Author Topic: Bias inlet manifold spacers  (Read 675 times)

neil parker

  • Guest
Bias inlet manifold spacers
« on: 22.02. 2013 23:17 »
Hi, I posted a question yesterday about my A10 running rich on one side lean on the other. It is suggested that i use a biased spacer. Can anyone tell me how much to bias the spacer from one side to the other side.
 I am in rural Australia so wanted to adjust (file) the one i have, before ordering one from  Cake street spares. I am off to a rally in 4 days so wanted to get the bike right before then.

Online muskrat

  • Global Moderator
  • Wise & Enlightened
  • **
  • Join Date: Jul 2009
  • Posts: 8926
  • Karma: 113
  • Lithgow NSW Oz
    • Shoalhaven Classic Motorcycle Club Inc
Re: Bias inlet manifold spacers
« Reply #1 on: 22.02. 2013 23:59 »
G'day Neil, welcome to the forum.
It's a bugga waiting for stuff from the motherland,ain't it.
I'd go 0.5mm at a time. Rough it in with a file and finish with 400 wet & dry. I assume you have a thick (1/8" or more) tufnol spacer and paper gaskets.
4 days should give you time to try a few set ups.
'51 A7 plunger, '57 A7SS now A10CR,  '83 CB1100F, 88 FXST .
Muskys Plunger A7

Offline duTch

  • Ricketty Rocketty Golden Flashback
  • Wise & Enlightened
  • *
  • Join Date: Oct 2011
  • Posts: 4538
  • Karma: 41
Re: Bias inlet manifold spacers
« Reply #2 on: 23.02. 2013 16:55 »

      Hiya Neil, I haven't been on board for a while, but was funny I was looking in my 'Hayes' the other day, and read the anti-induction blurb yet again and it's almost an official admission that the ports are not profiled very well, which I noticed on mine a while ago, and acted accordingly.
    That was when I bought a Dremel,and utilised the profile gauge I already have, and did some 'sculpting'; ie evened up the internal profiles of in/ex ports
 Not sure yet how effective it'll be but can't be too bad, I fired it up the other day for the first time in many fingers years ago, but the bottom line in my opinion is that the 'bias' is a crock of crap and just a cop out for the factory for not casting the heads well- I could be wrong, but that's me, so when you have a chance strip it down and have a check. (not much time for 4 days leadup)
 cheers, duTch

 I'm up in sunny/floody/?let me check? *conf* Qld
Started building in about 1977/8 a on average '52 A10 -built from bits 'n pieces never resto intended -maybe 'personalised'
Have a '74 850T Moto Guzzi since '92-best thing I ever bought doesn't need a kickstart 'cos it bump starts sooooooooo(mostly) easy

Online orabanda

  • Wise & Enlightened
  • *
  • Join Date: Nov 2008
  • Posts: 1088
  • Karma: 22
Re: Bias inlet manifold spacers
« Reply #3 on: 24.02. 2013 05:12 »
I have dyno tuned small fin and large fin cast iron A10 engines, and they have all showed a leaner mixture on the LH pot.