Hand reamers

[superbike]

I'm looking to find the best 7mm hand reamer I can find. At the moment I'm using an hss spiral flute by Dormer. It dulls very fast reaming bronze valve guides.

I have heard of reamers that also have serrated edges which can be a lot better ?

All help welcome,

Chris

[Guy Croft]

Chris,

there is nothing wrong with your Dormer reamer but it's almost impossible to ream copper-alloy guides by hand, esp in-situ. Before anyone jumps up and says 'I've done it.., well, yes I have too. I mean reaming by hadn or with a haevy duty drill is a very fraught job that is as likely to wreck the guide as be successful. The friction between steel and dry copper is so high you'll more likely end up with a jammed or snapped reamer, grooves in the guide or a guide bore that's way off line. There is no lubricant that will help much either, if water-based it will run out and leave your reamer completely stuck and if a sticky compound gum-up the bore with shavings. Reaming is best done in the milling machine of course but it must be aligned with great precision. That said, most well-equipped (well funded?!) shops who do a lot of guides are using automated hining machines now.

I don't ream, I use 180 and 240 grade Z grain alumina zirconia Flex Hones with a hand drill and oil. You can dwell on the tight spots inside the fitted guide without making the bore over-large. Get onto Pacehigh at 01707 327788. My latest generation guides are designed to be tight after fitment, honing with small brush hones produces really snug fitting valve stem with excellent oil retention. This is BTW - featured in my DVD!

GC

[4v6]

Just wished to add that after taking Guys advice regarding these flexhones i wouldnt use anything else now.
They are as Guy suggested, absolutely the tool for the job and theyre so easy and forgiving to use.
A fantastic product.