Basic Carb Question...

[BTaksier]

New info on post 7....


Thanks guys

 

[nanoonanook]

Hey,
I have no idea about the fuel delivery and how you are describing it. Frankly, if it were me and it was the only thinking keeping me from riding, I would pull the carbs off and clean them up with some compressed air. Do a good visual inspection while they are off and if all looks good - and given the recent professional rebuild, stick em back on and give it a try.

Good luck,
A

 

[BTaksier]

I pulled them off tonight and cleaned them. Just wasn't sure what was normal and what to look for. I'll reinstall them tomorrow and see what I get.

 

[XSLeo]

You say you lifted the slides and fuel was drawn up with the needle. Do you mean as the engine was running?
If idling there won't be enough air flow through the carb to draw fuel out around the needle. If not running then your float bowls are over filled.
This often means a float blocked open or the float level is way off.
I might suggest reading www.amckayltd.com/carbguide.pdf and goo through and check everything.
Write down all the numbers on the brass parts. Measure the float level. Report back what you find.
You say recently rebuilt, Who rebuilt them? Maybe they used rebuild kits that hardly ever have the right parts included. Best to replace only the worn parts. Saves money and you know the stock parts are right.
Leo

 

[BTaksier]

Im sure whatever is going on is the result of not having a fuel filter. I did install one and tore the carbs apart last night and found a bit of debris in the main jet of the carb that had the gas being pulled up by the needle. Is that possibly a cause of the issue? Wouldn't think so.

 

[DogBunny]

I would follow up on what XSLeo said. If the newly rebuilt carbs NEVER worked right, then it is possible that something float level related got cocked or stuck during transit, or something was left out or never adjusted. Read the carb guide that XSLeo linked to, and start by trying to understand how the float valve operates and by checking float height.

 

[BTaksier]

So I took the bike out for a spin after getting the carbs back on last night (I did not have a way to check the float height unfortunately) and it seemed to run fine....until I ran out of gas. I had checked my tank when I left and had what I thought was plenty. Only went a few miles and it sputtered to a stop. My roommate shows up with a gas can and we refill the tank and the gas pours right out of both air cleaners.

If this is a stuck float why didn't it dump gas before I left my house? Seems odd. Quite possible I didn't reassemble them again right. Is there something specific you have to do to not "jam" the floats during reassembly.

I have been looking over that carb guide and I understand the way the carbs work just don't have any experience with them. The were rebuilt by a highly regarded carb service which I don't want to name at this time. They came back spotless. I am sure whatever started my issues was caused by not running a fuel filter.

Thanks for any help you can give guys. First bike and build.

 

[DogBunny]

You already mentioned the name of the rebuilder. He is not God, everyone makes mistakes. I thought that he only used genuine Mikuni parts, I mention this because the MikesXS non-mikuni knock-off float valves are known to be prone to getting cocked and stuck. You only need a ruler to check float height. Your problem is not neccessarily due to not using a fuel filter. If the carbs worked once, they will work again. Go over the float valve again, make sure it moves freely, make sure there is no dirt on the valve seat, check height, and don't run out of gas again.

 

[BTaksier]

Is there anything I need to do during reassembly to avoid them getting stuck? Is there something that can happen when the bike warms up to cause this? I had gas in the bike when I left or at least what I thought was plenty to get the distance I was going. Just not sure why I didnt have gas pouring out my carbs when I started it at the house and I did on the side of the road. I pulled the carbs off again when I got home and the floats move freely. Everything inside looks spotless but I'm going to spray them out again when I get home today.

I wanted to leave his name out since I don't want to sound like I'm bitching about him or his work. Until I have reason to think otherwise I assume its from not having a filter.

I appreciate the help guys. Thanks

 

[deadchef]

your floats could be working correctly but look at the float valve rubber tips and seats like dogbunny suggested. the tips may have ballooned or deformed causing a poor seal.

 

[BTaksier]

deadchef- Ill check that out. is there some way to test them? Or just visually inspect?

 

[deadchef]

here is a pic of a float valve needle. sometimes the rubber tip gets malformed and doesn't seat correctly letting fuel slip by.

another part to look at could be the float valve seat (the brass part with the o-ring). the o-ring might have a tear which i believe could also let fuel pass.

 

[BTaksier]

Thanks so much deadchef! That gives me something to look at. Sorry, first time digging into carbs. Trying to minimize the amount of failed test rides. Can't really run my bike in my garage since the neighbors keep calling the cops for noise.

 

[BTaksier]

So after work I checked out the float levels and the valve needle and seat. Couldn't find anything wrong but blew them out with compressed air anyway and put the carbs back together. Bike seems to run fine now.

Is it possible running out of gas caused the floats to stick?

 

[deadchef]

most likely the floats just stuck open when you ran out of gas. might check the float from a fully open position and see if there is any stiction.

 

[BTaksier]

I couldn't see any hang ups anywhere with the floats, everything was really clean. I probably could have just tapped on the bowls with something. Well at least I learned more about my carbs through this. Thanks for all your help guys. I do appreciate it.