The winter plan calls for new valves and guides for my 1965 A65. Currently I have cast iron guides and steel valves but my supplier has both cast iron and bronze guides plus steel and stainless steel valves. What is the best combination?
Without frequent roadside repairs there is no fun in riding!
Gordo. What type of guides depends upon what type of valves. The guides need to be harder than the valves so that the stems wear rather than the guides as replaceing the valves is much easier than the guides and you can do it at infinitum with little problems for the head. OTOH there is a very limited number of times that you can remove the guides before the head is cactus.
For this reason I have changed my ideas & go for guide sleeveing rather than guide changing. If you do decide to replace the guides, remove the old ones first, then check the head for damage &/ or wear as often removal takes significant amounts of the head with them thus requiring you to replace them with oversized guides but you will not know till the old ones are out & you measure up ( or rather down) the hole.
Bike Beesa Trevor
Re: Cast Iron or Bronze Guides for A65?#30966 11/06/0710:24 pm11/06/0710:24 pm
I do not have good experience with phosphor bronze guides in A65 ( specially exhaust guides get used fast ). I changed them to cast iron + Black Diamond valves and after 1500 miles had a opportunity to check them ( seized engine ). They didnt have any sign of getting worn - no difference comparing to the new ones.
Re: Cast Iron or Bronze Guides for A65?#30969 11/07/077:25 am11/07/077:25 am
I use 'COLSIBRO', an alloy of copper,silicon and bronze. This enables the guide to be made with a 0.001" valve to guide clearance. This makes for a quieter engine, less likely to bounce and rattle. I've had two BSA unit twins with this mod, work done by P.Seager Engineering, IPSWICH UK. He turns a guide from scratch on the lathe after measuring the head and rather than an off the shelf guide, his actually WORK and FIT properly. Highly recommended A+
Gavin You can't make a silk purse from a sow's ear.
Re: Cast Iron or Bronze Guides for A65?#30971 11/08/0712:54 am11/08/0712:54 am
A Petro Canada told me the gas we're getting here,( unleaded, low sulpher, ethanol) no longer has any lubrication qualities. Transfer of bronze to the valve stem causing stickng or siezure is not uncommon. (mainly on Triumphs) I've switched to Rowe cast guides and black nitrated valves, no sticking and long life. The vast majority of engines now use cast guides, high quality valves. Rick
Re: Cast Iron or Bronze Guides for A65?#30972 11/08/071:09 am11/08/071:09 am