Hi fonts of knowledge. I can use a 13mm ring and open ender but I am no engineer. Our BMW 750 has Venolia pistons and is down on compression, from 150psi a couple of years ago to a paltry 95psi now. One thing we are looking at is rings but I am struggling to get two ring sets. It has 82.9mm bores, so that is 1mm over standard, in excellent fettle and the Venolias have two compression rings and an oil control/oil scraper ring. One of the compression rings was broken in its groove when I did an exploratory last night, but no other damage.
Anybody out there know where I can get a Venolia piston ring set? I am awaiting a response from some USA companies but obvs would prefer a more local solution. New pistons would be an easy option but have you seen the cost!
Cheers all, and well done me for not touching the engine for a full six months when it is the Mallory practice day tomorrow! Jon Ryden, Lincoln.
Venolia piston ring sets for 1970's BMW 750 twin
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spiney norman
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Re: Venolia piston ring sets for 1970's BMW 750 twin
Try these people, COX and Turner at YEOVIL tel 01935-826816.
They specialise in matching and supplying rings to suit any make of piston.
As you have the old rings as a pattern this should not be a problem for them.
It is always best to give the bores a "very" light hone when fitting new rings, and to make sure that the ring grooves are perfectly clean.
Check the ring grooves in the pistons have not worn oversize, especialy the groove which had the broken ring, if they are worn,new rings will fail very quickly.
As the compression is very low, it will be best to check that the valves have not stretched,and that the valve springs are still the correct length,
as you have the cylinder heads off.
Hope this helps, Howard.
They specialise in matching and supplying rings to suit any make of piston.
As you have the old rings as a pattern this should not be a problem for them.
It is always best to give the bores a "very" light hone when fitting new rings, and to make sure that the ring grooves are perfectly clean.
Check the ring grooves in the pistons have not worn oversize, especialy the groove which had the broken ring, if they are worn,new rings will fail very quickly.
As the compression is very low, it will be best to check that the valves have not stretched,and that the valve springs are still the correct length,
as you have the cylinder heads off.
Hope this helps, Howard.
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spiney norman
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Re: Venolia piston ring sets for 1970's BMW 750 twin
Howard, thanks muchly for the information, and for taking the trouble to respond.I shall be trying the Yeovil contingent on the morrow. Be nice to keep the old nail running a couple of more seasons before I buy a proper money pit in a final attempt to finish in the top ten in a niche avenue of a weird branch of a weird sport which is derived from a similarly weird sport. Jon Ryden, Lincoln.
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spiney norman
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Re: Venolia piston ring sets for 1970's BMW 750 twin
Just to box this off in case anyone searches for Venolia pistons and rings in the future.... it turns out that they have ceased trading, but if anyone still runs Venolia pistons, then the rings Venolia use are also American; Total Seal who are still trading and have a UK distributor in York called Performance Unlimited, Chessington Way. So despite Howards excellent advice I took a Pistonola to York, they measured up and are are supplying a set of rings, jobs a gudgeon as they say. Thanks again Howard but by chance I got sorted.
Re: Venolia piston ring sets for 1970's BMW 750 twin
Glad you got sorted, I never thought of Performance Unlimited, and they are only three miles from where I live !