true confessions: Admitting defeat - reinstalling barrells on a J

[kiwiz]

A week ago after return from an extended overseas trip I was delighted to find my Wiseco big bore kit had arrived. Down it went to the engine shop for the requiste 2.5mm rebore, taking the J out to 1015cc.

I had fretted over losing circlips and breaking rings during installation of the pistons but this turned out a pleasure. The trickiest part was with my failing eyesight trying to find the gap in the oil expander the hardest job. I found a trick which suited me. I would pin the expander using a small piece of wire pushed through it into the piston oil holes. This stopped it from rotating. Then using a tooth pick I would gently probe sections of the expander which would eventually show where the gap was. I would then remove the wire and rotate the expander until the gap was at the front.

The next step was to insert them in the bores. I made up two wooden rests to hold up the innnermost pistons and attched my ring compressors. The type I use are about 30 year old being clipped circles of spring steel which in theory compress the rings but are fastened so that they will push down as the cylinders are lowered.

I found these somewhat fiddley with them often springing loose partway through.

With the aid of my dear wife we attempted the job. After about three attempts we got the inner pistons in but had an enormous problem with the remaining pair. Sweat was starting to pour down and stress levels were building. Wife was worrying about chipped nails! Third one in and then the compressor came off the fourth just before the oil rings were to pass up the #1 cylinder. B***er!
Now I would have to lift it to start again on #1 & #4. In extracting the compressor off # 4 tore the base gasket. Just great! pulled the whole lot off again; fortunately all the rings were still intact.

So the J is on an emasculating short trip to the dealer. On looking at the cylinders their view was that there was not enough champfer due to the rebore to make the ring entry easy but having done the identical job 30 years ago It was a really humbling experience going in asking for help. Hoped an expert would make a house call but now the j has to suffer the embarassment of being ferried to the shop.

Wifey said: "If I'd know how much the rebuild was going to cost and how much stress it was going to create I would have agreed to you getting a new bike!" Thanks dear, but it really wouldn't be the same.

[Mark O C]

If your a club member, why write up your experiances for the magazine, I'm sure Chris would welcome the input.

[Pigford]

Kiwiz, did my Z1A up to 1015 (Wiseco) a few years ago.... similar trials & tribulations.... The chamfer on my barrels nigh-on dissappeared, but with 1/2 gallon motor oil & sweat, got em on with no upsets! Did you gap all the ring first, not a common thing to miss!!!! I used a small screwdriver to insert the rings!!!!! Its OK as long as you take your time. I'll second this one for a newZletter entry!

[london calling]

KiwiZ,if you've taken your 998cc J block out to 1015cc then it's very little extra metal out of the liner so i can't understand why the chamfer at the base of the liner would be affected so much??

[Rich]

2.5mm rebore would probably make it about 1075 - 1100 so I expect it is a typing error (I make loads of them - but actually starting to type is the worst one!!) Start by putting the inner two pistons in first and then you can rock the outer two in easier and get better access. Flat lollypop sticks are good or just good old fingernails. Which reminds me I must stop biting mine ready for the winter rebuild.

[chrisNI]

No chamfer eh? - I got my 1105 on the last time by putting the pistons and rings into the block on the bench, as far as the guggeon pin holes, and then lowering the block down slowly and slipping the pins in. Bloody nightmare.

[kiwiz]

Rich is right, it was a 2.5mm bore taking it out to 1075cc. Perhaps I gave up too early and the episode is a telling statement about my personality as a wrench.

Whilst I generally enjoy R&M work on my bikes every now and again I do a job which should be straight forward but proves not so, and then it really stresses me out. This was one. Did it 30 years ago on a 1A without any problems and expected the same result this time.

Same with the earlier valve guide seals episode. A straight forward job but in which I buggered up two of the seals (another wait whilst they came from overseas). Some good ideas from this site such as using the valve stem as a guide. Still a #### of a job due to my inability to get a pair of fingers far enough down the hole.
So the J is off to the shop today. What horrors befall her there I prefer not to know as long as she comes back with her barrels on and rings intact.

Hopefully I can get the head on okay but as one valve has been reseated so I expect a reshimming headache on that one.