1982 Seca XJ750, ZRX1200 has company now.

[bikerphil]

I have tried to get a hold of Yahman about a year ago with no luck. My friend bought a Yahman YICS tool back in '18 for one of his XJ's and he leaves the tool installed all the time. He wanted another for his second XJ. I think they would be pretty easy to copy, not much to it.

[Bonz]

Most of you guys here won't know CaptainZap. He was a guru, lived north of me in denver. He got me to my first XS11 rally in 2011 out in Durango. He ran the tool in his 80G full-time as well. Going to that rally was the Genesis of the Colorado rally I started in 2014. Unfortunately there's only so much room on the ride and the command central location, however looks like 16 bikes this year. It's the old guard, guys that have been doing this since the beginning with me in 2014.

[Bonz]

Getting back to the Seca 750 as the summer progresses. Three and a half weeks to go on summer break before the ankle biters start showing up again.

Valves... one intake and one exhaust are way tight, IMO. As in .004" #2 exhaust (.006-.008 spec) and .002" #4 intake (.004-.006 spec).

As JeffH said to me recently, hopefully some adjustments start making logical outcomes. Nothing has produced the solution. Specifically #2 not firing at idle, and then fire intermittently as RPM increases. Something I haven't mentioned, #4 runs hot at idle via the IR thermometer reading. Maybe there's something in the tight intake valve on that cylinder, as again, logical adjustments/solutions have not given logical outcomes so far.

Motorcycle shops are closed on Mondays, as they probably are everywhere else. Will make the rounds to a couple local shops tomorrow and swap a few shims with them.

Hopefully tomorrow I'll be able to check this off as a solution or just another step in the process.

Fwiw, used the "zip tie" method (but used a bent piece of 12 ga coated wire) to hold the valves open to pull the shims on all buckets (whether needing adjustment or not) to note sizes after taking measurements. Felt better using the wire as I was neurotic a zip tie could break and be a pain to get out.

For pulling the shims, used a small flat blade screwdriver in the bucket cut out, pried the shim up just a little bit, keeping the screwdriver in the small gap. Put a small squirt of brake cleaner into the gap, pushed the shim back down then repeated once or twice, and the shim popped right out with the screwdriver. I had ordered a dental cleaning kit with a pick and plaque scraper from Amazon for 6 bucks but after using it on the first shim, the method evolved to just using the screwdriver and it was easy peasy.

[cajun31]

I just did a search on Ebay for a set of carbs for your bike and there are several listings available. Saw one set for $99.00.

[Bonz]

The carburetors are not the issue. I've done enough of them to know when they've been cleaned thoroughly, with all candor. They have been taken apart and ultrasonically cleaned and put back together basically new. It's not them.

[bikerphil]

Does the bike still have the OEM 40 year old coils on it? That could cause an intermittent firing issue. They can become weak and not be able to fire both plugs simultaneously. I'm assuming it's a wasted spark system.

[Bonz]

Good timing on asking that question... It is a wasted Spark system. I swapped the wires on #2 and #3 early on in the process as the first change besides new plugs which are a given. Made no difference. #2 was not igniting at idle and intermittenttly would run at higher RPM as has been shared.

Put in a new ebay coil on 2 and 3, the exact issue remained. After a couple rides with the intermittent firing, that coil gave up the ghost entirely. 2 and 3 went silent. A resistance check showed 75,000 Ohms on the secondary circuit, lol. Anyway, returned those pieces of lovable junk.

In the process of attempting to take the wires out of the 2/3 OEM coil to trim them back, thinking that might be part of the issue, I did not realize they don't do that easily. So the OEM 2/3 coil is not going to be used again, thus the ebay coil.

1/4 coil is OEM, however no issues.

Back to the good timing part from the beginning of the post... A new coil literally arrived from Mike's XS today. When the shims for the valves arrive later this week I'll get it buttoned up and the new coil installed.

As well, I have checked resistance on the TCI and the pickup, everything is right there in spec. Picked up a used TCI, swapped it in and the same issue remained before the 2/3 coil went out as described above.

[Radioguylogs]

Doesn't it seem that if #3 is has spark, then #2 has spark? (unless #2 plug is shorted)

[Bonz]

Spark is not the problem with the changes and swap outs I've done to rule that out. A tight valve is not talked about as being a cause of the issue the bike is having, but it absolutely can. Valves need adjusting anyway, .004 is an extremely tight exhaust valve on number two, IMO. When spec is .006 to .008.

[cajun31]

The carburetors are not the issue. I've done enough of them to know when they've been cleaned thoroughly, with all candor. They have been taken apart and ultrasonically cleaned and put back together basically new. It's not them.

Sorry for the confusion. I wasn't posting about carbs available because of your current problem. Way earlier in this thread you mentioned that one of your carbs is from a 650 so I posted thinking you might be interested in a complete set. Of course you also posted that you found a box with carb parts and bodies so my post may well be irrelevant anyway.