cheap AF pwk30 knockoffs on the 72R5/RD

Dvsrd · April 01, 2026, 03:41:13 AM

Quote from: teazer on March 30, 2026, 04:09:55 PMI have a set of snowmobile VM34s and they are small body - not as small as a 28 but much shorter than a regular VM34.

The bad news is that they have zinc or Mazak bodies so they are a touch overweight.

Hmm, I have come across the opposite weight phenomenon. For example, the OEM VM28 for RD350 seem pretty heavy for their size, while a single VM34 or 36 from a fan cooled Rotax 503 snowmobile engine was amazingly lightweight. Almost so you would suspect it was magnesium...
Does anyone know what material genuine aftermarket Mikuni carbs are made of?

automan · April 17, 2026, 04:27:34 AM

Aluminum A383 or 360

teazer · April 17, 2026, 10:53:56 AM

I was under the impression that OEM carbs were cast with a zinc based alloy. I want to say its trade name is MAZAC but I cannot remember if that was the original UK company or the revised name used by Mikuni and Keihin.

I have a set of small body 34mm VMs from a sled and they weigh a lot more than aftermarket genuine Mikuni 34mm carbs. Their aftermarket carbs I believe were made with casting type aluminum. For example TZ carbs are Aluminum and RD carbs weigh more.

teazer · April 17, 2026, 10:59:25 AM

While I am here, has anyone tried the larger body "PWK" copies on anything? They appear to use a standard 2.60 needle jet (equivalent to Mikuni O-0) and a non standard Needle. All N427-48 needles are larger than that, so I don't know if there is another Keihin needle range in the N427-46 root diameter range but in 66mm length.

The only alternatives appear to be to drill out needle jets to an equivalent Mikuni size to suit the fatter needles or machine needles to suit. Keihin do not list needle jets for the larger PWK series unless I missed them somewhere.

I have done both on OEM keihin carbs to run on methanol in a vintage race bike, but that's back when I had access to a great machine shop with amazing inspection tools.

m in sc · April 17, 2026, 04:06:04 PM

I have a set of 34s i plan on running on the t500 eventually. thats about it. as far as the materials, i think you're right, 'MAZAK' rings a bell, but its definately a zinc alloy. oddly the stock r5/ds7 carbs were either pure or mostly aluminum by comparison

teazer · April 18, 2026, 11:11:58 PM

I found this for anyone interested in Zamak or Mazak.

https://en.wikipedia.org/wiki/Zamak

teazer · April 18, 2026, 11:15:15 PM

Quote from: m in sc on April 17, 2026, 04:06:04 PMI have a set of 34s i plan on running on the t500 eventually. that's about it. as far as the materials, i think you're right, 'MAZAK' rings a bell, but its definately a zinc alloy. oddly the stock r5/ds7 carbs were either pure or mostly aluminum by comparison

I would speculate that the PWK34 might use the same standard 2.60 needle jet with N427-46 needles which are used on the PWK28. I'll be interested to hear what you find. stock 2.60 needle jets are available in minimum order size of 1,000 so that's probably why they are used.

m in sc · April 19, 2026, 10:01:30 AM

the needle jet is fixed in the casting

85RZwade · April 19, 2026, 01:08:36 PM

Quote from: teazer on April 18, 2026, 11:11:58 PMI found this for anyone interested in Zamak or Mazak.

https://en.wikipedia.org/wiki/Zamak

I'm probably the only one who found this interesting. Now I have to know more about spin casting; I'm sure it has nothing whatsoever to do with fishing

teazer · April 20, 2026, 12:13:49 AM

Quote from: m in sc on April 19, 2026, 10:01:30 AMthe needle jet is fixed in the casting

That is probably true for a genuine PWK and would be consistent with Keihin not supplying parts. Unfortunately the knockoffs are a little different - no surprises there eh - and use the standard 2.60 needle jet as a PWK38.

I wonder what's in clone PWK34's

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cheap AF pwk30 knockoffs on the 72R5/RD