Triumphrat

Orpheus · 07-25-2006

I took my T100 in for 500 mile service yesterday. Last night, I rode it all up and down PCH and I-5 South from Orange County to San Diego. It was fine. It ran well and had plenty of power. This morning, I rode it back to work.

About five minutes into my ride, I stopped to get gas. I filled up (but not overfilled) and got on the freeway. I worked up to about 70-75 mph. After maintaining this range of speed for about 30 seconds to a minute, my fuel started cutting out.

I would start to feel weakness followed by surging, and then more weakness. I would pull in the clutch and rev the engine, but it wasn't a clean rev. It was just a messy burble. I pulled over to the side of the freeway and put it in neutral. It was idling sub-1000 RPM. After about 15-30 seconds, I would slowly roll on the throttle and it would be a clean rev again.

I pulled onto the freeway slowly and worked my way back up to 60 mph. All seemed fine, but after about a minute on the throttle, it would start to cut out again. I would pull over and repeat this process about eight or nine times on the way from Solana Beach to Orange County. I found that if I pulled in the clutch or rolled off the throttle regularly, I could go without the fuel seeming starved. Eventually, it mostly cleared up, with only one repeat occasion after riding around 80 mph for a couple of minutes.

I took it to the dealer. They looked at the carbs, fiddled with some stuff and took it for a ride. The mechanic said he could not repeat the problem, but that a few others had come in with a similar issue. One theory was that the EPA charcoal cannister accumulated gasoline fumes overnight and was messing with something. :???:

Another theory was simply that the flow of fuel was being inhibited slightly, causing the bowl to fill and allow me a minute or two of clear riding following by the repeated coughing fits.

Whatever it is, I don't like it. Especially not on a new bike.

Geoff · 07-25-2006

there seems to be a venting issue with some peoples gas caps.
remove or loosen the cap and see if problem goes away.
Geoff
ps- if it goes away get a new cap under warranty from dealer

JonahP · 07-25-2006

just had the exact same thing with my new scrambler.... When I loosened my gas cap the problem went away. Next step is taking it to the dealer to get the cap replaced and the breather hose checked for kinks.

wenzel850 · 07-25-2006

O,

This does sound like a kinked breather hose, especially since you said the bike just had work done to it. If when you remove the gas cap and then put it back on and the bike runs fine for several minutes, you have a kinked breather.
(I'd bet money that's your problem). In that case remove your gas tank, it's real simple, just a couple of bolts at the end of the tank closes to the seat. Pick up the tank and find the hose that is pinched. It's the hose that goes down to the swing arm and then put your tank back on REAL CAREFUL
so that you don't pinch the line again. It's a PIA but not very hard.

badrufus · 07-25-2006

A problem occurring right after service probably does not indicate anything bad about the quality of your bike. I'm always on the lookout for problems after I have taken my bike in--any bike, any dealer. You've probably got a kink or pinch in the breather hose. I had the same thing happen and it would go away when I cracked the gas cap a bit. The only other possibility that I can think of has to do with the hot weather. I had an in-line four Yamaha, with four carbs directly behind four hot cylinders, and only air-cooling. In hot weather, the heat coming off the cylinders could cause a vaporization problem, literally causing a kind of vapor lock with the fuel going to the carbs. I installed a heat shield between the cylinders and carbs, and that solved the problem. If that were a problem with the Bonnies though, more people would be reporting it, especially with the recent heat.

Orpheus · 07-25-2006

Thanks for your help, guys. I'll try that out when I get a chance. I hope it's something that basic.

RedBird · 07-25-2006

I agree with what has been said...if replacing the gas cap fixes the problem, you still have a vent hose problem. I rode 125 miles last week in 105 degree heat with a gas cap that has no vent...no problems, ran very good even at high rpms. I had lost my gas cap and it got run over before I could get it out of the street, so I made a temporary cap with no vent while waiting for the dealer's order of a new gas cap.

Larry