Topic: only one notch left...

[hymodyne]

morning,

After replacing a disintegrated intake valve spring with a spare I now have four cylinders firing on my 500/4!

While riding, I noticed that there was some hesitation and a lack of quick response to my throttle commands. The bike accelerates quickly through gears 1-3, with rpms topping out about 6-7k. In the Higher gears, the engine bogs and searches, revving more cleanly only after I back off the throttle slightly.  A mechanic suggested that the engine sounds like its running lean, so I'm adjusting the clip setting on the main needle (the long one inside the plunger in each throttle body).  As I posted a couple of months ago, the bike has carbs from a 550 on it, and since then I've replaced the head which was full of stuck valves with a spare from a '76 550 as well. I've ditched the pods and gone back to the stock airbox, but I still have a 4-1 system with a Keag canister.

now, I only have one notch left for adjustment of my main needle available to increase the flow of fuel.


I'm going to make the adjustment and see how it runs. If this doesn't do it, what are my options? How do you select new Needles? these needles are numbered D26. what others can be bought for these carbs?

hym
 

[hymodyne]

an update...

adjustments made, the bike accelerates and holds speed much better. there are still some issues with the setting of the air mix screws, but different adjustments and trips to test them should work that out. what a difference a millimeter makes!

hym

hym

[TwoTired]

While riding, I noticed that there was some hesitation and a lack of quick response to my throttle commands. The bike accelerates quickly through gears 1-3, with rpms topping out about 6-7k. In the Higher gears, the engine bogs and searches, revving more cleanly only after I back off the throttle slightly.  A mechanic suggested that the engine sounds like its running lean, so I'm adjusting the clip setting on the main needle (the long one inside the plunger in each throttle body). 
I'm going to make the adjustment and see how it runs. If this doesn't do it, what are my options? How do you select new Needles? these needles are numbered D26. what others can be bought for these carbs?

I can't imagine rejetting carbs without reading the plugs for combustion conditions.  If you are running lean it should show on the spark plugs.  I would use that as a basis for jetting/mixture changes rather than sound.
Have you looked at the plug deposits?
Is the the RPM limit a recent event since the valve repair?  Or, did it exist before?

There are two other needle profiles found in this carb type.  If yours have the 022A setup stamp common to the CB550K, then finding carbs with the 627B, or 069A will give you needles with 2 other profiles.

Some rebuild kits (K&L, or is it Keyster, I forget) supply needles and specify the carb setup they apply to.  I cannot vouch for their accuracy, though.
Cheers,

[hymodyne]

evening,

after a ride of about 25 miles, I looked at my plugs. light brown deposits. during the ride I still had issues with uneven running as I accelerated. when I opened the throttle, the engine bogged and would only accelerate normally if I either downshifted and accelerated or backed off the throttle and slowly edged my speed up.

air mix needles are set at one full turn out.

any suggestions on further tuning would be appreciated,

hym