Loss of power?

[Nightowl75]

I have a 1980 Suzuki GS 450L. I am the second owner of this bike, as the first owner is a co worker that I have worked with for 35 years, and I remember when he bought it new, and rode it to work. It has 6700 miles on it, and I have had the carbs cleaned, new plugs, and air cleaner. The most I can get out of it is about 55 MPH. The book says it should easily do 70 or more, but I sure can't get it even to 60. It does have a windshield on it, but would that put up that much resistance to lower the MPH? I have done the speed sign thing, and the speedometer is right on. I use non oxy gas in it, so I won't have a problem with the ethanol. My mechanic that did the 2 carb cleanings told me to go with that instead of the ethanol. Everything is stock. I have not changed the sprockets, but that was an option left open to me. I live in MN, so altitude is not a problem. It starts right up, but is a little cold blooded for about 5 minutes. Any thing else I can look at to get this up to speed? my brother in law has a suzuki 400, and that will run by mine. Thanks

Richard

[Johnj]

Hello and welcome to the forum.

Have you checked the compression yet?

I'd check the valves, just follow the manual.

[totalmotorcycle]

You should see a max of 90 MPH out of it. You are right 55mph max is too low and there is something in wrong. I would try the simplest things first. It IS a 32 year old motorcycle so don't expect it to be 100% of new, it's an antique!

The "L" is the "cruiser" version of the GS, I wouldn't be surprised it if was geared lower than the "E" "ES" sport versions, thus a lower top speed. I would ditch the windshield and give it a try, it is good for - 5 to -10 MPH of your top. As JohnJ metioned, you should check the compression and pull the plugs and see if any of them are running lean (white)/rich (black). It's possible you might also have a cracked carb boot (how is the rubber on those?)

Mike

[Nightowl75]

Thanks for the ideas. No, I have not checked the compression, and I did buy 3 ranges of plugs today, since I have not had time to pull them to see what they look like. I will be looking for a bigger bike anyway, but this bike is just a sweety to ride. My son has that Suzuki 650 naked bike, but I am not sure exactly what it is. It reminds me of my 1972 Kawasaki 750 triple that I had so many years ago. Trying to ride my sons bike is not much fun for me. My feet are to big, and by the time I get them on the footpegs, I am already putting on the back brake. I guess they are made for the younger set. LOL. Thanks again for the tips.

Richard