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Post by magoconnor on Apr 14, 2018 14:32:50 GMT -5
Hello.
What size carburetor would you guys recommend for 72cc gy6 ?
First hand experience would be great.
If you have good one, please post a link on where to get it.
Thanks in advance.
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Post by 90GTVert on Apr 18, 2018 7:33:36 GMT -5
20mm should work fine. PartsForScooters has them. Even stock is likely do do just fine as long as it's adjustable (not sealed, needle with more than 1 groove).
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Post by dexameth on Apr 24, 2018 11:06:51 GMT -5
Yeah, Brent is right. We sell a TRUE 20mm carb that is pre jetted Main 91 and Idle 32, should be great with your displacement. You can find the carb here. |
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Post by jackrides on Apr 24, 2018 13:27:53 GMT -5
Dexameth, what do you do for the intake manifold and/or port matching?
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Post by dexameth on Apr 24, 2018 13:56:57 GMT -5
Dexameth, what do you do for the intake manifold and/or port matching? Honestly I ran a 24mm stock carb from a GY6, but with a 110 jet. I used the GY6 intake, purchased a new one from work here and it seemed to already be ported/polished! Very clean, and more open than a "stock" intake. Ran amazing. I then got my hands on a Mikuni carb set (3 identical VM22) on a bicycle trade. had to order a tall intake for that one to clear the motor. I run a 110 jet in that carb as well. The 22mm Mikuni runs great, took FOREVER to tune, but I feel like I need to go larger on the venturi, maybe up to a 26mm honestly. I started to port/polish my head, found a crack in it, purchased a Hoca head from work and just popped it on. It's ports were so nice, I'd only have to polish them, they are perfectly ported. |
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Post by magoconnor on Apr 25, 2018 17:02:02 GMT -5
Does anybody know where you can find 20 mm carburetor in europe?
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Post by dexameth on Apr 26, 2018 9:31:38 GMT -5
Does anybody know where you can find 20 mm carburetor in europe? If you can't find one, we'll ship ya one, just gotta pay via PayPal during checkout. True 20mm Carb |
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Post by GrumpyUnk on Apr 26, 2018 9:52:00 GMT -5
I am sure someone knows where to find 20mm carburetors in Europe, but doubt they will read this post. I think you can get actual 20mm carburetors from aliexpress. They are not likely to be Keihin brand, but are about the same quality as the 'better' China factory carbs. I think there are a few quality levels(3). The lower end will have goldish colored vacuum chamber covers, next up will have black plastic, and the mo-bettah will have black plastic with the brand formed into the plastic. Likely many parts will interchange without problem, but inspection reveals the quality level of each.
The 20mm CV type carbs used on gy6/139qmb are medium quality. Little differences here and there from an actual Keihin(only brand name I know to be top-drawer). There are at least two other makers who brand their carburetors behind the linkage plates. Check the vendor pictures and note those that have lettering partially hidden. Those would be the 'better' brands, IMO. In the USA, I think there are a few that sell 20mm, true 20mm, not just bored up to within a mm of the throttle plate, which is NOT 20mm, but with an actual 20mm throttle plate.
Unless you are in a quest for higher top speed, you many not actually need a 20mm, but if you are using a larger BBK, it may help develop top performance. On a 'normal, unmolested 49cc', I did not think there was a noticeable difference. Don't bet the paycheck.
tom
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Post by dexameth on Apr 26, 2018 11:03:52 GMT -5
I am sure someone knows where to find 20mm carburetors in Europe, but doubt they will read this post. I think you can get actual 20mm carburetors from aliexpress. They are not likely to be Keihin brand, but are about the same quality as the 'better' China factory carbs. I think there are a few quality levels(3). The lower end will have goldish colored vacuum chamber covers, next up will have black plastic, and the mo-bettah will have black plastic with the brand formed into the plastic. Likely many parts will interchange without problem, but inspection reveals the quality level of each. The 20mm CV type carbs used on gy6/139qmb are medium quality. Little differences here and there from an actual Keihin(only brand name I know to be top-drawer). There are at least two other makers who brand their carburetors behind the linkage plates. Check the vendor pictures and note those that have lettering partially hidden. Those would be the 'better' brands, IMO. In the USA, I think there are a few that sell 20mm, true 20mm, not just bored up to within a mm of the throttle plate, which is NOT 20mm, but with an actual 20mm throttle plate. Unless you are in a quest for higher top speed, you many not actually need a 20mm, but if you are using a larger BBK, it may help develop top performance. On a 'normal, unmolested 49cc', I did not think there was a noticeable difference. Don't bet the paycheck. tom I measured ours myself, here at Partsforscooters.com, and they are not the "stepped" style, they are true 20mm to the venturi. |
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Post by dexameth on Apr 26, 2018 11:08:11 GMT -5
Dexameth, what do you do for the intake manifold and/or port matching? I may have misunderstood this one. On the true 20mm, I ran the stock intake manifold, but I removed the insulator spacer (it has a smaller bore than the intake/port, acts as a restrictor plate). I didn't get as far as port matching on that setup, but I'm sure it would have helped some. |
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Post by GrumpyUnk on Apr 27, 2018 10:07:10 GMT -5
Dex, I was not commenting about your companys product, just noting that some vendors, probably mostly on ebay, that are selling their 18mm throttle plate diameter carbs as 20mm. If you look down the bore from the engine side, you can see an actual 'step' just a bit closer than the throttle plate/butterfly. The butterfly itself is a smaller diameter. Someone is using a boring tool to enlarge the 'outlet' down to just short of the butterfly, so they can claim 20mm.
I think most would be fine with a good 19mm, or even 18mm. I have a 47mm bore that is using a KunFu or other branded carb, and it works reasonably well. I have not tried a 20mm on it. I have run it long enough that I should take a look at the spark plug to see if it is running rich/ok/lean. It has no flat spot, no stumble, starts reliably and quickly, so I have no complaint. It is not a Keihin, but is a KunFu or other(don't remember), and could be the same as your product. Wish my memory was better, but the point, what I tried to make above, is the carbs that DO have a brand name seem to be a step above the factory installed carbs, and you likely can find a decent one in different sizes.
Magoconnor wanted an European source, though he may do better going to you or a China firm, or Amazon/ebay to get a 20mm. I got a couple from China that claimed to be Keihin, but I have a strong suspicion they are not. They do indicate 'technology from Japan' on the black plastic lid, but the diaphragm and needle setup are not the same quality as an 18mm Keihin on another machine. (Or maybe it was a Kunfu?) Too many bits & pieces to keep track.
I have noticed that the plastic insulator seems to be poorly aligned with the intake port on the cylinder head. It was so bad on one, that I thought the insulator must have been installed 'upside down'. Nope. Just poorly aligned. I did some excavation and adjusting and got the insulator to sit a bit 'forward' from where it began, and opened up the intake port substantially. Likely I should check the others for alignment. I elongated the mounting holes and offset the insulator, holding it in place while I tightened the inlet elbow in place. Visually, it looked as if it opened up another 1/3 of the intake, but who knows.
tom
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