Got 82 750T back together, won't start again!

[froldt]

Finally got my bike back together after a top-end rebuild (honed cyls, new o-rings, cleaned pistons, new gasket kit, rebuilt carbs) and the battery's dead. Which isn't a problem, but my charger's apparently dead as well. So... today I finally jumped the bike, and after a couple of tries she started.

Once she got started, the idle was kinda screwy, revving a bit high, but I don't know where to set the idle screw at, so I figure that's no problem. I'm fiddling with the screw and notice that there is smoke coming from the front of the engine. I'm not sure exactly where, if it is from the exhaust (some cleaner I used remaining on it, quite possibly, now that I sit and think about it...) or just the engine itself or what... So I shut her off...

Then I decided to jump again, to try and pinpoint where the smoke is coming from. Being the oh-so-smart guy that I am, I tried to adjust the idle screw (the big screw between #2 and 3 carbs, I think that's what it's called) before I got it started.
So now I can't get my bike started again. She just cranks and cranks. Any suggestions?

 

[80GS1000]

This sounds *exactly* like what happened when I tried to get my motor running again after 7 months of it sitting around.

The fast idle may be an air leak on the intake or a lean condition. What kind of exhaust and intake does it have, ie airbox or pods? When was the last time the carb rubbers and o-rings were replaced? I had the same problem till I replaced them and richened up the idle settings. You'll need a new, fully charge battery too - my idle was screwy too till I replaced it and it's hard to diagnose problems with weak amperage in the system. Probably weak spark from the battery not being up to snuff.

If it started once, and it keeps cranking, it's probably not electrical. Is your clutch switch functional or has it been bypassed? Are you pulling in the clutch when you try to start it? Fuel perhaps? Kinked fuel line and/or not enough gas in the float bowls? You may have leaned out or richened up the mixture too much for it to start too by dinking with the idle screw - try turning the idle screw all the way to the right, then turn it back out 2 to 2.5 turns.

 

[Guest]

Fully charged battery. Did you prime the float bowls? Are you getting spark? How's the compression? I hope with the top end rebuild you made sure the airbox and intake boots are sealed. Smoking engine after rebuild is normal. Is the airbox installed?

 

[froldt]

This sounds *exactly* like what happened when I tried to get my motor running again after 7 months of it sitting around.

The fast idle may be an air leak on the intake or a lean condition. What kind of exhaust and intake does it have, ie airbox or pods? When was the last time the carb rubbers and o-rings were replaced? I had the same problem till I replaced them and richened up the idle settings. You'll need a new, fully charge battery too - my idle was screwy too till I replaced it and it's hard to diagnose problems with weak amperage in the system. Probably weak spark from the battery not being up to snuff.

If it started once, and it keeps cranking, it's probably not electrical. Is your clutch switch functional or has it been bypassed? Are you pulling in the clutch when you try to start it? Fuel perhaps? Kinked fuel line and/or not enough gas in the float bowls? You may have leaned out or richened up the mixture too much for it to start too by dinking with the idle screw - try turning the idle screw all the way to the right, then turn it back out 2 to 2.5 turns.

Fully charged battery. Did you prime the float bowls? Are you getting spark? How's the compression? I hope with the top end rebuild you made sure the airbox and intake boots are sealed. Smoking engine after rebuild is normal. Is the airbox installed?

Let's see if I can get everything answered...
The battery wasn't fully charged, but I was jumping it the whole time, so plenty of juice as I needed it. I turned the petcock to prime for about 30 seconds before I tried, and then after I tried to start it I did it again later.
I got the airbox and intake boots as sealed as I can, but the intake might be loose (those things are a pain!)
Everything is installed (except the fairing and sometimes the seat) when I try to start her. I have a K&N filter, but am using the stock one until I get her running, then I'll try the K&N out. Oh, it's an airbox.

I got spark on #1, but didn't try the others, nor did I try the compression. I figured that those are the next steps.

What's a carb rubber? I bought and installed the gasket kit for the carbs when I rebuilt them. It's been probably 6 months, but they haven't been used yet.

The clutch switch is functional. I pull it in anytime I do much of anything, so it's engaged. (I thought it wouldn't even turn over if it wasn't engaged. Could it just be loose and I need to tighten it so that it will start?)

try turning the idle screw all the way to the right, then turn it back out 2 to 2.5 turns.

Smoking engine after rebuild is normal.

I'll have to fiddle with the idle screw, and I'm glad to hear that a smoking engine is normal!
After the idle screw, looks like it's time to check the spark and a compression test.

 

[Guest]

That would be smoke coming off the engine and not out of it.

 

[80GS1000]

You might be out of gas in the float bowls. The vacuum petcock is slow at best to refill them when the petcock is on "prime". What works for me is to get a siphon pump (~$10 at Wallyworld in the automotive section) and use the "forcefeed" method to prime the carbs. You siphon gas straight from a gas can into the fuel hose on the carbs till the floats say they're full. Only do this though if the carbs have already proven their ability to fill properly on their own (like you've already been able to start it once) - you don't want to spill gas if you have a stuck needle valve etc. And be careful of course (no smoking etc) cause you're dealing with gas.

The carb rubbers/intake boots/whatever you call them are part 22 on this diagram. You'll need 4 of them. They dry out and start leaking air over time and should be replaced if hard or brittle. Makes putting the carbs and airbox on and off much easier. Should fix the high idle as well caused by the air leak.

http://houseofmotorcycles.bikebandit.com/partsbandit/oem_schematic_view~schem_dept_id~1029684~section_dept_id~1~section_dept_name~OEM+%28Stock%29+Parts~dept_type_id~2~model_dept_year~1982~model_dept_mfr~Suzuki~model_dept_id~988011~model_dept_name~GS750TZ.asp

 

[froldt]

That would be smoke coming off the engine and not out of it.

Sorry to mis-type. I'm not sure which it was, I just saw smoke and something smelled hot. So I turned off the engine. Then it occured to me later that it might have been off the engine (as I was typing that, actually.11)

The carb rubbers/intake boots/whatever you call them are part 22 on this diagram. You'll need 4 of them. They dry out and start leaking air over time and should be replaced if hard or brittle. Makes putting the carbs and airbox on and off much easier. Should fix the high idle as well caused by the air leak.

I couldn't get the link to work. I'm assuming that you mean the rubber tubes that connect the airbox thing to the carbs. They're a bit stiff, but by no means brittle. However, whenever I try to push them onto the carbs, then the airbox actually gives back in the middle, so that I can only get one of the two ends to fit at a time, and never the middle ones.

 

[80GS1000]

Sorry to mis-type. I'm not sure which it was, I just saw smoke and something smelled hot. So I turned off the engine. Then it occured to me later that it might have been off the engine (as I was typing that, actually.11)

I couldn't get the link to work. I'm assuming that you mean the rubber tubes that connect the airbox thing to the carbs. They're a bit stiff, but by no means brittle. However, whenever I try to push them onto the carbs, then the airbox actually gives back in the middle, so that I can only get one of the two ends to fit at a time, and never the middle ones.

Hrm, sorry about that link from Bikebandit. They're the rubber tubes that connect the airbox to the carbs, and the carbs to the head. Depending on their condition, you may need 4 to 8 of them. Common place for an air leak to occur. According to my service manual, they're supposed to be replaced every 3 to 4 years. #22 & #23 below. Mine worked fine till I disturbed them by taking the carbs on and off, which then led to an air leak and a fast idle. Do a search for reinstalling your airbox - difficulty there was half the reason I switched to pods. :lol:

 

[froldt]

Well, all four spark plugs have good spark.
Dunno what the compression should be, but...
#1 - low 80's
#2 - 92ish
#3 - 78ish
#4 - 118ish

Seems to me like they should be closer to each other. This is on a cold engine.
I was thinking they should be higher than this, and closer to each other. Does it mean that I put something back together wrong?

 

[Guest]

Did you do the test with a wide open throttle?

 

[froldt]

Did you do the test with a wide open throttle?

No, but if it's not running, will it make a difference?
I pulled the valve cover and the clearances are a bit loose. The feeler gauges that I used only had the larger measurement (don't remember the numbers off-hand) and it being my first time, I apparently didn't tighten down the valves quite enough.
So, I'm re-adjusting the valves.

The bad news... I lost one of the valve cover bolts, and the only place that I haven't been able to not find it yet is inside the engine! :shock:

 

[froldt]

WooHoo! She's up and running! I re-did the valves, put her back together, and she fired up after only a few tries. Then I noticed that since I had neglected to replace the tach cable, I had no idea how fast she was idling, though I knew it was too fast. Of course, I also noticed that I had forgotten to replace the valve cover gasket, so apart she came.
This is all after I finally retrieved that bolt from on top of the timing chain. Lucky thing that I had bought those extended grabber thingies, huh?

So I take her apart and put her back together again, and she's idling at about 3500, I mean 4000, I mean 4500. Hmm... maybe if I quit looking it'll quit going up?

Turn her off, replace the fairing and duck-walk out of the shed to give her a test spin. After one more jump, she turns on and screams at me. Apparently she's mad from being out of commission so long. Idling at 6000 rpm. So I shut her off and wheel her back into the shed. Tomorrow is another day, right?

The boots between the carbs and the engine seem to be good and sealed tight. However, the airbox (not the one with the filter in it, but the one between the filter and the carbs) is not connected well at all. I can't seem to get it, the best I can get is the outside two connected decently. I've even pushed on the inside with a long prybar, but to no avail. How do you connect that stupid thing!?

 

[jimcor]

To get it to seal up tight buy new boots. They're fairly cheap, about ten bucks each.

While you ordering, any of the hose clamps that are bent should be repalced too. Might as well get 'er done. Don't use stainless steel auto parts hose clamps. They don't have rolled edges and if tightened will cut your boots like a knife.

 

[jlgace]

I always try soaking the boots in really hot water before installing. Makes them much easier to work with and less brittle. Dry them off and slap 'em on quick before they cool down.

Did you happen to check your throttle cable adjustment and make sure the linkage isn't sticking? Sometimes it's the simple things...

 

[froldt]

Did you happen to check your throttle cable adjustment and make sure the linkage isn't sticking? Sometimes it's the simple things...

Nope, didn't think of that. There's actually a little slack in the throttle before it "catches." I suppose it could be stuck, though, and the slack is just there.

However, the longer I leave her running, the faster she revs. I assume part of it is that I brush up against the airbox and make it looser, or it vibrates looser, letting in more air.

 

[Guest]

Make sure your throttle linkage isn't hanging up on an intake boot clamp screw. I know it sounds silly but I did it once. Have you tried backing off your idle adjuster?

 

[ron bayless]

The only time my bike ever overrevved up like you are describing was when the throttle cable was stuck into the wrong position,like it was wide open.Once I got it back into its proper holder and adjusted it a little i wound up having to use the idle screw to get it to idle faster.

 

[froldt]

Well, I checked, and as far as I can tell the throttle cable isn't stuck, and the idle screw is set just about right (2.5 turns).
It took a couple of tries (low battery still, gotta get a good charger) but she fired up and immediately revved up to about 6k. Turned off the choke and she idled down to around 3500. It's been too long without a ride, so away we went! Of course, when I stopped to check on the idle screw, I bumped the kill switch, so I got to push-start her. Good thing there was a bit of a hill!

She's still revving high, and the warmer she gets, the faster she revs. I pulled back into the shed and she was running around 6000 rpm. Surely there isn't that much air getting in the boots? I didn't try to adjust them any, yet.
So I hit the kill switch and turned off the key... She kept running for a second or so... Could that mean she's getting too much fuel?

 

[DimitriT]

When it revs higher as it warms up it means its lean. You need to richen up the idle circuit (by backing out the idle mixture screws) and close up the throttles (by turning in the idle throttle knob). Make small adjustments these two things until its stable.

When's the last time you did a vacume sync?

 

[froldt]

When it revs higher as it warms up it means its lean. You need to richen up the idle circuit (by backing out the idle mixture screws) and close up the throttles (by turning in the idle throttle knob). Make small adjustments these two things until its stable.

When's the last time you did a vacume sync?

Where are the idle mixture screws (on the carb, I know, but where exactly)?

I've never done a vacuum sync. I rebuilt the carbs a couple of months ago and just got her running a few days ago. I bench sync'd them. I figured that would be enough to get her running and fine-tune from there. Hmm... now I'll need to find someone with a vacuum sync set.