Quick 4-1/airbox question

[SuzukiFail]

Hey guys,

I've been riding my '79 GS-750e around some, now that I've got it running. However, it runs really strange. At first, I thought it might need to be re-jetted for the 4-1 exhaust, since I have no idea if it was ever done before. It has weird flat spots as you accelerate, and feels less powerful than my Yamaha XS-650(even though it has 20 more horsepower!). After a further inspection, I found that there was no air cleaner in the airbox. Needless to say, I won't ride it again until I put one in there, but could that be the source of my misery? Would no aircleaner cause it to run really lean?

I have no idea of the brand of the exhaust on it, but here's a pic so maybe someone can identify it. I'll get better pics tonight or this weekend.

[almarconi]

You definitely want to have an airfilter installed. The bike will run like crap until you have a filter installed and the lid on the airbox. Did you vacuum sync the carbs yet?

[twr1776]

+ 1 on installing the air filter. While you are in there also check the box and inlets between the airbox/carbs and carbs/motor for air leaks. Have you replaced the O-rings yet? Without a well sealed air intake system you will never get the bike to run right. There is also a "snorkel" on the back of the airbox that should be connected as well. I am not sure what kind of header you have but you probably will have to re-jet for it. Seal off your intake system first and do some plug readings and you will see if you need to re-jet. My guess is you will unless the PO did it.

[Piston720]

The exhaust looks similiar to the one on my GS1100. It's a Kerker, at the muffler end, mine looks like a ball is pushed in the end with a hole.
Hope that helps.

[JTsGS650]

Nice looking bike. Both your lack of air filter and 4-1 exhaust would tend to make the bike run lean. What do your plugs look like? If you do end up having to rejet, I might suggest going with individual pod filters and a Dynojet Stage 3 kit. Good luck.

[SuzukiFail]

Thanks everyone,

No, I haven't done anything with the carbs yet. I just got it running, I haven't had time to fine tune it or anything. It runs really smooth, just with little power and weird flat spots. I'll check the intake system for leaks when I get a filter. Thanks again!