'89 Radian engine into an '85 XJ600/FJ600?

Hi guys!

Long-time lurker, second-time (I think?) poster. I recently dropped an '89 YX600W (Radian) engine into my daily driver, an '85 XJ600/FJ600. Before the heart transplant, the bike was in great running condition save for an oil-burning motor - I live in a crowded area and the smelly smoke was a daily embarrassment.

Anyway, unbeknownst to me, the late-model Radians have slightly different electricals, namely a flywheel mageto at the end of the crank and a single pickup coil, whereas the FJ uses dual pickup coils and a stator that sits under a different cover. I should've noticed the bigger bulge on the left side of the crankcase - doh!

I figured I'd try rewiring the bike. I'm using a period-correct Radian CDI and rectifier/regulator. The ignition and charging systems are wired as per the late-model Radian wiring schematic. I get spark and fuel and all my timing marks are correctly aligned. Valves are within spec.

My issue is - while I get spark on all four plugs when outside the motor, only cylinders 1 & 2 fire under compression. 3 & 4 simply get wet, and the condition stays the same if I swap spark plug wires (swapping 1 with 4 and 2 with 3).

I suspect an electrical gremlin but am at a loss as to what that could be.

So my question is - has anyone else here done a similar transplant? Late-model Radian engine into an earlier model XJ600/FJ600/FZ600? If so, I could certainly use your insights to get my baby back on the road.

Halp,

-Matt

 

For context, the new engine is a fresh rebuild that allegedly ran flawlessly for about 50 kms before it was pulled out of a Seca 550. Guy who sold me the engine has a small fleet of old Yammies and I have no reason to doubt his word.

Compression (measured dead cold) is 145-150 PSI across all 4 cylinders.

Here's what she sounds like running on 1&2:

 

Sound like you have eliminated ignition issues but it might be as well to ohm out your coils and change to new plug caps. Are 3 & 4 headers getting warm at all?
Did you swap carbs too or still using the xj/fj BS 32s ? In any case could be time for a strip and clean..
How about valve clearances (always a favourite topic on this board )?

 

I can't comment on the electrical but you might want to check the offset of the drive sprocket. I was told the output shaft was slightly longer to clear the wider rear wheel on the Radian. I put an FZ in a girlfriend's FJ many years ago and a guy told me that. Never did verify this. The bike and the girl are long gone.

 

Rule#1 - never trust a PO's word
Rule#@ - refer to rule#1

 

Unless you have plug wires hooked up wrong, it sounds like a tci issue. Or 2 bad plugs......

 

..except that it works on 1 & 2 and not on 3 &4 and yet 1 and 2 are on different TCI output 'channels' aren't they ?

 

The coils fire 2 leads per coil.... Should be attached to 1&4, and 2&3. If those are attached correctly,and still only getting spark on 1 &2, then something else is causing 1 lead of each coil to be bad. Could be a bad plug cap on each, could be the tci, could be half of each coil is bad.

But, if one coil is good, then both leads should fire. That's why I said " unless wires are hooked up wrong".......

But with only 1/2 firing, it seems at first glance like there is a tci issue

 

I recommend double checking the period-correct TCI. What is happening sounds like you have an earlier TCI.
I haven't studied the 89 ignition change but are you able to install the entire ignition system from the FJ on this newer crank case? If that is a possibility I would do try that.

 

One other thing is that the lettering on the pickup rotor and the TCI should match. That's another easy first check..

 

Still using the stock 32s with the stock airbox. I cleaned the carbs in April of this year and the bike was fully functional before the engine swap.

Thanks for the heads up! Good to know. The mechanic who did the engine swap didn't mention anything to that effect, but then again all he cared about was dropping the engine into the frame. I've got a shimmed front sprocket after doing a 520 conversion so I may need to remove the shims from the front and add some to the back.

Yeah it's looking more and more like I've got a faulty CDI.

It's definitely the correct TCI - TID14-79.

What do you mean by "the entire ignition system from the FJ?" I can't move the FJ's dual pickup coils over since they are at the end of the crankshaft, and on the newer crankcase that space is also occupied by the flywheel magneto and the stator. So right now I've got Radian CDI/TCI + rectifier and FJ starting circuit which uses a sidestand relay and also another combo relay that includes turn signal function and part of the safety interlock switches. The Radian uses no sidestand relay and only a flasher relay. I'm thinking that's where a wiring conflict may be happening, but have no idea where to start to even test that hypothesis.

Interesting, will go check that and report back.

Thanks all for the assistance, I'm at my wits' end with this thing.

 

So no markings on the rotor/flywheel. The TCI's Yamaha 3-letter model code (3LT) does match that of the engine case, so I got that going for me.

I suppose the next step is to try a TCI that's known to be good. There's one on eBay right now but the price tag is a little steep, especially after converting to Canadian tomatoes. Ugh.

If anyone sees a TID-79 (3LT) TCI on Craigslist or else, please do ping me! I'm told that a TID-78 (3KM) would also work but would rather use the very same unit to begin with.

 

Oh, another bit of info that is probably relevant - the '89 Radian uses a different diode block that has no Yamaha part number (!) The part doesn't even show up in the official microfiches. I only have a barely legible wiring schematic in my Haynes manual as reference (see the attached.)

 

Engine swaps often also require wiring harness swaps, or modification. I doubt that the TCI is at fault.

 

As per my original post, I did modify the wiring harness to accommodate the different components and pinouts. The one area I have not touched is the diode block since I can't find a part number for the '89 Radian. I'm fairly handy with a soldering iron and can try to make my own, I would just need some guidance as to what type of diodes, resistors and whatnot are commonly used in these things.

 

BTW here are both the '85 FJ and '89 Radian wiring schematics, should an amenable soul want to play along.

FJ: http://i.imgur.com/SYk1xRz.jpg

Radian: http://i.imgur.com/mqkL8Qn.jpg

(The Radian's schematic is just as borderline-unreadable in the actual hard copy I scanned.)

 

Wait, I found the part. What's described as a "diode" in the Haynes manual, Yamaha calls a "relay assembly", part number 2UJ-81950-00-00.

We're making progress here.

 

So did you wire the L/Y wire on the TCI through the side stand switch so it has a path to ground?

 

I wired the sidestand relay to the L/Y on the Radian TCI. I figured that when the sidestand relay is energized, it's the same as connecting the sidestand switch directly?

 

Your likely correct on that as you do have spark. I was trusting the Hayne's manual that states the side stand switch contacts close when up and it does not differentiate between models on that test. Could be on the YX it opens to remove ground, which is ultimately what the side stand relay does.

It appears to have a relay mixed in with the diodes and resistor, I guess that was their logic. That's going to be a challenge to wire since they don't give wire colors for it on the wiring diagram.

 

I think we're getting side-tracked here with the diode business. The thing is damn near running and sparking on all four.. what isn't yet known are valve settings plus OP is running the 'wrong' carbs.

FWIW in my Radian installation (albeit into a 550) I also tried at set of BS32s and after several clean attempts could not get the bugger to run. In desperation I cleaned up the original 550 BS28s and it started like a charm, then I tracked down some BS30s (from an FZ) and now it's fine, possibly not perfect but I'm satisfied. Now I always imagined that the 32s would work and it's quite possible that I didn't clean them thoroughly enough as I was about green wrt CVs at that point, but then again..

 

BTW my TCI is TID14-48 might not be 100% correct for the Radian (might be FZ) but it works OK.

 

Ooooh. So you're saying that an energized relay OPENS the contacts?

This is where I admit a sin. The PO mentioned tbat he needed to ground out the L/Y pin on the TCI for the bike to start. I blindly did the same, not thinking about the implications. Without that extra ground, I get one spark then ignition gets cut off. That'd be because of the sidestand relay then, correct?

I'll try removing the extra ground then disconnecting the wire that goes to L/Y, just to see if the misfiring somehow goes away.

Or maybe just remove the sidestand relay? For testing purposes I mean.

 

But the 32s are original to the FJ, and from my (admittedly limited) understanding the Radian engine is a virtual clone. My FJ is dead stock - even still has the original exhaust, so I really don't think this is a carburetion/fuel delivery issue.

 

Well sure that's what I figured but BS30s are standard for a Radian. At one point I was going to try the 32s again (once I figured out how to clean the idle circuit) but I snapped off a mixture screw and failed in all attempts to remove it so I settled for the status quo. An interesting side note is that while the FJ/XJ 600 is rated at 72 hp and the YX 66hp

 

Yup, with the YX having a bit more grunt lower the RPM range because of its distinct airbox/carb/exhaust configuration.

So I just tried disconnecting my extra ground AND the wire that goes to the L/Y pin and that got me one spark then nothing. I then reconnected the ground and was back to where I started - fire on 1 & 2 only. Bummer.

 

I just found a much clearer diagram that details the inner workings of that relay/diode combo (attached).

 

Well based on that drawing the TCI needs to have the L/W wire grounded to enable the TCI, which is reverse logic from earlier XJ's where the B/W wire is grounded to disable the TCI. You can make that case by just using the neutral switch and to illuminate the indicator bulb the neutral switch must be closed. That same line through the diode block would also ground the L/W wire, and obviously when the bike is in neutral the ignition should be enabled.

So, with that said it does not make much sense that you have the logic wrong, as you would expect if it is running at all the TCI must be enabled. However, just maybe with the older diode block and some extra wiring on the newer YX things are not as they appear.

Also, in reference to a100man's question are the 3 and 4 pipes stone cold? Does using the choke change that if they are?

 

3 and 4 are indeed stone cold no matter how long I run the engine on 1 & 2. Using the choke has no effect other than intensifying the smell of unburned fuel.

Another thought - the Y/B wire from the tach (which acts as a rev limiter) is disconnected. The FJ's TCI had a distinct pin for it while the Radian does not. I don't think connecting this wire is necessary but who knows.

 

PO claimed to have adjusted them, but I shall abide by Rule #1 in post #5 and check myself. I have a bunch of extra shims in case I was lied to.

 

So valves are right on the money, as promised by the PO:

I1 .004
E1 .006

I2 .005
E2 .006

I3 .004
E3 .007

I4 .004
E4 .006

Ever heard of a guy who's disappointed to find out that his valves are within spec?!?

Next step is to wait for the Radian relay/diode thingie and move stuff over to it. That'll be next week at this point.

Thanks again for all the ideas and support, I'm re-motivated to get her going. Seems like we're so close to a eureka moment.

 

So, if you move the spark plug from cylinder 1 and swap the plug wires between 1 and 4 then 4 has to come alive unless there is a fuel issue or a severely restricted exhaust.

Unless, it is sparking for every other revolution, and all you see is the wasted spark on number 4 that occurs during the exhaust stroke. Got a scope you can hook up?

Or, can you tell if the tach is reading normally?

 

Swapping the spark plug wires is one of the first things I've tried. No dice.

I don't think all I'm seeing is the wasted spark. I made a short slo-mo video of plugs 3 & 4 outside the engine and they spark at an even tempo. For some reason they won't ignite fuel under compression, as if I was getting weak spark every other revolution. Spark looks normal to me outside the engine.

Tach is functional and seems to read normally. That said I can't rev beyond ~2k while running on two cylinders. Also, I didn't mention it before but trying to rev up beyond idle makes the starter motor spin up. This is definitely a wiring conflict.

Here's said video of plugs 3 & 4:

 

I do have a USB oscilloscope (I make electric guitar pickups as a side hustle.) What would I be scope-ing on the bike?

 

Cool video, I have tried that before and couldn't get what I wanted.

So, if you are good with computers you might be able to count the FPS on that video to determine the fire rate. If you assume approximately 1000 rpm the wasted spark system should fire every 60 msec - thinking 1000rpm/60 = 16.6 times per second, then 1/16.6 = 60.2 msec. If you can step through the 120 FPS video frame by frame, which is 8.3msec/frame, then you should see the plug fire at approximately every 7th to 8th frame. Now I am not that well versed in camera technology, so I am not certain about that procedure. It may take a higher speed camera to get accurate results.

You would need a two channel scope. Trigger on the pick-up coil with channel 1. Connect channel two to 1,4 primary and verify it is pulsed with each pick-up coil pulse. I can try this tomorrow just to be sure I have it right, or maybe the FPS on the video will give you the answer. The scope will also assure the fire rate above in case I got that wrong.

That's a strange one also. If the starter is spinning and the solenoid is staying engaged then bad things can happen as the starter turns into a generator producing a substantial voltage that is fed back into the electrical system. I would make sure that is not happening before putting in any high dollar electrical parts. If the starter is spinning because the free wheeling clutch is not releasing, that's also a major problem - at least on the normal XJ.

Edit: See post 45, as the scenario of the starter spinning is not conclusive considering mechanical vs electrical.

 

I should also add that I still don't have a good mental picture of how the single pickup is working to fire the 2,3 cylinders. Is there an extra raised area on the rotor, is the TCI doing this with internal mapping for timing?? The Haynes is useless on the single pickup electrics as it just states timing is handled by the "microcomputer" within the TCI.

 

I think the TCI knows which coil to trigger because the magnets on the outside of the rotor are different sizes. I thought they might be reverse polarity but no, both are North up.

I don't think the starter is physically stuck - if I keep the RPM down it spins back down to nothing.

My scope has dual channels. It's this thing: http://www.syscompdesign.com/CircuitGear-Mini_p_29.html My working knowledge of it is very limited though, I've only been using it to plot guitar pickups' frequency response curves.

 

Have verified you're getting gas into the 3/4 carbs, through the carbs, and into cyls 3/4?

Have you tried giving each cyl a snort of starter fluid before putting the plugs back in?

 

Yes, yes, yes, no.

 

It looks more than adequate to test a TCI, as the frequency and bandwidth required in the ignition system is very basic low frequency.

I was curious to know what the rotor looks like. And that sounds logical that with two different size raised areas the TCI could differentiate between 1,4 and 2,3. And, as far as magnets I was thinking more of just raised areas that are operating on the same principal as your guitar pickups, or as transducers that generate electrical signals based on the changing magnetic field that occurs as the raised areas pass by, or the string vibrates. The magnetics of the rotor is there to generate charging voltage for the magneto.




Waveform captured with bike at idle indicating just above 1000 rpm on tachometer.

Note TCI fires for every revolution - two pickup system.

Measured frequency (with cursors) is 50msec. 1/50msec = 20hz X 60 = 1200 rpm

Scope displayed frequency for channel 1 is 18.52hz, or 1111 rpm, likely more accurate than the moving cursor.

Since you use the single pickup if you connect as above there should be double the number of pickup coil pulses, so the selected ignition coil should be firing every other pulse If one raised area is longer than the other, then electrically the pulse width would be wider, and that variable could then be used to identify 1,4 vs 2,3 to fire the correct coil.

 

... magic

 

Thanks Rooster53. Will try the scope once I get the Radian relay assembly.

After comparing the FJ and YX wiring diagrams, it looks like the only piece I'm missing is a relay that opens L/W on the starter circuit when I let go of the starter button. I'm not sure why the FJ setup is able to cut power to the starter whereas the YX keeps feeding it, but I suspect it has to do with the R/W pin on the TCI. I've got too much stuff connected to it right now vs. the stock Radian setup.

These wiring diagrams hurt my brain.

 

Just another thought that might be an issue. I was looking at the Haynes manual (not sure it can be trusted) and noted that the ignition coils are different for the early and late models for the primary and secondary resistance. Per the Hayne's manual the primary for the early model is 2.43 to 2.97, and for the later models 1.8 to 2.2 ohms. The secondary for FJ, XJ is 9,600 to 14,400 and for the FZ and YX 10,560 to 15,840.

I don't really see the extra R/W wires being a problem. I have also somewhat rethought the two scenarios - electrical vs mechanical for the starter not releasing. Now, the mechanical issue with the starter clutch is straightforward, and is easily diagnosed by measuring at the high current output side of the solenoid vs the high current battery side. If the voltage climbs on the high current output side with rpm, but remains relatively normal on the battery input side, then it is fair to state that a mechanical issue exists with the starter clutch that is dragging the starter along.

As for the electrical failure of a solenoid staying closed, my thoughts are a bit confused on this, but for now the conclusion is the starter would just spin at max speed - not good for it especially with a gear reduction starter. I believe the current into the starter would drop considerably, but where it gets confusing is at what motor rpm would it catch up and re-engage the starter clutch, or if could even spin that fast, and then what would happen if it did.

And, the only scenario for damage to the electrical system would be if the starter is mechanically bound to the starter clutch and while the bike is running the starter solenoid was closed, which would then feed the generated output of the starter into the electrical system.

 

I noticed that as well but dismissed it as an error. Looking at the Clymer, it is saying the same thing. Hmmmm. Current coils measure 2.9 primary and 13k secondary.

Could higher resistance coils make current "back up" in the system, so to speak? And do weird stuff like spin up the starter a couple seconds after starting the engine?

I just might have to grab a pair of 2.2 ohm coils.

Thanks so much for looking into this btw. I'm at the stage where I'm just throwing parts at it.

 

And looking at the service manual for the PO's bike (Seca 550), the stock coils have a primary resistance of 2.5 ohms, which is less of a discrepancy with those of the late-model Radian's... that might explain why he was able to run the engine on all four cylinders?

I ordered a pair of 2.2 ohm coils. What's another hundred bucks.

 

The resistance of the coils is really only part of the equation. The other is the inductance of the coil and is a consideration when pairing it with a particular TCI. It appears the Radian is very unique for the two years (1989, 1990) in that the TCI and ignition coils were only fitted for the two years. As to what might happen running different coils than what the TCI was designed for it would be just a guess. It could cause weak spark if there is insufficient dwell time, or it could cause overheating of the coil if the dwell time was excessive.

As for the coils causing the starter to spin up I would say no. I would suggest doing the test recommended earlier to see what kind of voltages are being produced on the output side of the solenoid vs the input side that connects to the battery.

Another test to eliminate an electrical control issue with the solenoid you could just disconnect the low current L/W - W/R connector to the solenoid after starting it and see if you can hear the starter disengage.

 

FJ (and I think Radian) motors changed when they moved the alternator from the piggy back position to end of crank. In the UK I think we only ever had the later type. Lucky for me that the Radian engine I have is the early type which is more like the Seca 550 original. In case you didn't see this before there's quite some info here..http://www.badrad600.com/

 

Thanks for all these leads, once again. Would make sense that the coil's inductance is a factor - probably even more so than the impedance? Anyway, will wait for the new coils to show up before doing any further testing - I hate starting her in her current condition.

I've also got a bunch of OEM '89 Radian parts on the way - when all else fails I'll try replicating the Radian wiring exactly.