Velvetelves breather valve
- Thread starter Chris
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It's a flapper valve. It even lets air back in the crankcase.
The current philosophy (ok, my philosophy...) is a one way valve (reed) to let gases out and not back in. Hopefully keeping the crankcase at a near neutral pressure.
The current philosophy (ok, my philosophy...) is a one way valve (reed) to let gases out and not back in. Hopefully keeping the crankcase at a near neutral pressure.
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I can track that part to 'Gearhead Racing':
http://www.gearhead-racing.com/Parts/Parts.htm
This bike is shown in the eBay ad.: http://www.gearhead-racing.com/Workshop ... 0850cc.htm
But the location of the eBay seller is Beckermet, so perhaps there's a connection to RGM Motors?
http://www.gearhead-racing.com/Parts/Parts.htm
This bike is shown in the eBay ad.: http://www.gearhead-racing.com/Workshop ... 0850cc.htm
But the location of the eBay seller is Beckermet, so perhaps there's a connection to RGM Motors?
Chris
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Hi
Lab thanks for that information. That is a nice site. I am going back to look up where the race circuits are!!!
Some nice bikes & bits.
John stripping down the bike to clean it up & inspect it. I will find out which breather (timing cover or bottom rear) is throwing out the most oil!
Again it was not much oil but plenty of force in the pumping forcing throth back out of the catch tank (can) Fitting sponge over the top worked well.
all the best Chris
Lab thanks for that information. That is a nice site. I am going back to look up where the race circuits are!!!
Some nice bikes & bits.
John stripping down the bike to clean it up & inspect it. I will find out which breather (timing cover or bottom rear) is throwing out the most oil!
Again it was not much oil but plenty of force in the pumping forcing throth back out of the catch tank (can) Fitting sponge over the top worked well.
all the best Chris
Chris
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Hi John
Last seasons Steve Maney engine. Its an early one with steel crank web strengthened Combat cases & breathers. Took your advice & reduced the amount of oil in the tank. Set up a seperate catch tank for each breather for the final race of the year. Seems to be a pressure pulse producing throth & spray.
Could not find a Bunns breather set up.
Chris
Last seasons Steve Maney engine. Its an early one with steel crank web strengthened Combat cases & breathers. Took your advice & reduced the amount of oil in the tank. Set up a seperate catch tank for each breather for the final race of the year. Seems to be a pressure pulse producing throth & spray.
Could not find a Bunns breather set up.
Chris
Chris
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Hi John
Thanks for the phone call. I have now ordered 2 of Mikes Yamaha XS breathers from the tuning firm in Holland.
15 euros each & 15 euros for postage. JB weld purchased as well. I will be taking off the breather at the base of the crankcase & making up a blanking plate & gasket over the weekend. Need to look at the MK2 Seeley project as it has fallen by the wayside.
Thanks for the advice
all the best Chris
Thanks for the phone call. I have now ordered 2 of Mikes Yamaha XS breathers from the tuning firm in Holland.
15 euros each & 15 euros for postage. JB weld purchased as well. I will be taking off the breather at the base of the crankcase & making up a blanking plate & gasket over the weekend. Need to look at the MK2 Seeley project as it has fallen by the wayside.
Thanks for the advice
all the best Chris
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I have never been able to understand how adding any sort of valve helps this function. In my performance car engine building days we often put in crankcase evacuation systems which worked really well but they were plumbed into the exhaust system in the header collector pipe and created a venturi effect that seriously applied vacuum to the crankcase and added HP on any Dyno/track test. You could shut down the engine and hear the hissing for several seconds as the crankcase came back to atmospheric pressure. So that, I can understand.
But I don't see how some passive valve can do anything useful any better than a simple opening from the crankcase to the atmosphere - as in the old pre-emissions road draft system. I'm not saying it can't - just saying I don't understand how it works.
So...how does it work?
But I don't see how some passive valve can do anything useful any better than a simple opening from the crankcase to the atmosphere - as in the old pre-emissions road draft system. I'm not saying it can't - just saying I don't understand how it works.
So...how does it work?
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Yes, I can see that . But at higher RPM can the valve actually react quickly enough to open/close in a timely manner to maintain some crankcase vacuum? I guess if they are used on Japanese bikes for that function, they must work! 
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MexicoMike said:Yes, I can see that . But at higher RPM can the valve actually react quickly enough to open/close in a timely manner to maintain some crankcase vacuum? I guess if they are used on Japanese bikes for that function, they must work!
Reed valves can. Flappers? No.
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AHA! It uses REED valves! (I'm saying that like I actually know anything about them!)
Looked up the Yammie valve and re the above information, it looks like it does exactly what is wanted - pretty cool. I'll have to order one of those for my next "in the States" pickup - sadly won't be there till May and won't return to the Norton in Mexico until July. I suppose any Yamaha shop here (haven't noticed any) would have it as well though at a premium price. There are several Suzuki dealers around - do Suzys use a similar part?
Looked up the Yammie valve and re the above information, it looks like it does exactly what is wanted - pretty cool. I'll have to order one of those for my next "in the States" pickup - sadly won't be there till May and won't return to the Norton in Mexico until July. I suppose any Yamaha shop here (haven't noticed any) would have it as well though at a premium price. There are several Suzuki dealers around - do Suzys use a similar part?
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MexicoMike said:AHA! It uses REED valves! (I'm saying that like I actually know anything about them!)
Looked up the Yammie valve and re the above information, it looks like it does exactly what is wanted - pretty cool. I'll have to order one of those for my next "in the States" pickup - sadly won't be there till May and won't return to the Norton in Mexico until July. I suppose any Yamaha shop here (haven't noticed any) would have it as well though at a premium price. There are several Suzuki dealers around - do Suzys use a similar part?
So, while you can read up on the extensive threads around this valve on this forum, the short version is that it's not a Yamaha part. It's some breather that I'm not sure we've figured out what it really goes to, but it works and it's not that expensive.
So for now, XS Mike is the only source for this particular part.
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OK,got it - In reviewing the listing...I see that it is listed for a Yamaha XS 650 but it is not an actual Yamaha part. Thanks...guess I'll just order one for pickup in the States.
http://www.mikesxs.net/products-40.html#products about 1/2 way down the page...
http://www.mikesxs.net/products-40.html#products about 1/2 way down the page...
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MexicoMike said:
Yup, this one.
Ron L
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Has anyone figured out just what engine this valve was originally designed for? I recall some one posting that they saw one on the new Symba scooter, but I haven't been able to confirm it from a parts diagram. They don't seem to have been used on the Honda Cub, of which the Symba is a clone.
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