1980 GS750L Air Filter Box Question

[Larry D]

Larry,
Does the hole on the bottom of the box(snorkel) connect to any thing or is it just open to the air?
The one I have looks the same except there are two holes in the part where you have the snorkel.

Doesn't connect to anything, it's just the air intake. The ONLY air intake. How does your lid look? I put some foam strip on the lid and it's inset slightly to fit onto/around the lip of the box. Makes sense? You want these airboxes tight, no leaks. Except, of course, for the snorkel.

Edit: Wanted to add that the float heights make a huge difference. Too much gas/not enough gas. Mine were 5mm off. I sorta forget, what they're supposed to be. But I do remember they were waay off. Also the hissing sound may be the lid leaking, it should be sealed, as mentioned above. The original foam that was installed 28 yrs ago is probably long gone.

[almarconi]

I had about an hour this morning to tinker with the bike. I tried starting it cold and it was a no go. Choke position made no difference. I noticed that 2 of the rubber carb boots on the front of the carb were backwards. Switched them around but still no start cold. I puffed on the breather tubes and the bike started up. I removed the airbox, sealed the lid and removed the tape from the holes. Reinstalled the box and the engine started. When I had the engine running I sprayed everything with carb cleaner and did not notice any change in RPM's.

I called a friend of mine who owns a motorcycle shop. From the conditions that I described, he seems to think that the engine may not be developing enough vacuum to get the fuel into the engine on initial startup. He said it could possibly be a stuck piston ring or valve train issue. I guess the next step would be to do a compression test and/or leakdown test to see if I have an internal engine problem. I'm going to drop the bike off to him on Saturday and see if he can get it squared away. I need to have a state inspection done anyway so I'll just pay him to finish the bike up.

Thanks for all your help. I'll give an update after the mechanic looks at it.

[dneomax]

I'm having the exact problem as you are having. I did the same thing, I rebuilt and cleaned the carbs thoroughly, and haven't sync it yet. I can only get it to start by puffing into the vent hoses. I'm looking forward on hearing what the problem is from your update.

[almarconi]

I dropped the bike off this morning at the shop. I had the bike running yesterday and noticed that gas is coming out of my airbox. This makes me believe that I've got either a stuck float, bad needle valve or the float height is not correct. The game plan is to get the bike running, check the compression to rule out any engine problems. If the compression checks out the mechanic will go ahead and work on the fuel system. Since the bike runs once its started I'm thinking that my problem is carb related. Hopefully he'll get it all sorted out in the next couple of weeks. In the meantime, I'll be riding my KZ.

[almarconi]

Wanted to let you guys know that the GS is alive and running well. Turns out the carbs were still dirty..they had some crud in the needle seats. The mechanic charged me $480 to do the following:

Remove and Clean carbs
Vacuum sync carbs
Md State Inspection
Install new chain and front/rear sprockets
Bleed front and rear brakes
Adjust choke,throttle and clutch cable
Install mirrors
Replace brake lever
Repair Oil leak(oil pan gasket)
Change oil and filter

I supplied him with the chain, sprockets, brake lever, mirrors and brake fluid. All that I need to do now is go get insurance and tags.

Once I get the bike on the road, I'll need to do some shake out runs and put some miles on it to see if any other issues creep up.

[almarconi]

1980 gs750l **update**

Wanted to post an update on the bike...After a couple of days the bike is back to its old self and will not start cold. The battery voltage is low and the bike is cranking slow. I now seem to be having charging problems. When the bike is running, the charging system is only putting out about 12.5 volts. The battery is about 4 month old. I placed the battery on a charger overnight and it is now reading 12.8 volts.

I read through the stator papers and the first problem I found was with the red wire between the battery and the RR. I took the fuse block apart and found what looked like a caterpillars nest. Several large masses of fluffy material. I cleaned this out and checked for continuity between the fuse block and the RR red lead. No continuity..apparently the bullet connector was corroded. I removed the connector and replaced it. Now I have continuity. I can see where this is going, I am going to have to go through all the connections and clean everything. When I got the bike the leads from the stator to the RR were burned at the connectors. I replaced them but didn't give it anymore thought until I got the carbs sorted out.

I've decided to replace the RR and the stator as a matter of PM. I'll go through and clean all the connectors and run a ground wire from the RR directly to the battery. I'm also considering upgrading the coils to Dyna units. Until I can get the charging and ignition systems straightened out it is pointless to fool with the carbs. I feel confident that the problems I am having are electrical and not fuel related.

[Newbee]

Airbox

I think your 750L box is the same as my 1000L box? The only factory hole I have is a roughly 4"x 1&1/2 " in the back on the lower side. Regardless you on to the problem and figured it out.

You could check the fiches out at either FLATOUT or ALPHA SPORTS and probably others to get a look at what a factory box looks like