Seems to bog at sustained speeds

[justme1100]

First I want to let it be known I have been scouring threads to see about finding something similar to my issue with little luck. 82 XJ K&N Pods (cleaned and freshly oiled), new inline fine filters, NO OCTY and clean in tank filters. No fuel restrictions that I have found in delivery. I've not had any carb problems since they were cleaned, synced and the delete installed. This bike ran great with two up and loaded UNTIL I got caught in the rain in late June. Was acting like a cylinder was cutting out but ??? no signs of which one. I pulled carbs and found crap in the bowls and internal screens, cleaned all the best I could. The bike always fires up immediately, low speed no problems but as soon as I am cruising at 55-65 mph at around 3500 rpm, I have a 750 final, it seems to lose power and sounds louder, go figure. If I keep it at just below 3500 rpms (57-58 mph) it seems better. Higher RPMs don't seem to suffer much, 65-75 mph but rarely am I going that fast as we mainly stay on the two lanes. I am going to install some very low milage stock coils I acquired and re check the pick up wires. I have not done the fancy involved bench testing of the carbs but floats seem to be oh so close to what they should be. The plugs are a bit sooty, I need to deal with my valves this winter, but new and look good after 350 miles. One was a bit whiter then the rest even though I seem to be a tad rich. My weak spot is my carb knowledge. I am just fishing for thoughts and am open to any suggestions.

[JeffH]

This bike ran great with two up and loaded UNTIL I got caught in the rain in late June. Was acting like a cylinder was cutting out but ??? no signs of which one.

I pulled carbs and found crap in the bowls and internal screens, cleaned all the best I could.

but as soon as I am cruising at 55-65 mph at around 3500 rpm, I have a 750 final, it seems to lose power and sounds louder, go figure. If I keep it at just below 3500 rpms (57-58 mph) it seems better. Higher RPMs don't seem to suffer much, 65-75 mph but rarely am I going that fast as we mainly stay on the two lanes.

m to be a tad rich. My weak spot is my carb knowledge. I am just fishing for thoughts and am open to any suggestions.

Not sure but just a few thoughts

Seems to possibly be a couple things going on. All common problems most have had to deal with.
The crap you found in the bowls and screens could easily have continued up and clogged the pilot jets to some extent. You cleaned the bowls but apparently haven't yet pulled out the pilot jets to inspect and clean. Only takes a speck of crud to clog those tiny holes or restrict the fuel flow. Maybe even a complete carb clean is in order if it has been awhile. BTDT, fuel filters looked ok but had gritty stuff in bowls which plugged up the tips of two of the pilot jets.

That 3,500 rpm and loose power sounds like a classic broken pickup coil wire.
Wire making contact until advancer starts to advance which changes the arc of the wire until the connection fails where the wire is broken. BTDT exactly as you described. I found a broken pickup coil wire and another one with about 4 strands from breaking.


As for the cylinder cutting out riding in the rain or after riding in the rain that's another issue. Coils or plug wires or plug caps grounding out from the water. Guess you are trying some different coils & plug wires so likely that will solve that problem. Also a BTDT before replacing the nasty old OEM coils with some new Dyna's and plug wires. zoom-zoom heavy rain and now bike runs fantastic

Anyway, I'm seeing maybe a couple different things going on based on your description of the problems you have been having.

Good Luck. I'm sure one of the guru's will provide some good insight for you.

Jeff

[motoman]

As Jeff stated, pilot jets ARE restricted. Metering hole in them is even too small to insert a point of a needle through. Inspect them internally using a magnifying glass. Internally, they are tapered outward and once a teeny tiny piece of debree gets in them, it can't get out unless pilot jets are removed and cleaned out from bottom side. Other issue is fuel bowl fuel levels are NOT correct. This HAS to be checked with bike at idle with a clear hose slipped on fuel bowl drain and held up along side each carb.Fuel level NEEDS to be 3mm down from carb base casting....at an idle. 81 and XJ carbs fuel level HAS to be checked this way as per Yamaha shop dealership manual. Highly important that all four carb fuel levels HAVE to be identical at 3mm.....if you intend for all four cyls. to be doing the same "work". Float levels WILL have to be changed accordingly to get all four fuel bowls at same levels. Float settings themselves being the same WILL NOT give the same fuel levels of all four carbs. After getting this portion correct, you WILL have to reset idle mixtures of ALL four carbs and re-sync. them.

[skids]

Not sure but just a few thoughts
You cleaned the bowls but apparently haven't yet pulled out the pilot jets to inspect and clean. Only takes a speck of crud to clog those tiny holes or restrict the fuel flow. Jeff

Well, pilot circuit might be bad, but troubles are above 3500rpm?

That 3,500 rpm and loose power sounds like a classic broken pickup coil wire.
Wire making contact until advancer starts to advance which changes the arc of the wire until the connection fails where the wire is broken. BTDT exactly as you described. I found a broken pickup coil wire and another one with about 4 strands from breaking. Jeff

Very true. Also, strange things can happen with a worn-out exhaust baffle. It can be an rpm range trouble.

As for the cylinder cutting out riding in the rain or after riding in the rain that's another issue. Coils or plug wires or plug caps grounding out from the water. (snip) Dyna's and plug wires. zoom-zoom heavy rain and now bike runs fantastic[/I] Jeff

Dynas certainly helped my crappy running in the rain. Also there are reported issues with the neutral switch circuit due to a short in the loom that goes to the pick-up coils and switch. There is a splice in there that foulss in the rain.

[BillyRok]

I don't think a broken pick up coil wire is your problem with that XJ, at least not the same way a broken wire can cause issues with the XS models. I'm pretty certain the timing plate on the XJ is stationary, unique to the XJ. The timing is advanced via a vacuum pressure sensor unit just in front of the regulator/rectifier, underneath the fuel tank. The sensor measures vacuum at the intake and sends voltage to the TCI to advance the timing.

[justme1100]

I'm gonna lean towards an electrical issue aka pick-up wires and/or coil for now. I just don't see the carbs, floats and/or a plugged orifice changing mid ride, but I'm not ruling it out yet. I just hate to mess with what was working wonderfully. It does seem to manifest after I've been riding awhile so everything is quite warm. I only have maybe 2-3 months left to ride then I'll get to some much needed maintenance and attention. Thanks, I'll keep this going until I have cured my issue.

[BA80]

Anything like this!

https://youtu.be/BLbZXaFoWlU

[justme1100]

https://youtu.be/BLbZXaFoWlU

Thank the Bike Gods NO. Its been suggested that it could be issue with the transition happening at the RPMs I am maintaining because if I accelerate I don't notice anything odd. The problem seems to be occurring at 60mph give or take a mph so about 3500 rpm. Now I am trying different coils before I spend any $$$ on the GREENs. I thought about it and seems to occur when I have been on the road a while. So I am still at it. Replacing some sketchy wires and going through connections.

[justme1100]

I don't think a broken pick up coil wire is your problem with that XJ, at least not the same way a broken wire can cause issues with the XS models. I'm pretty certain the timing plate on the XJ is stationary, unique to the XJ. The timing is advanced via a vacuum pressure sensor unit just in front of the regulator/rectifier, underneath the fuel tank. The sensor measures vacuum at the intake and sends voltage to the TCI to advance the timing.

Correct, but I did find a rather crispy wire cover and the wires inside have been retired and replaced this something that will outlast the bike to be on the safe side. I got a friend in injection molding and the wires are for mold heaters, stainless wrapped.

[DiverRay]

If you are bogging at one speed, I would take a second look at the carb sync. Classic sign of one carb being "off" a little, and bringing down the bike. A set of gauges for vacuum and 20 minutes is all it should take.

[justme1100]

UPDATE: Dang Nabit stripped a bolt hole

New (spare) coils installed, new wire to pick-ups (just cuz the old ones was ugly), cleaned numerous electrical connecters and cleaned out pilot jets because two looked restricted with dust. Found minute particles, of only Budda knows what, in the float bowls once again. I have stone filters and wonder if "stuff" is getting through. Hmmm, search is on for better SMALL in-line filters. Never had issues with them and been using them a looong time. NO, not the same ones but the same style. Now during some adjustments I stripped the bolt hole out of the clutch handle bracket. Well I wanted to replace with one off a standard anyway. As soon as this is repaired I'm going for a ride and report back. Thanks all

[BA80]

If you are running black rubber fuel line the debris in your carbs may be stuff flaking off inside those. Tygon works best.