The New And Improved Unofficial R65 Forum V2
Technical Discussion => BMW Technical Q&A, Primarily R65 => Topic started by: recondotexas on January 16, 2013, 09:08:10 PM
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SO I see on this site and a few other places how folks remove the Pulse Air system. I am not planning on doing the re-fit but was curious what yall's thoughts are on that. Does it help? What are the benefits? Thanks for your opinions in advance. Oh yeah and montmil feel free to set your boy straight.
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When I had my motor swapped, the mechanic didn't reattach those fiddly bits and just plugged them. He said it saved me a couple hours labor ($$). I never noticed any functional difference. Exterior looks a little cleaner I guess? I suppose the downside is some amount of extra emissions.. plant a tree in your yard and call it a day.
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The pulse system, was put there to reduce exhaust emissions .
I guess by introducing fresh air into the exhaust, more unburned fuel in the exhaust had one last chance to be burned before leaving the exhaust system .
If you remove it, or disconnect it,you will not notice any change in engine performance .
The rubber hoses that go on the brass tubes on the carb, along with the valves in the airbox, can be a source of a intake leak if they fail .
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I thought I had done that already on the '83. No? Maybe I was just thinking about doing it...
Here's a nice DIY photo essay with the parts list included.
http://www.webbikeworld.com/Motorcycle-technical-articles/pulse-air/
Cruise by Lone Star BMW-Triumph up on North Lamar. They'll probably have what you need.
Could'a sworn I did that ::) Been hanging around Bengt Phorqs too much.
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Some people simply remove the system because it adds weight and complexity, and is another potential source of issues - specifically:
The pulse air has 'snorkel valves' in the airbox which are controlled by vacuum from the carburetors. When you are riding along at a good clip and 'chop'/release the throttle, the vacuum lines from the carbs should cause the valves to close, cutting off the flow of fresh air into the exhaust stream. It is designed this way because in this state, there will be alot of excess/unburned fuel in the exhaust flow and it air is introduced at that point, alot of backfiring (pop-pop-poppopopopopopopop!!!!) can occur. If the vavles start to stick/bind or a problem with the vacuum lines cause the valves to hang up, a common problem is excessive backfiring anytime you are slowing down for a stop light.
When all is working well though, it does reduce exhaust emissions - depending upon what your states' requirements are for evaluating vehicle emissions on bikes this old, you may want to keep it on there.
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Here in the Lone Star State, any automobile, pick 'em up truck or motorcycle 25+ years old is exempt from any and all emissions testing.