I recently did my first valve adjustment and cleaned the carbs. Now, the bike will not run properly. It only starts if I am turn and hold the throttle about 1/4 turn. If i turn the throttle more, it will barely rev (1500 rpm MAX). If I let go of the throttle, it dies right away. Any ideas of why this is happening?
Too bad you didn't do the carbs and valves on separate occasions, that would certainly narrow down the possibilities.---I'm betting you messed up something with the carbs.
That is my guess, too. :cry:
I have checked all lines. They are in the proper places and none are pinched or anything.
Did you actually change a shim or did you just check the clearances? Unless you left something out or did something pretty drastic ( pulled the cam shaft and jumped the sprocket ) it shouldn't be the valves.
I know this may sound silly, but did you reconnect your choke cable?
If you let it run for a while with the throttle part open, does it get any better?
Did you mess with your pilot screws or any of the jets? Did you bend the floats at all - is your float height correct? Try this (http://gstwin.com/float_height_check.htm).
Also, did you take off the top covers of the carbs? Could you have damaged the diaphragms underneath?
Sounds like either a plugged pilot jet or a really bad vacuum leak.Did you replace any of the O rings in the carbs?You need to check your float levels also.
Thanks for the replies.
The choke cable is reconnected. I ran it for about 30-60 sec while holding the throttle.
I will try checking the valve floats.
I am a complete newb when it comes to carbs. I did take of the pilot screws but replaced everything. I ran air through the jets and I don't think they are clogged. What could cause a bad vacuum leak?
I didn't replace anything in the carb, just cleaned it. I am fairly certain that the diaphragms are fine.
I checked the floats. They are working fine.
For the valve clearance, I changed 3 shims, all minor adjustments.
I am going to take the carb apart again. What would cause a huge vacuum leak?
Quote from: jdmskier on June 07, 2011, 03:16:39 PM
I checked the floats. They are working fine.
For the valve clearance, I changed 3 shims, all minor adjustments.
I am going to take the carb apart again. What would cause a huge vacuum leak?
The vacuum line from the back of the petcock to the carbs.It is the smaller hose.
I will check that.
I notice that the thick wire that runs on the left side from next to the battery to the engine/transmission somewhere was pinched when I bolted on the frame. I could just see the copper and it may have been directly grounded to the bike. Is this a possible cause of the problem??
Quote from: jdmskier on June 07, 2011, 03:40:34 PM
I will check that.
I notice that the thick wire that runs on the left side from next to the battery to the engine/transmission somewhere was pinched when I bolted on the frame. I could just see the copper and it may have been directly grounded to the bike. Is this a possible cause of the problem??
It could be.I suggest wrapping it with electrical tape for testing purposes and then replace ASAP.
I fixed the wire, but it runs the same.
I'm taking apart the carb.
Anyone know what the symptoms would be if one of the cams was off by one sprocket?
It'd be a timing issue, and the valves may not be opening at quite the right time. It could also damage the engine, so make sure the timing is correct when you put it back together.
Obviously, it would be a timing issue, but what would the symptoms be. Like a lumpy idle or a weird sound? Mine seems to sound fine, if i am on the throttle.
Well if the valves are opening late you wouldn't be getting as much fuel/air mix into the cylinder. If they're opening early the cylinder might not be clear of exhaust when the exhaust stroke ends, which could also cause an inconsistent burn. It could be timing, but from what you described it sounds like a fuel flow issue...
I am going to check the carbs now. Also, I forgot to take a note of the throttle cables when i removed the carb. Do they go on so that each has no slack and the throttle is fully closed (when not turning the throttle)?
So far, I checked the following for each carb:
all 3 jets
diaphragms
floats
Everything seems fine to me...what is in the carb, right above each of the three jets? I ran some compressed air through everything. Anything else I should check?
Is it even worth opening the valve cover? There is no way that I missed a shim or anything as I rechecked clearances before reinstalling everything. I guess there is a very slight chance that the timing chain is off because I removed the cam holders to get to the shims.
Thanks for the help.
So i pulled the carbs off, checked everything. The floats work, jets are in the correct place, diaphragm seemed fine. I carefully reassembled everything.
I started it without the air box on and it started right away and would rev when given gas. Great, I thought....I put the air box and tank back on and now it is doing the exact same thing. It started without giving gas, but then wouldn't rev. Now, it only starts if I give it gas and when i give it a lot of gas, it doesn't go over 1500rpm :cry:
Anymore ideas?
When's the last time you cleaned the air filter?
I haven't really fully cleaned it before. Just ran compressed air through it
I just ran it with the filter off. It has the same problem :icon_confused:
Well if it was running well without the airbox on it would seem that that's your issue. Any chance there's something that got blown free of the filter and is now blocking airflow?
I really doubt it, but i will go look
Maybe the bike's running really rich then, and when you take the filter off it lets enough air in to get a better mixture?
One thing that I just noticed. When the bike hasn't been started for a little bit (15 min) It will start right up without giving it throttle. Once I give it throttle, the revs drop slightly and if i let go, the engine dies. From there on, I must hold the throttle to start it again.
If I have the petcock on PRIME, should the a lot of gas be coming out of the carb if I give it full throttle?
Another thing I just noticed.
I had the choke on for a long time. When I take the choke off, it starts right away and revs (slowly) to about 3000rpm if I give it gas, but it won't go above that.
I just checked the timing chain. According to the manual, it is off by 3 sprockets...that is probably my problem. I am going to fix it this weekend.
doh!!! Don't beat yourself up over it. My first bike, Honda Sabre 700, I did the same thing. At the time, didn't know what I did wrong and sold it cheap. Wish I would've had a great community like gstwins then!
Quote from: jdmskier on June 08, 2011, 05:12:30 PM
If I have the petcock on PRIME, should the a lot of gas be coming out of the carb if I give it full throttle?
If you have gas coming from the carbs then you either have a sticking float needle or the float level is way to high.
http://gstwin.com/float_height_check.htm
Quote from: jdmskier on June 08, 2011, 06:44:01 PM
I just checked the timing chain. According to the manual, it is off by 3 sprockets...that is probably my problem. I am going to fix it this weekend.
Damn. Like ryott52 my guess would've been a messed up mixture screw =)
jdm, do you recall way back in the beginning of this thread when I wrote;
"Did you actually change a shim or did you just check the clearances? Unless you left something out or did something pretty drastic ( pulled the cam shaft and jumped the sprocket ) it shouldn't be the valves".
sounds like it could be from reinstalling the cam shaft caps, the notches on the ends of the cam shafts should point directly at each other or away from each other. I usually only loosen the bolts to be able to like the cam shaft a little bit. You will still probably have to readjust the white plastic knob to get it just right after your done. good luck