rebuilding carb questions.

[trend]

Hello, I am rebuilding my carb because when I throw the throttle for the first couple of minutes on a cold start, it loose MUCH power and starts going back to 1k rpm.. that and I am getting backfire..

So I am inspecting my carb and cleaning it up (already changed my spark plugs and airfilter).. But need help on this:


1) I have extra pilot/main jets (stock jet size), but I think they are used.. they have some disscoloration.. How can I clean these?
2)I stripped out my pilot jet. .How can I get this out?

[NiceGuysFinishLast]

for cleaning use.. *gasp* carb cleaner.. available at any autoparts store in a large aerosol can, one can is plenty.

Edit: Oh yeah.. ALL gs' (and carbed vehicles) lose power and bog if you try to give it full throttle during the first minute or two of warmup. That's why we HAVE a choke. The lean jetting doesn't help either. Rejet to the proper sizes to eliminate cold start problems and long warmup times.

[scratch]

2) http://gstwins.com/gsboard/index.php?topic=30594.0

Do not use carb cleaner on rubber parts; including hidden rubber parts on carb body.

1) Cleaning has been addressed (put the jets in the cap of the carb cleaner and then spray some cleaner in there, shake 'em around a bit.)

Since you have 'extras' that are discolored, I'm guessing your jets/jetting has already been changed.  The size of the jets should be stamped on the barrells of the small pilot jets, and on the faces of the larger diameter main jets.  The pilots in the carb should be size 40 and the mains should be 125 (for a stock '89-'00).

[trend]

2) http://gstwins.com/gsboard/index.php?topic=30594.0

Do not use carb cleaner on rubber parts; including hidden rubber parts on carb body.

1) Cleaning has been addressed (put the jets in the cap of the carb cleaner and then spray some cleaner in there, shake 'em around a bit.)

Since you have 'extras' that are discolored, I'm guessing your jets/jetting has already been changed.  The size of the jets should be stamped on the barrells of the small pilot jets, and on the faces of the larger diameter main jets.  The pilots in the carb should be size 40 and the mains should be 125 (for a stock '89-'00).

Hmm. yeah I am thinking about upgrading my 37.5 to 40.. but then I have to mess with the needle.. and I am really confused.. I guess I need to do a bit more research.. i know 37.5/122.5 = 2 turns out on the needle..

So if I am using stock.. the only difference is a new exhaust and a dirty carb. Should I even worry about the new exhaust causing my gs500 backfires ? aka, should the cleaning hopefully fix it? Or is the exhaust def a problem ( I don't know specs at all on the exhaust)

[Egaeus]

Backfiring out the exhaust is caused by unburned fuel exiting the cylinder and igniting when it comes into contact with the hot exhaust pipe.  The exhaust is not a primary cause of backfiring.  It's almost certainly one or a combination of the following:

Carburetor - dirty, unbalanced, incorrect jetting, etc.
incorrect valve clearance
faulty ignition system (spark plugs misfiring)
timing (only if some doofus got into the engine and screwed something up)

Clean the carb, check the valve clearance, balance the carb, replace the spark plugs, and tell us what happens. 

[trend]

Backfiring out the exhaust is caused by unburned fuel exiting the cylinder and igniting when it comes into contact with the hot exhaust pipe.  The exhaust is not a primary cause of backfiring.  It's almost certainly one or a combination of the following:

Carburetor - dirty, unbalanced, incorrect jetting, etc.
incorrect valve clearance
faulty ignition system (spark plugs misfiring)
timing (only if some doofus got into the engine and screwed something up)

Clean the carb, check the valve clearance, balance the carb, replace the spark plugs, and tell us what happens. 

Cleaned it today, changed the spark plugs. I don't know how to balance carb nor check valve clearance.

Hopefully will try to put it back together on thur Will report back.. thanks guys!

[Egaeus]

First, adjust your valves.  You'll need a fancy tool to do this correctly.  Specifically, one of these.  While waiting for that to come, watch Kerry's valve adjusting video on google video. 

I forgot one: vacuum leaks.  Check for those in the obvious places.  Make sure the drain and blowby tubes are both connected to the airbox.  I did this on video.

I check for vacuum leaks

After (and only after) getting your valves adjusted, you'll need to balance your carburetors.  You need to make a carb balancer.  The description is in the FAQ but unfortunately, the picture is gone.  Helpfully, in my futile attempt to figure out why my bike's not running, I made my own video on how to do it while I did it, which has one of these balancers in it. 

Calibration 1
Calibration 2
Balancing the carburetors
Check for leaks

Note that my videos are unedited and made on a camera phone, so they suck, but you should get the idea.

[Tafran]

Why i can't see the video?
do i need some video codac?

[Egaeus]

Which video?

[trend]

First, adjust your valves.  You'll need a fancy tool to do this correctly.  Specifically, one of these.  While waiting for that to come, watch Kerry's valve adjusting video on google video. 

I forgot one: vacuum leaks.  Check for those in the obvious places.  Make sure the drain and blowby tubes are both connected to the airbox.  I did this on video.

I check for vacuum leaks

After (and only after) getting your valves adjusted, you'll need to balance your carburetors.  You need to make a carb balancer.  The description is in the FAQ but unfortunately, the picture is gone.  Helpfully, in my futile attempt to figure out why my bike's not running, I made my own video on how to do it while I did it, which has one of these balancers in it. 

Calibration 1
Calibration 2
Balancing the carburetors
Check for leaks

Note that my videos are unedited and made on a camera phone, so they suck, but you should get the idea.

man, those all look great.. thanks for the video! but for now, I am trying to get the bike back together and running to see if I fixed the problem. I might go back and balance/calibrate carb as well as adjust the valves

So far I have: changed oil&filter, rebuild carb, rebuild battery, rebuild airbox, changed spark plugs... Man, all I thought i was going to do was check out the carb before I set it on it's center stand...

Hah, oh well I am having fun. Next will be carb balancing/calibrate (they mean the same, right?).. but how can I tell if they are unbalanced when I am riding? or do I have to use that tool?

Also, what does adjusting the valve do?


thanks

[Egaeus]

YOU CAN'T BALANCE THE CARBURETORS IF YOUR VALVES ARE OUT OF ADJUSTMENT.  YOU MUST ADJUST THE VALVES FIRST.

Now that that's cleared up, adjusting the valve clearance makes sure that the valves are opening fully and closing completely.  If they do not, then your bike will not run well.  The valves should be checked (and adjusted if necessary) every 4000 miles.  You'll need more than just the shim tool to do the job correctly, but the rest of the tools (all mentioned in the video) are easily found.

Balancing the carburetors makes sure that the throttle position for both carburetors are the same.  There is no accurate way to balance them except by using a carburetor balancer.  Unbalanced carburetors will cause one cylinder to do most of the work, and you will have problems such as lack of power, backfiring, etc. 

[trend]

YOU CAN'T BALANCE THE CARBURETORS IF YOUR VALVES ARE OUT OF ADJUSTMENT.  YOU MUST ADJUST THE VALVES FIRST.

Now that that's cleared up, adjusting the valve clearance makes sure that the valves are opening fully and closing completely.  If they do not, then your bike will not run well.  The valves should be checked (and adjusted if necessary) every 4000 miles.  You'll need more than just the shim tool to do the job correctly, but the rest of the tools (all mentioned in the video) are easily found.

Balancing the carburetors makes sure that the throttle position for both carburetors are the same.  There is no accurate way to balance them except by using a carburetor balancer.  Unbalanced carburetors will cause one cylinder to do most of the work, and you will have problems such as lack of power, backfiring, etc. 

Check, check, check.. I am having problems with all of the above... ha

My bike runs horribly now (well atleast for a couple of seconds before cutting off).. So I am guessing I will need this done.. I am actually thinking about getting my friend to do all of the above if he doesn't charge to much (he works at the local cycle shop).

Thanks soooo much for pointing me in the right direction even though I didn't know I was lost

0-edit--0 so balancing is syncing?

[Egaeus]

Yep.  Different names for the same thing.