I bought my Honda cbx550f about one year ago from a guy
who sells and fixes somewhat older motorbikes. The cbx
had done about 57.000 km until then. I bought it because I
needed some kind of transport for the road, and the offroad
motorbike I had then, my Honda XR250R, was not very
suitable for this (not fast enough, but still a great bike for
offroad never had big problems with it).
I bought the CBX because I liked the looks of it (I like the naked ones, where you can see the engine), and it was not too expensive for me (I'm a student so...). I also bought another completely disassembled (almost complete) CBX550f from the same guy after a while, because I thought some spare parts would come in handy, and I also got the Haynes workshop manual from him.
After some test rides I found that the bike was reasonably fast, sometimes a bit unstable in high speed curves (this gave me a scare once!). Also the exhaust pipe that was fitted wasn't the original 4in2, but a partly selfmade replacement which was a bit low to the ground. When riding over big bumbs it tends to hit the ground, but now I've got used to it and this doesn't happen too much anymore. I also have a original exhaust, but this is rusted. Maybe I'll fix this sometime.
So I've been riding happily with my cbx until june this year.
But then when I was riding on the freeway I started hearing
a strange sound coming from the engine, and in a couple of
kilometres the sound got louder and louder, I continued the
ride with about 80km/h and at a low rpm.
When I came home the sound was very loud (it was like a knock) and it was obvious there was something wrong with my bike. So when I had the time I dismantled the engine, looking for the broken parts. After removing the cylinders I found that the third piston was the problem. The bearing shell of the connecting rod was broken, it was still in place but after examining I found that it had scratched the crankshaft surface. I don't know what caused this malfunction but it was probably due to lack of lubrication I think. (I think I should have replaced the engine oil a bit earlier ).
Since I had a spare crankshaft I decided that I would replace the damaged one. I replaced also the connecting rods, I thought it was better to keep the same rods with the same crankshaft.
When done this I could reassemble the engine again, I bought some 'liquid' gasket in a tube for sealing the two crankcase halves. And I made new gasket out of gasket paper (for tractors) this was a lot of work but since a complete new gasket-set was hard to get and also expensive.
I just made a print of the gasket by putting hobby-paint on the part that needed the gasket, and then cut it out with a sharp(!) Stanley-knive. When I was at it I already made some spare gaskets. For the cylinder head gasket I used the old one (made out of 3 layers), cleaned it before assembling.
So when I finished putting the crankcase together again with the torque wrench, one bolt broke while assembling (even when I used the torquewrench ), I reassembled the cylinders and everything else (after cleaning). I put a new oil filter in and then mounted the engine back in the frame. I found that the replacing of the airchanbers before the carburettors was difficult to do, but it worked.
Then I reconnected everything to the engine and the engine was ready for it's first test. This was after some days of work at 12 o' clock in the evening. The engine started with the second attempt of starting it, producing a lot of smoke and noise since the exhaust pipe was not yet fitted. But I was happy, it worked!
In the end this repair had only cost me some oil, a new filter
and the liquid-gasket(what's the right word for this?), but a
lot of time since I didn't have much experience with engines
and stuff so I had to check everything twice in the
workshop manual and by the expertise of some family
(thanks). I know it would have been better that I would
have fitted a new cylinderhead gasket, but I didn't have a
lot of money at that time. And this solution worked out
fine since the engine isn't leaking oil. I was back on the road.
After the first kilometres on the road I noticed that the gear changing was a bit difficult but it seems to get better now. Also one of the sparkplug caps came loose after a while so I had a significant loss of performance (maximum speed 110!!), so remember to tighten the caps well after work on your bike .
That's the story of my cbx until now, I hope the repair was okay and won't have to do that again for some time, because I like riding my bike more than fixing it.
Here's a picture of my CBX in front of my parents house
getting a tan ;) Ooh it looks good!
Ride safe and greetings, Michel Heusinkveld
Michel Heusinkveld (firstname.lastname@example.org)