Why is my bike so slow?

[Sasquatch]

A couple months ago I bought an 81 GS650L on Craigslist for $300. I haven't had time to tinker with it. The bike runs and seems in pretty good condition overall. First let me say, I haven't done any work on the bike or cleaned the carbs. It idles just fine at about 1100rpm and is smooth revving all the way up to about 6K (I haven't taken it past that yet). The only problem I notice is that it is molasses slow. I give it full throttle and it takes its own sweet time getting up to 50mph (the fastest I've taken it so far). Throw out ideas for me on culprits...again, it idles steady and revs smoothly.

 

[Steve]

Check the airbox and filter for a possible mouse nest. :shock:


Seriously. 8-[


.

 

[Sasquatch]

LOL...no mouse nest in there...I checked the filter awhile ago...other then being a little dry (I don't have any air filter oil on hand) no unwanted residents in there...

 

[chiphead]

Spin it up past 6K.
Make sure both wheels spin fairly freely with both wheels off the ground. You'll get some resistance from the rear because of the final drive. Take it for a easy ride and none of the brake rotors should be hot to the touch.
All four exhaust pipes burn your hand when you touch them?8-[
Are you a big boy?

 

[robertbarr]

I bought an 81 GS650L on Craigslist for $300.

... that could explain a lot right there.

No, seriously...

You've done no exploration at all, so the best you can hope for here are wild guesses.

Here's what I'd do: Take the bike out and let it get nice & warm. Then find some secondary roads (rural) and take the thing to redline in 1st, 2nd and 3rd, and repeat about twelve times. Don't be afraid of redline; if it were harmful, my Suzukis would have lasted about a day. I wouldn't draw any conclusions until you've put 150 'enthusiastic' miles on the bike with fresh fuel.

From there, start with the basics. Let it cool, of course, and check the compression. This is the best indicator of what ails your machine. If it's remotely near spec, you should be OK, and you're looking for something simple.

Finally, keep in mind that you're not riding a liter bike, either. A 650 can really perform, but don't expect a lot of muscle -- especially at lower rpm's.

 

[Sasquatch]

Well, actually the best I can hope for are educated guesses. Right now I have very little time to work on these bikes so was interested in what members had to say to help focus my energies. I will be checking the compression tomorrow and I'll be harder on the bike to see what it does closer to it's redline.

 

[Zooks]

Make sure it's got nice new oil in it before you go 'wringing its neck'.

 

[Sasquatch]

word.....I have a new(er) stator to put in it and was putting off changing the oil until that job was done but I might just change the oil now and then again whenever I find time to swap out the stator. The oil level is good but who knows how much protective value that oil has left remaining.

 

[49er]

... that could explain a lot right there.

No, seriously...

You've done no exploration at all, so the best you can hope for here are wild guesses.

Here's what I'd do: Take the bike out and let it get nice & warm. Then find some secondary roads (rural) and take the thing to redline in 1st, 2nd and 3rd, and repeat about twelve times. Don't be afraid of redline; if it were harmful, my Suzukis would have lasted about a day. I wouldn't draw any conclusions until you've put 150 'enthusiastic' miles on the bike with fresh fuel.

From there, start with the basics. Let it cool, of course, and check the compression. This is the best indicator of what ails your machine. If it's remotely near spec, you should be OK, and you're looking for something simple.

Finally, keep in mind that you're not riding a liter bike, either. A 650 can really perform, but don't expect a lot of muscle -- especially at lower rpm's.

Some good advice here, but make sure that you do the compression test when the engine is hot and with the throttle wide open.

 

[GS850_Coug]

I would suspect dragging brakes. If it sat for any length of time, especially in a damp/humid environment, the pads could have swollen. Does it seem really difficult to push?

 

[Steve]

No need to wait for the stator change to change the oil, too. If you don't have the bike on the side stand, you will lose very little, if any, oil by pulling the stator cover.


.

 

[Pearson]

Well, actually the best I can hope for are educated guesses. You also really don't know how much exploration I've done (though it really hasn't been all that much). It is true I said I haven't had time to tinker with it as relating to this problem. It wouldn't idle and would barely start when I got it. Right now I have very little time to work on these bikes so was interested in what members had to say to help focus my energies. I will be checking the compression tomorrow and I'll be harder on the bike to see what it does closer to it's redline.

I've got all of 50 mi. on my 750 and didn't recognize two things due to inexperience:
1. my rotor was dragging on the caliper and
2. there was a whole other power band at higher revs.

So as said before, check the brakes and give it some juice:shock:. If it's holding a good idle and accelerating smoothly, there shouldn't be all that much wrong with it.

 

[Sasquatch]

good question, but no..they don't seem to be dragging. I had a spare 15 minutes so I ran down to put some gas in it and while I didn't redline the old girl, I did take her up to about 8K rpm...no probs, revved smooth....some day soon I'll have to register her in my state, insure her and get a motorcycle endorsement

 

[Sasquatch]

I did notice that she got a lot healthier feeling and took on a different exhaust note above 6K...maybe I'm just expecting to much on the low end? In the months coming up as I have more free time she'll get more work put into her.

Just for giggles, here's a pic of her..
http://picasaweb.google.com/SasquatchMaxBoxing/Suzuki/photo#5050511228375403714

 

[eddiev]

Why does the throttle have to be wide open to do a compression test?

 

[Steve]

Because the purpose of the test is to see how well the piston can compress a bunch of air.

If the throttle is closed, it can't get enough air.


.

 

[Guest]

It would be wise to change the oil that is suspect, if not all of the fluids, before any testing @ redline....a set of fresh plugs too is not a bad idea....check out the old ones for any clues/fouling. Run a couple tanks of 'Sea Foam' laced gas through, too.

Tony.

 

[bradleymaynar]

I did notice that she got a lot healthier feeling and took on a different exhaust note above 6K...maybe I'm just expecting to much on the low end?

Remember that this is not a v-twin. Those types of engines tend to have a lot of low end torque. The I-4's tend to breath heaviest when in the upper end.

Brad bt

 

[Sasquatch]

you know, that may be part of my problem...I haven't owned a bike in about a decade, but my last one was a Honda V4....I'm going to change out the oil, do the stator, and keep running seafoam laced gas for the next couple tanks (it had some in the last tank) and she has new plugs/filters and I'll just keep the revvs higher for now until I get used to this old girl...

 

[Zooks]

How much do you weigh? LOL