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Post by billyboy on Jul 31, 2013 20:28:29 GMT 1
just cleaned and put back together the fibre reeds in their blocks and they dont seem to make an airtight seal at the top , the rubber seating face is all clean ,just think the reeds themsleves are a little warped , will this affect the running to any degree ?
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Post by ianr4863 on Jul 31, 2013 20:42:11 GMT 1
Had similar problems myself
Do you have the corner cut offs in the correct position ?
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Post by billyboy on Jul 31, 2013 20:45:53 GMT 1
not sure i know what ian ? the ones on the lower end ? how did you get round your probs ?
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Post by steve h on Jul 31, 2013 20:53:35 GMT 1
just cleaned and put back together the fibre reeds in their blocks and they dont seem to make an airtight seal at the top , the rubber seating face is all clean ,just think the reeds themsleves are a little warped , will this affect the running to any degree ? Pressure in the cases opens and closes them. (Harmonics) Back in the day Harpower reeds were the leading brand and they were slightly warped, with a gap of 1.5mm in the middle of the reed. When the reed was flush with the block you had to re-bend them using hot water and gentle pressure. I don't think a little air gap will do much harm if any, to the running of the bike |
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Post by billyboy on Jul 31, 2013 21:06:36 GMT 1
cheers steve ,the gap is only the thickness of some paper so i would think that would be ok , cheers
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Post by Bozzy on Jul 31, 2013 21:07:59 GMT 1
Interesting because I have the Yamaha racing reeds in and they did not fit flush. Unlike the metal ones that lay fit snug upto the seal the fibre one had slight gap......but I assumed the get sealed with compression etc
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iainw
Drag-strip hero
Posts: 289 
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Post by iainw on Jul 31, 2013 22:09:52 GMT 1
I had the standard reeds in my 4L0 and there was a slight gap that you could see when holding them up to the light. I replaced them with a set of Boyesen's which closed it completely. The flat spot was terrible from 4-6k more like shite running, but this vastly improved it and now it is just a slight flat spot and it'll pull through it in top.
My opinion is that the reeds are to prevent blow back and presurise the crank case, if there's a gap then they won't do their job properly.
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Post by Bozzy on Jul 31, 2013 22:51:56 GMT 1
Now that's interesting because that's the bad rev range that i have jetted out.......I know the fibre reeds did not fit flush with the seals....... My thoughts with 140psi going through those reeds compression must instantly seal.
You never know it could have just been a fact that replacing worn reeds with the new lighter performance ones was the actual reason for improvement....
But you are making me think when I fitted the yam ones.....not sure if it was before feeding bike with race exhaust.....
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Post by billyboy on Aug 1, 2013 6:24:18 GMT 1
mmmmmmmmmm. back to more playing then !
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Post by muttsnuts on Aug 1, 2013 9:36:08 GMT 1
a slight gap won't cause the bike any issues at all, if its more than a couple of milimetres then that's different, but a slight gap in my experience with fibre reeds is virtually the defacto standard, the reason the steel ones seem to seal fully is because they are alot stiffer than the fibre ones, so need more to open them, hence why you get better throttle response with fibre reeds etc
They open and close at a seriously fast rate, so the idea of a small gap causing "blow past" is very slight, and you would know if you have "blow past" as you would have fuel being blown back out of the carb towards the airbox and problems with it running properly at low revs etc
HTH
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Post by bare on Aug 1, 2013 17:44:54 GMT 1
IMO it was the crap 'boysens' that were the problem. Not a wee missfit. Lose them :-)
OEM Yama Banshee fibre reads are IMO the best available for oem Valvie reed blocks, for good midrange/street uses.
Very inexpensive as well, as happy bonus.
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Post by steven on Aug 1, 2013 19:15:07 GMT 1
I faffed about for ages with my reeds. I could not get the fiber ones to seal/seat properly, there was always a gap. I was also of the opinion that I wanted them to seal properly. The only test I could think of to confirm if they were sealing/seating properly was to blow through them and see if they "quacked." Holding a torch behind them and looking through for chinks of light worked too, but I prefered the "quack" test. I even wrecked a few reed blocks, by trying to "lap" in the rubber face, using some very fine wet and dry on a surface table  To get a "good" set of reeds I bought 4 brand new standard genuine yamaha petals, there about £10 each, and I kept buying reed cages off ebay, until I had a pair of reed blocks that "quacked" when I blew through them. I also learned not to use too strong a grade of loctite on the small M3 ? screws that secure the reed petals to the block, as I managed to shear a set of screws off, after trying to loosen them, after using too high grade of loctite. After weeks of buggering about, I got a good set, and I counted up everything it had cost me on fiber reed petals, standard reed petals, reed cages etc. I asked the very helpful people at Granby one day the price and availability of brand new standard reed block assemblies. Standard reed block assemblies are still available and are approx £100 pounds or so each, for what I spent fannyin about with mine, I could have bought brand new ones... steven. |
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Post by ianr4863 on Aug 1, 2013 20:21:29 GMT 1
I had pretty much the same as Steven .
One of my metal reeds failed - it was making a noise like a cat had got caught up in the wheels . Ran real bad at low revs as well .
Got 2 sets of YPVS cages off ebay , flatted them off on one of those £10 diamond sharpening stones .
Got some fibre reeds from Yambits and faffed away for two days until I got a set to seat properly .
Cost way too much time and money but at least I know its right .
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