Reclaiming flogged out Honda cam bores

[vmxrider]

Here's how this guy has done it on an XR 75, same principle for all Hondas that have cams running directly in the head.
Have a look at the picture in his add.
http://www.ebay.com.au/itm/HONDA-XR-75-80-HIGHLY-MODIFIED/121376179488

[HeavenVMX]

Is brass the best material for that application?

I'm no metallurgist but I would have thought bronze or phosphor bronze would have been the best material.

Straight brass is not really a great bearing material for loads or speed from memory. Not a machinist either so happy to be corrected.

[vmxrider]

I agree, bronze would be my choice of material if I were doing this.

[mustanggrahame]

I wouldn't have thought there was enough room to machine out the head and cam bearing shell and then put in another bearing. The best way would be to machine the cam bearing round again and make a new camshaft that fits.

[MX?]

This is why they do needle roller cams...much better job surely?

[brucey]

It all depends who is paying and the level of expertise of the person doing the Job

In this case a high brass tin content alloy would be okay as say full hard will be an excellent choice lets face it all the bottom end of your cars have the same.

You can certainly use Nickel alloy bronze as well you could even go full hog and remove the tower all together and replace it with new towers a la Laverda 1000 cams done this as well

The only problem is that there is no ears on the shells that i can see they might be pinned but the nip and crush will need to be good

If its me playing in the shed on my mill i would go for the bearings but you need to be careful as the oil supply would need to be restricted

As in all of these cases if you are paying to have it done or using mates rates be care full if you try to sell it on

Bruce

[sleepy]

That sort of job has been done for years although there is no need to have the rear bearing split as it can fit over the end of the cam. My guess is the shells are made out of bronze and not brass as the add says. Even making them out of aluminium would work ok.

[brent j]

A guy in NZ in the 70's bushed Honda XL250/350 motors with shells but used a countersunk capscrew to locate them (or at least the lower one)
The material was a bronze/Teflon matrix. I had my TL250 done and it lasted well.
The guy doing the conversion was the father of an apprentice I went through trade school with. The son had an XL350 and the cam flogged out the bearing surfaces

On XR200 motors I've bored the head and rocker cover, machined the cam end to take a roller bearing. The other end is a bit different. I've heard of removing the sprocket mounting flange, fitting a bearing and reattaching the sprocket.
I made a new ignition housing and incorporated a bearing in that so it sat outboard of the cam sprocket