venturi would do the trick. After my mods, the walbro four strokes pretty hard with the high screw all the way in and the low screw out two turns. The zama is better at 1/2 turn high and not sure on the low. Trying to slow the velocity through the Venturi to pick up a little less fuel at WOT.

As for the 338.... Already have the holes in the cover they do help some. I feel there is still lots of room for improvement.


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