250 N/C cyl head refurb

[themoudie]

Aye Mike,

Take the barrel and piston into your engineers and get them to measure up the bore and piston, they will have the necessary measuring instruments and if they don't, then you know not to use them!

By the way, for interest - I didn't have the tool for locking the camshaft (I wanted to remove the bearing and check it), so yesterday I designed a tool to do the job, and 3d-printed it. It's definitely a one-time use tool, as I broke it whilst doing the job yesterday evening.. but it did the job. The idea is that it bolts into where the cap is, then an aluminium drift can be inserted to lock the cam in place.

Just don't do the old trick of sticking a tyre lever between the top of the cam and the cylinder head! You could pop the top of the cam tunnel off! Don't ask.......!

If you need to borrow the proper tool, please ask, or purchase Nigel's very nicely made tool for the job; it will do the job. Those cam nuts are torqued up to 35 ft/lbs (47 newton meter).

Good health, Bill

[Jordan]

By the way, for interest - I didn't have the tool for locking the camshaft (I wanted to remove the bearing and check it), so yesterday I designed a tool to do the job, and 3d-printed it. It's definitely a one-time use tool, as I broke it whilst doing the job yesterday evening.. but it did the job. The idea is that it bolts into where the cap is, then an aluminium drift can be inserted to lock the cam in place.



Regards,
Mike

Are you happy to give away the file for your tool?

[Mike]

Are you happy to give away the file for your tool?

Of course! - I made some adjustments to the design last night, which should make it more effective. Once I've finalised it, I'll post the STL file here.

[Jordan]

Thanks Mike.

[Mike]

Take the barrel and piston into your engineers and get them to measure up the bore and piston, they will have the necessary measuring instruments and if they don't, then you know not to use them!

Yes, you're right. I'll give JEM Engines a call today, as they are very close. Hopefully I can pop along to see them at some point over coming days to discuss the rebore and valve guide liner work necessary.

[Mike]

Are you happy to give away the file for your tool?

Of course! - I made some adjustments to the design last night, which should make it more effective. Once I've finalised it, I'll post the STL file here.

Here's the final design for the cam locking tool - STL file in the attachment. It has a 6mm hole for fitting a metal drift, because I suspect that the plastic won't be up to the job on it's own. I've printed in PLA+, with 100% infill for the section that will take the pressure from the cam lobes. It will likely be some weeks before I'm ready to reassemble, so I've not been able to test, but I currently expect that it might be a "sacrificial" one-time-use tool, use at your own risk.

[Jordan]

Thanks Mike.
I understand the disclaimer which is reasonable.
I haven't tried 3D printing yet, but bought one after a brilliant success with having a gear printed for my Ducati's speedo drive.

Jordan

[Mike]

I've had my printer for a couple of years now, and it has been useful in many ways, quite often for things like this where I unexpectedly need a tool to make the job at hand easier. It takes a while to fully get the hang of the CAD tools, but once there, these things are so easy to put together.

[Mike]

It has been a little while since my last post, but I have some news...




The barrel has been rebored to match a piston that I bought and new valves and new valve guides. Even the feel of the valves sliding in the guides is very much different to how it was previously - much smoother.

Bill - I ended up using Pitcairn Engineering, near Bonnybridge - thank you for the recommendation. Ryan there was very accommodating, and I'm pleased with the job. He didn't want to use K-liners however, and so I deferred to his experience and ordered new valves guides from Nigel.

I'll start the reassembly at some point soon. I'll be surprised if I get it finished this month though, because I'm off to india for a little trip, to include two weeks on a royal enfield in the high passes of the himalayas

Mike

[themoudie]

Aye Mike,

I do hope that you find Pitcairn's work is satisfactory. Finding knowledgeable and competent engineering workshops is becoming increasingly difficult.

As for the jolly into the Himalayas on an Enfield, my friend and his wife went on one of these and found some of the other riders boorish behaviour at best tedious and some points downright dangerous, when riding some of the difficult tracks. Added to which he is sensative to rudimentary toilet facilities and they were manky!

Dinnae rush the rebuild, better to have it right than not.

Good health, Bill