BensonTweed

So the other night I was riding my SH through Beverly Hills and my bike died at the light. I fired her up and she sputtered, back fired, and wouldn't keep idle. I rode the clutch out just to get going and had hardly any acceleration or torque. I rode it home and and thought maybe I fouled a plug. I could smell gas coming out of the Jardine's and felt like I was running on one cylinder. I changed the plugs but she's still running way too rich and I have no power. Its like riding a 996cc scooter. I checked and there was a lot of gas in my air cleaner and all around. I think something must be holding the carb open but I know jack **** about fuel systems. Any ideas?????



-Benson Tweed
'98 Italian Red SuperHawk
Jardine RT-1's
Pirelli Dragon SuperCorsa's

Hawkrider

Did you brake realllllly hard at that light right before it died? If so then you have two problems...well, not problems, but that's just the way this bike is.

First, the gas from the rear carb bowl will overflow into it's own vent due to the extreme braking forces. This essentially causes vacuum lock on the carb...or something like that. Most Superhawks do it. If you go to my website there's a fix you can do to minimize or prevent this. You just reroute the rear vent line.

Second, if your tank was full or close to it then it's likely you also spilled fuel into the tank vent. This WILL cause vacuum lock and all that's needed to fix it is to open the fuel filler cap to break the vacuum, and then you will probably see a little gas come out of the vent hose at the bottom of the bike. Wheelies and stoppies after a fillup can/will cause this to happen. Filling the tank to the brim can also cause it.

Hopefully your problem is no more than the "characters" of our bike as stated above. Only other thing I can think of is a dead coil, but since this all started after braking for a light, this is what made me think of the two problems I listed.

kai ju

Check for fuel in the vacuum line to the fuel valve.
Did you recently have the tank off and maybe hooked the vacuum line to the tell tale tube instead of the vacuum tube ?
Or if there is fuel in the engine oil you may have a stuck float just dumping fuel into one cylinder.
You mentioned that you replaced the plugs but did not report their condition, the one that's wet would be the one with the stuck float, unless it's the cylinder that's actuating the vacuum petcock which leaves us with a leak from that source again. Pinch the tube off with the engine running and see if it starts to run better.

Good luck,

Kai Ju

XLSR-VTR1

Hawkrider :"Second, if your tank was full or close to it then it's likely you also spilled fuel into the tank vent. This WILL cause vacuum lock and all that's needed to fix it is to open the fuel filler cap to break the vacuum, and then you will probably see a little gas come out of the vent hose at the bottom of the bike. Wheelies and stoppies after a fillup can/will cause this to happen. Filling the tank to the brim can also cause it"

This happens and it runs like its on one cylinder.. First time this happened it took a second to figure out since I just gassed up... popped the fuel cap open and close and was good to go.

Hawkrider

Yup! I wouldn't lie to ya'.

It's highly unlikely that a float valve would get stuck. The strainer in the tank wouldn't let anything get by to clog it and by its design there's really no way for it to stick open. Something would have had to break, and that's unlikely too.....though I have heard of floats getting holes in them and sinking. That could do it.

I still think it's one of the two problems I suggested earlier.

BensonTweed

So I followed everyone's advice.......but to no avail. I knew it wasn't vaccuum lock with the fuel cap. I knew it wasn't a vaccuum hose connected wrong. I even changed the spark plugs. Finally I took the SH to the guys at MotoShop in Santa Monica,CA. They found that one of my carbs was clogged up. So.........I go pick her up today and hopefully she runs like new. Thanks for all your help everyone..................Keep 'em rubber side down.



-Benson Tweed
'98 Italian Red SH
Jardine RT-1's
Pirelli Dragon SuperCorsa's

XLSR-VTR1

clogged up? where? did they give you any details?

Hawkrider

Hmmm, did the bike sit for a while? I can't think of any way for them to get clogged other than that....unless someone took your strainer out of the petcock. Doh! That would be bad.

saxman

Ever since I did the "relocation" of the vacuum line, I have smelled gas. Today I took the tank off, and on the "tell tale tube", there seems to be gas seeping out. Could I have damaged the internals of the petcock by hooking up the vacuum line wrong?

Hawkrider

Yes, that's entirely possible. You're sucking the wrong way on the diaphragm. I'm sure it's designed to have a vacuum on one side only. Possibly you've torn it. They do come apart for inspection. There just aren't any repair parts....yet. K&L has lots of petcock repair parts. If you're torn then you might be able to give them a call. They should develop one.

saxman

That's what I was wondering......thanks Greg, will see what they say.
T

BensonTweed

So the shop cleaned my carbs.......but found my bike was running on one cylinder like I first thought. Come to find out, there was a little blue wire going into the ECU that was cut in half. After replacing the wire, she runs on two cylinders again. That combined with new spark plugs and clean carbs and she runs better than ever. Cheers to Victor and the guys at MotoClub in Santa Monica.