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· Registered
352 Posts
Discussion Starter · #1 ·
Beware: a bit long-winded, as usual. Hopefully it'll help someone that hasn't done troubleshooting like this before. Worst case it'll be ignored and archived for someone's search later

I've had a random problem on the TW since I bought it.. thought I took care of it, then it seems to have reappeared.

I got smacked in the face by the cluebat this morning on my way to work, and I believe I've taken care of the issue: tomorrow I'll know more

Problem description and scenario goes a bit like this:

Yesterday I started the bike, warmed it up, took off out of my driveway. About 1/8 mile from my house, there is a large hill leading into a small valley with

and equally large hill on the other side. After descending the hill and ascending the other side, about 500 ft down the road, the bike starts cutting out hard (quitting, actually) and if I roll hard into the throttle, it'll keep sputtering like that, but when I let off at all, its done, and I clutched in and rolled to

a stop. There's a nice dirt road entrance right there, so I pushed the bike onto it to get out of the way of traffic and started troubleshooting (in the rain).

When this happened before, no amount of kicking it over would make it start and run right for 5 minutes or so, and it really wasn't worth trying until that point. Wasn't sure what to make of this, but the bike is just getting up to full operating temperature at this point, and I'm only 1/2 mile from my driveway.

Well, I was impatient and after about 45 seconds I kicked it over and to my surprise, it started, and ran like absolute crap: sputtering, barely idling, couldn't touch the throttle or it would quit, etc. I then waited out the 5mins or so and kicked it over again and it ran great. My gut feeling was turn

around and head back to the house, since its a lot closer than my office, so I did. About 50ft from my driveway, it quits again, so I roll in and push it

into the garage. Last night, I pulled the carb after work and cleaned it out thoroughly, ran copper wire through all the jets and passages. At the same time, I put a single washer under the needle and turned the pilot screw out a bit (to 5 turns, I was at 4 prior). After getting it back together and doing a

test fire, 5 just wasn't right, so I started over and tried 3 turns out. So far so good on 3 turns with 1 washer.. ran much better, so I parked it with

a good tune and called it a night.

This morning, I fired it up and noted that even though the humidity and temperature are MUCH higher than when I tuned it, it still ran great. So I warmed it up, and took it for a blast out back to make sure everything was well. Without shutting it off, I took off toward work, descending and ascending the same two hills, and wouldn't you know it: the bike started sputtering and quit within 5ft of the SAME SPOT as the day before. I pulled the carb/tank vent lines and tied them off (open, instead of to the canister), waited the 5 minutes, and fired it back up: running great again. Today I was more adventurous due to it being a REALLY nice day, so I continued on to work. About the same distance, but instead of a few hills, theres a long "fast" (45mph) stretch, and then a sharp corner: bike quits again right after the corner, so I let it sit for 5 minutes, knowing my vent-line test didn't do a darn thing. Fired it back up, continued on to work. Same distance, no sizable hills, 30mph speed zone: quits again. Pull over in a parking lot (in town at this point), wait 5 minutes, then fire it up and ride to the gas station for a soda and breakfast. I did that because I was about to get into traffic lights and didn't want the bike to quit in my lane and cause real trouble. I also did it as a test: to see if I let it sit for a while, close to the end of that same distance, would it react differently? Well, lucky me, I idled through town with about the same throttle that I didn't have trouble with out back in the woods, and didn't hit any red lights and made it to work without trouble.

Well, the end of the day came and I wasn't looking forward to dealing with this again: so I did what anyone would do: I tore my bike apart next to our loading dock at work to do some testing and hopefully some fixing.

My theory was fuel starvation, since my tests above didn't point to CDI troubles. I had adjusted the float level before (by the manual spec) and it relieved some of the more severe cases of this problem that I was having at the time. Well, Yamaha was nice enough to ship these bikes with a clear tube already hooked to the carb bowl drain, so I pulled it from the J down by the swingarm and did some fuel level testing: nearly half an inch below the bowl gasket! I repeated the test a few times to verify that the float/inlet valve wasn't sticking, and the results were identical all three times. So, carrying a good compact set of tools with me, I yanked the carb and did a by-eye adjustment of the float level with my pocket knife, then reinstalled, turned on the fuel and hoped it wouldn't overflow all over the parking lot. A few minutes of watching nothing later, I decided that it was worth a try and headed home.

Impressions: I flogged it good all the way home, took the long way and hit a new top speed on the TW: 55mph, according to my questionable speedometer. For all I know, it could've been 40, or 180..

The important part: it DIDN'T QUIT! Well, we had some fairly tropical weather, so I decided to take a little ride, and put a fresh tank of E10-87octane in it (all we can get in NY) and put 25 miles on it, mostly offroad, and the bike ran better than ever. I'd call it a candidate for a valid solution, but I'll know tomorrow after I descend and ascend the same accursed hills that killed the bike the last two mornings

Good luck!

· Registered
352 Posts
Discussion Starter · #3 ·
Still running great, after ~100 additional miles: 40-50 today involved some pretty hard rock/gravel/loose hill climbs with lots of throttle..

(And, in direct response to qwerty: yes, its on the jazz)
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