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Post by flyboy on Apr 29, 2007 21:59:10 GMT -5
I am a new guy. Now with a 2006 Yamati UC250. Did all the normal stuff. Replaced the fuel pump, battery and spark plug. Cleaned up a mess of loose wires, fuel lines etc. Had fixed rear shocks that were really stiff. Replaced them with Tank stuff from Scooters Georgia, fast answers and great service. 500 miles with no big problems. Decided that the muffler was holding things back. Took a while to find something that looked right. Side entry mufflers are rare. Today installed a Kohler 237550 for a garden tractor. I got lucky, it works just fine. Good increase in acceleration and about 5 mph top end by GPS. Got home after a 40 mile run and pulled the plug. Before it was a light brown, now it looks like a new one, pure white. Can the carb be adjusted or will I need to rejet. Looks like it has to come off for either.
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Post by flyboy on Apr 30, 2007 1:43:22 GMT -5
Sorry folks, it's hard to help a dummy who does not tell you what he is talking about. This is a 244cc Honda clone with a Keihin carb.
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Post by 12string on Apr 30, 2007 6:49:00 GMT -5
It's re jet time! How fast were you running before the muffler mod? 5 MPH is a great improvement for just a de-restriction. Pull out your jet and see what is in it, increasing the jet by 10% would be a good starting place, trail and error. Keep watching that plug color! Good luck!
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Post by flyboy on Apr 30, 2007 11:12:02 GMT -5
Thanks 12string, it was at 69 and am now getting 74mph. I think that is fast enough. Was not really looking for speed,a good wind gust could mess up things at top speed. Hope I can find a source for jets online as the nearest cycle shop is 120 miles down the road.
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Post by 12string on Apr 30, 2007 13:13:03 GMT -5
You don't want your scoot to run lean. It will cause it to run hot!
Air cooled engines use some of the fuel to cool the engine, just like an aircraft engine. Running lean could do damage to your engine! With the exhaust de-restricted ( letting the engine breath more air) you will need more fuel. Get that spark plug a nice light brown to be safe.
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Post by 12string on Apr 30, 2007 14:21:42 GMT -5
oops, I see that you have a 244cc Honda clone (water cooled), My bad. Running lean may still cause your water cooled engine to run hot.
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Post by mgreenfield on Apr 30, 2007 14:41:21 GMT -5
Running lean, bumps heat way up, and can erode the thin section around the edges of valves.
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Post by mgreenfield on Apr 30, 2007 14:41:50 GMT -5
Running lean, bumps heat way up, and can erode the thin section around the edges of valves. Another indication of running lean is backfiring.
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Post by robbovius on May 1, 2007 7:02:50 GMT -5
Flyboy, try Dennis Kirk for your carb jets. I've rejet a couple motorcycles (with Mikunis) and that's where I bought the jets. google search "keihin jets" as well, and you'll find a couple other good mail-order sources.
rejetting involves removing the carb and taking off the float bowl to get at the main and pilot jets.
another thing you could do right away is raise the slide needle. that requires removing the carb top cover and pulling the needle out of the slide. the needle often has notches in it with a small circlip that you can take off and move to a different slot to raise or lower the needle in the slide (raising it richens midrange mixture, lowering leans midrange) you can also richen the idle mixture by turning the idle air adjustment screw in a bit.
ultimately though, you're going to want to replace the main jet with one richer than stock.
I think it's really kewl youmade a garden tractor muffler work ;-) yay CBMMA!
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Post by scooterollie on May 1, 2007 8:37:49 GMT -5
The slide needle on the Keihin carb. on my Bali 250 cannot be adjusted - it is fixed. You won't know about yours until you eyeball it.
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Post by robbovius on May 1, 2007 14:01:23 GMT -5
The slide needle on the Keihin carb. on my Bali 250 cannot be adjusted - it is fixed. You won't know about yours until you eyeball it. Ollie, I forgot to mention needles without the grooves, d'oh! in those cases, you can place small washers under the circlip to raise the needle and richen midrange. |
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Post by scooterollie on May 1, 2007 15:31:50 GMT -5
robbovius;
Thanks, will give that a look.
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Post by flyboy on May 1, 2007 20:54:07 GMT -5
Thanks for your good words. The carb is on the bench awaiting the assortment of jets I ordered today. Someday I will learn not to tinker. Being 75 now that will probably be when they pat the dirt down.
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Post by 90GTVert on May 3, 2007 18:31:54 GMT -5
As I recall, the 250 CFMoto scooters had something on the order of 114 main jets as stock. Try a 120 or 125 and you should be about right. You can get them at your local Honda dealer if you don't say what it's for and just tell them you want the small round Keihin main jet (not hex). Stan I am a new guy. Now with a 2006 Yamati UC250. Did all the normal stuff. Replaced the fuel pump, battery and spark plug. Cleaned up a mess of loose wires, fuel lines etc. Had fixed rear shocks that were really stiff. Replaced them with Tank stuff from Scooters Georgia, fast answers and great service. 500 miles with no big problems. Decided that the muffler was holding things back. Took a while to find something that looked right. Side entry mufflers are rare. Today installed a Kohler 237550 for a garden tractor. I got lucky, it works just fine. Good increase in acceleration and about 5 mph top end by GPS. Got home after a 40 mile run and pulled the plug. Before it was a light brown, now it looks like a new one, pure white. Can the carb be adjusted or will I need to rejet. Looks like it has to come off for either. |
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Post by flyboy on May 3, 2007 22:03:50 GMT -5
Thanks Stan, Since the Honda store is over 2 hours away I ordered the jets. I had a 38 and a 110, Ordered 40- 42 120-125. Been riding since 1948 and that was the last scooter I had. Got rid of the Fat Boy last year. Just too darned heavy for an old man. Since I am in the boonies so far it's 20 miles for milk and bread the scooter is a good solution.
Bob (TX)
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