1982 Seca XJ750, ZRX1200 has company now.

[Bonz]

Thanks for posting up. You are correct. Went down to smaller pilots, brand new from Jets R Us yet number two was not coming online until the throttle is open to 1500-2000 rpm or more. Stock pilots in there are clean, did another soak in Berryman's can of cleaner, rinsed them with gasoline, blew them out with compressed air, holes are as wide open as they can be for pilot jets.

Did an impromptu cleaning on all 4 pilot circuits. Removed screw, spring, washer and o-ring. Sprayed cleaner in the hole while the engine was running. Then four or five seconds later chased it with gasoline from the auxiliary fuel source tube straight through the pilot hole for 5 or so seconds. I could watch the gasoline burble in the pilot screw hole itself. Something's functioning in the circuit. And it was the same response on all for pilot circuits. Number two was not weak or any noticeable difference. I've compared pilot screws, 1,2 3 are identical (#4 is the course thread for the XJ650 carb body, that is adjusted fine on number four) and are clean, smooth and no damage to the tips. Hitachi carbs, pilot screws are on top and easily accessible with the tank off and remote fuel source.

As a thought, I could pull a pilot screw from one of the other spare XJ750 carb bodies and give it a try. In any case, getting the carbs on and off is not a problem to clean that pilot circuit specifically on the bench.

[cajun31]

Just food for thought I had a brand new pilot jet that was just bad. I fought with that until I finally just replaced it and then all was good. Question for you and I haven't spent the time to re read the whole thread but did you have the same issue with the smaller jets? If you are sure the jets are good then I have to agree with you it's time for another clean. I know you are aware, but for the collective a good soak in a gallon can of Berryman's might do the trick.

[Bonz]

40 pilots back in, screws 2.5 turns out. Starts with enrichener as it did with the 38 Pilots at 4-4.5 turns. A change for the better as I have adjustments both ways now.

Been dealing with an intermittent #2 cylinder. Swapped two and three plug wires, as there's a "wasted spark". For those that aren't familiar with wasted spark, this means both 2 and 3 fire from the same coil at the same time but only one of them is on the compression stroke so the other is wasted in space so to speak. New plugs are in, new eBay coil with new plug wires on two and three produces the same result.

I've discovered it's idle where #2 pipe stays cold. Hold the throttle at 1500 - 2000 RPM or higher, number two heats up. Either sync w/o YICS block off has a throttle plate covering the number two idle hole in the carburetor throat or number two pilot circuit needs another thorough cleaning.

What does the collective say? Been talking with JeffH, he agrees those are two things to check as I've been narrowing it down talking with him over the last week.

[Bonz]

Thank you for that input!

Found another inconsistency with the carburetors today. Number four is from an early XJ650, needle was also from the XJ650, wasn't paid attention to by the dealer who rebuilt the carbs for my uncle, nor by me when unracking for cleaning last fall... XJ650 needles are much richer (#Y-10) than the XJ750 needles (#Y-13). Changed it out for the proper needle today from a spare carb.

A "my bad"... In going down "one size" on the pilot jets, I inadvertently went down two sizes. Hitachi's go by one number vs most others go by 2 numbers per size. Makes sense now why 38's are too small and 4+ turns out still isn't enough fuel at idle, even at 7200' elevation. Putting stock pilots back in, #40. Slowly sneaking up on getting this thing dialed in from all angles.

[Radioguylogs]

I would choose the smallest available fuse, like 1A or less.

This circuit will draw negligible current.

[Bonz]

I think the logic is a bit different than the sensor is at 12V vs the voltage on one cell. I honestly don't remember the whole story. The XJ forums can serve as a refresher. I think the sensor itself was around 1k ohm when the electrolyte was present, and the cluster reads the voltage more than the current.....or something like that.

Thanks! That's what I was trying to say in the last post. As long as the voltage is higher than what a single cell should be, the "Batt" warning will be off to my logic.

Even though it functions when all is well connected to the positive battery terminal, a single cell would never feed 12 volts to the cluster. As has been said, if something goes wonky, not sure what would happen or if I would like what happens given it's a perfectly functioning 44-year-old cluster.

Back to the question, running it off of the battery with a fuse in line and a resistor, what size fuse would you all go with? A 5 amp, 10 amp etc?

[Radioguylogs]

I'm reading what you're saying. As it's 12 volts coming off the battery, it's more current than a single cell would be showing to the sensor, the resistor knocks that back so it's not feeding 12 volts to the instrument cluster? The sensor only needs minimum voltage from one cell, and 12 volts is higher than the minimum so the gauge cluster reads the battery is good.

Thinking on this, an inline fuse along with the resistor would be the way to go. Does a 10 amp inline fuse sound good or could/should a smaller one do the job? I'd rather isolate it coming off the battery versus vs fuse it off the fuse block.

I think the logic is a bit different than the sensor is at 12V vs the voltage on one cell. I honestly don't remember the whole story. The XJ forums can serve as a refresher. I think the sensor itself was around 1k ohm when the electrolyte was present, and the cluster reads the voltage more than the current.....or something like that.

[Bonz]

Wouldn't hurt to put a 1k or 2k resistor in the circuit. That's what many XJ owners do.

I'm reading what you're saying. As it's 12 volts coming off the battery, it's more current than a single cell would be showing to the sensor, the resistor knocks that back so it's not feeding 12 volts to the instrument cluster? The sensor only needs minimum voltage from one cell, and 12 volts is higher than the minimum so the gauge cluster reads the battery is good.

Thinking on this, an inline fuse along with the resistor would be the way to go. Does a 10 amp inline fuse sound good or could/should a smaller one do the job? I'd rather isolate it coming off the battery versus vs fuse it off the fuse block.

[Radioguylogs]

Thanks for that. It's an easy thing to pull that wire up and do that.

Wouldn't hurt to put a 1k or 2k resistor in the circuit. That's what many XJ owners do.

[Bonz]

Just a word of caution regarding the battery electrolyte warning bypass. Did that on some other projects and picked up some fused power off the fuse block. Just in case something goes wonky it won't fry your sensitive electronics.

Thanks for that. It's an easy thing to pull that wire up and do that.

[LenB]

On another note, the Seca 750 had a very advanced monitoring system for 1982. The one bugaboo in this day and age is the battery fluid level/charge indicator. It's a sensor that would screw into one of the six cell cap holes. These days they are plugs and not screw in caps and the sensors are scarce as hens teeth or batteries are AGM and sealed. I put in an AGM battery. Found a work around. Cut the sensor wire, attach it to a any 12 volt source and it keeps the dash light from coming on. I hooked it up to the positive terminal on the battery and it keeps the "Batt" warning LCD segment from coming on the display.

Just a word of caution regarding the battery electrolyte warning bypass. Did that on some other projects and picked up some fused power off the fuse block. Just in case something goes wonky it won't fry your sensitive electronics.

[Bonz]

Well, I out-thunk myself on the pilot jets at elevation. In a nutshell, after the carburetor sync last weekend, started the bike this afternoon when I got home from work. For grins opened the pilot screws from 3.5 to 4.0. Steadied things out more on the idle and got rid of the remaining lean return to idle hang when blipping the throttle.

With that, 4.0 turns is further out then they should be. 3.5 turns is the max in my book if the pilot jet is the correct size, going back to stock pilots.

[Bonz]

I've been breaking my number one rule of synchronizing the carbs right away as soon as the engine will run after major carb cleaning/work. Pulled my head out of my fanny and did that today. I attribute my recent posts and agony, lol, to not doing that.

As you know I don't have a block off tool. However I got them matched up nicely and it has made a difference. A blip of the throttle still returns a bit slower to idle than I want/than it should however it doesn't hang for a couple seconds anymore and comes down much more quickly, smoothly and consistently

To refresh, I went one size smaller than stock on the pilot jets. I am at three and a half turns out on the pilot screws. As a general rule I don't want to go past four turns otherwise they're not really making any difference because the idle circuit is running pretty much wide open at that point from what I understand. Going back to stock pilots may be a quick swap to see how it does.

It'll be very chilly in the garage in the morning, a good test to see if it still starts without enrichener or if it will need some. Hopefully I need to put in a good lever full of it, lol.

On another note, the Seca 750 had a very advanced monitoring system for 1982. The one bugaboo in this day and age is the battery fluid level/charge indicator. It's a sensor that would screw into one of the six cell cap holes. These days they are plugs and not screw in caps and the sensors are scarce as hens teeth or batteries are AGM and sealed. I put in an AGM battery. Found a work around. Cut the sensor wire, attach it to a any 12 volt source and it keeps the dash light from coming on. I hooked it up to the positive terminal on the battery and it keeps the "Batt" warning LCD segment from coming on the display.

[Bonz]

Can you share any more about Scott/3Phase? Bob XJOK2PLAY had told me he heard it when he alerted me to Joe's daughter's Facebook about Joe's passing.

I'll synchronize them the standard way, it'll get it close like everybody says it will. The YICS tool would be nice if you are going to make it out. We can check it in Westcliffe. If I pick one up in the meantime I'll let you know.

[Socer4m]

Sounds like a nice little ripper getting some love,,,hope the seca keeps on going strong. If I get back from Pa end of June, hope to get out to Colorado for the annual Bonz XS rally, get together and I can bring the gauges and yics tool out..if it can wait that long..or if you are coming out to the NE rally I can bring them there,,,,,..still bummed about our fellow member Joe and Scott,,,,so, keep on restoring,,,seeya, Mike in S.Diego and Pa