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Post by sussexscooterhead on Aug 9, 2006 14:37:46 GMT -5
I'd like to to hear people's thoughts in regards to using a carb with an accelerator pump on the GY6 engine. I'm thinking something off an older Honda XR250 or the Yamaha TTR230. They're pretty inexpensive on eBay.
So far the smallest I've seen is a 26mm from the TTR.
Does anyone have information on a small bore 'pumper' carb?
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Post by Jacine on Aug 9, 2006 21:08:37 GMT -5
Similar concept to the dial a jet. More demand more fuel injected. The dial ajet is pre carb, wherease the pumpers are usually mid to rear carb .
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Post by sussexscooterhead on Aug 10, 2006 8:54:55 GMT -5
I would argue the Dial-a Jet system is not very similar at all.....as neat as it is.
The fuel delivery of an accelerator pump isn't dependent on vaccum and is present for only a specified span of throttle position, ideally eliminating the bog you might associate with 'whacking' the throttle.
I thought a pumper carb might offset some of the downsides to using a carburetor with a larger venturi.
I had forgotten about the Dial-a-Jet but it is a simple installation and would provide an easy way to make across-the-board jetting adjustments. Hmmmm.....
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Post by Jacine on Aug 10, 2006 9:05:39 GMT -5
You're right, the pumper carb has a limited range of function. I think its usually mid range, and dial a jet is throughout and vacuum based. But the concept of more demand adds fuel (at some point) in the throttle is the same.
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Post by sussexscooterhead on Aug 10, 2006 23:28:10 GMT -5
Hmmm.....
The Yamaha Virago 250 comes with a 26mm downdraft carb with an accelerator pump.
I like the idea of being able to stack the carb and air filter in the space normally occupied by the air box.
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Post by sussexscooterhead on Aug 11, 2006 14:03:06 GMT -5
The carb used on the Virago is a Mikuni BDS26.
This is also the carb used on the Lifan 250cc copy of the Virago.
And it's used on the Suzuki VL125 Intruder, which might not be imported into the US.
So I'm thinking that if it can be jetted to work on engine displacements from 125-250cc it can be jetted for the 150cc GY6. And being a mikuni, jets should be pretty easy to come by.
I sent an email to motortoyshop.com (because they carry Lifan bikes and parts) to see it they could supply the carb. I'm guessing they'd be cheaper than Yamaha and haven't been able to track one down on eBay.
Can anyone suggest where else I might get my hands on one of these things?
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Post by woodlark on Aug 11, 2006 15:52:12 GMT -5
What about checking junkyards for a wrecked Virago?
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Post by sussexscooterhead on Aug 11, 2006 18:19:12 GMT -5
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Post by dwestmodesto on Dec 2, 2006 14:01:19 GMT -5
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Post by sussexscooterhead on Dec 2, 2006 14:34:54 GMT -5
That's a good find! I'm jealous. I wound up with a Mikuni TM24 flatslide but will eventually try out a pumper carb as well. I had been in touch with the guys at www.motorcyclecarbs.com/PHBH-L_W15.cfm in regard to a Dellorto 26mm with accelerator pump but the price was a little out of range - $300. Yikes. Please keep us updated as to how things go with this carb and please let us know the make once you get it. Thanks! |
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Post by dwestmodesto on Dec 2, 2006 19:35:20 GMT -5
The carb I am dialing in now is a 24mm K&F carb. It is a clone copy of a Keihin pb24. The only difference between it and the real keihin that was oem for my bike is that the speed screw and airjet are on the wrong side of the carb. I have enough space to turn them with a really short screwdriver, but it is a pain. I run a speed pipe on my bike, and it required a jetting change from a main 120 to a 115. I added the larger carb and went to a UNI foam filter. The scooter has been too rich so far. I thought I would have to upjet. The 120 main fouled the plug right away. The 115 was a little better and the scooter would ride up about 40mph and then start bogging and missing. Smallest jet I have is a 112.5. I installed it, Scooter is better, but over 40 I still had the bogging problems. I posted on the Bajaj forum on Yahoo for people who had replaced the airbox with the UNI filter, and 3 others responded that they had to go down to a 108 jet to get the bike to run properly. Only one other Bajaj owner has written about going to the 24mm carb. He used the stock airbox and had no jetting problems. I have a 110 and a 105 jet ordered that was supposed to be here today..but it isn't. Next week...lol. Dave That's a good find! I'm jealous. I wound up with a Mikuni TM24 flatslide but will eventually try out a pumper carb as well. I had been in touch with the guys at www.motorcyclecarbs.com/PHBH-L_W15.cfm in regard to a Dellorto 26mm with accelerator pump but the price was a little out of range - $300. Yikes. Please keep us updated as to how things go with this carb and please let us know the make once you get it. Thanks! |
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Post by Darthchile on Dec 6, 2006 10:59:38 GMT -5
My Scoot (Vento Phantom 2006) came with a Mikuni BS24, 115 main jet, round type.
So I swithced to a Mikuni TM28, 220 main jet. Great performance, since I installed a big valve head. A little flaky sometimes and very sensitive to barometric pressure changes.
I'll experiment with a dial-a-jet which seems a pretty cool conecpt, and for what I've read it's seems a better idea than a pump.
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Post by Darthchile on Dec 6, 2006 11:02:13 GMT -5
Ah! keep in mind the XR came with a round slide type, if you a re looking for poerformance then maybe you want to go flat slide, but the smaller I would go is 28mm, sussexscooterhead started another thread about his experience witht he TM24. Check it out.
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Post by sussexscooterhead on Dec 19, 2006 13:57:07 GMT -5
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Post by tankcommander on Dec 19, 2006 16:26:26 GMT -5
Don't laugh me off the fourm but, for those of us in snow country-
You can find more trashed snowmachines than scooters/bikes. Quite a few brands of older (pre-fuel injection) machines came with Mikuni carbs, but most of them are side draft aren't they? Ideas anyone?
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Post by sussexscooterhead on Dec 19, 2006 21:48:51 GMT -5
The sled carbs are often too big and one of the things that separates this one from a snowmobile carburetor is the accelerator pump, I've never seen a 2 stroke sled with a pumper carb.
All ideas are good ideas, though, so keep 'em coming!
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Post by funderp47 on Dec 20, 2006 10:06:56 GMT -5
I have read that the Yamaha Vino 125 has an accelerator pump in the carburetor. Their Yahoo group has a thread about disabling it to increase gas mileage. I would prefer to have it for cold weather starting and the little boost it provides throttling up , although mine without the pump responds o.k. I don't know the brand or size of the Vino carb.
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Post by Darthchile on Feb 5, 2007 15:57:49 GMT -5
Hey guys, autotech355 in ebay has a Keihin CVK30 with pump, and also an OKO replica which is cheaper. THe both have an acc. pump even when they are CV carbs.
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