'85 GS550L bogs at 5,000 RPM

[GSJim69]

Got the bike on the road a couple of weeks ago and I am trying to work out the bugs as I find them.
I noticed that once I reach 5,000 RPM the bike starts bogging down and accelerates very slowly to not at all. I noticed that if I open the throttle more it bogs down even more, release it a little and it improves a little. Another symptom possibly related is the gas milage. I currently get 33MPG, This is below what I expected.
The bike starts fine, idles fine and runs good until 5,000 RPM.
I suspect that the carbs need cleaned, something I would rather wait until winter to do.
Is there any other items that I should check before cleaning the carbs that could cause this?

[Dave8338]

Leaking intake O-rings. Where does your bike idle once warmed up? It should stay right at that 1000-1100 RPM range. Could be (since it hits the wall at 5000) the main jet circuit as it transitions from one to another.

[GSJim69]

I checked to see if I could find an intake boot leak by spraying WD-40 around the boot and watching for an RPM change. I could not notice a change.
Any other ideas?

[chef1366]

Check the ignition. Igniter to be exact.

Are the main jets clogged
Are the slides lifting?

[dewayne egerton]

same prob

i have the same prob on the same bike. please let me know what you find out and will do the same if i do.




dewayne

[dewayne egerton]

try this

one of the guys on here told me to try the choke when the bike starts to bog down. this fixed the bogging down, but not sure what to do to fix the prob yet. hope this helps and if it does help you and you know how to fix. please let me know too.


dewayne

[Steve]

one of the guys on here told me to try the choke when the bike starts to bog down. this fixed the bogging down, but not sure what to do to fix the prob yet.

If applying the 'choke' seems to help it run better, that is a sign tht it's running lean. Cleaning the carbs would be the first step. While you have the carbs off, change the intake boot o-rings, if you have them. If the problem is still not corrected, you might have to change to larger jets.

Are your intake and exhaust stock or modified? If stock, a good cleaning and tuning should work. If modified, a re-jet is in order.

.

[GSJim69]

Everything is stock. I will try adding choke when it starts to bog down and see what it does.
This is the kind of trouble shooting tips I was looking for. Before I tear the carbs down I want to make sure that they need it.

[GSJim69]

Just had another thought. Could a weak battery cause this problem?
I had a bad R/R that was overcharging that may have taken a toll on the battery. Could this have anything to do with this problem?

[GSJim69]

Carb cleaning and stripped air screw and pilot jet

After checking every thing else that I could, I have removed the carbs for cleaning. My bike has the two twin carbs.
I am pretty sure that I have found the problem. The slides on one of the carbs did not slide freely. They would move but they needed lots of gentle help.
On the first carb the air screw was stripped by someone before me. I tried an easy out and ended up breaking it off in it.
I then grabbed a spare carb I have and started the cleaning procedure on it. Everything went smooth on disassembly except I stripped one of the pilot jets.
Do the pilot jets have to be removed for cleaning or should I drill it out?

Also, any suggestions on identifying the man jet size?
I had a brain fart and did not identify them when I removed them from the first carb.

[hikermikem]

Also, any suggestions on identifying the man jet size?
I had a brain fart and did not identify them when I removed them from the first carb.

I on't remember the exact sizes off the top of my head, but i believe #1 & #4 mains are different from #2 & #3.

My suggestion is to go up one size on each (assuming completely stock bike) when you find out what the OEM sizes are. That model runs VERY lean.

[GQROD]

You can download the manual it will have the jet sizes in there for your year, also these bikes do run lean so you may have to go up one or two sizes on all your jets and do plug chops as you already know.

Clean it with berryman's chem dip and take out all the jets, extract them and buy new ones they are cheap so just replace them.

Also order new o-rings for the carbs from www.cycleorings.com and replace choke cable plastic plug o-rings, be careful putting these back on the threads strip very easily!!!!!!

There is a site for us with teh twin carbs and members there have gone through this so we can help with the tuning questions, i have a 1983 GS550E that i just got back on the road with help from this sites members and from those on the site for us with twin carb gs's.

PM sent,

Hope this helps.

[GSJim69]

Final Fix

Just to follow up with information to help others in my position (future searches).

The final fix for this bogging problem was adjusting the needle height. It was actually running to rich. I lowered the needles to correct the problem.

[hikermikem]

After checking every thing else that I could, I have removed the carbs for cleaning. My bike has the two twin carbs.
I am pretty sure that I have found the problem. The slides on one of the carbs did not slide freely. They would move but they needed lots of gentle help.
On the first carb the air screw was stripped by someone before me. I tried an easy out and ended up breaking it off in it.
I then grabbed a spare carb I have and started the cleaning procedure on it. Everything went smooth on disassembly except I stripped one of the pilot jets.
Do the pilot jets have to be removed for cleaning or should I drill it out?

Also, any suggestions on identifying the man jet size?
I had a brain fart and did not identify them when I removed them from the first carb.

I have the same bike:

1 & 4 mains - 95
3 & 4 mains - 105

The stock carb runs very lean, I was thinking that next time I would bump the mains up a size each.

Good luck,

mike

[hikermikem]

Guess I should check the post dates!!