1992 GSF400 Carb Conundrum
Posted: Tue Dec 15, 2015 2:52 pm
Hi all, first post here. I'm in NC over in the US and I picked up a 1992 GSF400 Bandit a couple of weeks ago. It is a real garage queen with only 3800 miles on it. The previous owner had it running (showed me a video) but let the bike sit. Pilot jets got clogged and wouldn't start the day I went to pick it up...so that's the background. I should also mention the bike apparently has a Dynojet Stage 1 kit.
Fast forward a couple weeks, I have stripped the carbs of all internals for a thorough cleaning. I have also replaced the idle air jet and the pilot fuel jet because the head was stripped, so those are brand spanking new. I have also cleaned all ports and verified that both air and carb cleaner is adequately making its way through all circuits of the carb.
The only thing I am thinking I should have replaced was the O-rings, but to foreshadow a bit, I have just purchased a set from Lite Tek. No idea when they will be here.
Now fast forward a little more to last night. Got the bike buttoned back up and had a terrible time getting it to start, after some coaxing, turning of the idle jet, playing with the choke lever, she fired up....and went right to 9k.
I immediately backed the choke off, and the RPM's dropped to about 5k and held there. Any time I would apply the choke, the revs would climb again. Before I go further I should also say I'm confident the throttle is installed correctly....however, when I applied throttle, the RPMs would actually fall, like it was bogging.
I did notice that the float assemblies were a little difficult to install, making me think I should need new o-rings there. The o-rings on the pilot screws looked OK, maybe a little dry - hard to tell from looks. O-ring under the top cap felt and looked good.
So to get started, I have a few generic questions:
1. Is there a standard setting for the throttle stop screw? I found the manual and the only comment it has in there the following, which confuses me: "Set each throttle valve in such a way that its top end meets the foremost bypass" What?
2. I have the pilot air screw set at 3 turns out because that's what dynojet's website says - sound right?
3. I have read a lot about an o-ring at the emulsifier tube? Is that just for a different carb model? My carb does not look like the following, but there definitely isn't an o-ring around my emulsifier tube. There may be around the slide holder (white thing). Am I missing something?
To make my symptoms more clear, and to give you guys the best information as possible, I took a video. You can't quite hear it, but the diaphragm slides are also chattering quite a bit as well. I did check for holes in the diaphragms, but didn't notice anything.
Thanks in advance.....
https://www.youtube.com/watch?v=tAV4Dv5HFVU
Fast forward a couple weeks, I have stripped the carbs of all internals for a thorough cleaning. I have also replaced the idle air jet and the pilot fuel jet because the head was stripped, so those are brand spanking new. I have also cleaned all ports and verified that both air and carb cleaner is adequately making its way through all circuits of the carb.
The only thing I am thinking I should have replaced was the O-rings, but to foreshadow a bit, I have just purchased a set from Lite Tek. No idea when they will be here.
Now fast forward a little more to last night. Got the bike buttoned back up and had a terrible time getting it to start, after some coaxing, turning of the idle jet, playing with the choke lever, she fired up....and went right to 9k.
I immediately backed the choke off, and the RPM's dropped to about 5k and held there. Any time I would apply the choke, the revs would climb again. Before I go further I should also say I'm confident the throttle is installed correctly....however, when I applied throttle, the RPMs would actually fall, like it was bogging.
I did notice that the float assemblies were a little difficult to install, making me think I should need new o-rings there. The o-rings on the pilot screws looked OK, maybe a little dry - hard to tell from looks. O-ring under the top cap felt and looked good.
So to get started, I have a few generic questions:
1. Is there a standard setting for the throttle stop screw? I found the manual and the only comment it has in there the following, which confuses me: "Set each throttle valve in such a way that its top end meets the foremost bypass" What?
2. I have the pilot air screw set at 3 turns out because that's what dynojet's website says - sound right?
3. I have read a lot about an o-ring at the emulsifier tube? Is that just for a different carb model? My carb does not look like the following, but there definitely isn't an o-ring around my emulsifier tube. There may be around the slide holder (white thing). Am I missing something?
To make my symptoms more clear, and to give you guys the best information as possible, I took a video. You can't quite hear it, but the diaphragm slides are also chattering quite a bit as well. I did check for holes in the diaphragms, but didn't notice anything.
Thanks in advance.....
https://www.youtube.com/watch?v=tAV4Dv5HFVU