[BowdawG]

I have a 73 Yamaha GP338 (twin carb). It has 421 original miles. I rebuilt the carbs about 10 years ago and used it for a few winters then stored it with sta-bil. Last winter I could not get it to run, so I drained the fuel and put in fresh fuel and sta-bil and put in new plugs. I just disassembled the pump portion of the carbs and the float level needles in both carbs were stuck.
Currently it will start and idle around 2k rpm but when you tip into the throttle it will rev up, but only to about 3,000rpm max and after 2-3 seconds at that speed will start to lose RPM and die. If you give it full throttle when its idling some fuel spits back out of the carbs and it just makes a 'blaaaaat' sound and does not rev up.
Any tips / things I can check for would be appreciated!

 

[Carter]

Check the throttle safety switch. push it in and try it. My 1980 jag did the exact same thing.

 

[88Jag]

i have an 88 jag 440 and it bogs anytime i give it throttle and when i adjust the throttle cable on the top of the carb its like im using the throttle and it will rev up and ingage the clutch and ideas on what the problem is?

 

[Carter]

Have you tried to bypass the throttle safety switch? It is the little button where the thumb throttle hits when not depressed. I just bought my 1st sled this year. I brought it home and wouldnt rev up. Hell, I rode it where I bought it, so I was puzzled after checking everything. I found that button and pushed it in with my finger....damn near ran thru the garage door..so open the garage! lol

 

[88Jag]

its an 88' arctic cat jag 440 it only has the key, and stop switch on the handle bar its not like a yamaha with the safety switch on the carb

 

[RJ Gleason]

Yamaha uses a system called TORS (throttle over ride system) which consists of 2 sensors on the carbs and a switch in the throttle block.
Unplug the wires from the carbs and connect the harness ends together. This bypasses the system and should solve the problem.

 

[BowdawG]

mine is too old to have a throttle safety switch! dual kehin carbs... anyhow I just found the problem- there was about 2 pounds of birdseed the damn mice had packed into the resonator (about half the total volume of the resonator)! Needs a bit of a tuneup now, but runs around the yard good while partially choked.

 

[RJ Gleason]

Damn meeses!!

Steel wool pushed into the exhaust outlet for storage will keep them out. Also moth flakes in the engine compartment will keep them away from the air box and wires.