1982 550 LTD #2 cylinder issue

I did just visually watch the timing advancer move. I didn't take it out or time it with a light.

As for a jet issue, I doubt it. They are spotless. Choke circuit is operating fine too because I was inspecting it the last time I had the carbs off.

I was just thinking that my slides may be goofed up since I'm not even hitting the adjustment screw that limits the maximum throttle openeing. Maybe one of them is going so far up there it's allowing air in or messing with the vaccum?

I will re-check compression, but 1,3&4 have about 150 psi and #2 (the cylinder I holed last year had ~130, but it was increasing everytime I checked it. Figured this was normal because it had new rings, hone and valve seats cut and things were wearing into place and seating better)

Does it feel like a lean fuel starvation, or a miss? Do you have a in-line fuel filter that's able to flow the volume needed for your bike? Have you checked that the in-tank screen is clean, and the petcock is flowing enough fuel?
Good spark quality is extremely important! All of the previous suggestions check out? Bad wires/ Caps/ Coil?
Missing screw should be replaced so throttle reaches WOT and no further.

I would say fuel starvation, but it does it right from the get go and does it at the same throttle position EVERY time. I can have the throttle at 65% open for 4 min with no issues, I just try and blip the throttle from 65% to 75%, it immediately does it.

I will verify these other recommendations. I will also inspect how far the slides are actually being openned when it gets to WOT. The screw isn't missing, it's just adjusted short. I have a feeling when I took these completely apart to lemon bathe them that I mixed some parts around or didn't get them exactly back to adjustment like they were when they came apart.

apbling wrote:

...thinking that my slides...not even hitting the adjustment screw that limits the maximum throttle opening. Maybe one of them is going so far up there it's allowing air in or messing with the vacuum?

I will re-check compression, but 1,3&4 have about 150 psi and #2 (the cylinder I holed last year had ~130, but it was increasing every time I checked it. Figured this was normal because it had new rings, hone and valve seats cut and things were wearing into place and seating better)

I don't suspect an issue related to throttle slides, especially after having done the bench sync.

Compression test alone isn't enough.
Should also check and assure valve clearances to specs.

For good measure, if not already done, would install four brand new spark plugs per factory specs. And, before installing, again visually observe spark quality on plugs with bases grounded against the engine head while spinning over the engine.
Look for healthy blue spark. Not weak orange spark.

Good Fortune!

apbling wrote:

I did just visually watch the timing advancer move. I didn't take it out or time it with a light....

Without a timing light, I see only a blur through the inspection window, regardless of rpm. :lol:

Good Fortune!

I will check the timing and plus/electrical.

I know for a fact that the valves are adjusted properly because I had to adjust them after I had the valve work done on the #2 cylinder.

It just really seems to be carb related because it did not do this before I took all 4 carbs apart.

If the throttle slides go way beyond fully open, the mixture gets rich. I verified this on a wideband o2 sensor. The reason is, the needle raises up and lets in more fuel without any increase in air.

On the tk-22, you can check the full throttle position without taking the carbs off if you have an accurate depth gauge (most measuring calipers have a depth gauge included). Remove on eof the top caps and gasket.

When the slide is 100% open, the distance from the top of the body to the top of the slide is about 11mm (.427"). Set the stop so the slide stops 11mm below the top of the carb.


If your carbs are off the motor, you set the stop so the bottom of the slide is just flush with the roof of the bore on the engine side (not the air filter side!).

This is what I was thinking/hoping might be occuring! I bet one of my slides is way off and actually hitting the top of the caps (or the linkage is hitting the cap) and that cylinder is the one missing. I did throw the vacuum gauges on right before I wrapped things up and 1 & 3 were similar, but 2 had way more vacuum and 4 had more, but not as much at 2. When synching carbs, does lowering the slide increase the vacuum or decrease the vacuum between the motor and carb (where I have the gauges tapped in).

BTW, all the slides are indentical in these carbs, right? I really think this is my issue since throttle response is good all throughout except on the WOT end of things.

Thanks again for the replies!

If not already done, would test ride with petcock in PRI position, to determine whether same problem continues.

If problem persists, unsnap the fuel tank cap, and leave it ajar (not fully closed), while again test riding to determine whether same problem continues.

If problem still persists, continue test riding with petcock in PRI and cap ajar, and while the engine is missing, add a little choke to see whether it improves or worsens performance.

These test rides should at least help rule out possibility of a vacuum related petcock problem, and also help rule out possibility of a fuel tank venting problem, and also help rule out possibility of a mid-range mixture problem.

When re-assembling the carbs, would assure that all jet needle clips are in the middle position, or whatever default position is specified in the FSM which might be one clip position lower (next slot under the middle). A lower clip position enriches mid-range by raising the needle relative to its position inside the needle jet.

Question -- Is one of the exhaust header pipes still failing to instantly vaporize (sizzle) water mist sprayed onto it?

Good Fortune!

I did the prime thing, no change.
Yes, they all idle like a charm now. Everything is A-ok with the carbs, except at WOT throttle or close to it it feels like a miss.
And when I just rev it and quickly close the throttle I get a lot of chatter or poping in the exhaust (which I found gets better once you synch)

The slides are all the same.

If the vacuum was higher in the sync test, then the slide in that carb is actually lower.

Sorry, I don't have any suggestions other than what Patton is already saying.

The only time I've had a miss at WOT-only was when a plug had too large of a gap.

loudhvx wrote:

If the throttle slides go way beyond fully open, the mixture gets rich. I verified this on a wideband o2 sensor. The reason is, the needle raises up and lets in more fuel without any increase in air...set the stop so the bottom of the slide is just flush with the roof of the bore on the engine side....

...the needle raises up and lets in more fuel without any increase in air....

Am leaning something new here, as understanding has been that at WOT the mixture allowed through the needle jet is governed solely by main jet size, with jet needle being then so high as to have negligible effect. In other words, that at WOT the needle jet passes all mixture metered through the main jet, with no restriction by any then remaining skinny part of the jet needle inside the needle jet.

Carried to its extreme, my understanding would mean that at WOT, complete absence of a jet needle wouldn't make any difference in performance, as all fuel allowed (metered) through the main jet would be passing through the needle jet, irrespective of whether some minimal part of the jet needle then remained inside the needle jet at WOT. At which time the carb bore is of course wide open (with no restriction by the throttle slide).

But where interface between jet needle and needle jet continues to regulate volume of fuel metered through the main jet at WOT, such result seems to conflict with the "general rule" that jet needle governs mixture during mid-range and that main jet does all the governing at WOT.

Dang it! More homework for me. :laugh:

Good Fortune!