1987 Suzuki GS450 - running again; tuning commences

Re: 1987 Suzuki GS450

The new flasher works; thanks for the tip everyone. Now I've gotta figure out why the brake light is staying on and not responding.
 
Re: 1987 Suzuki GS450

Everything looked good to go this morning so I try to start her...no go but not surprising since she's been sitting for two months now. When I moved the petcock to prime she started leaking gas from somewhere below the carbs. I double checked everything under the tank and its good. It's certainly coming below the carbs.
 
Re: 1987 Suzuki GS450

Sounds like you might need to replace the o-rings in the carbs and check the float needle/seat for wear.
 
Re: 1987 Suzuki GS450

Haven't done a carb clean yet but got it started. Running pretty rough and rich. Going to be adjusting idle screws today to see if that helps. If not, then the carbs are coming apart, getting cleaned, new o-rings installed, and then carb synch.

As slow as my progress may be, I just wanted to say thanks very much to everybody here for adding their knowledge to this site. A lot of great minds on here with some surefire wisdom.
 
Re: 1987 Suzuki GS450

biggiesmalls said:
Haven't done a carb clean yet but got it started. Running pretty rough and rich. Going to be adjusting idle screws today to see if that helps. If not, then the carbs are coming apart, getting cleaned, new o-rings installed, and then carb synch.

As slow as my progress may be, I just wanted to say thanks very much to everybody here for adding their knowledge to this site. A lot of great minds on here with some surefire wisdom.
Click to expand...

I went through the exact same situation. Bike was running pretty well and just needed some tweaking (or so I thought) but I decided to dip the carbs for peace of mind. I ended up finding that the slide on the #1 carb had been severely gouged by the PO probably trying to lever the carbs in our out of the air box with a screwdriver and the #2 carb's adjustment screw had no spring. Both needle jets had been crushed to hell with pliers. The strip and dip isn't hard and you have the benefit of starting from a known baseline instead of blindly tweaking and adjusting. Do a search for a write-up by "Flaming Chainsaws" for basic outline of the procedure and another by "Nessism" for more in-depth info on measuring float height and bench synching.
 
Re: 1987 Suzuki GS450

Boiled the carbs in lemon juice yesterday and got 'em back on. All the o-rings etc. seemed good to go and not shitty. One of the springs in the diaphragm is much longer than the other one...how big of an issue is that?

Anyways, as before, the bike is still only running with the choke on. However the idle is no longer climbing or revving high, but the bike still dies when you close the choke. I'm going to be tweaking the air screws and throttle adjustments tonight. Aside from that, anyone have any other suggestions?
 
Re: 1987 Suzuki GS450 - carb issues

The choke on your carbs is actually an enrichening circuit. So instead of blocking air (like a choke), it is adding gas. If it only idles with the choke on, your pilot jets aren't providing enough gas. Are your mixture screws accessible? They have plugs on them stock. Set them to 2 turns out from bottom, and if it still won't idle without the choke on, your pilot jets are clogged. Oh,the slide springs should be the same length - either one was cut to shorten it or one was stretched out.

Fwiw, I highly recommend GS500 carbs. They are cheap and very easy to work on.
 
Re: 1987 Suzuki GS450 - carb issues

Rich - the mixture screws are currently 1 1/2 turn out from bottom. Will be messing with that tonight. Pilot jets were blasted with carb cleaner and compressed air after the boil and look good to go.

Could the slide springs cause the carbs to be out of sync?
 
Re: 1987 Suzuki GS450 - carb issues

The pilot jets I pulled last night were labeled 17.5. Would bumping that up a size or two change things? I plan on installing pods this winter anyway.

Edit: and by "change things" I mean help me find the correct idle level by bringing more fuel in, or am I headed in the wrong direction there?
 
Re: 1987 Suzuki GS450 - carb issues

biggiesmalls said:
Could the slide springs cause the carbs to be out of sync?
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Some people cut length off the slide springs for better throttle response. As long as the spring compresses the slide down all the way at idle, it shouldn't affect anything.

Also, turn the screws out another full turn. It sounds like you have them set even leaner than the factory.
 
Re: 1987 Suzuki GS450 - carb issues

hardline_42 said:
Some people cut length off the slide springs for better throttle response. As long as the spring compresses the slide down all the way at idle, it shouldn't affect anything.
Click to expand...

That statement is so wrong that I have to chime in here.

The two springs should be identical. Yes, I have heard of people shortening a spring slightly so that the slides will open up sooner. That may or may not be a good idea, but both springs need to be identical, otherwise the two carburetors will be delivering a different volume of fuel and air under some conditions, and could cause some serious confusion with tuning.

As for the original question, it would not affect carb synchonization, because that is done at idle. However, underway, the carbs will definitely be delivering unevenly.
 
Re: 1987 Suzuki GS450 - carb issues

AlphaDogChoppers said:
That statement is so wrong that I have to chime in here.

The two springs should be identical. Yes, I have heard of people shortening a spring slightly so that the slides will open up sooner. That may or may not be a good idea, but both springs need to be identical, otherwise the two carburetors will be delivering a different volume of fuel and air under some conditions, and could cause some serious confusion with tuning.

As for the original question, it would not affect carb synchonization, because that is done at idle. However, underway, the carbs will definitely be delivering unevenly.
Click to expand...

I should have typed -Some people cut length off of their slide springs for "better throttle response" (airquotes)...- I don't agree with the practice either. But at idle, it shouldn't affect synch. I didn't mean for it to sound like sound tech advice.
 
Re: 1987 Suzuki GS450 - carb issues

Double-checked the carbs, put 'em back in, got the air screws out two full turns, dialed in the idle adjustment, and now she's purring pretty good. Gunna take her out tomorrow for the first time in two months (yikes) and see if everything feels right.
 
Congrats on "hopefully" knocking out all the carb issues. ;D

Ride/ running videos or it didn't happen.

Gary
 
On those carbs, the MIXTURE screw is different to the AIR screw on slide carbs. On yours screwing IN makes it leaner and OUT makes it richer - the opposite to what most people are used to. If idle is rich, screw the screws in slightly to reduce fuel flow and vice versa.
 
It's funny, but I never really know which way is which on the idle mixture screw. I guess it doesn't really matter, because I adjust them for best idle, and never really think about whether it's richer or leaner. <G>
 
I have just recently acquired a 1987 GS 450L. It had not been started for over 20 years and was really a mess. Tank and carbs have been cleaned and I have been able to get .

I do havea couple of issues. Starter switch will not engage the starter but I am able to jump start at the battery connections to the sylinoid and get it running. Any ideas?

Also. It dies every time I try to put it into gear? Ideas?

The rest of the bike is nice (only 8600 miles on the engine) Any ideas what I could sell this for as is?


As you can see, my daughter really likes this bike and I want to use it to teach her to ride.

Thanks

Tom
 
Alrighty folks - fell off the wagon for a few months but getting back on here. Video of her running here: http://www.youtube.com/watch?v=NBMyfKPBmv0

You can kinda hear the rising idle in the video. When I'm pulling up to a stop sign and shift down, the idle remains high, and I have to let the clutch out a little bit to bring it back down. This video is a couple months old but her condition is the same. Any thoughts?

Also, anyone have an extra screw for the choke lever (pictured missing below) or can tell me the thread? Can't seem to find one to buy.

 
Your wandering idle is caused by a leak in your intake boots. Either the boots themselves, or the orings between them and the head - best to just order all new parts from Japan. As far as that screw goes, sometimes you can find the thread pitch and length on a parts diagram.
 
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