Pinging thoughts

[muskrat]

G'day John OR,
                    I use Nulon pro strength octane booster at a rate of 8ml per lt and caster oil 500/1 in 98 always from the same servo (caltex). Can't use ethanol blend with fibreglass tank.
Cheers

[muskrat]

Update, Head back on running 98 (no additives) 30 deg adv. Colour tune says lean at 1/4 throttle, good at idle. On the road very rich at 1/2 and above. Pinging starts after about 5 minutes running so is related to 1/4 throttle. So either thinner needle or richer slide needed. 2 carbs cost $250, 2 slides cost $220, ouch ! Try needles first as both cover this region.
Cheers

[Triton Thrasher]

Slides can be altered weaker bt filing the cutaway, as you probably know.

You can alter them richer, at least experimentally, by supergluing slivers of cork to the edge of the cutaway. Might be better than spending thousands on slides that don't work out.

[muskrat]

Good idea with cork on cutaway TT, not sure if possible. Going down now to lift needles further but thats going to make 3/4 too rich so will have to go smaller taper angle. Needles are $20 each. I know it would be easier to go back to A(ni)mals, but I like a challenge.
Thanks all for your input.
Cheers

[muskrat]

PS might have to moove this to carb section !

[muskrat]

Getting closer. went for a richer pilot from 38 up to 45 !! A bit fluffy at idle good acceleration to 1/2 and rich at 3/4 but good on mains. Just a slight hint of ping after a good flogging. Ordered needles from the US.
Saw 100MPH today at 6000rpm felt great.
Cheers

[terryk]

I have heard that you can use acetone (however you spell it) to boost your octane level. Im not sure how much to put in but I will try and do a search about it. My mate runs a bit of it in his BSA.

[muskrat]

G'day Terry,
                acetone can be used as a cross link for mixing methanol with petrol as well. I use Nulon pro octane boost, but have decided to go back to 98 PULP.
I have tried the std needle clip in all positions and none give good results over the whole range. There are about 30 different needles for the Kehin PWK carbs. Needle thickness = 1/8 to 1/4. length = 1/4 to 1/2, taper angle = 1/2 to 3/4. Lots of trial and error.
Cheers

[Hubie]

Going back to your original question about springs Muskrat;

I had a pinging problem with a Royal Enfield Bullet I put a big bore kit in and went up from 6.5 to 8.5 compression and had all kinds of trouble with pinging.  Was only ever under load and the only solution I originally found was to retard the timing.  Problem was it was so far retarded it caused the bike to stall all the time and it had no go higher up the rev range.  After stuffing around with carbs and carb settings I had some stronger springs made for the auto advance unit and all my problems were solved on the spot.

It is well worth the try as it stops the ignition going to full advance too early.

Cheers,

Hubie.

[muskrat]

G'day Hubie,
                 Yep, that's what I thought, thanks for letting me know. But unfortunately it's not that simple for me as I run Boyer with no way of adjusting the advance curve. I had so much trouble with magy's years ago I won't go back. So it's carb tuning till I can find a programable black box. I've ordered needles that richen 0 to 1/2 and lean 3/4. Fingers crossed.
Cheers