95 cbr f3

my sig has build thread

cleaned carbs, bike started and ran, rode it twice

lost spark, pulled plugs, carbon covered so i turned in my mixture screws to compensate

bike started to flood gas out of air overflow tube when trying to start

i figured it was stuck float valves - local powersports shop agreed with me when i brought it in

inspected my old ones, one of them was indeed stuck - meaning that the needle on the top was not moving freely, the other three were moving but kind of sluggishly, decided to replace all 4

FINALLY got them the other day and put them in, put bike back together, tried to start it, turned over briefly..then started spewing gas out exactly as before.

I am very close to my wits end with this bike! I am now completely uncertain of what the answer to my problem is.

please help, i can provide more/specific information if needed

 

Which ones are over flowing? Might be bad float. Have tried blowing air throw gas line while carbs are off ? Air should pass through when right side up then stop when when you turn the upside down. Either way gas should come out unless you turn over flow screw out. Are theyscrewed in all the way?

 

sounds like float levels are off

 

How do I check/adjust levels?

 

any help here guys? should i order new floats? the valves were 80 bucks, new floats are about 120, i'll order them if its going to fix it but i'd rather not throw money at this for no reason!

 

don't buy from the dealer...not unless you want to go broke.

buy an entire rack off ebay

cbr f3 carburetor | eBay

That way you have two racks. Personally? I'd clean the rack off ebay, install and see how that goes. If you don't already have one? I'd get a service manual for the bike. I can tell you how to check float heights, but the manual has pics etc.

 

The float levels are not adjustable. The floats themselves are plastic. It only takes a grain of sand to hold the float valve from being able to sit in that seat. One thing I've noticed is that the float valve can bind inside that brass tube. You'll notice that the float valve is square in it's profile and it's going inside a round hole. This reduces the contact area of the valve to the brass tube. There tends to be wear marks on the inside of that brass tube where the float valve was rubbing. Using your hands you can feel the float valve drag against the inside of the brass tube as you move it in and out.

What I do is first use some scotchbrite on a small screwdriver to clean the inside of that brass tube, then I use some Brasso or other metal polish to really buff up the inside of that brass tube. You will feel a difference in how it moves.

If your floats are not broken or have holes in them, there is nothing wrong with them. Replacing them isn't going to help. If you do this proceedure, make sure you clean the passage ways out good as the green scotchbrite pads tend to leave little bits behind. A good rinse is required.

The top arrow in this photo is the brass tube I'm referring to.



This is an example of what I'm talking about with the scotchbrite. (you probably have one under the kitchen sink).

 

Thanks dirt will try that today

 

well encountered more problems, cleaned out the float seats like you described dirt, the valves appear to move a lot better after, reassembled bike and tried to start it, basically it didnt start for a couple tries, and then fuel SHOT out of the exhaust, and then it stopped even trying to turn over, it just clicks. searched a bit and i believe the engine is probably hydrolocked, i pulled my spark plugs and checked my oil, smelled strongly of gas so i drained it.

i'm going to leaved the plugs out overnight and put oil in tomorrow. should i be changing the filter as well? its about a month old but i dont know if gas would have gotten into it or not? any other tips for or suggestions let me know, going to resume tinkering with it tomorrow..

 

Well, that's not good (fuel out the exhaust). It certainly seems like the floats are not working properly. When you look at the float valves, how do they look ? Particularly the rubber tip and the tiny little spring loaded pin on the back end. To check the float valves for proper operation, I blow air into the fuel line while holding the carburetors in their normal position. Then I turn them upside down. When they're upside down, you shouldn't be able to blow air into the fuel line. If you can, one of the floats isn't working right.