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Post by alyn on Oct 31, 2016 13:40:47 GMT -5
The cruel joke is I did disassemble over a 2 white bath towels and took extensive videos of the disassembly and I do believe it was the process of taking the video that caused me to miss seeing the little sucker fall out. Never again with the cell phone video thing. Still photos only. lesson learned :-)
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Post by alyn on Oct 28, 2016 21:57:17 GMT -5
That's the little bugger! Amazing what havoc that little thing wreaks if it lives on the garage floor instead of in the carb.
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Post by alyn on Oct 27, 2016 0:26:31 GMT -5
SOLVED - First off, thanks to everyone who tried to help. Couldn't fix it even though I rebuilt it 5 more times to try and find my mistake. Then I decided to clean up my garage and lo and behold - I found the Keihin NEEDLE COLLAR on the floor. It must have slid out when I didn't notice when I pulled the needle jet. I popped it back in the carb and runs better than ever.
The carb clean really helped, the initial issues are gone though I would love to get back two days of stress trying to figure out what I did wrong :-(
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Post by alyn on Oct 26, 2016 10:34:31 GMT -5
Ok, will try this and report back. Thanks for the tip!
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Post by alyn on Oct 25, 2016 22:13:48 GMT -5
Thanks for the suggestion :-) I tried running it with the enricher unplugged. Same thing happens unfortunately - dies at slow throttle application at around 3400 rpm. Blips fine.
FWIW, if I just run the bike at idle for 10-15 minutes with a clean plug then shut it off, plug is burning great, neither rich nor lean. Same thing if I get it out on the highway by cranking the throttle quickly past where it normally would die. It runs great doing about 60mph (gps) at around 5500 rpm. Then if I quickly bring it to a stop, cut the engine and check the plug - it is also burning fine, neither rich nor lean.
But if I just run it around the yard, slow speed, slow throttle with it dying and almost dying over and over, if I pull the plug then it is BURNING SUPER RICH, black and fouled but NOT wet. Pic attached, but plug is only fouled like this in the problem range.
So on the rebuild I did something to the circuit that controls that throttle range to the point where it floods the plug, then when the upper throttle range kicks in it burns it off and runs fine. I did pull the air box and watched the needle/piston operate - it seems to be working fine - plunging all the way down or up depending on throttle and seems very responsive.
So still confused...
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Post by alyn on Oct 25, 2016 18:33:07 GMT -5
Update:
Completely cleaned the carb again, disassembled and reassembled again with stock jets. Started it, auto choke works fine, Did an idle adjustment when warm, idles perfect and smooth doesn't miss a beat. Decided to ride it this time, I give it slow throttle to get to speed and it dies just like before. If I whack the throttle hard it stutters a bit but then the main jet kicks in and it literally pinned my head back as the clutched grabbed and the Linhai was a rocket, faster than it's ever gone, more power that it's ever had - would leave my Kymco Xciting 500 (0-60) in the dust, so the carb cleaning was gold for the bike if I could just get fix the dang 1/4 way throttle issue that makes it die every time. It's frustrating because when it's at 3800-5500 rpm this scoot is faster than heck. Completely baffled...
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Post by alyn on Oct 25, 2016 13:53:08 GMT -5
Thanks, and I did do that. Cap is new and on there tight with new plug. Problem remains the same. Stumped.
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Post by alyn on Oct 25, 2016 0:58:15 GMT -5
Hi all,
I just picked up a 7900 miles 2008 Linhai Aeolus Classic 260 YP250 clone with its normal 257cc engine. Had a Znen 250, SSR Rowdy and an Xciting 500 so am not new to scoots. Was getting slight stumbling when returning to idle so decided to pull the carb and give it a clean and also wanted to check the jets as my other chinese scoots all came jetted too lean from the factory. Then the nightmare began....
The good news was my carb is a genuine Keihin 30MM CVK and came with a #128 main (the same size specced by Yamaha for the 2000 and above YP250) but it only had a #38 pilot (yamaha spec for the YP250 is a #43 or 44 with same engine). I proceeded to disassemble and clean everything with air, carb spray and a needle cleaning kit (I've cleaned these kind of carbs many times without issue). The membrane still looked good, needle was clean, found no obvious clogged jets. Disassembled accelerator pump, etc. all looked great. No varnishing, no debris. Cleaned every hole, tube, orifice, etc. and reassembled. When I got it all back together it started perfect. Idled great. The auto choke did its thing immaculately and when it was warm I adjusted the air/fuel mixture with a tach and could blip it hard without it stumbling and if I revved it fast it would wind up to 7k (I only did this briefly) without stumbling BUT --
If I slowly rolled on the throttle from idle when I would slowly get to 1/4 throttle or so, the scoot would stumble and die (on the center stand). Vacuum hoses were fine, fuel hoses were fine and like I said if I revved it fast it was a monster, the slow rev up is what killed it.
Decided to break it down again and while I was at it, I wanted to see what a bigger pilot would do. I cleaned the whole carb again but popped in a #42 and a #130 main to test. It fired right back up, idled great, I adjusted the mixture after it warmed up, it blipped fine (but I could hear it was too rich) but it revved up to 7k without issues and idled back down fine. Yet again, when applying slow throttle, at about 1/4 it died. Took it off reassembled again, popped in a #40 pilot, keeping the stock #128 main, reinstalled and it did the same thing. Took it off, cleaned it again and put both jets back to stock, reinstalled and it is still doing the SAME THING. It idles perfect, blips perfect, fast full throttle works great it JUST dies at 1/4 throttle if I rev it slow.
I am baffled. I did Alleyoop's test - when I slowly revved it I would get to the point where it was about to die and I would back off slightly a 1/4" or so and the bike would stumble but it would settle back down to perfect idle (it would not speed up) - apparently this suggests a rich condition but I don't understand why all of a sudden it would do this with the stock jets unless I screwed something up consistently in the 4 reassembles?? FWIW, have adjusted the valves and rechecked them. They are perfect.
Scoots down and I'm out of ideas. Solutions anyone??
Thanks in advance!
EDIT - FINALLY SOLVED! Cleaned my garage and found the NEEDLE COLLAR on the floor. Put it back in the carb where it belonged and life is good again :-)
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