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

... 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.

 

Yes, good site, that's where I found the much clearer YX600W wiring diagram (as an appendix to the earlier model's manual.)

To think that I could've avoided all this trouble had I sourced an early-model Radian engine. #facepalm

 

You can also use XJ600 parts from 1989 - 1990. I have this model and it's the same engine as your Radian. Is your engine 56 hp like mine?

 

Official Yamaha specs claim 66hp for the Radian.

 

There is a way to regain some of that horse power for XJ600. The only difference are carb boots and slide needles (not sure if that's the proper term but I hope you know which part I mean). I got this info from a guy who got his Yamaha "unblocked" at a dealership in Germany. You might check part numbers for Radian if they are different for early and late models.

 

It'd be interesting to get the bike on a dyno if and when I get it running properly. I know the 72hp (at the crank) FJ used to dyno in the mid-50s RWHP.

I don't know if the cam profiles are different on this engine - just by looking at them, it seems as though the Radian's exhaust cam lobes are beefier, but it's hard to tell without pulling them out.

 

You might as well switch cams

 

I even have an extra set of FJ camshafts. One thing at a time though! Let's get her going on all four.

That sounded wrong.

 

Looks like XJ600 engines can ba a pain in the backside I rebuild mine and it doesn't want to start.

 

Installed brand new 2.2-ohm coils today. Got one spark then nothing, most likely because of a bad crimped connection. Will solder and heatshrink everything tomorrow and go from there.

Interesting nerdy fact - the old 3-ohm coils (green) have an inductance roughly two times higher than that of the 2.2's (grey). 12mH vs 6.6mH. I have no idea of the implications in the context of an ignition coil, but that seems like a large difference.

 

Huge difference, and if dwell was not adjusted to compensate the spark would be considerably weaker with the old coils.