Engine bogging down while cruising

[TheCafeKid]

I ripped the carbs apart and they looked pretty good. The main jet and needle jet, and the jet needle, all look perfectly fine. I havn't taken the pilot jets out yet. They're a pain.

The float heights are as follows:

Left side carb: 23mm
Right side carb: 22mm


Clymer says for all models except the GS450, it should be between 25.6mm and 27.6mm. The GS450 should have between 21.4mm and 23.4mm.

I'm basing it off the GS450 model, as I think they're the same carbs as mine, and by doing so, my float level is correct.

I'm kind of at a loss..

Go with the 22.4 +/- 1mm ALL the GSs im aware of use the same hight stock. set em at 22mm and call it good. AND, make sure they're BOTH the same hight exactly, or as close as humanly possible. Being a twin, loading up on one cylinder is likely to be more noticeable than four. NOW, WHERE are you measureing that from? dont forget to take the gasket out, or subtract 1mm if you leave it on. Also, you made no mention as to whether or not the adjustment screws onthe carbs had ever been fiddled with (if they havent they're under a cap and youre not likely to see them) If they HAVE, they're the screws on top of the carbs, motor side. Those SHOULD be set to about two turns out from lightly seated as a good starting point, and then adjust to highest idle speed from there. If you havent PULLED the pilot jets and checked em out, they use MICRO TINY holes thru the shaft of it as their own lil emulsion set up. Rust WILLL get in there, and cause your issue. Im having a similar issue of my own, but im rich for a reason ive yet to track down... Take a look at those things, and see where you're at from there...


PS: MUSTANGFLYR...WHICH connection were you having an issue with? I have a bit of a twitchy wire going to my fuse block that will suddenly kill the bike dead cold once in a blue moon. I havent been able to track which it is yet, perhaps your info could help me out.

[MrZig]

Here's updated carb specs:

Float height
Stock 22.4mm +/- 1mm
Left 23mm
Right 22mm

Jet Needle P-1 - STOCK: P-1
Needle Clip Center - STOCK: Center
Needle Jet 5D69 - STOCK: 5D69
Main Jet 110 - STOCK: 117.5
Pilot Jet 42.5 - STOCK: 42.5

As you can see, everything is fine except the main jet is 7.5mm smaller. This shouldn't be causing the symptoms I'm having, right? Just WOT.

The carb is completley ripped apart now. All jets and needles were clean, pilot needle included, and no jets were clogged. Passages unknown, I'll spray them down with solvent. I'm pretty sure this might not be a carb problem after all.

[mustangflyr]

Connector

In reply to TheCafeKld it was the connector between the fuse box and the main harness, to be exact the orange wire with a white tracer. I went ahead and replaced all the terminals (8) and the connector block. Fixed it. As I noted I crimped and soldered them. Again hope it helps.

[MrZig]

Oh sorry Cafe Kid I didn't see your reply there

I measured from the gasket surface (without the gasket) to the highest point on the float, but not the step up. IE This image explains it perfectly of what I did:





The idle needle/pilot needle has been messed with by me personally. It has a new o-ring, and I believe each one was between 2 and 2.5 turns out. When I took it out an hour ago the tip was perfectly fine. And the pilot jets were also perfectly fine.

[TheCafeKid]

In reply to TheCafeKld it was the connector between the fuse box and the main harness, to be exact the orange wire with a white tracer. I went ahead and replaced all the terminals (8) and the connector block. Fixed it. As I noted I crimped and soldered them. Again hope it helps.

That does help. Thank you sir. That Orange wire with the White tracer actually feeds your ignition, just for future reference. I am sort of glad you said that because I believe THAT very wire is the one that is at fault on my ES. This could also be the source of my senseless rich problem when i SHOULD be lean by all rights, as I may not be feeding enough voltage to the coils.

[donimo]

If you need any more specs let me know, but I can't think of anything that hasn't been tried...

[MrZig]

I took shop air & good spray solvent to every part of the completely dissasembled carb I could. Everything carb wise is as clean as I can get it.

One thing though, I noiced in the female part of the carb body where the needle jet slides into, there seems to be a small hole in the middle of that, where does it go?

[KEITH KRAUSE]

Regarding your earlier post, the gas cap itself has a vent. It can become clogged when years of fumes become a varnishy film. If the venting is compromised, you can get fuel starvation, most noticable at steady speeds.
I mentioned it because it's quick to clean it and re-rest. From what I read it sounds like your float bowl vent lines are clear.
Have you tried testing with the petcock in PRIME position?

[MrZig]

Regarding your earlier post, the gas cap itself has a vent. It can become clogged when years of fumes become a varnishy film. If the venting is compromised, you can get fuel starvation, most noticable at steady speeds.
I mentioned it because it's quick to clean it and re-rest. From what I read it sounds like your float bowl vent lines are clear.
Have you tried testing with the petcock in PRIME position?

After getting the carbs back on if it still bogs down I'm going to try choking it, and taking the cap off to see if it makes a difference. I did run it in prime with no difference.

I also just did the coil relay mod and I'm getting good spark, however I noticed that before the mod I was losing 2 volts. It may make a difference, may not, we'll see.

I'm also getting new main jets which come stock on my type of carbs. The ones on mine are 3 sizes too small, that may make a difference as well.

[KEITH KRAUSE]

OK. Good luck with it.
The mains should be stock anyway. Generally, the smaller mains should only effect 3/4 to full throttle but it's still possible that 3 sizes smaller could have the effect you describe. It's the smallest opening in the circuit that regulates flow. You would think that the space between the jet needle and needle jet would be adequate (at the throttle position your problem is noticable) and uneffected by a smaller than stock main but since the mains should be stock anyway it's worth a try.

[MrZig]

OK. Good luck with it.
The mains should be stock anyway. Generally, the smaller mains should only effect 3/4 to full throttle but it's still possible that 3 sizes smaller could have the effect you describe. It's the smallest opening in the circuit that regulates flow. You would think that the space between the jet needle and needle jet would be adequate (at the throttle position your problem is noticable) and uneffected by a smaller than stock main but since the mains should be stock anyway it's worth a try.

Yeah I know, right? The weird thing is, the needle jets and needles were completley clean in both carbs, same with the main jets. I just don't know why that would cause such a dramatic bogging effect that I had. I wonder if it's igniton or cam timing.. I doubt it, because 0-60 times are generally pretty good.

[MrZig]

Ok I did a coil relay mod giving full battery voltage to the coils, as I was losing at least 2 volts. I also got the new intake boot and sealed it around the airbox with black tape. Everything is aligned good. I plugged the drainage and crankcase breather holes on the airbox, too. Is there anything 'bad' with leaving the crankcase breather open to the atmosphere?

I also cleaned the carbs out, set the pilot needle out two turns, installed new spark boots and fired the bitch up. After warming it up, and lubing the chain, I took it for a real ride and the hesitation/bogging seems to have dissapeared. I used to have a missfire just cruising at 50 KPH and that's gone, and I didn't get much of that major bogging, either. Yay! Only time will tell now

Oh I also noticed that I'm losing oil. When I did my oil change I set it to the high mark on the dipstick, and after two 1 hour rides and some garage-running, the oil level was near the low mark. There are no obvious drips of oil on my carport floor, and it doesn't blow blue smoke or smell of burning oil. I did notice that the end of the crankcase breather hose was oily. could that be the culprit?