and how I repaired it
fj1200 engine left 2 unrestored.jpg
fj1200 engine left unrestored.JPG
fj1200 front view .jpg
fj1200 left side.jpg
fj1200 left silencer.jpg
fj1200 right hand side.jpg
fj1200 right side .jpg
fj1200 right silencer.jpg
Appearance is not good, bits of rust and alloy corrosion on frame, engine and cycle parts, paintwork is not too bad though.
Smashed plastic on fairing.
Front wheel Bearings worn.
Gear changed wobbly because captive nut in frame is loose.
Exhaust collector box holed.
Fork seals leaking.
Carburetors have water in float bowls and tank has water in it.
Not running well because of water problem
It's not all bad. The bike has a very low mileage, it has only had two owners, it has been datatagged, it is a project that is not so big that I will get bored with it before completion (hopefully). My feeling is that most of it can be sorted with mainly a time investment rather than a cash investment. The first thing I wanted to do was get it running properly so I could check if the engine was OK because if that had serious problems then that would be the end of the project for me. I quickly diagnosed water in the carburetors as being the problem so the carburetors were removed and the float bowls removed. The jets were taken out and cleaned in petrol (gasoline) and blown through with compressed air. I didn't bother stripping the diaphragms as that risks damaging them and they can be changed with the carburetors in-situ if necessary. The jets were easy to clean but I had major problems with the float bowls themselves. It turns out that there is a tiny passageway in the float bowl which was blocked on two of the carburetors. One of the carburetors responded to cleaning in an ultrasonic bath but the other did not. I eventually solved it by making a special nozzle which allowed me to pump grease through the passageway using the hydraulic pressure of the grease gun to dislodge the blockage. I then used the ultrasonic bath to finish the job.
The petrol or gas tank was the next challenge. This bike had been sitting outside in the Aberdeen rain for three years and it seems that the aircraft style fuel filler, although it looks great can let water leak past the seal and into the tank. The result is that you end up with a tank containing a mixture of petrol and rusty water. I emptied the contents out as much as possible and removed the fuel tap to try and get the last drips out. I then flushed it repeatedly with petrol until there was minimal evidence of the rusty water. I am still a bit concerned that there may be some water left in the tank so will have to check it for a while when the bike is in use. I also plan to fit another in line petrol filter to act as a water trap or at least give visible indication of water trying to reach the carburetors.
With the carburetors rebuilt and the tank clean and a new battery fitted I was able to try it out. It started fairly readily and ran OK but was very loud because of the rotten collector box. I reckoned that the engine was healthy though because there was no smoking once it had warmed up and the bearings were good with no rumbling or knocking. This was expected because the bike had been in daily use before it was laid up.
The collector box was dealt with next.
All I did was jacket the rotten area in new steel. I usually do this kind of repair by making a cardboard template out of a Kellogg's cornflake box. You just wrap the cardboard round the area the way you would like to do it with steel and cut it with scissors till it fits nicely. Then place the cardboard on some thick sheet metal ( thick - because you don't want to be doing this again soon) and draw round it with a felt pen. Cut the metal out with snips and tack one edge onto the job. While it is still hot hammer it so it curves round the job and weld in stages between hammerings. Normally you will make several repair sections and weld them in one at a time preferably onto each other. This is easier because you are welding onto clean metal not the rotten stuff underneath. Another trick is to try to weld onto existing welds because the metal is thicker there so less chance of blowing through. I use a gasless mig welder, because it gives good results and works well outside even in windy conditions.
After the welding was done I sprayed the pipes with red Sperex high temperature paint to give them some protection. I may paint them black later because I am not too keen on the red colour.
The fork seals were tackled next. You can do them in either of two ways. Either remove the fork leg down through the yokes and replace the seal from the top or undo the Allen bolt at the bottom of the slider and remove the sliders from the stanchions and do it that way. Probably the first way is quickest.
The seals are fitted on my model at least with the spring uppermost. I have read that some manuals describe it wrong.
Next came the brakes. Basically all that had to be done was to dismantle the calipers, clean out all the muck and put them together again.
Removing the pistons can be tricky because there are two in each half and when one pops out there is no way to pressurize the other. I usually work them against each other until they are both reasonably free then blast one out with compressed air and then remove the other manually.
It is important to keep the seals away from anything other than clean brake fluid. When I removed the seals I put them in a clean jam jar and allowed them to soak in clean brake fluid until they were ready for refitting. You may want to replace all the seals as a matter of course, no doubt that is the best thing to do.
My pistons had no scoring or other defects so I rebuilt everything and refitted the calipers.
The pads were quite new and just needed the surface rust cleaned off the edges where they contact the calipers. Rocol anti-slip was applied to the back of the pads and the sliding edges. This is a high temperature grease which helps prevent the pads from seizing and also prevents squealing from resonances.
Before the front wheel was fitted the wheel bearings were replaced. You don't need to get them from Yamaha just look at the bearing numbers on the sides and get them from a bearing supplier. Phone round though the prices are quite variable. You just knock the old ones out with a long screwdriver fed through from the other side. When fitting the new ones use a socket or similar to drift them in so that only the outer ring of the bearing feels the blows otherwise the bearing can get damaged. Don't forget to insert the spacer between the bearings if you are doing this job yourself
Disclaimer: - The information on this recreational site is not advice it's just a narrative about the way I chose to do repairs on my own bike.