Air filters, Oils arent Oils Sol

[James RookyardMember]

I use kero. I have a bucket with a lid and in the bottom I have a raised bottom made from an old truck airfilter (the mesh on the outside). This way the dirt settles out of the kero and it stays clean for ages.
I have a second bucket with a lid and I have my filter oil in this. I drop the filter in and oil it in there. I also make sure I roll the foam around in my hands to get a good uniform coating right through the foam.
the biggest killer of CRF-X valves I reckon is the ridiculously designed airbox. Why did they make it so hard to get the filter in there????????????

[Geoff ForshawMember]

Hey Jimmy, the biggest killer of CRF, WRF, YZF valves etc and most other manufactuers with titamium valves is not the air filtration, because if it was the bore and rings would be rooted and the piston skirt would probably be scuffed. And in most instances bore, piston, rings etc are ok. After many hours of engine building, then disassembly and inspection and after consultation with many other people experienced in the field both here and overseas.
The main reason is that the valves in these bikes are manufactured from a compressed titanium powder not a billet. (Cheap to manufacture) They have a hardened external surface which after time the valve seat actually work hardens and becomes far harder than the valve; which in turn breaks through the surface hardening of the valve. Then the valve seating surface pounds away at the seat and starts to take the same shape as the seat. Then slowly loosing valve clearance till there is none and the bike won’t start as it has no compression. It is called Valve Recession.
This is also a common problem with the Toyota BEAMS 3SGE engines that I build for rallying. (The cylinder Heads are manufactured by Yamaha and they have the same valves). Another reason for this is cam profile, but this is a story for another day.
The fix for this is alternative valve seat/valve combination, and I don’t mind saying this as the best people to sort this out is RAMS Head Service in Windsor.

Hope this helps a little to understand this “Valve Recession” issue.

Cheers,
Lefty

[GregMember]

Lefty wrote:

Hey Jimmy, the biggest killer of CRF, WRF, YZF valves etc and most other manufactuers with titamium valves is not the air filtration, because if it was the bore and rings would be rooted and the piston skirt would probably be scuffed. And in most instances bore, piston, rings etc are ok. After many hours of engine building, then disassembly and inspection and after consultation with many other people experienced in the field both here and overseas.
The main reason is that the valves in these bikes are manufactured from a compressed titanium powder not a billet. (Cheap to manufacture) They have a hardened external surface which after time the valve seat actually work hardens and becomes far harder than the valve; which in turn breaks through the surface hardening of the valve. Then the valve seating surface pounds away at the seat and starts to take the same shape as the seat. Then slowly loosing valve clearance till there is none and the bike won’t start as it has no compression. It is called Valve Recession.
This is also a common problem with the Toyota BEAMS 3SGE engines that I build for rallying. (The cylinder Heads are manufactured by Yamaha and they have the same valves). Another reason for this is cam profile, but this is a story for another day.
The fix for this is alternative valve seat/valve combination, and I don’t mind saying this as the best people to sort this out is RAMS Head Service in Windsor.

Hope this helps a little to understand this “Valve Recession” issue.

Cheers,
Lefty

Now Lefty let me start my saying your knowledge of performance engines is way above my level and I agree with what you have written above but not all valve recession is because of that

If dusting has nothing to do with it why is it only the inlets. I have done enough dusted bikes here in the last few years to say I have seen dust evidence that destroyed inlet valves, yet piston and bores have been ok. I know what your are saying we see the results of dusting at work

Why in the past has CRFs suffered not WRs if they have the same style valves

Why did only the GHR bikes that raced off road as opposed to their motard bikes (when they did a few seasons) close inlets, yet they admit the motard engines got flogged harder. No dust motard remember or no where near as much

Why with the use of new filters every filter service did they extent valve life to over 100hrs (can be no residual dust left in a new filter eh)

Not arguing that valve recession can be and is caused in some cases from material failure as you stated

Lastly RAMs do good work but after seeing some of their bills they don’t mind charging, which is ok if your the builder passing it on :laugh:

TB

[James RookyardMember]

They should have just put stainless valves in them and forgotten about the titanium. The power loss is pretty much un-noticable. I havnt had a valve issue since fitting them.
I agree its the hard surface of the valves that lets go, as to the causes I will stay out of the debate.
On an aside, my bottom end has just failed, due to running too lean according to my dealer. Perhaps this may have a bearing on the valve issue on standard CRF valves as well?
Sorry to go off topic.

[RoyMember]

I won a can of spray on air filter oil at the north star trail ride. Can’t remember the brand. No way it’s going on my air filters though. Figured it would be alright for chain lube though.

[DeanMember]

Bundyroy wrote:

I won a can of spray on air filter oil at the north star trail ride. Can’t remember the brand. No way it’s going on my air filters though. Figured it would be alright for chain lube though.

Roy you can spray your pre-filter with it or use on your whipper snipper or lawn mower, wouldnt use it for chain lube tho.

Ollie

[SeanMember]

An old thread but well worth a read, been using Maxima filter oil and cleaner.

[Author]

Posts