CB350K I don't believe it!

[florence]

It's only taken me twenty one years to get round to getting this bike going again. 
Rebuilt engine, new brakes front and rear, wheel bearings, replaced silencers etc.......

After doing some tests today   I went for a ride through some fields, had it running for about half an hour, adjusted the tick-over and clutch and generally doing the things that you can only really tweak properly during a proper run, when, it started making a noise from the left hand crankcase which doesn't sound terribly good at all.  I think the second hand crank has started to fail.  The big ends on these things cannot be repaired, once they fail that's it and it's really hard to find spares.  I do have another crank but I'm left feeling rather despondent and wondering why I bothered in the first place.  I should have just put it on ebay as a 'barn find'.

Now I have to decide whether to bother stripping it down and finding out what's happened or just chuck it in the corner of the workshop for another twenty years. 

[Nurse Julie]

Oh dear Florence, what a shame. Maybe give it a day and have a closer look, it may not be as terminal as you think.

[AshimotoK0]

Sorry mate .. but stick with it .. DK will have loads of cranks. CL is the same but they will probably sell the CL cheaper than CB. You probably know this but the 250 crank is not the same. Could ask the Hales's people for you if they have any left. Main thing is are the rockers & cam OK cos they are rocking horse poo.

[florence]

I can't bring myself to take the top off but I guess I will have to at some point.  I do have one set of rockers and camshaft left in the spares boxes but after that there's only dodgy ones.  It's pretty sad because I was so close to getting a MOT.  This will be the fifth engine rebuild since I bought the bike in 1984.

The 250 crank has thinner connecting rods but a chap who races them told me the 250 crank will work.  Perhaps he was wrong Ash?  Tell me more...

[AshimotoK0]

I can't bring myself to take the top off but I guess I will have to at some point.  I do have one set of rockers and camshaft left in the spares boxes but after that there's only dodgy ones.  It's pretty sad because I was so close to getting a MOT.  This will be the fifth engine rebuild since I bought the bike in 1984.

The 250 crank has thinner connecting rods but a chap who races them told me the 250 crank will work.  Perhaps he was wrong Ash?  Tell me more...

No ..it will work but it's weaker ..less rollers in big end I think. I had a 250K2 with 325 pistons from Read Titan back in the day . Hepollite pistons..went great as it had the 'fat' cam

[florence]

always wanted the K0 cam but never found one but then probably a good job as I managed to go through three cranks back in the day purely down to trying to keep up with bigger bikes and riding flat out with a pillion.  these things will rev like mad and are pretty fast but quite fragile.

Oh well, had a bike for a moment, now it's a pile of bits again....

[matthewmosse]

Gutted, geuss you will not need a tyre then. I hate that expirience, was a big part of why my 500 went off the road in the end, a rapid sucession of problems as bits said, enough.

[florence]

thanks Matthew, no need for tyres just yet, I will probably build another engine on the bench then do a swap.  Goodness knows when.

[florence]

Took off alternator cover, grey sludge and metal flakes.  Turned engine over to TDC on left and definite play and clunk.  Great, I think it's covered less than three miles since rebuild.

[MarkCR750]

Gutting, feel for you there , you know you've got to dig in and sort it though!

[Bryanj]

Probably teaching granny to suck eggs but the centrifugal filter on the RH side was clean?

[florence]

Thanks Bryan, you are right.  It was a complete engine rebuild and I had cleaned it thoroughly.  The second hand crank was a bit unknown, not as good as I thought.  I had tried feeling for up and down movement on the con rod but I hadn't taken any proper measurements before assembly.  Just bad luck really. 

Next I shall try the other spare I have and hope it's had a less punishing life.

DK sell cranks but they are £100 - £130    I can't justify that kind of expenditure so I'll try the 250 one i have.

As long as I can get to the MOT station and potter about the lanes I shall be happy.  My original plan was to make a CB/CL hybrid by putting off road tyres and scrambler handle bars and use it to go up to the woods to feed the pigs.  It's actually very good off road even in road trim.

[Bryanj]

Don't be disheartened, when I was at Meads in Glos I stripped and rebuilt a Kawasaki 4 stroke 250 twin that had been sold used due to a LH big end failure, crank went to Alpha in Brum for overhaul and damn me if the RH one went a month later so had to do it all over again under warranty

[AshimotoK0]

Try Charlie at Oxford Classic Honda, he may have one and always very reasonable on price. Catch DK on the right day or go in there and you would get one way cheaper than they sell on eBay.

[florence]

Thanks Bryan and Ash, I will try them and see what they have to say.

 I looked through the workshop today and realised I have three spare engines but only one camshaft and one crankshaft (250) between them.  Might put some spares on ebay to raise the cash for a good 350 crank.  The other option is to build a 250 but if I remember rightly they just don't have the same kind of low down traction as the 325.