Bogging question

[Surfpilot]

Hey guys I need a little help:
My bike's been bogging around 1/2 throttle (or so). It's generally between 4-5k RPM and then it seems to smooth out. Recently I took off the air filter and rode for several miles, and it didn't seem to bog-down nearly as much, or even at all. I just put in a new UNI filter the other day, and it's back to bogging. The weird thing is, I know that I'm running rich. Fuel consumption has been as high as 25mpg. I attributed this to a dirty air filter...but even with a new clean one I'm bogging (I haven't taken a reading on fuel consumption yet).

What should I do? I was thinking maybe re-jetting the carbs? I've never done it before...I have a stock exhaust (which has been popping alot). Am I on the right track? Any help would be great.

 

[Guest]

Assuming the airbox is in good condition. First thing I would do is clean(rebuild) the carbs with the stock jets and replace the intake O-rings.

Factory exhaust?

 

[Surfpilot]

Assuming the airbox is in good condition. First thing I would do is clean(rebuild) the carbs with the stock jets and replace the intake O-rings.

Factory exhaust?

I recently rebuilt the carbs and replaced ihe intake o-rings.. I began experiencinging the bogging afterwards. The airbox is in decent condition and is clean.

 

[piester]

check an make sure that the airbox is actually sealed. use some weather stripping if need be

 

[Big T]

You're really getting only 25 mpg?

You'd better run the basics for us:

1. Valve adjustment?
2. Carbs synced?
3. Airbox all sealed?

The fact that you have a stock set up (other than the Uni), you're getting 25 mpg instead of 45 and that it runs better without an air filter leads to something very wrong with your carbs.

Run us through your rebuild

 

[Guest]

Float heigth adjusted?
I've had main jets back out and fall into the bowl.
Which plugs read rich?

 

[Dave8338]

If the UNI filter is foam, is it over oiled?

 

[trippivot]

Pull the spark plugs see what they look like.

 

[Surfpilot]

You're really getting only 25 mpg?

You'd better run the basics for us:

1. Valve adjustment?
2. Carbs synced?
3. Airbox all sealed?

The fact that you have a stock set up (other than the Uni), you're getting 25 mpg instead of 45 and that it runs better without an air filter leads to something very wrong with your carbs.

Run us through your rebuild

Valves were adjsuted 2 months ago along with carbs synced and airbox is sealed. The one problem I ran into with the carb rebuild was that the air screws are seized. I tried EVERYTHING. They will not come out. So I have no idea what position the air screws are in.

Just so you know, my carb rebuild consisted of dipping carbs multiple times, followed by spraying and compressed air. All o-rings were replaced(except the airscrews of course). I did neglect to set the float height...could this be the source of my problem??

All plugs read rich before the filter change. I'll pull them again once I have some miles on the new filter.

 

[Surfpilot]

If the UNI filter is foam, is it over oiled?

I don't think so because I have the same problem as before the new UNI foam filter.

 

[JTsGS650]

Sounds like you're bogging due to your rich condition.

Check your float heights and possible sag in needle valve springs.
Confirm proper jets for airbox/exhaust configuration.

Report back.

Good luck.

 

[Surfpilot]

Sounds like you're bogging due to your rich condition.

Check your float heights and possible sag in needle valve springs.
Confirm proper jets for airbox/exhaust configuration.

Report back.

Good luck.

Sounds like I need to check the float heights for sure. I'll do that. How would I determine if there is "sag" in the needle valve springs?

Also, I assume jets are stock since PO did not take care of this machine. I have stock airbox and exhaust. How do I determine jet sizes??? Excuse my ignorance, but I'm new to motorcycle maintenance.

 

[Guest]

Send those carbies to me an I'll get those idle mixture screws out and replace those o-rings.
If you soaked the carbs you messed the o-rings up and it will never run right at the bottom end.

 

[JTsGS650]

Sounds like I need to check the float heights for sure. I'll do that. How would I determine if there is "sag" in the needle valve springs?

Also, I assume jets are stock since PO did not take care of this machine. I have stock airbox and exhaust. How do I determine jet sizes??? Excuse my ignorance, but I'm new to motorcycle maintenance.

The float 'tang' should just contact the top of the needle valve. If the spring in the needle valve compresses at all when the float is resting on the needle valve, it will cause the bike to run rich (ask me how I know). You can try to set the float heights to compensate, but it's easier to replace the needle valves. Replacement needle valves are available at Z1 enterprises.

Most likely, the jets are stock, especially if the bike retains the stock intake/exhaust setup. The jets will have size markings on them and you can compare them to the stock jet sizes in your manual or in the sticky at the beginning of the Tech forum.

However, if you soaked the carbs with the mixture screws still in place...

Send those carbies to me an I'll get those idle mixture screws out and replace those o-rings.
If you soaked the carbs you messed the o-rings up and it will never run right at the bottom end.

Chef's right. I'd take him up on his offer.

 

[Surfpilot]

Send those carbies to me an I'll get those idle mixture screws out and replace those o-rings.
If you soaked the carbs you messed the o-rings up and it will never run right at the bottom end.

Chef, I might take you up on that, but I need a little time. Unfortunately, the moto is my main transportation. I'll try to find a gap in my schedule when I can get them to you. I'll be in touch.

 

[Guest]

Chef, I might take you up on that, but I need a little time. Unfortunately, the moto is my main transportation. I'll try to find a gap in my schedule when I can get them to you. I'll be in touch.

I'm in Santa Barbara all the time. We can plan it out.

 

[Surfpilot]

I finally got around to pulling the carbs today and found the problem. The main jet on the #3 carb had worked it's way out and was just sitting in the bowl! I screwed it back in, and problem solved. No more bogging. Hopefully this solves my poor fuel consumption--I assume it will. Not sure how the main jet could unscrew itself...