600 shadow


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hugger-4641
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Joined: Wed May 25, 2011 1:07 pm
Location: McKenzie, TN
Motorcycle: 1994 GL1500 Aspencade, 1982 CM 200 Twinstar, 1984 VT500 Ascot

600 shadow

Post by hugger-4641 » Tue Nov 08, 2016 11:16 pm



Ok, just shot in the dark for suggestions here. Friend has a stripped and heavily modified late 90's model 600 shadow. Don't know where he got it, but he paid some guy who was recommend to him to rebuild the carbs with bigger jets and do some cosmetic work and other modifications. I think he got screwed. He brought it to me to see if I could help with several problems. I managed to help him fix all but one problem. I won't bother with all the little details, but the bike barely ran, missed, stalled, spit, sputtered, idled too fast when it did run. After replacing some missing and open vacuum lines and adjusting the mixture screws on the carbs, I've got it where is runs pretty smooth and accelerates good, but will not exceed 70mph. Keep it under 70, it runs great and will go all day. Hit 70 to 75mph and it starts missing and acting like the fuel is shutting off. Let off the gas and give it a few seconds and it picks back up and runs fine again as long as you stay under 70. I'm thinking maybe the other guy set the floats or something in the carbs wrong and it is emptying fuel from the bowls. I should mention that it now has straight pipes that stop just in front of the driver pegs, so I'm also wondering if there might be a back pressure issue. Any suggestions are welcome before I devote my time to helping him tear these carbs apart!



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WingAdmin
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Re: 600 shadow

Post by WingAdmin » Wed Nov 09, 2016 4:52 pm

Sounds like a fuel delivery problem. It takes an awful lot of power to keep a bike going that fast, which means more fuel is required. If the fuel delivery system isn't up to the task, the bike literally runs out of gas.

Check the fuel filter, and fuel pump. Check to make sure the fuel volume being delivered is within spec. Check for kinked fuel lines. Check for a clogged screen in the fuel tank (if there is one).

If he gets up to 70 mph and it runs good for 5-10 seconds, THEN starts to sputter and die, this is a good indication of exactly this problem: it runs fine until the carb bowls are emptied of fuel, at which point it sputters from fuel starvation because of insufficient fuel delivery. Slowing down allows the fuel pump to catch up, it refills the bowls, and the engine comes back to life.

If everything checks out, and the modifications (bigger jets) actually demand more fuel from the fuel system than it is capable of delivering, you might be needing to look at a different fuel pump with larger capacity.

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hugger-4641
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Motorcycle: 1994 GL1500 Aspencade, 1982 CM 200 Twinstar, 1984 VT500 Ascot

Re: 600 shadow

Post by hugger-4641 » Sat Nov 12, 2016 9:36 am

Thanks for the response WingAdmin! I didn't even think about fuel pump, but I just happen to have an electric pump laying around I could use to test with. I believe it is 7 to 12psi, do you think that would be too much for those carbs?

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robb
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Re: 600 shadow

Post by robb » Mon Dec 12, 2016 9:36 pm

Been away since selling my Wing. Hope you have resolved the problems by now. My Honda Shadow 600 had similar issues, due to extended times of not being ridden. Petcock was partially stopped up and its not that much flow to start with. Also the fuel filter was blocked and greatly limited the small flow. Bad idle is probably a stopped up pilot jet in carb, requiring removal and cleaning. With only 3 psi my dressed out 480 pound bike can easily accellerate to 90 for passing.




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