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Post by JonW on Feb 17, 2015 23:52:05 GMT 1
Some one has had a little go at tidying up the transfer intake and also the flashing (I guess) on the reed cage mount on my LC cylinders, do we think this will have any detrimental effect on these cylinders, and / or is there anything else I could do to improve their work without resorting to sending them away to a pro? The reed area:  The transfer intakes: (my other cyls with no work)  These cyls:  Together:  The rest of the cylinder seems to measure and look much like standard luckily  |
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Post by steve h on Feb 18, 2015 0:12:39 GMT 1
None? Don't look like they've been attacked by a monkey with a rotary file  Look pretty good in pics. Std measurements =  Now you can get them ported properly |
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Post by JonW on Feb 18, 2015 0:13:37 GMT 1
Thats my hope Steve, but I thought I should check |
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Post by arrow on Feb 18, 2015 0:44:27 GMT 1
Agree with Steve, look ok to me.
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Post by slinger on Feb 18, 2015 13:24:14 GMT 1
Nothing been done to them really Jon!!
Air don't flow through the reed box, air flows from the center of the reed cages. Removing the large "wind breaks" at the inlet window will help. It looks like the EX duct has been cleaned as well but I guess it retains the stock height, pretty much a stock cylinder.
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Post by JonW on Feb 18, 2015 22:37:59 GMT 1
Thats guys! Glyn, I did check the heights of the ports between the cyls and while it wasnt an exact measure (i used a tape) I found them to be the same across the units, so I was hopeful that whoever had them had just done a bit of cleaning up of flashing etc and not any real work. The exhaust looks and feel (its pretty grubby LOL) to be un-messed with but like you I would have expected them to had had a play in there as well. by wind breaks, do you mean the ones on the main inlet either side at the top? |
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Post by slinger on Feb 19, 2015 1:40:20 GMT 1
Yeah the liner that hangs down at the top of the inlet window.........they rob you of power everywhere in the power curve.
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Post by slinger on Feb 19, 2015 1:47:38 GMT 1
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Post by JonW on Feb 19, 2015 7:58:54 GMT 1
Ohhh, I can actually do that... have grinder will travel etc  I did wonder when I looked at that inlet port quite what Yamaha were thinking, they seem to be agreeing that what I asusme is the port duration is ok by using the height, yet only allow a small amount of air/fuel in via it - its almost like they wernt sure when they designed it and thought they'd give it a partial go or something LOL! I always remember that any obstruction loses power, so adding these two side curtains would be detrimental, and they could have just made the power height lower with the same width to achieve the same thing, couldnt they? I asusme from what you said that if i do just that 'removal' Im not going to make it too peaky or anything as Im all about using this on the road? Its moving the ports up and down that causes the peakyness I think? As usual your work always looks so nice n clean Glyn! |
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Post by Tobyjugs on Feb 19, 2015 9:53:09 GMT 1
Yeah very tidy. I always think how do it, just like a sculpture with science thrown in!
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Post by slinger on Feb 19, 2015 12:16:45 GMT 1
If we look at the inlet window for common Yamaha engines like the LC,YPVS,RD400/350 etc which are cylinder reed fed it's good to understand how the air flows into the engine. Below is a CFD model picture of a set of reeds flowing when the petals start to open,it,s quite a thin column that will exit the reeds.This column will be heading for the point of origin (the intake pulse)which is under the piston crown. As with anything to do with fluid dynamics it will take the shortest root.  In the next pic I've set the piston to 80* BTDC, this 80* is quite important as this is where the max flow will happen.50% of your window area is closed off to the piston skirt.........not good.Lifting the roof of the inlet window to the bottom ring @bdc will gain a huge amount of window area at this critical phase of the intake.   Lifting the roof will have no effect no reliability as long as the bottom ring is still supported @bdc. There is a lot of WTF with Yamaha cylinders lol |
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Post by JonW on Feb 19, 2015 22:23:30 GMT 1
WTF indeed. that pic is mental, its like the cylinder was made by one guy and the piston by another to fita bike neither of them has seen. Thanks for posting this stuff Glyn, I love seeing and reading about this, its the one area i always wish I knew more |
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Post by Tobyjugs on Feb 19, 2015 22:26:42 GMT 1
Very interesting thanks for the explanation. Right where's me file |
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Post by billyboy on Feb 19, 2015 23:05:43 GMT 1
great pics and work Glyn
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Look pretty good in pics. Std measurements = 
