New GS750ES owner

[acksys]

Carbs are back in (sort of, caveat below). Bike isn't starting now. I'll take the tank back off and try to prime the bowls with a funnel tomorrow.

I had a hell of a time getting the carbs back on. In the end, I couldn't get the airbox boots on #2 and #3 all the way onto the carbs before clamping them. I got them maybe 1/2 way on. I'm not sure yet if this is keeping the bike from starting. The #3 airbox boot is also cracked in a few places.

It looks recommended to get all new boots. Well worth it if it makes carb maintenance easier. Would all 4 airbox boots, all 4 intake boots, and 8 clamps do the trick?

Is this the right part # for the airbox boot: http://www.bikebandit.com/oem-parts/1983-suzuki-gs750es/o/m21353#sch245075 part no # 1051789

 

[acksys]

Bad petcock! With vacuum it works, prime position doesn't. So the petcock wasn't priming the bowls. I did it with a funnel and the bike is starting now!

I'll try rebuilding the petcock soon.

 

[acksys]

I got the tank back on and went for a short ride without bodywork on. MUCH smoother acceleration now!

Here are videos of engine sound before and after the ride. Crappy phone cam, so I don't know if they'll mean much.

https://www.youtube.com/watch?v=t89lzEQ86wg
https://www.youtube.com/watch?v=jEDZ9eHhwW8

Idle is rough and I had to start the bike with the choke every time, even after warming up the engine. I know I damaged 2 of the idle screws by cranking them down too far when I rebuilt the carbs. I'll replace them soon.

I should play with the idle screw adjustment, too. They're at 2.5 turns now.

 

[acksys]

I spent some time planning next steps tonight and came up with a shopping list. I have a few questions. Any help and suggestions are appreciated.

Fuel tank petcock. It looks like the prevailing opinion is to just replace this rather than try to rebuild.

https://www.z1enterprises.com/product/KL18-4359 $41.73
http://www.ronayers.com/oemparts/p/suzuki/44300-45471/cock-fuel $74.20

Huge price difference. Am I missing something?

Idle fuel mixture screw x 3. Two to replace the ones I messed up and 1 spare.

https://www.z1enterprises.com/product/KL18-2645 $9.28



Plan is to use carburetor cleaner or starting fluid to test airbox side and head side for a vacuum leak tomorrow and then replace both sides as needed. I came up with the parts below.

Cylinder head intake boots, left x 2, right x 2

http://www.ronayers.com/oemparts/p/suzuki/13110-31310/pipe-intake-rh $25.82
http://www.ronayers.com/oemparts/p/suzuki/13120-31310/pipe-intake-lh $25.82

Cylinder head intake boot clamps x 4

http://www.ronayers.com/oemparts/p/suzuki/09402-50208/clamp $3.12

I'm confused on if I need the o-rings or not. When I ordered the carb o-ring kit from Robert Barr, I tried to order intake o-rings as well and he said mine doesn't use them. But the fiche here is clearly labeled GS750ESD and shows them: http://www.ronayers.com/oemparts/a/suz/50d400fcf8700230d8b4e3e6/cylinder-head

Airbox boots

Looking at this fiche, I'm confused about what exactly I need to get to replace the boots on the airbox side: http://www.ronayers.com/oemparts/a/suz/50d40103f8700230d8b4e3f0/air-cleaner
Any suggestions? Looks like some parts are not available.

Airbox boots clamp x 4

http://www.ronayers.com/oemparts/p/suzuki/09402-60208/-clamp $3.35

Carb sync tool

I've seen lots of nice DIY designs on youtube, but some of the tools I've found sure look nice: http://www.carbtune.com/. I may just buy a tool since I have been working on the bike a lot lately and want to get riding.

 

[eil]

I spent some time planning next steps tonight and came up with a shopping list. I have a few questions. Any help and suggestions are appreciated.

Fuel tank petcock. It looks like the prevailing opinion is to just replace this rather than try to rebuild.

https://www.z1enterprises.com/product/KL18-4359 $41.73
http://www.ronayers.com/oemparts/p/suzuki/44300-45471/cock-fuel $74.20

Huge price difference. Am I missing something?

The one from Z1 is made by an aftermarket manufacturer called K&L, the other one is OEM. The K&L one will probably work just fine. (Verify that it looks exactly the same as the one you have before removing the old one.) You can buy the OEM one if want to be super-safe, but obviously it'll cost more.

Idle fuel mixture screw x 3. Two to replace the ones I messed up and 1 spare.

https://www.z1enterprises.com/product/KL18-2645 $9.28



Plan is to use carburetor cleaner or starting fluid to test airbox side and head side for a vacuum leak tomorrow and then replace both sides as needed. I came up with the parts below.

Cylinder head intake boots, left x 2, right x 2

http://www.ronayers.com/oemparts/p/suzuki/13110-31310/pipe-intake-rh $25.82
http://www.ronayers.com/oemparts/p/suzuki/13120-31310/pipe-intake-lh $25.82

Cylinder head intake boot clamps x 4

http://www.ronayers.com/oemparts/p/suzuki/09402-50208/clamp $3.12

I'm confused on if I need the o-rings or not. When I ordered the carb o-ring kit from Robert Barr, I tried to order intake o-rings as well and he said mine doesn't use them. But the fiche here is clearly labeled GS750ESD and shows them: http://www.ronayers.com/oemparts/a/suz/50d400fcf8700230d8b4e3e6/cylinder-head

Maybe Robert is thinking of the 2nd-gen 750 which indeed does not have o-rings (or a flange because it's cast into the head). I'd politely point him to the parts fiche, we all make mistakes.

Airbox boots

Looking at this fiche, I'm confused about what exactly I need to get to replace the boots on the airbox side: http://www.ronayers.com/oemparts/a/suz/50d40103f8700230d8b4e3f0/air-cleaner
Any suggestions? Looks like some parts are not available.

You're looking for #2 and #3. Unfortunately, #2 appears to be no longer available brand-new. That's a bummer. Maybe someone else here has an idea where to get them.

Airbox boots clamp x 4

http://www.ronayers.com/oemparts/p/suzuki/09402-60208/-clamp $3.35

Carb sync tool

I've seen lots of nice DIY designs on youtube, but some of the tools I've found sure look nice: http://www.carbtune.com/. I may just buy a tool since I have been working on the bike a lot lately and want to get riding.

You won't go wrong with the carbtune pro. Throw this in on your Z1 order as the Carbtune's only failing is that it comes with less-than-effective fiberglass/plastic adapters: https://www.z1enterprises.com/product/TU15-0438

 

[acksys]

You're looking for #2 and #3. Unfortunately, #2 appears to be no longer available brand-new. That's a bummer. Maybe someone else here has an idea where to get them.

This is a bummer. Do I need 2 x #2 and 2 x #3? Or is it 3 x #2 and 1 x #3, hard for me to tell from the fiche.

 

[eil]

Two of each, they apparently come in "inside" and "outside" editions. The outside ones probably have an angle to them while the inside ones are straight.

You might be able to get away with using the outside boots on the inside carbs as well (possibly with modifications), but don't take my word for it since I'm far from an expert in that area. Maybe someone else can chime in with advice.

 

[acksys]

First, I want to thank eil, steve murdoch, and everyone else who helped me get through my first engine and fuel system maintenance.

Carbune Pro arrived a couple weeks ago and I got them synced pretty well at low and high RPM. Now I have a very nice ride--my daily for the last couple weeks. Beginning of this video has post-maintenance idle and low RPM engine sound: https://www.youtube.com/watch?v=e5_pOua-FvA&feature=youtu.be&t=1s

I sprayed starter fluid around the boots on both the airbox and engine side. No surges. So I am going to consider myself lucky I don't have a vacuum leak and leave that alone for now. I think I'll take it back to the mechanic who did the tires in a bit and see if he has any ideas on replacing or making the discontinued airbox boots.

Bad petcock replaced. The gaskets under the bolts were missing and someone had simply torqued the screws into the metal of the other petcock to keep fuel from leaking. I bought gasket material and made a couple rather than ordering the part.

The front brake lever doesn't activate the brake light. I have a pretty good idea of where to start troubleshooting that.

So here's the next larger issue, the bouncing tach needle. This has happened since I picked up the bike, but I got a cam recently and got some video. It happens intermittently and is worse at highway speeds. Sometimes the needle bounces around, and frequently it pegs to the right.

Bouncing/pegging tach needle: https://www.youtube.com/watch?v=e5_pOua-FvA&feature=youtu.be&t=10m30s

I read somewhere else the bouncing tach could be a symptom of charging system fault. I can check that soon for starters. Any other ideas to pursue?

 

[eil]

The front brake lever doesn't activate the brake light. I have a pretty good idea of where to start troubleshooting that.

Probably the switch itself on the handlebar. These are finicky. Either fiddle with the switch (it can be taken apart) or replace it with an aftermarket pressure-actuated one that replaces the banjo bolt on your master cylinder. I have one on my bike, it works great. Does require opening the brake lines (which means you'll have to bleed them again) and you have to know that it doesn't trigger the brake light until there's a decent amount of pressure built up. So you can't blip the brake light from the lever, you'd have to use the rear brake for that.

I read somewhere else the bouncing tach could be a symptom of charging system fault. I can check that soon for starters. Any other ideas to pursue?

It's an electronic tach, so it's possible. But I'm not super convinced because there was no change in the gauge backlights or headlight that I could tell on the video. Do you have the stock R/R? If so, replace it with a Polaris R/R because it will die eventually. Search the forum for "polaris R/R" for all the gory details.

It could also be caused by loose or corroded connections inside the gauge cluster. See about opening it up and giving everything a once-over. If I recall, there are a number of plugs and wires terminating to screw terminals. All of these should be cleaned.

And finally, there are some components on the tach itself that could go bad. Capacitors, perhaps. If you're good with electronics or know someone who is, you could try desoldering and checking them. There aren't that many, it's a pretty small board.

 

[Guest]

these electronic tachs are notorious for going bad, my 1100 did the same thing. Worth checking the charging system ANYWAY, but probably not the problem. Many have tried to fix the tach, changing caps has worked for some, maybe, but the real culprit seems to be a faulty transistor which apparently is proprietary. To my knowledge, an effective and universal solution has never been found....but search around and you might find one. I ended up swapping my gauges for some from a 90's gsxr, e-tach and mech speedo, some massaged wiring, and a fabbed bracket. Good luck, if you fix the tach, definitely post about it!!!

Looks like you are on the right track otherwise, nice to see a relative newcomer who can take advice and work through problems!!


Oh, and good looking bike!

Greg