Bike reving up on its own

[chris6888]

My 83 650 katana is reving up on its own. I have it idleing at about 1000rpm than all by itself it will jump up to about 3000rpm for a few seconds and then idle back down to under 1000rpm and stall. I start it back up again with some choke and it idles fine for a while then does it again. Also some times it has a small back fire (pop sound) in the number one carb. Has a bit of hesitation when i rev it up.

[Nessism]

Intake boot o-rings is my guess.

You might want to check the Top Newbie Mistakes thread, as linked in my signature.

[BassCliff]

Hi,

I concur. The first suspect in this case is an air intake leak. Have you gone through all of the maintenance tasks in your "mega-welcome"? You recieved it in THIS THREAD.

Airbox sealing, new intake boot O-rings, probably new intake boots themselves, don't forget the airbox boots, etc, all have to be checked, repaired, or replaced. See:

Air Intake Repair:
(Airbox removal, intake boots and O-ring replacement)

Airbox Sealing

Keep us informed.


Thank you for your indulgence,

BassCliff

[chris6888]

I have not done the carb rebuild yet the boots look good also there is no air box it has k&n filters

[tom203]

I have not done the carb rebuild yet the boots look good also there is no air box it has k&n filters

Remember you're flying blind here- you don't know how the bike was maintained BEFORE it sat for years waiting for you. Carb problems can be very frustrating and unlikely to be fixed unless you do a proper cleaning- this will also give you the opportunity to see if the jets were changed when the pods were applied. The o-rings are in the boot/cylinder head interface- visit cycleorings.com to see an example of dried out ones !

[BassCliff]

Hi,

Have your carbs been re-jetted for the K&N pod filters? See: Top 10 Newbie Mistakes



Thank you for your indulgence,

BassCliff

[1_v8_merc]

Check your floats immediately, they can easily cause your rpms to jump on and off.

I just fixed the exact same problem on my 750, my carbs were running WAY too rich,(fuel screws), and the Floats were Completely off.

If you put the bike on the sidestand, do the rpms go excessively high and Stick? If so, your floats are to blame.

Also, make sure your mixture is set to factory spec, and airboots are tight.

[Gonzo]

I have not done the carb rebuild yet the boots look good also there is no air box it has k&n filters

You can't just eyeball the boots while they are still on the bike. The only way to know for sure if they are good is to pull them off, and give em a good squeezin'. Old boots will be stiff as plastic. Good ones will bend and flex and be very supple. Then there are the o-rings too. They should be pliable and round, not stiff and flat.

As Tom said, assume nothing about the P.O.'s dedication to maintenance or even the quality of it. It sounds like it's more trouble than it's worth to take the long road, but on the contrary, it will save you from doing the double work you would have if you take short cuts.

[robertbarr]

Intake leaks and/or (probably more and than or) carbs out of sync. Either of these can cause the idle speed to creep up and stay up after the engine warms.

http://www.cycleorings.com/intake.html