Runs great, then loses all power and dies

[oldyam80sg]

Also did you pull the plugs after doing a throttle chop -that is with a load on them?As i understood it that way you could tell if it is running rich or too lean.Also did you verify that both petcocks when turned to on actually have flow coming out?

[Grimace]

dbeardslee, I adjusted the idle mixture screws by ear, (thought it was in the tech section but I can't find it now) always keeping the idle at 900. I started with the screws out 1 1/2 turns, and turned them out listening for the engine idle to rise, and as soon as it started to fall, I turned them back in 1/4 of a turn.

My petcocks are manual, and yes, I have a nice steady stream of fuel coming out. I made my own fuel manifold out of stainless brake line so I could bend it making sure the fuel was always running down hill into the carbs.

I gunned it to full throttle, then chopped it and hit the kill switch coasting back home. Then pulled the plugs and read them.

[dbeardslee]

Grimace - Just something to think about. When I adjust mine I use a colortune plug so I can see what's going on in the combustion chamber. Due to slight differences in the shape of the mixture screws (they aren't all straight, with varying degrees of 'bend'), and I'm sure other factors in the carb, one turn on a given carb does not necessarily produce the same mixture as one turn on a different carb. With the colortune I adjust the carbs at the combustion chamber so the fuel air mix there is at it's optimum - which is sort of the point of the whole operation. None of my carbs is adjusted to the same number of turns and I get nice consistent results across all plugs - light brown. If you have all your carbs adjusted to the same number of turns out, you may have different mixtures across the cylinders, which could account for the variation in the coloring of your plugs.

You mentioned previously that at one point you 'lost all power' - did the electrical stuff (lights, instruments, etc) go off, or were you saying that the motor just lost power?

[Grimace]

All electrical power lost. Bike died and I lost all electrical power.


When I said I turned the mixture screws out 1 1/2 turns, that was just for a starting point. Then I adjusted each one individually for the best idle.

I thought about a colortune kit, but I would just settle for getting rid of that annoying stutter from 4k to 5500. After 5500, she picks up and gets it done.

I am exploring all options here, and I think I am gonna try moving the main circuit needle up a groove to see if what I am experiencing is lean out during accelleration. I talked to a local lead mechanic last night, and he was telling me a few things to look for, and one thing he said I should try is when I pin the throttle and it stutters, pull the choke out one click. If it picks up and runs great, I am lean. If it gets worse, I am rich.

[oldyam80sg]

If you are losing all electrical power than something else is wrong beside your carbs.Are the battery connections tight? Did you check the wires behind the fuse block?Is the battery low on any cell?I have had batteries start to lose a cell and you can tell by looking at the minimum line on the battery if it not sealed.Did you check the fuse box connections?I know you said you are waiting on a fuse block from Tomcat but did you check each individual fuse to see if its good? Just a thought.

[dbeardslee]

Oldyam80sg said :

If you are losing all electrical power than something else is wrong beside your carbs.

Ditto.

I'd be checking around all connectors, particularly those inside the headlight bucket, and the wiring behind the fuseblock, as well as cleaning and dyelectric greasing all connectors. Like Oldyam said, there's something else wrong there besides the carbs if the electric shut off. I'd find that problem first. You never know, it could be related to the power-loss.

On the power loss issue, I found another thread from an xsive that was having trouble in the 4-5k range . He was addressing the problem with jetting. Had some good info, so I pass it along.

[Grimace]

Good info guys, and yes I did check the old fuse block and all wiring behind the headlight, fuse block, etc. What I found was a broken ignition fuse holder, which I replaced with an inline spade connector as a temp fix till I get TC's new block.

I went ahead and got into the carbs again and changed the other three pilot jets to the 8 hole style. BAD IDEA!! It ran so rich, I bet I wasted half of a gallon of liquid gold just trying to get it to run. Switched back to the other style pilot jets, and looked at my diaphrams again. The originals looked good until I checked the "new to me" diaphrams I got from cokeman. My originals were pretty hard compaired to the new ones. The new ones are very soft and pliable. I think that may be a huge problem with the 4k-5k stumble. Re-synced and reset the idle screws again (like the 10th time this weekend) and gonna go ride in a bit. Will report back later.


Thanks for the carb link dbeardslee, it has some great tips there.