27th August 2008 / 18:10
Overhauled the carburetters today, they had the usual cleanout
04th August 2008
I brought my 1986 NC24 'Wayne Gardner' Rothmans off a couple who had owned it for just a few months. The lady who owned it said was happier on her 125cc and wasn't going to do her full bike test just yet. They were a lovely couple and both fairly new to biking. I didn't have any reason to doubt that they didn't have a clue about this bike, or any other bike maintainance for that matter.
However, whoever sold them the bike probably knew that there were a few things shafted.
I got the bike home (150 mile journery) and the temperature was showing 1/2 way all the way home, which at the time I thought was ok.. it wasn't (see below) but when I got home it wouldn't start, as if the battery was dead... then the problems began to surface.
The battery terminals were covered in crystalline white powder and there was no fluid left in the battery ...it had boiled dry.
A fairly common problem with these old Honda bikes is that the Regulator/Rectifier(RR) unit packs up. From what I gather it is mainly caused by using a defective / old battery. As a battery gets old it cannot accept as much charge as a healthy battery so the RR unit has to supply less voltage / current to the battery. It gets rid of the excess amounts of current / voltage generated by the alternator unit as heat! These old RR units do not have fins to aid the cooling so they soon overheat and break down. If you run it for too long it will also burn the generator coils out as well, all for the case of not having a good battery!
If the bike is being stored for any length of time keep a battery maintainer on them, like a Datatool smart charger
The plug that connects the Generator coils to the RR unit had melted completely, I knew then i'd more than likely need a new RR unit, a quick test later showed it wasn't outputting the right voltage. A quick scour of the net showed a whole host of alternate regulators the can be used, including modifying a Yamaha R1 unit. I went for a direct fit aftermarket part made by Electrex World (RR63)
Note the cooling fins
I checked the stator too, an ohm test reported it was ok! When the bike was hot and running one of the phases was giving out a lower voltage than the others, I removed the flywheel to check the stator. The stator is made up of 3 phases of 6 poles, giving 18 poles in total. In the picture below you can see that 2 of the phases (12 poles) have gotten hot enough to darken the coating on the coils. This has probably weakened the enamel coating of the wires enough for it to breakdown underload.
Electrex World also make a new Stator unit for the bike, which comes with 12 months guarantee so I ordered this as well, it arrived the next day.
I also ordered a new battery for the bike, put it all back together and voltages are now fine!
I did relocate the regulator so the engine heat wouldn't add to the problem and mounted it to the side of the frame like so...
When mounting the regulator I noticed that the coolant in the expansion bottle was a muddy brown colour, this muddy brown liquid was also all over the rear swinging arm... it had been boiling over! I checked the radiator cap and it was all corroded and worn out, I presume it was the original 22 year old cap it has japanese writing on it, time for a change.
I replaced the worn out centre rubber but the cap wasn't holding pressure. A quick call to david silver spares ensures that a new cap is on the way.
Putting the new cap on causes the bike to run constantly hot and overheat! Somethings not right.
I decide to flush out the cooling system by disconnecting the lower hoses and running fresh water through, the water that came out was like rusty sludge! I decide to up the ante by using a chemical cleaning treatment by Barrs. A 2 step treatment that cleans the cooling system. Using this causes even more crud to come out of the system. I refil with fresh coolant, bleed the air from the system and to my dismay it is still overheating! :(
I check the thermostat in a pan of boiling water and it opens, just to isolate this problem I remove it all together, it still overheats!
The final thing to check is the water pump, located at the bottom of the engine, I have read that these are pretty much bullet proof. Mine wasn't!
Water had gotten in the bearings, causing it to sieze solid and suicide itself. This is what probably caused the water to turn rust coloured.
The water pump is easy to remove but all the engine oil will spill if you remove it so I had to drain that first.. it needed changing soon anyway. The end of the waterpump shaft had actually snapped off when it had siezed! Had to remove the sump to find the pieces of broken shaft in the oil strainer.
I ordered a 2nd hand pump off ebay. It arrived 5 days later...
After fitting the new pump and new coolant, the engine now runs nice and cool! ^_^
Last Updated: 27 August 2008 @ 18:24:43
