GS 650 Can't Accelerate

[superdave]

I hear that line so many times from the ones who like pods.

The flip side of that coin is that, once the carbs are properly cleaned, you don't need to remove them again for a LONG time if you have the stock airbox.

Seems that most of the reasons to remove the carbs so often are so they can be re-jetted and re-re-jetted to compensate for the pods.




I have seen a few different options for that.
- One stylish solution is to go to Auto Zone, get the little filter that looks like a pod filter and put that on your hose.
- Another solution is to install a longer hose and run it down the frame so it exits in the airstream below the swingarm.
This would be like the old-style cars before PCV systems were in place.
Cut the hose at an angle, it will set up a little suction to ventilate the crankcase.
- If you are more concerned about your environmental impact (ironic, since you are going to pods), you can install a trap in the middle of that longer hose.
You would have to decide what would work for you, but make it so the trap can be removed and emptied, but keep the vent hose to evacuate the vapors.

.

Good options, pretty simple. I guess the real reason I was asking is if having that thing open made a difference on the engine's running. I have an old VW Bus that would not run properly until I found and installed a proper oil filler cap. Somehow that air that leaked past the old ill-fitting cap was enough to throw off the engine's computer. I'm not sure if it was because the pressure was no longer being relieved to the intake system or what, but it threw it off.

If anyone has a used airbox off a parts bike, I would love to hear about it! Sounds like it would make my life much easier.

The only reason I'm "going to pods" is because that is what was on the bike when I got it, and I want to ride the thing!

[chuck hahn]

Breather hose will be fine with one of those tiny round K&N looking breathers on the end..i have seen a few guys that buy a longer hose and make small hole in the top of one of the pods to stick the hose in also..either way its ok. Basically that hose acts like your PCV valve on a car..relieves crankcase pressure and reburns any vapors.

[Nessism]

The bike won't run right with stock jetting and pods, and unfortunately we don't have a good database of information on what jetting to use. You are going to have to move the main jet up at least a couple of sizes and maybe the pilot jets as well. Shimming the needle helps, although not as much as a Dynojet needle which has more taper.

Good luck and please don't skip any steps when cleaning the carbs. Also, make sure you support the float post when driving out the pin or the post may snap off - check the archives for more details on this.

[superdave]

I think I've found a stock airbox for my bike. It is considerably less expensive than buying a Dynojet kit and putting things back to stock just seems like it will probably be a lot less dicking around with things.

I guess what I'm wondering is if going that direction vs finding the jets to make my bike work with the pods that came with it means that I would be missing out on a few horses or better economy or something?

I'll bet that finding bigger jets to work with the pods won't help fuel economy, but how about horsepower? Will I end up with a few more if I can get the pods and bigger jets to work?

[BassCliff]

Hi,

Maybe I'm a lazy old fuddy-duddy, but the measly few horses that you might gain aren't nearly worth the hassles and headaches of fiddling around with your carbs every other day until you, hopefully, get it dialed in properly. Don't get me wrong, there are many here who can perform this voodoo magic and get their bikes to run great. But it's just not for me. Feel free to experiment but I can almost guarantee that the outcome will not be worth the effort.

I could see attempting it on a liter bike or larger because then the "wow" factor would be greater. But on a 30 year old 650cc bike, I don't see much "wow" factor available.


Thank you for your indulgence,

BassCliff

[themess]

Hi,

Maybe I'm a lazy old fuddy-duddy, but the measly few horses that you might gain aren't nearly worth the hassles and headaches of fiddling around with your carbs every other day until you, hopefully, get it dialed in properly. Don't get me wrong, there are many here who can perform this voodoo magic and get their bikes to run great. But it's just not for me. Feel free to experiment but I can almost guarantee that the outcome will not be worth the effort.

I could see attempting it on a liter bike or larger because then the "wow" factor would be greater. But on a 30 year old 650cc bike, I don't see much "wow" factor available.


Thank you for your indulgence,

BassCliff

From what he describes, it is exactly what he needs - unfortunately. I rode a GS650G for 15 years, and never touched the carbs. It would pull in any gear from less than 2000 rpm to redline without a stutter or any hesitation. Throttle response was like that of a DC motor controlled by a rheostat. It had enough torque to raise the front wheel from torque alone, at 30 mph. It had throttle left at 110 - 115 mph, and didn't hesitate to accelerate at that speed. It used fuel frugally. In other words, there is a lot of performance to be wrung out of those by getting it back to 100% stock tuning.

One other thing, Superdave writes about the slides on his carbs. Stock carbs on a GS650G or GL are BS32s, and those don't have slides. Perhaps Superdave should get a stock airbox and BS32s before working on tuning.

[superdave]

From what he describes, it is exactly what he needs - unfortunately. I rode a GS650G for 15 years, and never touched the carbs. It would pull in any gear from less than 2000 rpm to redline without a stutter or any hesitation. Throttle response was like that of a DC motor controlled by a rheostat. It had enough torque to raise the front wheel from torque alone, at 30 mph. It had throttle left at 110 - 115 mph, and didn't hesitate to accelerate at that speed. It used fuel frugally. In other words, there is a lot of performance to be wrung out of those by getting it back to 100% stock tuning.

One other thing, Superdave writes about the slides on his carbs. Stock carbs on a GS650G or GL are BS32s, and those don't have slides. Perhaps Superdave should get a stock airbox and BS32s before working on tuning.

I fully admit that I am the new kid here and don't want to doubt expert advice but the carbs on my bike (and the identical parts bike) look just like the ones in the manual I bought for the bike, and nothing like the image results that came up when I googled "mikuni bs32 carbs." And the pic in the manual shows "slides" as part of the diaphragm assembly. Though maybe we are calling the same thing two different names?

Anyway, tonight I installed new boot o-rings and bolts as well as non-separated boots. (I guess the silly-cone didn't do too much before on the old ones...)

*Warning* You may think I'm crazy here... I ordered an airbox off ebay, but all day had been thinking about how you all say that part of the problem is that the airbox creates a bit of a restriction and the pods make things too lean... So I thought, "what if I create a bit of a restriction...?" So I covered each pod with a sock!

And voila! The bike is now ride-able! Of course I will install the airbox as soon as it arrives, but this totally makes me feel a bit better about ordering the aribox and the prospects of being able to really ride and enjoy the bike!

It really rode very smoothly and pulled well and seemed to have real nice acceleration. Anyway, it is much better than before.

[themess]

Nice diagnosis, and sock-analysis.

What manual are you using that shows "slides" in the carbs? I bought my 650 new, and have the factory manual for it. Definitely B32Ses.

That being said, some people switch carbs to improve performance under some conditions. That might have been the previous owner's intention. If you can get the bike running well without finding B32Ses and replacing the present carbs, more power to you. If not, there are lots of B32Ses out there. GS850s use them, too, but I think that they have larger jets.

[BassCliff]

Hi,

Yes, nice work. I guess now you know that there is too much air in the system. So either bigger jets or a stock airbox should fix you up.

Here's a picture from the Carb Cleanup Series for the Mikuni BS32SS (CV) carbs:




Thank you for your indulgence,

BassCliff

[chuck hahn]

AND lets not forget that CV carbs need a bit of CONSTANT VELOCITY air to accuate the diaphrams that operate the slides..PODS that are made WITHOUT built in VELOCITY stacks dont provide the VELOCITY that is required to opertae a VELOCITY designed carb such as VELOCITY carbs..Did i mention VELOCITY enough times to make any light bulbs go off???

[superdave]

Hi,

Yes, nice work. I guess now you know that there is too much air in the system. So either bigger jets or a stock airbox should fix you up.

Here's a picture from the Carb Cleanup Series for the Mikuni BS32SS (CV) carbs:




Thank you for your indulgence,

BassCliff

The manual I am talking about is the Clymer manual for GS650s from 1981-1983. Mine's an '82. Not sure what year "themess" had.

But the ones in this pic also look like the ones on my bike(s) and the part labeled "slide" in the pic is the same thing in the manual. So it appears that we were indeed calling the same thing two different names.

I have a stock airbox somewhere between Ebay and here, but the fact that it rode so well last night makes me confident enough to drop the cash for new tires so I can more safely ride it longer distances.

[koolaid_kid]

In the olden days (pre-CV) the slide had no diaphram, just the slide that, well, slid, up and down to control air and fuel. The throttle cable directly controlled the slide position in the carburetor.
With the advent of CV carbs, the name stuck, even though it is now more complicated than that. A rose by any other name...
AFA keeping your current jetting, as long as you are happy with it and your plugs read OK, you should be fine. Just be aware that the addition of the socks has cut down on the amount of air entering the carbs, which means you are jetted too lean to truly take advantage of the added air you gain with pods. Which means, in a round about way, that you are giving up a few horsepower. Not a big deal IMHO, but just wanted to point that out.

[Dave8338]

From what he describes, it is exactly what he needs - unfortunately. I rode a GS650G for 15 years, and never touched the carbs. It would pull in any gear from less than 2000 rpm to redline without a stutter or any hesitation. Throttle response was like that of a DC motor controlled by a rheostat. It had enough torque to raise the front wheel from torque alone, at 30 mph. It had throttle left at 110 - 115 mph, and didn't hesitate to accelerate at that speed. It used fuel frugally. In other words, there is a lot of performance to be wrung out of those by getting it back to 100% stock tuning.

Yep...that sounds about right, to me.

I rarely ever down shift while cornering, just not needed and it is a blast to feel that much torque from such limited displacement. You expect it from the litre bikes, not from a 650 (667cc IRRC)

[superdave]

In the olden days (pre-CV) the slide had no diaphram, just the slide that, well, slid, up and down to control air and fuel. The throttle cable directly controlled the slide position in the carburetor.
With the advent of CV carbs, the name stuck, even though it is now more complicated than that. A rose by any other name...
AFA keeping your current jetting, as long as you are happy with it and your plugs read OK, you should be fine. Just be aware that the addition of the socks has cut down on the amount of air entering the carbs, which means you are jetted too lean to truly take advantage of the added air you gain with pods. Which means, in a round about way, that you are giving up a few horsepower. Not a big deal IMHO, but just wanted to point that out.

Thanks Koolaid, that seems to help clear up our miscommunication.

I know that the socks provide a little less air, but that was the point! I was trying to simulate having the factory air filter in there, as being able to ride the bike and not messing with jets is more important to me at this point than having a couple horsepower. The airbox is hopefully on the way so I hope be able to install it soon! (And have my socks back!)