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Post by jdl357 on Oct 16, 2018 17:35:41 GMT -5
Looking to get carb to get most out of my 50mm bbk. Is it best to stay with the CV type carb or would a different style be better like pwk? I can tell the engine is not getting the air it needs through the stock carb. Best advice for 50mm bbk?
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Post by dexameth on Oct 22, 2018 10:38:59 GMT -5
I actually just installed a CVK 26mm carburetor on my 93.4cc setup on Friday night. Had a 24mm CVK carb. The CVK is the stock style vacuum operated carb. I have used the PWK (slide) style carbs as well, couldn't tune my 26mm PWK on the build because of a faulty intake I found later... I might try another PWK carb.
The CVKs are easier to tune all around, and will handle a heavy wrist better than a PWK. Sometimes when you crack the throttle on a PWK carb on a 4 stroke it will lean out too quickly and sputter or stall.
Most members will tell you to run the 20mm true carb jetted correctly, but I'll always advise on a 50mm bore or bigger to use a 24mm stock GY6 carburetor and intake (the bigger carb will not fit the stock intake manifold).
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Post by jdl357 on Oct 22, 2018 12:09:53 GMT -5
Thanks Dexameth, I've been reading some of your posts on the 24mm carb you had on and I'm quite stoked to get one installed.
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Post by dexameth on Oct 22, 2018 12:24:23 GMT -5
Keep in mind I'm at sea level, so I have the richest air available so this setup may not be the best for higher-elevation riders. I've only tested this setup here in Florida and every person so far has claimed a "grunt" or power increase.
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ratdog
Scoot Enthusiast
Posts: 342
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Post by ratdog on Oct 22, 2018 19:11:59 GMT -5
Most of the carbs you see from good dealer will have the electric enrichment device. This is a good thing. Don’t get an aftermarket carb without the electric enrichment device (for cold starting). Also make sure it has an acceler pump.
Size wise, it depends where you want to have you best power. If you want to build a “8500” rpm motor, then I would go with a 22 mm the stock cam and stock valve springs will live with 8500 rpms. IMHO, building an 8500 rpm engine with a 24 mm carb is overkill. To take advance of that much carb, I think you need to look at a 12,000 rpm engine. This brings up some issues. First is valve springs. I don’t see many places to get heavier valve springs for the 50 engine. I have tested a bunch of stock springs, and frankly they are all over the place on spring pressure. This may be because all the springs I have tested were used from stock engines. At any rate, if you want a 12,000 rpm engine to live, you really need heavier valve springs. The other issue is your cam. Right now, there are really no “high preformance “ cams (at least that I can find). The much pushed “A9” cam actually has less duration then the stock cam, and does not have any more lift.
Now my personal experince with very highly modified engines ( more so then about 99% of the posters on here), is that we got no gain with the 24 mm. And at least the 24 mm that we tried made the bike very hard starting ( when cold)
We have had a lot of very informative posts on here from guys from Partsforscooters. I’d bet that they could fix you up with the right stuff right from the start. They choose to sell the good stuff rather then the cheapest stuff, and that may be money well spent
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Post by jdl357 on Oct 22, 2018 19:38:30 GMT -5
Hey, every 24mm carb I see doesn't have an accelerator pump. Are they not necessary on 80cc or bigger engines?
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Post by magoconnor on Oct 22, 2018 22:15:01 GMT -5
Hi ratdog.
Do you have a link for that 22mm carb?
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ratdog
Scoot Enthusiast
Posts: 342
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Post by ratdog on Oct 23, 2018 0:26:16 GMT -5
If I recall correctly, two of them came from Amazon. As I recall, the carbs were like $30 each but we had to pay an additional $11 for shipping. The one on Earsplitingloudenboomer I believe came from scooter parts unlimited. Jim bought that one and I think he said it was around $60. Sorry I can’t be more specific, but I have bought so many parts from so many different people that I kinda loos track.
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Post by dexameth on Oct 23, 2018 9:02:07 GMT -5
Hey, every 24mm carb I see doesn't have an accelerator pump. Are they not necessary on 80cc or bigger engines? I've never used one with an accelerator pump, and I don't get any dead spots or hesitation at first initial throttle opening. I'm really digging this setup now. Since removing the e-start this baby is firing up first kick even yesterday morning when it was 66 degrees out! |
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