1980 gs1000g

[gsrick]

Free time? What is that? I'm half way there. Just started my last core course. Performance tuning. That means, TWO WEEKS OF DYNO RUNS. YEAH BABY!!!!

[BluePlateSpecial]

How is it fouling John, fuel or oil? Is it smoking out the exhaust, black or blueish gray? Is 1 and 4 squelching your spark with too much fuel? If all 4 carbs are set up the same then you might have a weak coil. 1 and 4 plug use the same coil. If you don't have a good multimeter to test the primary and secondary ohms, try swapping coils. The boots unscrew if needed to reach the inner (2&3) plugs or if you still have the coils from the spare parts bike, try one of those. Just for testing you don't even need to mount it, since isn't grounded that way. Secure it to something with a zip tie if you do a test ride though. What are your carb conditions, as in jet sizes, pilot jet, main jet, how many turns out are your idle air screws? Is it hesitating at certain throttle positions, 0-1/4, 1/4-3/4, 3/4-WOT?

The story is we were finally able to get the bike idling and running well up to about 1/4 throttle but it was totally bogging down when you gave it more gas.

I took it home and cleaned the tank out, cleaned the carbs (the tank had some rust and was letting the powdery rust into the carbs) and set the float heights and still no improvement.

I had a little leak from the petcock so I ended up tearing it apart, cleaning it up and replacing a couple of the gaskets from a spare that I had. I didn't think much of it so I didn't do a test the bike after that but the next day I rode it up to my buddy Matt's house (the one you met awhile back) in Casselberry. Since it wasn't running well when I give it throttle before I took it very easy getting up there. When I got there Matt pulled the plugs and 2&3 looked great but 1&4 were black as night.

Matt cleaned up the plugs and jumped on the bike for a test ride. When he got back he looked at me and said "I don't know what you're talking about, this thing is running pretty damn good!" I took it for a spin and sure enough, it was running much, much better. It was still stumbling some in the higher gears, but as long as the RPM's stayed up it wasn't losing significant power. I don't know why it started running better all of a sudden but the only thing I did was fiddle with the petcock so that must have had something to do with it.

I have had it out again since and it is still running fairly well but I can tell it isn't quite dialed in.

As far as the jetting and tuning, I know that the mains are 127.5's, we swapped the needles and drilled the slides out a bit and I know he opened one of the other sets of jets as well. I can't remember which ones and I'm not sure about the air screws but I will try to remember to ask him about everything tomorrow.

I was wondering if it might be the coil as well since it is only on 1&4. I do have an extra from the parts bike I can throw on there.

[Creekwalker]

The best thing to do before investing much and eventually discovering things that are not obvious at this time would be to locate a leak down tester and use it. It Will tell you condition of the motor, whether it is rings, intake or exhaust valves. Do this on each cylinder and you will be in a much better position to determine expected cost. You do not even have to invest in a battery to do these tests.

[BluePlateSpecial]

The best thing to do before investing much and eventually discovering things that are not obvious at this time would be to locate a leak down tester and use it. It Will tell you condition of the motor, whether it is rings, intake or exhaust valves. Do this on each cylinder and you will be in a much better position to determine expected cost. You do not even have to invest in a battery to do these tests.

Already did a leakdown test on the original engine and the one from the parts bike that we put in. That's why we swapped them. New engine is fine, old one was losing pressure on #4.

[Flyboy]

Pssssssst........ throw that sh1te off and get an airbox, you were offered more than one.

[gsrick]

John, did you bench sync the carbs to balance them?

[gsrick]

Pssssssst........ throw that sh1te off and get an airbox, you were offered more than one.

My 80 1000G has K&N pods and will pull the front wheel. It even has a full fairing with stereo.

[Flyboy]

As will my 1000G with its stock airbox and I think I have tinkered with my carbs twice in 30 years.
I am not saying they don't work, I am saying that they make the bike a pig to dial in correctly and cause no end of grey hairs trying to get it tuned correctly.

[BluePlateSpecial]

The stock airbox might have been the easier way to go but it would have cost me more money to assemble all of the pieces, and where's the fun if you aren't able to learn things the hard way?

Rick- carbs have been fully synced every time they came off the bike.

[gsrick]

Just covering the bases, John. Trying to isolate the problem by elimination and being that it's 1&4 and not say 1 or 2&4, etc. I'm still leaning toward the coil or a weak spark. With that said, back to the carbs. ;-) How were the carbs cleaned? A good soaking followed by compress air, spray carb and choke cleaner, then comp. air again? You might recheck the float levels again, if they are running higher, it will enrichen all of the circuts. You mentioned up to 1/4 throttle is good, so that leaves out the pilot. If it idles alright, then we can forget about the idle screws for now. What has me concerned now is why you changed the jet needle and drilled the slide. I'm still running the same stock needle and hole. I have a slight hesitation a mid throttle that raising the needle by lowering the clip one spot might solve, but it isn't a pressing issue for the time involved. I'll get to it when I replace my cylinder gaskets. What position are the clips at on the new needles, too high not enough fuel and too low and too much fuel. Is it the same taper? Also why did you drill the slides? This causes the slides to raise quicker, maybe too quick, which would be adding too much fuel to the your air/fuel mixture @ 1/4-3/4 throttle, all causing a too rich a mixture than the engine is ready for. What makes CV carbs work better (for street riding), is that they respond to what the engine needs instead of what the rider thinks the engine needs. This also is why they get better fuel economy and can function in different altitudes without as much adjustment to the a/f mix like with mechanical carbs.

[BluePlateSpecial]

The carbs have been cleaned pretty thoroughly. They were completely disassembled when I got them and looked clean at that time. They got cleaned again when they were assembled, and when I cleaned the tank out a few weeks ago we cleaned them one more time.

As far as the needle being changed, all I know is that the one that went in had more of a taper to it and when it went in the bike ran a lot better. Same thing when the slides were drilled.

I should be able to clarify some things with Matt tonight at bike nite.

[BluePlateSpecial]

Rick nailed it....swapped out the coil and it made all the difference in the world.

It is now running about 95%. I think I need to try tweaking the needles cause it seems like the problem is between 1/4-3/4 throttle. It runs a lot better in 1-3rd gear. 4th stutters a bit and 5th even moreso, especially when the load increases going up a hill.

At least it is perfectly rideable now. Did a 3 hour round trip ride to a swap meet yesterday and met sedelen by chance on the way back. Taking it to Daytona on Thursday as well.

Awesome, awesome bike!