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83 GS450T !@#!* Air leak I think.

  • Thread starter Thread starter Ohioan
  • Start date Start date
O

Ohioan

Guest
Okay,

I just cleaned my carbs, replaced all the o-rings inside, replaced the intake o-rings, and put new clamps on the boots. I've got it sychned up pretty well, where the throttle response is good and it doesn't seem to run rich or lean.


When I am just sitting, before putting in gear or touching the throttle, it idles at 1.5k rpm.

okay, the bike has warmed up.

When I blip the throttle past 3k, it won't drop back down below 3k. If I kill it, and start it back up, it will idle at 3k RPM. If I'm cruising down the road in 6th gear, and pull the clutch in, it won't idle lower than 3k.

If I'm at a stop light, and keep the clutch in the friction zone, the idle will stay at the 1.5k area, but if I take the clutch off, it shoots back up to 3k.

Air leak?

I've sprayed carb cleaner around the boot and it doesn't change it's idle.

So it is probably in the carbs correct?

But where do I start to look?

I'm trying to find someone who has a mercury manometer locally.
 
Where are the pilot screws set? Also, is the bike stock or modified?

You can do a quick and dirty sync on a twin by setting up the idle and pulling off one of the spark plug caps; set both for the same level when running on one cylinder.
 
Uhm, I think they're like 2-3 turns out. I didn't really keep track. It was a long drawn out process over a couple of days to get it to run just right. First time.

My main concern is this air leak.
 
May not be an air leak. Maybe your idle setup is just a little out of wack. Sounds like the bike bike is running well otherwise.

Once the bike is warm and it's idling to high. Turn the big brass knob counterclockwise. This will close the throttle plates and make the idle come down some. This knob faces the rear of the bike so adjust your clockwise/counterclockwise accordingly.......

The idle air/fuel screws which only control the air/fuel mixture at idle, should be set approx the same. You should also have some kind of idea where they are set from lightly seated.

And do this it will probably help get you going in the right direction.:)

http://members.dslextreme.com/users/bikecliff/images/highest_rpm_plug_chop.html
 
Ohioan said:
Okay,

I just cleaned my carbs,
Click to expand...

IF you removed the throttle plates from the throttle shaft when you dipped the carbs, you may not have got the plates centered in the bores when you reassembled them - causing the throttles to not completly close.
 
I did not dissasemble them that far. I followed the carb cleaning guide from TheGarage. The throttle was functioning fine when I had them off the bike (snapping shut)

pdqford said:
IF you removed the throttle plates from the throttle shaft when you dipped the carbs, you may not have got the plates centered in the bores when you reassembled them - causing the throttles to not completly close.
Click to expand...
 
Once my 450 warms up, I typically have to lower the idle adjustment. If I don't, the bike will idle high.

Also, try setting the screws at 2 turns out. That's what my mechanic did for my '81 the last time I brought in my bike (discussing this on another thread). Although I know the '83 carb is a bit different from the 81 - 82, I would imagine this setting would be roughly the same.
 
That's interesting. I wonder if this is indicitive of the 450 carbs.

My buddy said there might be some sort of airleak inside the carbs. Like in a vacuum tube or something. I dunno. It runs otherwise, and I can sorta ride the friction zone to keep the idle down. That's probably hard on the clutch/transmission.

There seems to be something up with the choke also. (it doesn't need the choke on to start)

I'm missing the choke lever on the left hand control cluster, but it's on order and I should be getting it sometime soon.
 
If something is wrong with your choke that could be it too.

all carbs idle higher when warm than cold.

My bike does not need choke either.

Mine starts and idles at 800rpm, when warm it is at the factory spec of 1100rpm.

You could check the idle adjustment screw, have you tried setting it lower once the bike is warm? does the idle go down when you turn it?
 
You might want to try opening the pilot screws a little more. Also, do a vacuum sync.
 
I'm trying to find someone with a manometer to do a vacuum sync.

When the bike is warm, and ideling at 3k, and I turn the knob to lower the idle, it drops down and sometimes it dies, other times it gets really low. Once it gets below 3k it drops all on its own.
 
hmmm, sounds like something is binding to me still. If forcing it below 3k causes it to fall back to normal then something is physically hitching it there IMO, vacuum leak wouldnt do that.
 
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