High Rev / Backfire

[rx-1 blue reverse]

I have a couple questions:

First. My 03 starts without the choke(when cold) it has never done that before. It is also running at almost 3k once it starts. As soon as I touch the throttle it backfires. I then moved the choke lever, while watching the choke bracket on the carbs. Everything seems good and free. I did notice that when I moved the choke lever there was no change to the engine sound or RPM.

I took the crabs off and checked all the jets, they are clean. the slides are free and I checked the choke mechanism again.

Anyone have any ideas?

Now for the second question. When I was putting the bowls back on I broke 1 of the screws, what thread size are they?

 

[rxrider]

When you start With a Cold engine it's supposed to idle high until the engine temp light goes out.
Does it drop the RPMs when the light goes out?

You may run With the choke on all the time???
Have Your checked the choke mechanism?
Does the choke lever arm at the carbs move back and forth when applying and letting off the choke?
At the each carb there is a choke activator arm, where it enters the carb there is a rubber plug the arb goes thru. Are the plugs in Place?

 

[rx-1 blue reverse]

I checked all of thay and it all looks good. No it did not drop after the light went out.

 

[rx-1 blue reverse]

I wonder if I got some bad gas. As soon as I get the scew replaced I will check a few more things. Still looking for the thread size on those screws

 

[rxrider]

What screw do you need to replace?
Japanese machinery, metric or UNC threads.

 

[rx-1 blue reverse]

The phillip ones that hold the bolws on. I think they are 4 x.7

 

[rxrider]

Metric

 

[fryguy]

Do yourself a favor and swap out the Philips screws for Allen head screws. Made carb work much nicer for me.

 

[rxrider]

Or torks even better yet

 

[rx-1 blue reverse]

So here is a update. I took apart my carbs everything looked good. I put everything back together and started the sled up. No problems. It seemed to run good. I took it for a spin aroung the neigherbood good power seemd fine, until I came off the throttle. I got a backfire and high revs (just shy of 3k). After that everytime I touched the throttle I backfired. To fix this I went full choke and then the rpm came donw to normal and I could run it again. Any ideas?

 

[smokingcrater]

sticking cable? the backfiring could be a sign of TORS kicking in.

 

[rx-1 blue reverse]

I will pull the TORS tonight and try it

 

[rx-1 blue reverse]

Another Update: I bypassed the TORS, all good. So I started looking at the cabeling, I added a ext. to the throttle cable and now the cable routing is NFG. I can run w/o the TORS, but I am not going to. Time to go get a 05 mtn throttle cable. Also going to look at a teather.