Introduction & Help/Opinions Needed

[XS400D]

Let me start out by introducing myself. My name is Taylor, I live in Daly City just under the border of San Francisco. I Picked up my first XS400 and my first bike a few months ago. Pics under XS400D When I got it she had just recently had a bunch of work and rebuilding done (i still have the list from the CL add if anyone thinks reading it will help with figuring my problem out.)

The first month I had it she ran fine and started up real easy even in the cold. Then all of a sudden it wouldnt start up, electric or kick (like a dumbass i killed the battery trying). I realised that i had left the petcock in prime for a day or two after starting her up a few days prior to keep her fresh. (beginner move). I let the carbs dry up for a few days before i tried to start her up again and she came to life.

Ever since then i have had these problems. (i've read around but my problem doesnt quite meet all the factors others have)

#1 when i start her up easily after riding for a few blocks she will die at stop signs. basically seems like chocking out. the idle just falls and falls til the bike dies. sometimes i can give it a blip and it will come to life.

#2 early on i was able to just electric start it up but now not so much. after the bike dies and honestly on a lot of days to start it i need to twist the throttle adjust near the handgrip way out and only kickstart will get it up but then it revs up to like 4500 (previous idle was like 12-1500). it is not fun to clutch in at 4500rpm

#3 after it gets better i can twist the throttle back as i ride but eventually it still dies out.

from reading around I am thinking it is either a petcock issue or a carb issue

i have read that vacuum petocks just kinda suck or well they dont and that switching to a manual is a good idea.

the other theory i have is that perhaps i have gunked up my carbs and i should tear them off and tear them down.

any consensus on the problem, ideas of other culprits or for that matter soem advice on what to do next would be greatly appreciated


THANKS!!!

 

[dongrady]

check the vacume line to the intake, sounds stupid, but mine popped off and caused similar headaches. took me a while(on the side of the road) to figure out what happened. it won't draw fuel propperly if the hose is off. check the simple things first.....

 

[XS400D]

I checked everything in general but I'll look at the vac specifically. It has the same problem when I have the petcock in prime as well.

 

[mcrowell75]

Check your oil dipstick. Smell the oil. Does it smell like gasoline?

If it doesn't smell like gas then I am not sure what your issue is and you can quit reading now

BUT if it does smell like gas... I think I have an idea.

You'll need to think about an oil change soon. Gasoline has most likely thinned the oil out.

When you leave the petcock on, you are relying on the floats and the float needle valve to hold back all the gas in your tank for an extended period of time. If the float needle is worn it will slowly let gas fill the carbs and then it will spill in to the engine.

Here is what I would do: smell the oil, change it if necessary.

Then I would take the carbs off and inspect the float needles and the floats. Take the floats off and shake them. If you hear gas swishing inside, that means that float is shot and it will need to be replaced.

The fact that the issues began after you left the petcock on is what leads me to believe you may have a float issue now.

If your floats and/or your float valves have failed, then you will have too much gas flowing thru the carbs while the engine is running. Which in turn will give you running/idling issues.

If you do decide to go ahead and take the carbs off. You might as well clean 'em. There is no sense neglecting that. You may be right after all and just got some crud from the tank in there.

Hope that helps

 

[drewpy]

sounds like an air leak to me, may need a casrb strip. forst try and turn your pilot screws 2 turns anticlock wise each side and see if that helps

 

[XS400D]

Check your oil dipstick. Smell the oil. Does it smell like gasoline?

If it doesn't smell like gas then I am not sure what your issue is and you can quit reading now

BUT if it does smell like gas... I think I have an idea.

You'll need to think about an oil change soon. Gasoline has most likely thinned the oil out.

When you leave the petcock on, you are relying on the floats and the float needle valve to hold back all the gas in your tank for an extended period of time. If the float needle is worn it will slowly let gas fill the carbs and then it will spill in to the engine.

Here is what I would do: smell the oil, change it if necessary.

Then I would take the carbs off and inspect the float needles and the floats. Take the floats off and shake them. If you hear gas swishing inside, that means that float is shot and it will need to be replaced.

The fact that the issues began after you left the petcock on is what leads me to believe you may have a float issue now.

If your floats and/or your float valves have failed, then you will have too much gas flowing thru the carbs while the engine is running. Which in turn will give you running/idling issues.

If you do decide to go ahead and take the carbs off. You might as well clean 'em. There is no sense neglecting that. You may be right after all and just got some crud from the tank in there.

Hope that helps

Dipstick didnt keep any oil on it and it smells of gasoline. I put my nose over the oil res and whoooeee GAS!

 

[mcrowell75]

http://www.dansmc.com/carbs.htm

This page discusses the internal parts of a carb and how to clean them. In the very last paragraph he talks about fuel thinning the oil out if you leave the petcock on. You should probably change your oil now.


There is a lot of very good info on this guys site. It is literally an online motorcycle textbook. I cant tell you how many times one little sentence he wrote has been the answer to my problems.