dyno-tron
Member
- Messages
- 444
- Location
- Near Chester, UK
Hi Peeps,
The attached pic is of a crank half from a 100cc racing engine (not the actual one I need to work on but basically the same). The main bearing journal nominal size is 20mm diameter, the minimum size due to wear before it is considered scrap is 19.95mm. The one I want to repair is 19.90.
Refacing is not permitted for racing - no mods, machining or additional metal allowed.
However - for a playtime engine it will rejuvinate an otherwise scrap engine, the reason this engine would be scrap is 'cos a new crank assembly is approx £500 and this engine with a new crank fitted would be worth approx £250 - go figure!! (BTW - a brand new engine is approx £1800).
As it is otherwise scrap I'm going to have a go at refacing the journals :-))
So - the question, could someone advise what welding rods to get please, I probably only need a couple? what amperage? any pitfalls?
I don't know what grade steel the crank is, just that it is "special grade" maybe EN24 at least, quite tough, spins up to 16K. the bearing that this journal rides on is a standard type deep groove ball bearing and it is a "sliding fit", e.g. snug fit and can be separated by hand, that is why the damn thing wears down :-(
Any advice gratefully received
The attached pic is of a crank half from a 100cc racing engine (not the actual one I need to work on but basically the same). The main bearing journal nominal size is 20mm diameter, the minimum size due to wear before it is considered scrap is 19.95mm. The one I want to repair is 19.90.
Refacing is not permitted for racing - no mods, machining or additional metal allowed.
However - for a playtime engine it will rejuvinate an otherwise scrap engine, the reason this engine would be scrap is 'cos a new crank assembly is approx £500 and this engine with a new crank fitted would be worth approx £250 - go figure!! (BTW - a brand new engine is approx £1800).
As it is otherwise scrap I'm going to have a go at refacing the journals :-))
So - the question, could someone advise what welding rods to get please, I probably only need a couple? what amperage? any pitfalls?
I don't know what grade steel the crank is, just that it is "special grade" maybe EN24 at least, quite tough, spins up to 16K. the bearing that this journal rides on is a standard type deep groove ball bearing and it is a "sliding fit", e.g. snug fit and can be separated by hand, that is why the damn thing wears down :-(
Any advice gratefully received