the little engine that wants to ..

[first timer]

I have a 81 gs550t w/ 1450 miles on it, it's been in very good storage I did a basic tune up on it, had the carbs rebuilt and synced (a shop did it), and it was working really good for 2 days, I put 150 mile on it and it got mad. Now it will idle then hesitate and go to 4k (seems like its trying to suck hard or overcome something) or it will not idle below 2500 rpm and will hesitate to get to 4000 rpms. I gaped the plugs right, that seems to help a little, and all 4 plugs are firing, it will start right up with the coke on, also if I pull either the 2 or 3 plug while the engine is running it will keep running like not much has changed but if I pull the 1 or the 4 plug it turns off immediately. The outer plugs also have a little lighter color then the 2 or 3 plug. Also I don't know if this means any thing but my exhaust pipes on the 1 and 2 are blued from heat right by the engine but the pipes on the 3 and 4 are only a gold color. Here is a real dumb? but which way do I put the petcock to turn the fuel off, the PRI, ON or RES (when I turn it to PRI the fuel flows but if I turn it to ON or RES nothing comes out. well thanks for your help I know this post is long and this is my first bike so I need tutoring. If you have any further tests I can do please let me know, Thanks again.

 

[Anonymous]

I can help with some of that.

ON and RES are actuated by the vacuum of the engine, with the bike shut down they are the same as OFF. PRI allows fuel to flow without the vacuum of the engine, it is used to fill the bowls after the bike has been sitting and the gas in the bowls has evaporated.

As for the others, 1 and 4 run off one coil and 2 and 3 run off another. I'm not the best with carb/ignition probems, so someone else will have to help you with that.

 

[first timer]

thanks

 

[Anonymous]

Here is my two cents. It ran great for two days then yuck. Look into the gas tank with a flashlight (not a lighter) and look for rust. This rust will clog carbs. Install a good cycle fuel filter in-line and maybe have the inside of the tank coated. Creem is a 3 part product sold for this purpose but for novice use I'd say have the shop do it. The fumes from the second part will eat paint. If the float bowls have rust in them the carbs may need a cleaning again. Rust particles can get in the small passages and need to be (tanked) out.
?Now it will idle then hesitate and go to 4k (seems like its trying to suck hard or overcome something) or it will not idle below 2500 rpm and will hesitate to get to 4000 rpms. *Sounds like Carb problems, most electric issues are on or off. It works or it don't. Very few are intermittent like a coil lead wire shorting to ground due to vibration and causing intermittent firing of two cylinders.

?I gaped the plugs right, that seems to help a little, and all 4 plugs are firing, it will start right up with the choke on, also if I pull either the 2 or 3 plug while the engine is running it will keep running like not much has changed but if I pull the 1 or the 4 plug it turns off immediately. *Triple check the plug wires are on the right plugs. The engine should run with one plug wire removed. You may have a weak coil on the #2 & 3 plugs. Also you can feel the exhaust down tubes to see which are firing and which are not. (Use the back of your fingers and don't burn yourself. Best done right after starting the bike)

?The outer plugs also have a little lighter color then the 2 or 3 plug.*You may have a weak coil on the #2 & 3 plugs.

?Also I don't know if this means any thing but my exhaust pipes on the 1 and 2 are blued from heat right by the engine but the pipes on the 3 and 4 are only a gold color. *Blued pipes usually mean a lean carb condition, causing that cylinder to run hotter, but on an 81 bike you have no idea when that happened.
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[HiSPL]

Also check your carb boots for cracks.

 

[Anonymous]

Sounds like dirty carbs to me. Clean them, and try again.

 

[first timer]

thanks for the advise, my tank was rusty i did use the kreem i have a new petcock, with all new hoses, the plugs are right (reading from the left) the wires go 1234. i just try the wd40 trick nothing changed, (what am i suppost to look for) i also checkd the exhust pipes, the outside ones (1,4) hot as s@#$ the inside 2 (2,3)were luke warm. i do rember from last night that all 4 sparks looked the same ( i had all 4 plugs out and turned it over), could it be the shop did a poor job cleaning it? i can try starting it when it cools down and just leave the coke on to see if all 4 pipes get hot at the same time. other then that i don't know. thanks for everyones help, i'll get to the bottom of this some day

 

[earlfor]

Since the bike ran fine for 150 miles and then two cylinders are running/not running because they are getting no fuel, and you do say you had rust in the tank............. I think its a very safe bet that the no2 and no3 carbs are packed up with silt. The first thing I would do is take the carbs apart and clean them. If you are not sure about how to do this, take it back to the bike shop and have them do it. You can destroy more than you fix quite easily in working with the innards of the carbs. After they are cleaned out again, I would put an inline fuel filter on the fuel feed line.

Earl

thanks for the advise, my tank was rusty i did use the kreem i have a new petcock, with all new hoses, the plugs are right (reading from the left) the wires go 1234. i just try the wd40 trick nothing changed, (what am i suppost to look for) i also checkd the exhust pipes, the outside ones (1,4) hot as s@#$ the inside 2 (2,3)were luke warm. i do rember from last night that all 4 sparks looked the same ( i had all 4 plugs out and turned it over), could it be the shop did a poor job cleaning it? i can try starting it when it cools down and just leave the coke on to see if all 4 pipes get hot at the same time. other then that i don't know. thanks for everyones help, i'll get to the bottom of this some day