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Discussion Starter #1
I have a 2002 that lags 3800 -4200 when cracked open. Runs fine off idle 2 3/4 on pilot. It's worst when motor is hot and not too bad when cold. Cleaned stock carb and tried 130 main .040,060 shims . Checked for air leaks and checked plug color was a little soft black. Sea level and 60 degrees. Didn't see a tear or hole in carb diaphragm . Compression 125 psi and clean air filter. Could this be a vacuum problem ? or ?
 

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Elaborate a little more on the symptoms. So, the engine starts and runs normal until around 4,000rpms, then it starts cutting out? Does it only do this under load? When did it start? Has anything changed recently that may be attributable? Any additional info helps. Good start BTW with the info you already provided.
 

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Discussion Starter #3
The only time it does it is when you crack the throttle from 3800-4200 it starts and runs fine other than that. I changed the stock 126 and gaskets when I cleaned carb. With the mods it stopped the backfire or pop when you let off the gas from high speed. The needle is 5B31 the float level looks correct. It's hard to feel when cool but when hot very noticeable in 2nd - 4th. When you hold steady 3800-4200 and then pin it it blubbers or bogs for a second or two and then accelerates fine. Only tried stock, 130 .040 and 130 .060. I have a 128 but if it does it stock ?
 

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Discussion Starter #5
Yes but I will recheck and set to the loose side.
 

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Discussion Starter #6
Checked the valves and couldn't get a .0025 feeler in intake or feel any play by hand. Set intake to .004 and left exhaust at .006, needle .040 and 130 main . Runs nearly perfect , just a little hiccup when throttle is snapped anywhere between 3000-4000 and good if it's rolled fast. I set the valves last fall (10 hours run time) .003 IN .005 EX, sure I triple checked and one got looser and one got tight ? . Hooked a vacuum gauge to plugged end of hose from intake manifold and had 9 cold 11 hot . Manual spec. 8.66-10.24 or more so that should be good . Is it possible to get that little hiccup out altogether with this carb , it does comes off idle really good.
Thanks 50short
 

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Is your bike running stock exhaust? Has the airbox been drilled? sorry to keep asking questions, but there are a lot of variables when troubleshooting fuel related drivability issues. The CV carb used on the "modern" TWs should run without any hiccups at alll.
 

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Discussion Starter #8
All stock
 

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Hi DKV, I'll add my 2 cents if you don't mind. 1. Try the double dose (4oz.) Seafoam to a tank of fuel remedy that seems to clear up a lot of people's carb issues, as it really is helpful for getting the internal passageways cleared up that your normal cleaning just can't seem to quite get. 2. Make sure that you're getting good fuel flow from the tank. Sometimes, the petcock screens or an inline filter (if user installed) can get a little plugged up. 3. if you haven't, give the http://tw200forum.com/forum/technical-write-ups/591-carb-tuning.html sticky a read and follow what qwerty wrote. Following the steps helps eliminate the guessing games, as you can undo the changes and know where you're at.

Okay, with that being said, I think that the slight hesitation at that rpm may indicate a flood situation there. Good luck. Keep posting your progress, and we'll try to help you along as we can. -Larry
 

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Discussion Starter #10
Going to try more seafoam (4oz per gal) and driving it through. Seafoam saved me from having an ultrasonic cleaning on my 50 honda outboard. Ran a quart of 50% seafoam and gas and cleaned things up.
 
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