Need help on timing with dial gauge.

[Coyote]

the mm measurement times .0394.

Close but no cigar. Actual multiplier is .03937 Doesn't make a lot of difference till you get into really big numbers.

[Vintageman]

Craig380,

You are quite right now that I look into what you wrote. I just reviewed the GT750 service manual and it shows gauge in alignment with plug threads and that the center is 0.136" versus 0.143" for same 24 degrees. So I may set a +1/2 degree more advance but new points always wear in. I will buy a gauge too

pearljam724,

I am not so sure about timing affecting sound that much but, I have learned in life everything has an affect just to what level. I think what might be significant to sound at idle is how well fuel mixture is.

Sometimes I here pipes sound only partially smooth followed by a pop every second (more or less): like voom-voom-voom-voom-voom .... Pop .... voom-voom-voom-voom-voom .... Pop ..... The Pop tone is shaped by the pipe design and material. Thin wall pipes absorb it better and stiffer walls don’t and send the Pop as a slap or sharp note sound out the pipe. What gauges are Higgspeed? I know they are stainless.

The Pop is at a lower frequency then the engine speed. I think the reason for the Pop (so I read somewhere... if I can find again I'll post it) is a lean condition . You know like a 4 stroke letting off throttle at a higher rev and flames come popping out exhaust.

When lean, what little fuel there may not fire in cylinder every time but comes out and that fuel builds up/pools in pipe, and eventually explodes.

One of my pipes is steady smooth sound and air flow (hand placed at out let of chamber) at idle. The other two have flow not so steady and pop every second or two.


I ordered carb sync gauges and will start here. Then I plan to try the Idle mixture fuel screw. I used 3/4 turns as stated for the later GT750. I also put the air jet for surge issue and stock pilot jets. I may go a little more on fuel screw if sync does not make all the same smooth flow and popless sound.

This could all be BS, but where I am at in my head.

Every time I run chambers it seems like a little more fuel is needed at idle. My bike runs wonderful too, but I get real fussy about low speed running behavior and must say it is a challenge.