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CB750F2 .... silk purse from a sows ear.
SumpMagnet:
Got the barrels off today after a major fight....and hte pistons are really nice skirtwise. No signs of scoring or rubbing. I need to give them a bit of a clean as they are oily from the oil I put down there .... but them and the barrels look good to go back in as they are.
The head....yes. I have at least one exhaust valve not seating properly, and to be honest...I think it would be silly to put it back without replacing the valves and having new guides. I would also want to look into getting the cam plain bearings re-worked if that is possible. Still need to see what the main bearings are like.
Barrelslook fresh as a daisy inside....but getting them off. Not fun. Now...the K series engines have 8 little plugs with seals that fit over the top of hte barrel studs. On the F2, Honda decided to cut that to 4.... and that leaves recesses to collect condensation, muck and whatever. This had gummed up a couple of the studs, making it a job to get the barrels off. The only seal they have is a rubber one at the bottom....to make sure whatever gets in can't get out... A bit of surface corrosion on 2 of the studs, and a collection of crud which needed a good soak with oil before it shifted.
Camchain guide wheels are rock hard....as was the tensioner blade. Where they run on the chain, it has pitted the rock hard rubber. All fit only for the bin...
So...next job is to look for someone I can send the head off to.....not at all confident about refacing valves and seats, and fitting new valve guides.
Then source a full gasket set ( spotted an NE set on E-Bay which looks pretty comprehensive ) and will also pick up the camchaion tensioner parts to put away for the rebuild.
Can anyone recommend me a good engine paint? I want to strip and repaint the barrels and cam cover ( head will get done later... ) I want a nice glossy black finish :)
Laverda Dave:
I took my 250RSA engine cases to I Cleenz Machinez in Penge, SE London. The original black paint was a bit rough so I had them aqua blasted and repainted. So far the finish has stood up well but the engine is apart again after a siezure (read my CB250RS rebuild thread for the full story!). The painter did an excellent job, everything was properly masked, no overspray anywhere.
SumpMagnet:
I'll give them a call and see what's what :)
Meantime...i did solve one problem. The bike was leaking oil from, the alternator cover.... Just took it off and found out why. Only half the gasket is there. Plus 2 bolts had been put in that were obviousdly short, and stripped the thread from one of the lower bolts. All the screws are pretty rough...so I suspect I will not be putting them back. Time to buy that helicoil set.....
I also have my first unshiftable screw. Well....I knew it was FUBAR...but I had to try. Will have to drill it out to get the left hand gearbox cover off. I also have no way to undo the 3 screws on the end of the alternator cover as those are well rounded out. At least I can attack those off the engine with the cover off.
Can't complain...as 90% of the screws have undone nicely, and quite a few of them had been butchered before.
Also on the good news front, the pistons all look good. No nasty scoring and just light wear on the skirts.
paul G:
Things now moving along at a nice pace. Keep up the good work.
SumpMagnet:
NgggggGGNGggnnsngngdfkgnfdgngngnnn.....
that was the noise I made when I started cleaning the rest of the odds and sods off the frame. A random set of 'earth' wires seem to have been bolted on, which may have been related to the electrical issues I was told about before I bought. Especially the one by the coils..
The loom is quite corroded on the terminals and the wires seem to have lost a lot of the flex they should have. It's also been unwrapped around the headstock...which is usually an area of concern with a loom. That's where wires tend to break internally leading to all sorts of interesting 'amusements'. I had a Moto Guzzi that did that to me. First the horn would sound on full lock...then the lights would go out when you turned....and finally when I went to swap the head bearings...I found it had been arcing across the ball bearings...which it was using to earth everything up front.
I might go crazy and buy a pattern loom from Dave Silver Spares so I can refit a good set of fresh unbroken wires for the inevitable electrical fault finding. That's one to bear in mind.
I have enough stuff off the motor to make it light enough to get up on thw workmate now...so I can crack on and strip the gearchange side. I also need to get a 3 leg puller.... I did have one, but it seems to have gone AWOL. No idea where...but I must have lent it out, and not got it back. That's the danger with tools you use rarely. I presume it's a 3 leg job to shift the rotor off the end of the crank...
I also need to consider what I am going to do with the alternator end cover. It's a bit scuffed and needs either replacing or refurbishing as it is pretty grotty. Someone has tried to repaint it black with matt paint. Now...the screws holding the fixed magnet on to the case are chewed. One certainly is already pretty rounded off and I doubt it will shift. Not sure how much bolt length is going to be left if I drill it....and I can't use heat
The jobs and parts list is growing....but the whole thing is breaking down into smaller and smaller assemblies, and the amount of 'bike' left is pretty reduced. Soon...I am actually going to have to start spending money and doing stuff other than taking it apart!
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