5000 rpm "wall" .....

[AJ]

As several have said, the jets won't make fuel pour out of the carb. It's the fuel level system that you need to check

1) You should check to make sure the floats are good. One or more of them may be cracked or saturated and no longer "float" in gasoline.

2) Check the fuel needle valve assembly. Look for scoring or crud on the pointy tip (top) of the needle. Check the little spring plunger on the bottom of the needle (where it contacts the float).

3) Pull the body (seat) of the fuel valve and check the o-ring. Be sure to look for a little filter below the valve seat if your carb has one and make sure it is installed properly when reinstalling the valve seat.

4) Reassemble everything and check the float height per the book.

5) Hook up gas to the carbs and verify one by one that the fuel flow shuts off when you lift the float. If you need more than the lightest pressure on the float, the valve pin or the valve seat is either dirty or damaged.

[jaywelchy]

Understood. Thanks guys. I adjusted the floats to spec when I replaced the pilot jets ... so I guess I made a connection in my head .... wouldnt be the first time I was wrong

So all that aside, I got my O rings in the mail(Thanks Rob!), and new main jets. (I am replacing the main jets due to possibility of a previous owner drilling them out)

Yes, I have a full shop .. due to building an airplane in my garage

Air compressor and the like. Got the tutorial downloaded and ready to print, and got to get some berrymans solvent for the dip.

I forgot to order up the O rings for the intake boot/cylinder head joint ... going to get them too.

CafeKid ... I will hit you up if I need some help.

Jason

[JAMAC1120]

I am a newb to GS's but had the same problem with my 77 GS550 cleaned the carbs myself and still 4000-5000 rpm it lost it. when i hooked up a vacume sync. it read late valve timing or intake manfold leak. after inspection i found i have 4 shims needing replacing and when i get that finished ill let you know if that helped my rpm's or not.

[Suzuki_Don]

Or your cam chain could be off by one tooth. Check valve timing while valve cover is off.

[IanDMacDonald]

Similar Issues!

Fellas-

I had similar issues with my Yammie. I could rev all day in Neutral, but, as soon as I hit the road, I had a rev limit, which in-turn gave me a speed limit of 70mph. This was last summer, and my bike was my only means of transportation at the time. So, I had to drive behind semis so my slow speed would not be noticed.

Anyways, I found out that the problem was a combination of improperly tuned carbs (wrong jet sizes), cracked intake boots, diaphragms that were improperly seated, and aftermarket pod filters that were ill-fitting, causing air restriction to the carbs.

I worked on each one of these issues one at a time, changing the pods lastly. I had this thing running like a raped ape in a cage until the engine seized up on me due to a couple factors.

Timing should definitely be ruled out as a factor. If your marks match up, that's one less thing you gotta worry about. Checking your valve clearances in another biggie!

My Yammie and GS will be my wintertime projects keeping me busy. Thank God for that, as my girlfriend and I just broke up.

Keep us posted.

[jaywelchy]

Or your cam chain could be off by one tooth. Check valve timing while valve cover is off.

So if the timing is off a tooth ... it will start and idle perfectly?? And run out to around 5000 rpm perfectly??

Funny how I hear these things wont break down and just keep on running. Which is a good thing most of the time .. but leads to abuse and/or lack of maintenance ... which I think is what I am dealing with on this little 550. So many little things ..

It is 30 yrs old too ...

[TheCafeKid]

I'd check the cam timing just to be sure, but in my experience I've never had the timing off a tooth and have it idle worth crap. It sounded bloody horrible.

[Mercaholic]

Is the exhaust completely clear of hidden obstructions

That would be my call too

[jaywelchy]

the exhaust is ... original, and has pin-hole leaks here and there .... I sure replacement wouldnt hurt ... but still think my carb slides arent coming up ... and a complete rebuild is in order ..