midrange, under load, only when warm

[rlong74]

Well, I am back again after a few months of hassle free riding.
It started a couple of weeks ago on my '81 450. There would be a sporadic hesitation in the midrange which i could negate with a touch of throttle. It has now degraded to something akin to a bucking bronc in the midrange under load when warm. I am safe if I am above 6k or below 4.
Before I just started tearing into it i wanted to see if the sages had anything to say.
Thanks to all.
I would just like to add that a couple of months ago I followed the carb cleaning guidelines laid out here and I ran like a champ. I have also recently installed a new signal generator (last fall). new plugs went in 1k mi back.

[Nessism]

If the bike stock or modified? All the maintenace all up to snuff including a valve adjustment? How is the gas tank? Free from rust?

[rlong74]

The bike is stock. I might also add i threw in a new air filter not too long ago. Tappet clearance is good too. I have noticed a tiny bit of rust in the tank. appears to be the beginning.

[Nessism]

The bike is stock. I might also add i threw in a new air filter not too long ago. Tappet clearance is good too. I have noticed a tiny bit of rust in the tank. appears to be the beginning.

Maybe rust is plugging up the carbs?

[rlong74]

Thanks nessism.

[Guest]

Clean the carbs, knock the rust out of the tank and run a gravity fed type filter.
Try POR-15 sealer on the tank.

[rlong74]

Noticed something odd today.
Was going through the electricals and when I got to the R/R the cover on the bullet connector for the red wire had a little brown melted spot. there was also a melted spot on a white with green tracer wire at the connector. I believe this wire to be a phase of the generator.
Hmmmm

[Nessism]

Noticed something odd today.
Was going through the electricals and when I got to the R/R the cover on the bullet connector for the red wire had a little brown melted spot. there was also a melted spot on a white with green tracer wire at the connector. I believe this wire to be a phase of the generator.
Hmmmm

Yup, those stator feeds run hot. I recommend routing those feeds directly into the R/R and bypassing the extra wiring in the harness. Also, make sure your R/R has a proper ground. This topic comes up all the time so you can find tons of info in the archives.

[rlong74]

Thanks for the input guys.
I pulled the carbs today and they were as clean as the day I put them in. However the float on #2 was way out of wack so I adjusted and there was also one loose screw on the float bowl anyhow she runs fine now half hour test ride with no problems.
Thanks again
Ryan