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Rebuild Keihin Carburetor - Information

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Built2Fly

Well-Known Member
Joined
Feb 21, 2020
Messages
48
Location
San Diego, California, USA
I am recording some of my findings here in my building and learning process. Please feel free to add information, and hopefully this would be helpful for people who are looking to find such information down the road.

I have a couple of Keihin carburetor with the project I recently bought. It looks like that they have been sitting around for a long while, so I went ahead to rebuild them. First I need to figure out which Keihin model it is. It says PE on the case, so it is a Keihin PE model. From Keihin website, there are three dimensions that are important. As marked on the pictures here: A - intake opening, B - air box opening, and C - air box to intake distance.

20200915_162746.jpg

On mine, I got A = 41mm, B = 58mm, and C = 95mm. Looking up on Keihin website, I have a "PE 34mm". So I thought I know the model.

And then I got in touch with Sudco, one of Keihin's distributor from their website, and talked to someone. It turned out that having "PE 34mm" is far from enough to know what it is. There are so many variations (OEM and aftermarket), and it is important to know which "motorcycle" or "ATV" it is from.

Here is another important point: never tell them it is for an airplane, or they will refuse to talk to you. I got this hint from another Keihin distributor I talked to. Anyway, just tell them that it is for a one-off vehicle or go kart. Indeed, ultralight is technically not airplane, but vehicle. So I am just being precise.

Eventually they found only one vehicle that uses PE 34, which is Honda ATC250R (it is an ATV). Shindy makes rebuild kit for this. If you order, please specify 1985 model (earlier model looked a bit different, model after 1986 uses a different carburetor), or Shindy Part 03-014. The rebuild kit is about $20 or so. Another option (besides Shindy) is to find a carburetor rebuild kit for Honda ATC250R 1985. There are a few of those on eBay (from under $10 to slightly over $20).

Of course, you can also order just the rubber gasket from genuine Keihin part (I think it is Part 16163-ND4-7510-M1 for a few dollars). I think that is the only part that for sure needs replacement (and maybe the gasket on the drain bolt).

Another note would be interesting to share. When I cleaned up the case, the text on it reads G50BYA. The word "G50" stands out here, and I am guessing that this might be a special Keihin that is custom made for the Zenoah G50. The guy from Sudco otherwise thought it is a Japanese motorcycle that is never imported to US (I didn't tell him about the Zenoah G50 engine it is on).

20200917_200350.jpg
 

n3puppy

Well-Known Member
Joined
Jun 25, 2019
Messages
172
I agree G50BYA is likely specific to your engine. But it is still probably still a standard "PE34" carb body.

Mikuni does something similar - one carb body "VM34" but dozens of model numbers based on the guts of the carb - jets, needles etc. And Different engine OEM's get different numbers based on part combinations inside.

Good news is - like Mikuni - The PE34 Keihin rebuild kits are probably interchangeable since the gaskets, o-rings, etc are not normally changed by the engine application. They are sized to the carb body only.
 

Built2Fly

Well-Known Member
Joined
Feb 21, 2020
Messages
48
Location
San Diego, California, USA
Very good point. These rebuild kits will usually have the compatible gaskets, o-rings, and clips, but the jets and the needles might be different. On the other hands, the jets and needles are steel or copper, and not likely to be worn out, so you should be able to re-use them anyway.
 
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