Mikuni RS settings

[tlc]

Can anyone help with idle mixture settings.
The manual says 1/4 - 1/2 turn but I have acceptable running at 1 turn.

Am I doing something wrong?

[PAULJAC47]

Wouldnt say so Chris,guidlines only,bung a colourtune on and see!

[Al]

Mine are at 1 turn out each across the four.
My manual says 1/2 turn for the RS36, that said, i could not get it to run with the stated 1 1/4 turns with the CV's they were all over 2 turns each.
On the colourtune; the 1 turn out on the flatslides is the point where yellow changes to blue.
Probably 60 - 40 yellow to blue.

AL

[tlc]

Thanks Al. That chimes with me.
I haven't carb tuned it yet but will be off to the dyno soon.
Incidentally I am on otherwise stock settings but just dropped down from 125 to 120 mains.

Seems okay as far as I can tell.

[Al]

1170, high comp version, RS flatslides, Dyna ignition etc etc. super un-leaded you will need a minimum of 130 mains for dyno runs or you will destroy the top end with overheating.
There seems to be a trend recently with dyno operators running aircooled stuff the same strength as water cooled, thinking that will be ok because that is what we always do.
Aircooled cant dissipate their heat on the dyno and in real world applications; bikes of the approx above spec used in anger,... 130 is the lowest i have seen and not do damage.
125 or 120 will give you power that frightens and a throttle response to match a modern bike but i guarantee you it will not last.
You need B9ES also, to keep the heat away from the valve gear and piston crowns.
Wiseco rings also seem to suffer very badly with hotter running engines.

If you felt that it was running rich with 125 mains it was possibly because it wasnt properly up to temp or you are still running it in!
I know they come with 125 as the maximum standard size mains in the box but like the pilot settings; that does not make it right.

AL

[Ginger Bear]

Chris,

This was my Unitrac engined Wiseco 1170 on Debens dyno. Running RS 38's (Bigger than necessary, but they were a bargain!) Note the carb settings/jet sizes at the top of the screen.

[tlc]

Thanks Al / Steve.
I'm going to get some 130's and I've ordered W27 densos.
Al. From what you are saying the 130's are not just good for the dyno but also for the street. I realise these are only base settings and technically I'm still running in but obviously I don't want to do any damage.
Naturally the dyno will give me a better idea when I get there.

[Al]

I cant use it on the road any longer Chris as you may recall but take the above from the last three years on track with the z brigade and five years at Santa Pod with Fatty and the Z1R.
125's damaged both mine and Brians' top ends and 130 is the absolute minimum i would suggest as that would be a poor trade off with heat vs performance.
Both Brian and myself have 137.5 in the two outers and 140 in the two inners.
He is much faster than me but both bikes have near ideal fueling and very good performance characteristics at those settings.
It gets a bit more complicated when you consider that we (all of us) have to run effectively strangled exhausts for noise regs where a more free flowing exhaust would give a leaner mix.
Ambient temp. fuel quality, humidity, air filter type etc. all play a part too.
Its also true that track riding is either full on throttle gear changes and then full on brakes, full on throttle,... [repeat] which; with flatslides, brings the accelerator pumps into play constantly. Not something you would necessarily do on the road.
The above also includes the use of a decent sized oil cooler which does make a significant difference to the amount of heat maintained around the top end in particular.
Any how, to be practical about it, if i was going to the dyno i would ensure the rings were not still tight and start off with bigger mains and come down not the other way round.
By way of a comparison; with the 34mm CV's i was using 135 /137.5 mains and that was near on perfect, now it 36mm RS's at 137.5 / 140.
Steve was at 142.5 for his 38's
What size are yours??

AL

[tlc]

Mine are 34's and I rarely go full throttle for long.
Most of the time I'm winding on on the midrange.
I'll buy some 130's 132.5's and 135's stick the 130's in to finish running in and then take it to the dyno.

[Pigford]

My old A2 ran 1075 Wiseco - gas flowed, std cams, RS36's... had 130 mains, 17.5 pilots - also Iridium Denso's IW27's no probs for years - included sprinting and general use.