GS1100G charging issue (yes another one)

[Peter#1266]

Hi, I'm getting a rather neglected 1100G back on the road, originally purchased as a parts bike to go with the 1100GK, then I decided it was too good to wreck and I needed a retirement project.
OK, 1985 GS1100G, complete, stock other than mufflers, I've put in new rings, inlet manifolds, carb kits, valve grind and valve guide seals , fork tubes and seals, rebuilt calipers, rebuilt master cylinders, - the usual suspects. Engine starts and runs well. All electrics are good with the exception of the charging system. Have been following the factory service manual to test the stator - 1.8 ohms between pairs, 86 - 88 volts AC at 5000 RPM between pairs, no shorts to ground. Headlight switch / phase delete has been done, all three phases go direct to R/R. 6 wire R/R is unknown make and model (has MT56 ST602 printed on) but appears to pass the Suzuki tests ok. Waiting on an enquiry with an Ebay vendor abut a 775. Battery (car battery with jumper leads) is good. Cable connectors to the R/R - 3 x stator and the other three (battery, ground, sense) have been reterminated with new spade and blade connectors. Problem manifests as follows. Start the engine and within seconds the 10A fuse labelled "Head" (top fuse in the fuse box) will blow. This is the switched +12 (sense) to the R/R, among other things. Noted the R/R gets warm with a few minutes of engine running . Have tried another R/R - a sh532-12 which does exactly the same things.
Any suggestions?

 

[Nessism]

That's strange. Is a 10A fuse enough? I think that circuit requires at least a 15A fuse. The only other thing I can think of is a shorted wire somewhere.

 

[Peter#1266]

Hi, strange indeed. The service manual shows all fuses are 10A with the exception of Main which is 15A. With the key off, at the R/R, the sense wire is 0v and open to ground (using a Fluke DMM and I am pretty ok with electrics). Key on and sense shows battery voltage. This is as it should be. I cant understand what would be ok with the engine stopped but shorting with the engine running, so todays experiment will be try again with the stator disconnected (stator and other wires are two seperate plugs) .

 

[Peter#1266]

Sorted. Partially lack of information, partially self-inflicted. I mentioned that I had tried a Shindengen SH532-12 and got the same result. Turns out the SH532 uses green for ground and black for sense and not the other way round. Found that info on a Triumph forum. So the no-name R/R has been removed and the SH532 fitted, nice steady 14.4 volts charge at idle, rising a bit at 5000RPM, and 13.9 with the headlight on high beam. I can live with that

 

[Who Dat?]

I would still try to source a 775.