Honda xl250r cam journal problem

[guest1931]

Here you can see my job.hope to work
First of all I decreased the diameter of cam shaft by a grinding machine to 21.8mm.
Then I made a phosphor bronze bushing,I.D is 21.8(+0.05mm).This bushing splits by a hand saw.






I tried to fasten/bind the phosphor bronze half-bushing by mean of a retaining compound... most exciting point.whish to work

[Propellor]

Tolerances sound ok. Good luck!

Is the scroll necessary?

[steveD]

Have you considered fitting a small peg to stop it from rotating?

[guest1931]

Dear steveD,
You are right.A peg is a safe lock and a standard  method.I tried to find out a stiff and small peg to avoid probable movement,but I do not know how.
It's a  not a thick bushing,so shocks would loose the peg(pin).It experienced by some experts.Here I wish the individual retaining compound fixes the bushing.
do you have any comments?thanks. 

[timbo]

Great bit of engineering. Really enjoying this thread, and learning a bit as well, so thanks 

[Propellor]

...
do you have any comments?thanks.

I've been following this thread with interest and I wish mehranx good luck. I hope you get a good result!

The observations I  have are:-

The new bush will need a good concentric seating in the head with the most contact area possible to support the bush and give the best chance for the loctite to work.

The clearance between bush and shaft looks about right IMO, but I'd worry about the roundness once it is cut.

The main worry I have is that oil will surely leak quite badly out of the slots left by the cutting in half.

I don't expect the loctite will hold out, but I have been wrong before!

To get a perfectly circular bush, in two perfect halves with no gap in the joint, of that very narrow wall thickness is a very difficult challenge, to say the least!

The very best of luck mehranx.

[guest1931]

Thanks allot friends,I'll check and report the result...

[Dick Scratcher]

If you're successful there methranx your could have the makings of a viable business.

[guest564]

What about using some kind of 'tab' like on a car's main bearing shells.

[steveD]

The biggest problem is that you have made a bearing and then split it by hacksaw. This is fine for a slow speed bearing NOT under pressure.
You will lose oil pressure through the gap, which will loose oil pressure to the rest of the engine.

Steve

[Propellor]

The biggest problem is that you have made a bearing and then split it by hacksaw. This is fine for a slow speed bearing NOT under pressure.
You will lose oil pressure through the gap, which will loose oil pressure to the rest of the engine.

Steve

Yip, that's exactly my take on things Steve.

I can't see any oil feed holes anywhere either, which is puzzling.

[steveD]

I have just had a look at the manual and it says that the bearings can be replaced by needle roller bearings, which leads me to think that there is NO pressure feed to the plain bearing surfaces! In which case how is the camshaft lubricated?
I haven't got a head to examine so tis is purely speculation, but the lubrication can be only from 'splash' in the area. In which case it will not make much difference to have a gap in the 'shells', which may help lube in that area.

Just my thoughts.

PS I have got my RS working and MOT'd, looks good but too busy to get it out for a ride

[Propellor]

Maybe the oil is fed up a stud and into the end of the camshaft.

The end bearing could take a straightforward needle bearing but the other bearing would need to be a split bearing because it is trapped between the cam and sprocket mounting flange. Unless the flange is machined off.

're oil pressure . If the little hole I see on the photo is for oil feed then it maybe is just restrictive enough to maintain pressure upstream even if switched to needle bearings? This is pure guesswork however! I can't see the standard setup relying on splash.

[guest1931]

Now,the engine completed montage, first testing was ok during two 10 minutes in 1200 rpm.

[guest1931]

First riding test don,every thing is ok,just a little noise due to cam and new plain bearing.