Topic: Tales From the Lonely Builder - Pin dowels again!

[The Lone Builder]

Think I'll change my forum name!!

Working in isolation, far from the civilised world - well the biking civilised world – can be a frustrating and depressing experience. Just when you think you are on a roll, BAM! the Great Spirit decides to test you yet again and another spanner drops (not literally) into the works.  So what is it this time?

Spent an hour yesterday trying to figure out which way up the piston rings went, until I "accidentally wiped of the film of whatever hiding the markings. Problem solved, rings on. Cleaned up the mating surfaces; dry fit and all seemed well.

I had one dowel pin already in situ and had another used one - 12x18 – plus a newly ordered one - 12x15. Read all the posts; tried both and the old one, once cleaned up and smoothed seemed, heightwise, to be the same as the existing one – the part of the 15mm one protruding from the case was clearly shorter. So in went the 18mm pin.

Pistons attached, barrels on and all seems well. Oops! Forgot the cam chain guide. Fixed quite easily thankfully.

Now on to the head. Got 2 new 12x22 dowel pins as per the parts book - oh the bike is a confusing (to me anyway) one. According to the timeline, it's a K2 model (Frame - 2086807) with a K4 engine (23010522). It's a UK model where from '72 onwards everything was a K2, until the K6 appeared, so I'm told, so it makes some sense.

Anyway having read all the posts I got a bit concerned about the length of the dowels - they were bought quite some time ago. A dry fit revealed - yep, you guessed – they are too long! A refit without the pins and the head sits nice and flat.

So now I start to worry about the case-cylinder pins too - the book says 12x15! Closer inspection reveals a gap between case and cylinder. At the back it sits at about 0.6mm and at the front 0.38mm. Some pressure on top closes the gap at the front, but not completely at the back.

So now my question.  thought I'd never get there, didn't you.

Clearly I need to get 12x18 pins for the top, but what about the bottom. The bottom gasket seem very thin, esp when compared to the top one. The gasket set is NP, "made in japan" and the head gasket is 1.7mm thick. I didn't measure the bottom gasket.

• Can I leave it as is? Dry. Will tightening down the head close the gap?
• Should I put some liquid gasket on and tighten up?
• Must I take it all apart and replace the 18mm pins in the case with new 15mm ones?

Thanks for the advice.

PS Although in the pic the gap looks bigger on the left, the difference is minimal and I checked surfaces for trueness before starting.

Off to change my name now. 

[madmtnmotors]

When in doubt I will use a vernier caliper to measure the recesses within the mating parts to confirm that the dowels being used are not too long. 

You can use this principle with a simple piece of stiff wire to measure the depth of the dowel openings. 

[754]

Tip when removing diwels, use a threading tap, as soon as it starts to bite the dowel should twist out.
 On really stuck one's it may cut into the dowel. Better to clean up inside burrs than outside ones.

[The Lone Builder]

When in doubt I will use a vernier caliper to measure the recesses within the mating parts to confirm that the dowels being used are not too long. 

You can use this principle with a simple piece of stiff wire to measure the depth of the dowel openings. 

I did that and it seemed OK on the bottom, plus the fact that the old one I had out looked about the same as the one that stayed put. SO I went with that.

On the top, when I measured, it seemed pretty clear that it wasn't going to fit. Another way to measure, I discovered is to put the dowel in the hole and turn it a few times. This leaves a faint mark where the dowel & case interact. Do the same on the other side and if you have a gap between the two lines, you have a problem. I have a problem! 

However although it will take time, this bit is easily fixed. I just have to wait till someone, willing to carry the bits, makes the trek from civilisation. Hopefully in a couple of weeks.

My concern is more with the gap between the case and the cylinders. Will that close up when I tighten everything down? Or should I take it all out and put in 15mm dowels?

[The Lone Builder]

Tip when removing dowels, use a threading tap, as soon as it starts to bite the dowel should twist out.
 On really stuck one's it may cut into the dowel. Better to clean up inside burrs than outside ones.

Thanks 754.

I saw you made that suggestion on another thread. I will try it if I have to change to 15mm on the bottom, 'cos the 2nd dowel was left in place for a reason! 

Sean

[The Lone Builder]

I decided "The Lonely Builder" was too "Oh poor me!" What a wimp!!

So I changed again! 

[madmtnmotors]

I just have to wait till someone, willing to carry the bits, makes the trek from civilisation.

If the dowels are too long you can grind/file them down and file a bevel on the ground edge to get the length you want. I've done it more than once! 

[Stev-o]

You ma be he Lone Builder in E. Africa, but we are all here to help each other.   

Mind if I ask how you ended up there? Assuming you were not born there...

[The Lone Builder]

Hi Steve,

I left Army 20 years ago, didn't find work in the UK NHS to my liking so I went a ran a rural hospital in South Africa for 5 years. Then had a stint in East Timor, but missed the red dust, so when a job came up in Harare, I applied and ... well the rest is history.

The bike came too BTW - not to ET – safely stored in a box or two where I had put it as a student in 1980 (ish). The plan is – once it's rebuilt – is to ride it from Belfast, S Africa back to where it came from - Belfast, N Ireland!

FYI, Zim is more Southern Africa that Eastern.

Thanks for moral support.

Sean

[The Lone Builder]

Hi All,

So after a bit of a delay – been trying to get a 450 K1 back on the road and at the time it seemed like it would be a relatively quick exercise  – I'm back to take up where I left off.

I ordered some new pin dowels, and then took cylinders off again. One of the dowels in the crankcase was stuck fast and I managed to get it out using a suitably sized drill bit (Thanks 754, but didn’t have a big enough tap) - once the bit bit into the metal, the dowel freed up; it measured 12x18.

My parts manual says the one that just came out should have been 12x15, so because of this and the previous confusion over sizes, I decided to measure the holes for these things.

The case/cylinder holes are 6.2/13.98, making a total of 20.18mm. The parts book says use a dowel of
12x15!
The cylinder/head holes are 10.38/9.22, making a total of 19.60mm.  The parts book says use a dowel of
12x22!

So because I didn’t realise I had ordered another two 12x18s, I decided to go with what I had and put 12x15 in the bottom and 12x18 in the top. I reckoned that this was what the book said for the cases and that with nearly 9mm sticking up, it should do the job. If I had found the new 12x18s sooner, I think I wold have put them in.

This time, after a bit of a battle getting pistons in, the cylinder settled down nicely on the case and the head on the top. Now it’s a matter of bolting it all down.

However before doing that I need to do a bit of research on the cylinder studs. When installed they are different lengths and whilst the torque (I’m going to 8ft-lbs) has not been reached, the longer ones feel like they are tight and then go loose – you know that feeling when you strip a bolt? Well a bit like that, so I’m afraid to tighten them too much.

Cheers – it’s good to be back on the job. And I just found another post where this was all set out before!! 

Sean

[PeWe]

Important to measure both sides where the dowel pin is ment to sit. I have 15mm, 22mm and 18mm. I know that my K6 had 22mm once, but I used 18mm case-cylinder.
My cylinder-head got 15mm, 18mm will be too much. Fiber gaskets will compress and become thinner.

I investigated the different lenght on CMSNL where they have the different charts for all years.

[The Lone Builder]

I know; confusing innit?

Closer and more careful inspection revealed the problem with lengths. Two studs were in upside down!! 

All rectified and the head in now firmly in place and resting for the recommended 24 hours before retightening. Happy day 

Sean