Xs650 mount near tank or breather?
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JimC said:
Always the best way after all some owners know a lot some a little and maybe some almost nothing but thats what this forum is for even after 28 years of owning a Commando it was only after joining this forum that I discovered thw wonders of the XS650 reed valve and it really does work, minor irritating oil leaks like the one from the rev counter drive dissapeared without having to modify the part which was always on my list....(I also did some research work for Bernard Hooper) and this modification had never crossed my mind.
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"Research? It reads like snake oil."
The blog contains measurements of crankcase pressure, time to distance runs with/without system, etc. To me, that's testing. There is nothing like this available related to the XS650 valve. Sure, he's trying to sell something but the fact is, he has meaningful data posted. Whether the data supports the fact that it's a better system than the XS650 alone is up to the reader/buyer. However, based on the logic of the two and the design of the engine, I believe the Bunn provides better crankcase ventilation than it is possible for the XS650 to provide since the bunn allows air in and out as opposed to just out. In any case, as the old saying goes, you vote with your pocketbook!
The blog contains measurements of crankcase pressure, time to distance runs with/without system, etc. To me, that's testing. There is nothing like this available related to the XS650 valve. Sure, he's trying to sell something but the fact is, he has meaningful data posted. Whether the data supports the fact that it's a better system than the XS650 alone is up to the reader/buyer. However, based on the logic of the two and the design of the engine, I believe the Bunn provides better crankcase ventilation than it is possible for the XS650 to provide since the bunn allows air in and out as opposed to just out. In any case, as the old saying goes, you vote with your pocketbook!
Hortons Norton
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Mike, The idea is to not allow the air to flow back into the crankcase.
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Hi , that's why , i am scratching my head , the "bunn" allows some air to go in , while on the other he tries to get rid of air inside..............all I had understood from Comstock posts and other XS valves is that we are trying to empty the cases with that air...........
Although the xs650 valve is a very nice item, I have found that the pressure needed to actuate the reed is just a little to great and has caused leakage from the crank seal where the motormite unit has operated with out leakage.
I have revamped the outlet part of the xs650 unit by pulling the pipe out, tapping to 1/8 pipe tap (no drilling needed) and screwing in a 3/8 brass barb.
Anybody who may want it is welcome to it. Private message me to discuss.
I have revamped the outlet part of the xs650 unit by pulling the pipe out, tapping to 1/8 pipe tap (no drilling needed) and screwing in a 3/8 brass barb.
Anybody who may want it is welcome to it. Private message me to discuss.
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pvisseriii said:
PM sent.
acadian said:
Being that this is a free flowing (breather) intent, any pressure would be too much. Any more than a very little could cause oil to build up before the reed valve, compounding the problem requiring even more unwanted pressure to operate the valve.
Try this: blow air through the valve, then try to blow 20w50 through it. Or straight 50w. It won't be long before engine oil starts collect in the primary and on the ground.
Keeping air from coming back through is one thing. Keeping it from escaping is another. Any restriction is unwelcome.
When I changed to a belt drive I noticed I had oil passing the crankshaft seal. I installed a new seal. Still passed oil. I then installed the Motormite vacuum brake check valve. Primary was dry for a few hundred miles, but soon had oil in the primary. Finally got around to installing the XS650 PCV valve. No more oil in the primary. No more oil leak from the tach drive. Like they say, "The proof is in the pudding".
Description of the XS650 PCV valve:
Reed type Positive crankcase ventilation Valve.
Valve hooks to engine top breather vent and allows expelled air out but reed
prevents air re-entering quickly so a very small vacuum is created in the
crankcase. A small power increase has been noted during dyno tests (most
notable on pre-77 engines) and the crankcase vacuum helps prevent crankcase
pressure from pushing oil past oil seals and case joints.
Mike's XS web site
If you are running a chain primary the small amount of oil passed through the crankcase seal is probably unnoticeable and of no consequence. Getting rid of the other oil leaks is a big plus in my book, not to mention a power gain. All for $16. The CNW/Jim Comstock crankcase breather valve will probably do an even better job.
Description of the XS650 PCV valve:
Reed type Positive crankcase ventilation Valve.
Valve hooks to engine top breather vent and allows expelled air out but reed
prevents air re-entering quickly so a very small vacuum is created in the
crankcase. A small power increase has been noted during dyno tests (most
notable on pre-77 engines) and the crankcase vacuum helps prevent crankcase
pressure from pushing oil past oil seals and case joints.
Mike's XS web site
If you are running a chain primary the small amount of oil passed through the crankcase seal is probably unnoticeable and of no consequence. Getting rid of the other oil leaks is a big plus in my book, not to mention a power gain. All for $16. The CNW/Jim Comstock crankcase breather valve will probably do an even better job.
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A couple of other thoughts -
I agree that the CNW setup is probably the way to go with a closed crankcase system.
Closed crankcase setups were implemented for engine emissions, not for best crankcase breathing; I think that a traditional road draft system from the crankcase (NOT the timing case) would be an improvement over any valve using an existing Commando breather setup.
The statement (which I have read) re the xs650 providing a slight increase in HP is of no value at all. There is no data and no statement of the conditions. It's meaningless - anyone can make a claim such as that. In a previous life I was very involved in dyno testing of automotive performance parts and that's a classic statement that SOUNDS meaningful but is not. I have seen published dyno tests (including some I performed) advertising a 13 HP increase for an aftermarket muffler when, in fact, the muffler would result in a slight LOSS in HP over a new factory muffler. The advertisement left out the pertinent data. The new aftermarket muffler replaced an old, rotted out, clogged oem muffler. Stuff like this is REALLY common in the aftermarket parts advertising world.
I'm not saying the XS isn't as good or better as the Bunn (which has a filtered intake per what I've read) but It's worth looking at and investigating all this stuff. The CNW is the way to go IMO because it get's the timing case out of the picture which has to help breathing and oil drainback from the int rocker. But since it requires crankcase machining and welding up the holes between the crankcase/timing case, it's only feasable to me if the engine is being disassembled for another reason.
I agree that the CNW setup is probably the way to go with a closed crankcase system.
Closed crankcase setups were implemented for engine emissions, not for best crankcase breathing; I think that a traditional road draft system from the crankcase (NOT the timing case) would be an improvement over any valve using an existing Commando breather setup.
The statement (which I have read) re the xs650 providing a slight increase in HP is of no value at all. There is no data and no statement of the conditions. It's meaningless - anyone can make a claim such as that. In a previous life I was very involved in dyno testing of automotive performance parts and that's a classic statement that SOUNDS meaningful but is not. I have seen published dyno tests (including some I performed) advertising a 13 HP increase for an aftermarket muffler when, in fact, the muffler would result in a slight LOSS in HP over a new factory muffler. The advertisement left out the pertinent data. The new aftermarket muffler replaced an old, rotted out, clogged oem muffler. Stuff like this is REALLY common in the aftermarket parts advertising world.
I'm not saying the XS isn't as good or better as the Bunn (which has a filtered intake per what I've read) but It's worth looking at and investigating all this stuff. The CNW is the way to go IMO because it get's the timing case out of the picture which has to help breathing and oil drainback from the int rocker. But since it requires crankcase machining and welding up the holes between the crankcase/timing case, it's only feasable to me if the engine is being disassembled for another reason.
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"I'm not saying the XS isn't as good or better as the Bunn (which has a filtered intake per what I've read) but It's worth looking at and investigating all this stuff." Mike I think this has already been done over the last couple of years, On my bike alone I know for a fact it has stopped all of the little weeps my bike had. Norton knew a long time ago that the crankcase needed to be vented and tried with the timed breather, But there was no way it could move the volume of air needed. I don't think the guys on here are using them to get more horsepower but just trying to stop the little leaks they have, And for this purpose they work very well. I notice you are fairly new to the forum and want to say welcome, Do you have a Norton? Take care and ride safe, Chuck. :wink:
After I installed my XS650 valve I passed a Ducati Monster 1200. Did I mention the Ducati was parked?
No, it's not about a power increase or getting the crankcase to expel air any better. As far as I can see, it's about keeping the crankcase from being charged with air during the compression and exhaust strokes. I.e., ideally no air in the crankcase to pressurize during the intake and power strokes. That is a big benefit for eliminating oil leaks caused by a pressurized crankcase. I think we can all agree the XS 650 valve does not rob any horsepower.
From the research that Jim Comstock did with reed valves, I'd venture to say the place to hang any valve is the crankcase itself. Unfortunately, I did the Old Britts crankcase/timing chest mod on my 72. Now, I'm going to undo the timing chest mod and see if I can get the XS650 valve to mount on the crankcase, ala CNW.
No, it's not about a power increase or getting the crankcase to expel air any better. As far as I can see, it's about keeping the crankcase from being charged with air during the compression and exhaust strokes. I.e., ideally no air in the crankcase to pressurize during the intake and power strokes. That is a big benefit for eliminating oil leaks caused by a pressurized crankcase. I think we can all agree the XS 650 valve does not rob any horsepower.
From the research that Jim Comstock did with reed valves, I'd venture to say the place to hang any valve is the crankcase itself. Unfortunately, I did the Old Britts crankcase/timing chest mod on my 72. Now, I'm going to undo the timing chest mod and see if I can get the XS650 valve to mount on the crankcase, ala CNW.
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"Do you have a Norton? Take care and ride safe, Chuck. "
Thanks Chuck. Sorry if I am rehashing something that had been done to death by folks with a lot more knowledge of these bikes.
Yes, I have a 73 850 roadster that I just recently converted to a fake fastback - brought all the parts (tank, sidecovers, tailpiece, rear mudguard) back from the UK to Mexico when we were visiting the UK last fall. Fake because, of course, there was no 73 or 850 fastback. But only us Norton Geeks would know that. I had a 71 commando back in the day that I road as my primary transportation and amateur road-raced in my quest to become a professional road racer and the next Mike Hailwood. I was not successful.
But I have a pretty good bit of "performance-riding" experience on a Commando...though some years ago! I get a bit of a kick out of all the Commando "problems" that exist today that we didn't know existed back then and we rode them a HECK of a lot harder than we do today!
After I sold that bike in '78 I had a sucession of Honda sport bikes until the early 90's when I swiched to Ducatis. I bought a new 92 900SS, sold that for a 916, sold that for a 996. I tracked the 996 regularly at Lime Rock when we lived in NY up to late '06. I also bought a new Hardly-Ableson in the mid 90's but it just wasn't/isn't my style and I sold it a year later. I decided to buy a Commando because I always missed my '71 and, in late '06, since we were moving to Mexico City, I sold the 996 but kept the Commando.
Thanks Chuck. Sorry if I am rehashing something that had been done to death by folks with a lot more knowledge of these bikes.
Yes, I have a 73 850 roadster that I just recently converted to a fake fastback - brought all the parts (tank, sidecovers, tailpiece, rear mudguard) back from the UK to Mexico when we were visiting the UK last fall. Fake because, of course, there was no 73 or 850 fastback. But only us Norton Geeks would know that. I had a 71 commando back in the day that I road as my primary transportation and amateur road-raced in my quest to become a professional road racer and the next Mike Hailwood. I was not successful.
But I have a pretty good bit of "performance-riding" experience on a Commando...though some years ago! I get a bit of a kick out of all the Commando "problems" that exist today that we didn't know existed back then and we rode them a HECK of a lot harder than we do today! After I sold that bike in '78 I had a sucession of Honda sport bikes until the early 90's when I swiched to Ducatis. I bought a new 92 900SS, sold that for a 916, sold that for a 996. I tracked the 996 regularly at Lime Rock when we lived in NY up to late '06. I also bought a new Hardly-Ableson in the mid 90's but it just wasn't/isn't my style and I sold it a year later. I decided to buy a Commando because I always missed my '71 and, in late '06, since we were moving to Mexico City, I sold the 996 but kept the Commando.
Hortons Norton
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Sold the Ducati and kept the Norton, Wow that's cool to hear. Wait your Mexico Mike right? Ha Ha, LOL. Had me thinking there for a minute.
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