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Post by capt1992 on Sept 22, 2010 7:56:42 GMT -5
Thanks jmkjr72! Yeah, it's always a good idea to ask questions when you buy something on ebay. I opened the carb up and there is nothing visually wrong with it except the seat in the a/f opening looks a little screwed up. I'm going to try a new carb. I'll report back after I get it on. Thanks to all!
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Post by Rocketdog on Sept 23, 2010 18:49:58 GMT -5
I bought a cheapo 18mm standard 50cc carb from ebay and it was trash. The gaskets were all dried up, like they had been soaked in salt water, and there was mud in the bowl. That being said, I'm sure not all of the purveyors of carbs. on E-bay suck. Just the 35 dollar one I picked.
RD
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jmkjr72
contributing staff
Commander 132nd Northern Cav. Division
Posts: 2,779
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Post by jmkjr72 on Sept 23, 2010 21:33:09 GMT -5
let me look around i might have an extra 17.5mm after market carb that didnt get used on a customers bike
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Post by Rocketdog on Sept 27, 2010 19:19:53 GMT -5
I know I have one. I was running one on Mao for the drags. I only want the postage. He can have it. I think I have three lying around. Am I a Scooter junkie or what? That's what the wife said. And I pride myself on it. LOL
RD
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Post by capt1992 on Oct 11, 2010 6:55:52 GMT -5
I replaced the carb with a new one and it made no difference at all. The engine will only run if I completely close the a/f screw and block the other hole in the throat of the carb. I was wondering if I might have a problem with my reed valves.
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Post by Rebel on Oct 11, 2010 11:11:07 GMT -5
I'm not a 2 t guy but sounds like a good next step to me to pull the reed valve out and take a look at it.
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Post by 90GTVert on Oct 11, 2010 15:56:57 GMT -5
Some of the symptoms still sound like it could possibly be a vacuum leak. You said you couldn't find any, but how did you check? Were you able to check as jmkjr72 suggested or was it too hard to keep it idling to do that? Another option is to use a leak tester. Can be a pain to seal, but a great thing to have around if you are a 2T fan. They come in handy whenever you swap cylinders, intakes, or reeds and especially if you ever split the cases. 49ccscoot.proboards.com/index.cgi?board=yamajog&action=display&thread=50649ccscoot.proboards.com/index.cgi?board=yamajog&action=display&thread=425The fact that pressure may be moving in the wrong direction does sound like a reed though. If the reeds are sealing and working properly, they shoudl be keeping most of the pressure from the crankcase headed in the right direction and not back toward the carb.
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Post by Rebel on Oct 11, 2010 16:13:41 GMT -5
Nice vacuum leak tool. One suggestion, when it comes to tools like this, theoretically it is best to use hoses that are as short possible.
I think I would pump up the pressure and instead of letting it sit just go ahead and spray some soapy water around and look for bubbles.
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Post by 90GTVert on Oct 11, 2010 16:49:35 GMT -5
If it sits for a few minutes and the pressure doesn't drop, there's no need to make a mess. Trust me, it takes next to nothing for pressure to start dropping. The longer hose has came in handy for mine. The fittings and hose I use are so tight that I just cut them off and use a razor to split the hose so I can remove it when I need to change adapters for a different intake.
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Post by capt1992 on Oct 12, 2010 7:58:51 GMT -5
Thanks for all the responses. When I checked for vacuum leaks I used starting fluid at all the usual spots with no difference is idle speed. I'm going to check the reed valve assembly. It looks like it should be pretty easy to get out.
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Post by Rebel on Oct 12, 2010 11:23:10 GMT -5
the pressure test system Brent posted looks like a great way to check if you do not find a problem with the reed valve.
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Post by capt1992 on Oct 16, 2010 7:49:06 GMT -5
Reed valves are on the way! I'll let you know how I do.
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Post by Rebel on Oct 16, 2010 11:50:10 GMT -5
So they were bad then?
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jmkjr72
contributing staff
Commander 132nd Northern Cav. Division
Posts: 2,779
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Post by jmkjr72 on Oct 16, 2010 18:01:44 GMT -5
if they were chiped or broken you should post a pic and make sure there are no large chinks of trash metal floating around in your engine i have not had a catostrophic failure of steel reeds but have seen some and its not good destroyed cyl and piston
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Post by capt1992 on Oct 18, 2010 6:35:11 GMT -5
Reed valves were bad. Small piece missing on one, couldn't find it so I'm hoping it passed through. I'm starting to think that the missing piece could've been what caused my initial loss of compression and maybe it was what caused the circlip to dislodge. The scooter has been running, even if running poorly, for awhile now so I'm hoping the chunk is gone.
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