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Bikes, Hints'n'Tips => Fazer 1000/FZ1 corner => Topic started by: Gray fox on 07 May 2012, 08:47:06 pm

Title: Exup theory
Post by: Gray fox on 07 May 2012, 08:47:06 pm
The following theory was expounded following the consumption of several pints of real ale (Stella) in my local hostelry. The exup valve causes back pressure at low (sub 5000) rpm engine speeds, this in turn prevents unburnt fuel from exiting the exhaust due to valve overlap. At high rpm there is no time for the incoming mixture to get to the exhaust valve. This is the reason for the exceptionally good fuel consumption of my Gen 1, and a good reason for not removing the exup. Any comments most welcome.
 
Title: Re: Exup theory
Post by: solorider on 07 May 2012, 08:55:24 pm
it is a bit more complex than that,it works by sending the pulse back to the exhaust port which stops the incomming mixture from going into the exhaust,an exhaust can only be designed to work for a short rev range efficiently.but the exup only works on the mk1 fazer in this way,on the later fazer all it really does is to quiten the exhaust,it is the same as the valves on other make bikes
Title: Re: Exup theory
Post by: rjd1 on 09 May 2012, 10:58:00 pm
looked at mine the day
heared bike up cracked bolts for cover plate an both sheared
need to get easyouts
its all workin fine on the plus side
Title: Re: Exup theory
Post by: VNA - BMW Wank on 10 May 2012, 07:09:21 pm
That's a bummer rjd1.

Best ask others about getting those screws out.  I've got a feeling it's generally a down pipe off job.

Do replace with stainless, you can get packs of cap screws from screw-fix which are ideal.  Just cut down to required size.
Title: Re: Exup theory
Post by: solorider on 12 May 2012, 09:48:11 am
I bought my screws off Ebay and I got the correct lengths,if you see the state of my downpipes mine were fit for one thing,scrap.the screws holding the exup valve in place were non existent,I had to dremmel the heads off and that did not take long