Run-away motor!

[matt glascock]

Hello all. For those of you who've never experienced the helplessness of a runaway motor, the best description I can provide is "gut-wrenching". I was taking a Model 94 Wombat out for the annual reawakening after hibernation. Everything was working properly and then at a stop sign it began winding up and it didn't stop until REEEEEEEEEEEEEEEEEEEEE! While maintaining a death grip on the clutch lever, I turned off the key and on she ran. I yanked off the spark plug wire and that didn't stop it either. Finally, out of great ideas and happy I survived yanking off the plug wire bare-handed, I blipped the throttle and that broke the uncontrolled revving. Considering I'm the guy who reassembled a motor and left a blue shop towel plug stuffed in the intake manifold, I figured it well within my spectrum of stupidity to have perpetrated similar malfeasance reassembling the slide. It all appeared in order, but the carburetor cap was loose. Quite loose as a matter of fact. Fortunately, we both survived the stress test (her mechanical, me cardiac), it restarted, and we limped home at idle speed. I'm all ears, guys. What do you think happened? Where do I need to look. Thank you!

[dirty_rat]

The loose carburetor cap would in all probability cause a major air leak. While the air is still going through the carburetor, it's not flowing over the jets as intended. That, plus if the cap was loose, the slide might not be returning all the way to the bottom of its travel, leaving it like an extremely high idle. Just a couple of thoughts.

[MTrat]

I once worked on a Kawasaki with rotary valve that someone else had put together. The oil injection feeds into the intake between carb and engine. The vent hose to the carb and the oil injection hoses had been crossed. The straight air into the intake downwind caused an ultra lean situation and the bike ran wild and dieseled so that the only way to stop it was blocking the carburetor. Pulling the spark plug wire did no good. Now that was a little hairy until I figured it out!

[viclioce]

Another thing I’d check is this. Is the carb top missing the spacer? This gives a little bit of spring tension to the cap, kind of like a lock washer. Without it, a tightened cap could vibrate loose a little more easily? Just a thought. Victor

[matt glascock]

Thanks fellas. This is for sure: checking the carburetor top tightness will now be a fixture of the pre-ride walk around!

[taber hodaka]

Never use a wrench to tighten, fingers only. Would this be another plus for using a compression release??