GS450 Troubles

[jeffasaurus2]

Hello again,

So I just finished rebuilding my GS450T's Carbs with Cycle-O-Rings, float height adjusted, the works. Fuel Petcock and Chain Tensioner rebuilt, Replaced the intake boot O-rings, and made sure everything is sealed properly in the air box.

I've got the air adjuster screws set at 2 turns out from lightly seated and bench synced the carbs.

Now it starts however it has troubles.

The Idle is difficult, I can get it to stick around 1100 or so but as it warms up it starts to drop and eventually die.

The throttle seams to stick when you rev it as well. Not the throttle itself, or the cable, just the engine takes much longer than it should to drop down to idle speed again.

I haven't synced the carbs by vacuum yet as I can't seem to keep it running consistently and same for adjusting the air screw.

Any ideas what my next steps should be?

[Guest]

Part of what you you describe is the notorious "hanging idle" problem, which generally points to intake or at least a lean condition.

You say you've replaced the intake boot O rings, but what about the boots themselves? Do they leak air?

If you can keep it running for a few minutes, you should be able to see by the spark plug colour whether it's rich or lean or if they're wet which means all the fuel isn't be burnt.

Also, regardless of the above, you definitely should check your valve clearances if you haven't done so already, this will affect how it runs.

[jeffasaurus2]

I replaced one of the Boots, the other had some cracks around the base but looked like it was usable, I think I'll be replacing that.

And I forgot to add, I did adjust the valves and they are all within spec.

[jeffasaurus2]

Just took a look at the plugs, the right cylinder is normal looking, whitish tip. The left cylinder however is black and dry, Too rich? would turning the Air adjuster in or out be ideal?

It seems to run for a bit then die at idle after warming up. It still has the hanging idle however I can't seem to locate any noticeable leaks.

Any other suggestions?

[Guest]

Black is definitely rich and if memory serves correct turning the screw out will lean it out a bit, but I may be wrong...

Something's still not quite right if you have the hanging idle though. Is your airbox all sealed up nice and tight and is your filter oiled?

[BassCliff]

Black is definitely rich and if memory serves correct turning the screw out will lean it out a bit, but I may be wrong...

Hi,

Turning the idle mixture screw out (counter clockwise) adds more fuel to the idle mixture, making it richer.

Have you checked your spark on that cylinder? Hanging idle is a classic symptom of an air leak. Air leaks in cracked intake boots can be all but undetectable. It's always best to replace the whole set.


Thank you for your indulgence,

BassCliff

[jeffasaurus2]

I've decided that It'd be in my best interest to just replace the other boot as well as the carb / air box boots. For all I know they're original to the bike, even if they cosmetically appear to be OK.

I'm even considering replacing the clamps on the intake boots as, not surprisingly, they don't seem to be the ones that belong to the bike. I can tighten them to their limit and it still seems like the boot could go tighter. So rather safe than sorry I suppose.

The air box is sealed and a new filter was put in with oil as it comes from Suzuki.

As for checking the spark, what would you recommend as the easiest way to go about that?

[refeicul]

the easiest and safest way to test spark is an in-line spark tester. which can be purchased from your local auto parts shop. some members will say just have plug hanging in such a way as to ground it to the frame and/or engine and see the spark that way. i don't recommend this cause Ive been juiced more than once that way

[Guest]

Hi,

Turning the idle mixture screw out (counter clockwise) adds more fuel to the idle mixture, making it richer.

Have you checked your spark on that cylinder? Hanging idle is a classic symptom of an air leak. Air leaks in cracked intake boots can be all but undetectable. It's always best to replace the whole set.


Thank you for your indulgence,

BassCliff

Ooops, thanks BassCliff! Guess I had a 50% chance of being right hey?

[Guest]

I've decided that It'd be in my best interest to just replace the other boot as well as the carb / air box boots. For all I know they're original to the bike, even if they cosmetically appear to be OK.

I'm even considering replacing the clamps on the intake boots as, not surprisingly, they don't seem to be the ones that belong to the bike. I can tighten them to their limit and it still seems like the boot could go tighter. So rather safe than sorry I suppose.

The air box is sealed and a new filter was put in with oil as it comes from Suzuki.

As for checking the spark, what would you recommend as the easiest way to go about that?

Sounds like it could be a worthwhile idea as even if they appear ok, if they're not supple then they won't seal real well.

I replaced the clamps on the intake boots from the carb to the cylinder head as one of them seemed to be right and the other seemed wrong altogether, so I just replaced both.

I will say that even tightened up completely, they only *just* clamp the boots to the carbs, so it seems they're designed to clamp them just enough for the ridge in the boots to hold onto the ridge on the carb bodies.

Sounds like you're definitely heading in the right direction though.

One thing with spark is that if it's not happening, I would expect your plugs to be wet depending on how long it was getting fuel without burning it.

the easiest and safest way to test spark is an in-line spark tester. which can be purchased from your local auto parts shop. some members will say just have plug hanging in such a way as to ground it to the frame and/or engine and see the spark that way. i don't recommend this cause Ive been juiced more than once that way

I haven't had issues with this *yet*, and all my ignitor testing was done exactly like this, but I won't be surprised if I give myself a jolt at some point.

[jeffasaurus2]

I figured if the spark wasn't there then the plug would be wet, but might as well rule out any possibilities.