Carb Problems

My 08 CRF450R ride before last started to cut out when blipping the throttle to get the front end up. Never did this in the past. Yesterday, the bike did the same, but not as frequent or as severe. Temps were cooler yesterday. Then the float stuck, draining fuel out the overflow tube. Tapped on carb bowl with wrench and it stopped draining. Fuel drained out the overflow tube a couple more times. Tapping with wrench corrected the problem.

When fueling, I looked into the tank and noticed bubbles coming from the fuel screen in the bottom of the tank. Closed fuel valve bubbles stopped. Checked the vent tube on the gas cap. It was clear. 

Any ideas what is going on with this carb?

Thanks in advance for the help? 

 Yes

 

You need to service the carb, or it will get worse as the corrosion spreads

You need to do a full service of all sections, or you will just be chasing gremlins one at a time.

 

http://www.dirtrider.com/features/protips/141_0707_keihin_fcr_carb_rebuild/

 

If you do it soon enough, you probably won't have to soak the body to remove the internal corrosion.

When the float needle starts to stick, that is the tell tale sign of corrosion spreading inside the carb at the dielectric points (unlike metals).

 Yes

 

You need to service the carb, or it will get worse as the corrosion spreads

You need to do a full service of all sections, or you will just be chasing gremlins one at a time.

 

http://www.dirtrider.com/features/protips/141_0707_keihin_fcr_carb_rebuild/

 

If you do it soon enough, you probably won't have to soak the body to remove the internal corrosion.

When the float needle starts to stick, that is the tell tale sign of corrosion spreading inside the carb at the dielectric points (unlike metals).

 

Thank you for the feedback!

 

Is there any way to prevent the corrosion or slow it down?

Thank you for the feedback!

 

Is there any way to prevent the corrosion or slow it down?

 

Yes

Treat your gas with Tri-G, Torco, Maxima, or any 'real' ethanol gas treatment, every tank, and drain the floatbowl if the bike is going to sit for more than 4 weeks. 

I put a few hours on the bike Saturday. Weather warm and traction good. Almost identical conditions to the last time I logged seat time on this bike and no problems. The bike ran perfect. No stalls and or flame outs. No hesitation when aggressively opening the throttle. No fuel coming out the overflow due to stuck needle. I didn't do.a thing to the carb other than add sea foam to the fuel. I am waiting for a rebuild kit to come in.

Someone mentioned the bubbles coming from the bottom of the tank could be the fuel boiling. Unfortunately I didn't check the tank for bubbles Saturday.

Any ideas why the carb goes from performing poorly to working well with nothing being done to it?

Edited by cleaner1

Seems odd the fuel

Would be boiling since it's not really that got anywhere right now and I can't see things getting quite that hot internally but I am just guessing.

Krannie is always right. Working good one day and poorly the next cleaning that thing out like a champ will at least clear your mind next time if something happens that at least you've serviced things and know seals and o-rings are good and jets are good. Also not sure if it could be a fuel screw mixture issue since you mentioned some sig differences in temperature. Just some thoughts. Again, trust Krannie and have a little fun tearing that carb apart in the garage. Good

Luck.

Seems odd the fuel

Would be boiling since it's not really that got anywhere right now and I can't see things getting quite that hot internally but I am just guessing.

Krannie is always right. Working good one day and poorly the next cleaning that thing out like a champ will at least clear your mind next time if something happens that at least you've serviced things and know seals and o-rings are good and jets are good. Also not sure if it could be a fuel screw mixture issue since you mentioned some sig differences in temperature. Just some thoughts. Again, trust Krannie and have a little fun tearing that carb apart in the garage. Good

Luck.

 

 

:facepalm:

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