Carbs are rebuilt and clean. Coils are brand-new Dynatek, points replaced with electronic ignition. Plug wires are new. Choke plungers rebuilt. New fuel lines, new spark plugs, and a Pingel dual-outlet petcock.I am not trying to turn carbs into fuel injection.At idle, the bike audibly stumbles, and that stumble happens at the same moment the AFR spikes. I don’t know which is the cause and which is the effect.Cylinder #2 shows intermittent pockets of lean AFR. Cylinder #1 does the same thing, but to a lesser degree. These traces are all at idle (~1000 RPM). The issue largely goes away if I raise idle speed to ~1200 RPM.The bike is fully warmed up, but the issue is worse when cold. I don’t believe there are intake or exhaust leaks. Carbs have been synchronized.For reference on the graph:
• Green ≈ 12 AFR
• Red = anything above 14.7 AFRThis puzzle probably has nothing to do with jetting, and I’d prefer not to go down that rabbit hole—but for completeness, here is how it’s currently set up.Dec 20 update (after rebuilding choke plungers):
Everything seems to go lean on throttle snap.

• Cylinder 1:
  (Pilot 10 / Main 100 / Clip 2 / 3 mm)
  Small AFR pops at the same frequency as #2, but much smaller. Otherwise AFR looks good.
• Cylinder 2:
  (Pilot 12.5 / Main 102.5 / Clip 3 / 3 mm)
  Large AFR swings—almost like a backfire, but still within range.
• Cylinder 3:
  (Pilot 10 / Main 105 / Clip 4 / 3 mm)
  Perfect idle.
• Cylinder 4:
  (Pilot 10 / Main 105 / Clip 4 / 3 mm)
  Idle is too rich; pilot screw is almost fully closed.

Looking for insight specifically on the intermittent lean pockets at idle and the synchronized stumble—not general jetting advice.
 

 

The used cylinder head I bought has several leaky valves, I set it off to the side. New exhaust valve installed into the old head, reassembled and put back on the bike.  Valve clearance was loose, intakes all over 0.32mm and exhaust all at 0.50mm or more.  The cam chain is at the edge of the service limit.  New front(it had a 17t) and rear sprockets(39t was on it) installed, new rear tire to replace the oversized one on it.  I removed the swingarm to check the bearings out, they're fine but there was very little grease and the seals are done. I am waiting on parts from Japan because surprise, you can't find them in the USA. 

 
 
 
 
 

 

Fabrication so far has been minimal, shave swing arm to fit, engine mounts for the J motor, brackets for the instrument pods. We did slot the Cam sprockets and make some bushings here and there but all in all it's coming along. I'm happy! 

It you remove the swingarm (a great opportunity to lube the bearings), you can use a homemade punch and the back side of your vice to peen the rivet.  

I do not think the 24s are problemmatic, rather they are 50 year old (almost) tech and the CVKs are more like 20 or so year old tech. Take a look at some of the project bikes displayed here and see newer tech for forks, swing arms, tires, shocks and  breaks etc that are done on these old machines to increase (at least that is the thought) the ride, and aid in overcoming any of the shortcomings of the older tech. 

I think this will probably be the last of my "tour reports" for this year: today is the last of the pleasant, dry days with sunshine and 13°C for quite some time. Atlantic low pressure systems will dominate the next few days or even weeks here; that always means a lot of rain and no riding weather for me, and autumn is in full swing with nighttime temperatures near freezing... This brings my bike season to an end here for this year.




Here are a few more pictures from this later morning. I rode a short distance on the Z1000 after it had warmed up from 3°C to about 12°C. A few impressions of my area, and four bridges out of many here in and around Hamburg...( Hamburg have about 2500 Bridges, the town with the most bridges in whole Europe, and more than Venice

Next year, starting March 1st (if all continues for me to go well!), I'll be reporting back here!

And of course, i like to see and read maybe some pictures and reports from you all here...!

 
 

Wookie58 wrote:

daveo wrote:

Bozo wrote:

Assuming this might be the same problem as yours. The way to check is use a video scope to check if the intake/ exhaust valve is oiled up (see my previous scope photo).

I was lucky, I had a hose made for another job. make sure the piston is down as the air will push it down, unless the air drops completely there should no be any problem.

Remember my problem was obvious i.e smoke on de acceleration, it could still be another issue.


 

I'm surprised that the hose typically provided with compression gauge kits has the proper end fittings needed for this purpose.

What was your #1 spark plug condition compared to the other three?

With the clutch engaged, will it work to lock the engine's forward rotation in-position (slightly beyond TDC) with a block of wood placed between a wheel spoke and the swingarm?


 

Yes but the cams will be removed at this stage and when the engine tries to rotate you will need to ensure it doesn't "snag" the cam chain on the crank !!
 

Sounds like a plan!

😉

Bozo wrote:

Assuming this might be the same problem as yours. The way to check is use a video scope to check if the intake/ exhaust valve is oiled up (see my previous scope photo).

I was lucky, I had a hose made for another job. make sure the piston is down as the air will push it down, unless the air drops completely there should no be any problem.

Remember my problem was obvious i.e smoke on de acceleration, it could still be another issue.
 

I'm surprised that the hose typically provided with compression gauge kits has the proper end fittings needed for this purpose.

What was your #1 spark plug condition compared to the other three?

With the clutch engaged, will it work to lock the engine's forward rotation in-position (slightly beyond TDC) with a block of wood placed between a wheel spoke and the swingarm?
 

When the wheel is straight ahead, the handlebars are turned somewhat left. In this position there is only 1 finger space between the stopper on the back of the steering stem  and the post/stopper below the headset, and twice that amount on the right side. So the front wheel will only turn partway to the left before the stop engages.  The whole fork-wheel assembly appears twisted rather than bent, I can't see a definite bend in any specific component but the right fork may be bent.  This linked post states the only reason this can happen is if the fork stanchion is bent. I've seen other posts referring to bent triples with similar outcomes kzrider.com/forum/5-chassis/618992-front-end-alignment#885462

I don't see a problem with replacing forks and triple Ts if needed, but it won't happen right away.  Short term project becomes long-term project.

But I need to make 100% sure the frame isn't badly bent, because there is nobody who straightens frames around here.  I noticed what looks like some deformation on the opposite side from the crack, a barely measurable swelling (nothing like the other side) and a possible bend or bulge outward. I need to come up with a better way to measure things because stuff like engine covers get in the way of accurate measuring. Think I may make something out of wood or make a large caliper out of a large wood clamp.  

Edit: made a giant shallow u-shaped measuring board out of plywood and measured the frame, swing arm pivot to multiple points on the engine mounts, front of frame, etc. Everything is equal on both sides so far, but can't be too careful. Will double and triple check it but looking good.