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Workshop => Carburetor, Intake, and Exhaust => Topic started by: Victork on April 12, 2016, 10:20:35 PM

Title: another carb and more questions (41.5mm pwk air striker)
Post by: Victork on April 12, 2016, 10:20:35 PM

I now have a 38mm as bored to 1.6300 inches (41.5mm)and am thinking about trying it on my bike over the 40.5mm pwk. I don't know much about modded as besides the fins are gone and it has 2 more vents obviously. 41.5mm vs non modded 40.5mm, thoughts?(http://forums.trx250r.org/vbulletin_imports/79_7555_2017-04-18_3286.jpg)(http://forums.trx250r.org/vbulletin_imports/79_7556_2017-04-18_2098.jpg)

Title: another carb and more questions (41.5mm pwk air striker)
Post by: Aceman on April 12, 2016, 11:47:31 PM

What size is your engine?

Depending on the size, I've heard you can lose throttle response due to a weaker vacuum signal being pulled through a larger bore carb.  But, if you have a big enough motor to need it, you could gain some top end due to more air being able to flow through it.

Title: another carb and more questions (41.5mm pwk air striker)
Post by: Victork on April 13, 2016, 12:07:41 AM

350 pro x. I get the fact the extra 1mm will in theory shift the power higher but I'm wondering about the fact it's a air striker and has 4 vents and how the performance differs because of it

Title: another carb and more questions (41.5mm pwk air striker)
Post by: Aceman on April 13, 2016, 09:44:42 AM

I just took delivery last night on an 86 stock framed R with a CT350PV cylinder.  I'm curious to hear what the other posters say as well.  I'll have to see what this one is running for a carb too.

Title: another carb and more questions (41.5mm pwk air striker)
Post by: Victork on April 13, 2016, 10:39:39 AM

I wouldn't run anything smaller than 39 on a 350 that's for damn sure

Title: another carb and more questions (41.5mm pwk air striker)
Post by: Victork on April 13, 2016, 01:24:41 PM

Can someone tell me is the 38mm as bored to a 41.5mm performs any different from a non as 41.5mm?

Title: another carb and more questions (41.5mm pwk air striker)
Post by: Jerry Hall on April 13, 2016, 04:23:48 PM

A 38 PWK bored to a 41.5 will perform the same as a 39 PWK bored to a 41.5.

Title: another carb and more questions (41.5mm pwk air striker)
Post by: Victork on April 13, 2016, 05:54:29 PM

Thanks Jerry

Title: another carb and more questions (41.5mm pwk air striker)
Post by: RIDE-RED 350r on May 25, 2016, 06:35:51 PM

Based solely on what I have seen said, the quad vent setup on the AS carb is mainly beneficial in applications where one is hitting jumps frequently, mainly MX. I am not an MXer so I cannot say if it is true or not based on my limited experience. I would defer to the wisdom of folks more experienced in this area for final judgement on that.

I recently replaced my PWK38AS with an ESR PWK bored to 41.2mm on my ESR 350. So far I am very pleased with it and I have not noticed any drawback about it in terms of only being a standard dual vent compared to the quad vent with the type of riding I do.. After all, how many years were dual vent carbs in use before the quad vent came out?