What is Carb Octopuss Thingy?

[Captain Bob]

I recently picked up a 99 WR 400 which I believe has most mods done (throttle stop, YZ timed, airbox). I still have the stock pipe (no baffle). I assume the bike has been rejetted, it seems to run very well and strong! I do not have the YZ cam/auto de-compression installed. I do not believe have the Zip Ty throttle screw installed as well.

I have heard something about removing the carb octopuss? Could someone please explain to me what the carb octopuss is? Also, what is the benefit of the zip ty throttle screw over the stock screw?

Thanks!

Bob

[dbailey223]

THe zip ty screw makes it easier to adjust the screw because it has a large round head on it and it sticks out further from the bottom of the carb (and you can turn it by hand), unlike the stock one where you have to have a scre driver, etc.

Isn't the octoposs something in the suspension, not the carb?

[griffithds]

The octopus thingy might be referring to the AIS plumbing on the carb. It's an air injection system that pumps exhaust gases back into your exhaust system. (You can thank California for it). Once your bike is jetted correctly, you will experience backfiring on deceleration, T/T store has kit that will remove the AIS thereby eliminating the anoying backfire. Doing this when installing to Zip Ty screw would be good timing and a worthwile investment.

[Rich_in_Orlando]

The octopus is the first generation version of the air cut valve (ACV) on the carburetor. Those early FCR carbs didn't have a hot start or an ACV built into them. You will know if the carb still has the ACV if there is a bunch of external plumbing connected to a "diaphragm assembly" which is bolted to the outside of the carb.

As far as the benefits of removing it, go to www.thumperfaq.com/acv.htm for more info (it also links to pages on Thumpertalk.)

[Captain Bob]

Thanks much! The link you provided was very helpful. Being a newbie to TT I need to better familiarize myself with the archives. Thanks again!

Bob

[Captain Bob]

Thanks much! The link you provided was very helpful. Being a newbie to TT I need to better familiarize myself with the archives. Thanks again!

Bob