Airbox Replacement Issue: Wrong Airbox

[Guest]

Hi All,

In an effort to get my 1977 GS750 Running Correctly, I have decided to go the route of getting rid of the pods that were on the bike and go back to a factory setup. I bought an airbox on ebay (checked the part numbers to confirm it was the correct year, and bought new airbox to carb rubber and a new filter. When I was trying to install it yesterday, I realized that the new rubber didn't fit in the airbox very well, huge gaps, and the old rubber fit in the airbox but not on the carbs. I have a feeling that I bought an airbox off of the new GS's. So, if this is the case: 1. Is there any way to make the airbox fit onto my small carbs? (rubber that goes from the bigger size to the smaller carbs or can I make something?) 2. Will this affect the way the bike runs?

Thank You

[tom203]

I can't answer...but yesterday as I was stumbling on Boston CL , I came across this parts lot with an airbox pictured
It might offer clues

https://boston.craigslist.org/gbs/mpo/d/lowell-suzuki-gs-parts-lot/6977305528.html

[Andrewb.95]

Thank You,

I messaged the Seller for pics of the Airbox. Going to see what the parts numbers are on his.

[tom203]

I just reread your prior posts.....this stuff about it running ok for your friend one time and then running poorly next time doesn't suggest an airbox issue. Your carbs - VM's- should run fine with pods. The CV carbs on later models are the tricky ones to get right with pods.
Don't knock yourself out finding the correct airbox,cuz it might not be your problem. As it has been mentioned, the points/condensers in your ignition circuit can cause erratic running where 2 cylinders seem to cut out at times .

[Andrewb.95]

Tom,

I did buy new condensors and points as well while I was at it. I will put those on just because I know mine are OLD. I'll see if that makes a difference.

[gsgeezer]

I have an airbox for a old GS750, in the garage, that I got in a parts box.

I can check on it, if you or anyone else needs it, they can have it for the cost of shipping.

[Andrewb.95]

I just reread your prior posts.....this stuff about it running ok for your friend one time and then running poorly next time doesn't suggest an airbox issue. Your carbs - VM's- should run fine with pods. The CV carbs on later models are the tricky ones to get right with pods.
Don't knock yourself out finding the correct airbox,cuz it might not be your problem. As it has been mentioned, the points/condensers in your ignition circuit can cause erratic running where 2 cylinders seem to cut out at times .

Got new points and condensors in and got it timed. It made a slight difference in how it ran, but still after 1/4 throttle it would start to bog down. But it idled perfectly as before. Then I set the choke to about half-way, and then it started running better than I have ever had it running. I could go from 0 Throttle to 3/4 Throttle and it was completely smooth. I am going to be opening the carbs soon to investigate and clean and rebuild since running with half choke on is not practical, and it would stall sometimes when coming to a complete stop with the choke halfway. But whatever adjusting the choke does, completely evened out my poor performance above 1/4 throttle.

[Andrewb.95]

I have an airbox for a old GS750, in the garage, that I got in a parts box.

I can check on it, if you or anyone else needs it, they can have it for the cost of shipping.

gsgeezer,

I might follow up with you on that offer, I will let you know.

Thank You!

[tom203]

Sounds like progress....sadly, it's best to do carbs yourself to be sure of what you got....as it's hard to find a shop that gets motivated by these old things (other than your money). If it's running ok thru 3/4 throttle with a bit of "choke" to help, it's ok to get some riding in before you tear into carbs if you feel comfortable
Have you been steered to this link yet?

http://members.dslextreme.com/users/bikecliff/images/vm_carb_rebuild.pdf

consider putting in Stabil in gas now , in case you forget or get distracted later! Use the blue stuff.
remember the " choke" is actually an enricher. Seems that your bike needs a extra fuel buzz away from idle

[Andrewb.95]

Sounds like progress....sadly, it's best to do carbs yourself to be sure of what you got....as it's hard to find a shop that gets motivated by these old things (other than your money). If it's running ok thru 3/4 throttle with a bit of "choke" to help, it's ok to get some riding in before you tear into carbs if you feel comfortable
Have you been steered to this link yet?

http://members.dslextreme.com/users/bikecliff/images/vm_carb_rebuild.pdf

consider putting in Stabil in gas now , in case you forget or get distracted later! Use the blue stuff.
remember the " choke" is actually an enricher. Seems that your bike needs a extra fuel buzz away from idle

I have plans to tear the bike down completely over the winter and re-paint the frame, and replace all gaskets in the engine and fix any cosmetic and minor issues with the bike. I do just want to get it running well before I do that. I also have a 2018 Triumph Street Twin that is my every day bike, so riding the GS isn't at the top of my priority. But I do like the bike and want it to run well. I did just ride it yesterday a little bit, and then parked it for 30 min and tried riding it again and it started running like *@%^$*@%^$*@%^$*@%^$ again. So any progress that I made there may have been lost .

[eil]

Because I didn't see it explicitly mentioned, the airbox for engines with VM (slide) carbs is different than the one for engines with CV carbs. Everything is the same except for the carb boot holes. The CV carbs have larger holes for the boots. Larger boots too.