Vacuum advance

[strom]

OK, I don't know how many of (us) techno geeks will read this, but here it goes anyway...

I've read the vacuum advance article in the tech tips - mods section, and have a question...

How important is vacuum advance, and how much would it show if there wasn't any?


LP

[oldnortonrider]

We need for someone to build for us >> a left hand twist-grip,
manual mechanical timing control . Like the old Harleys used to have!

[TopCatGr58]

Re: Vacuum advance

Originally posted by strom
OK, I don't know how many of (us) techno geeks will read this, but here it goes anyway...

I've read the vacuum advance article in the tech tips - mods section, and have a question...

How important is vacuum advance, and how much would it show if there wasn't any?
LP

Hey there Strom,
Well, with the timing "retarded", or not properly advanced, the engine usually runs a bit hotter than normal, the acceleration curve would be a bit slower, I think the fuel economy would also suffer.

As the speed at which the pistons and crankshaft are speeding up and moving faster with acceleration, if the ignition pulse is static, then the piston woill be further along/down thru the compression stroke when the combustion is starting to take place, the air-fuel mixture is not being ignited quickly enough while it's still under it's maximum compression allowing for better utilization of the expansion of gases during the burn process to push the piston back down, there is less time to burn with the engine running faster, so the ignition pulses timing is moved to an earlier point so that it can take better advantage of the compressed mixture in time to assist in pushing the piston from the top of the power stroke instead of from past that point due to the speed of the engine turning faster. The vacuum advance provides for quicker advancing at lower RPMs, and the centrifugal advance for the higher rpms, until the maximum advance is reached. Hope this helps, and I hope I've stated it correctly, but if not, I'm sure someone will correct me!

PS. Norton, you're showing your age there!!! Heck, why stop there, why not add the suicide shifter onto the tank as well, save all that stress on our left foot, and since we can control the steering one handedly with our counter-steering technique, it shouldn't be any problem with our free hand to handle the shifting job, and that would have to be our left hand, too.....but, oh, then we need that free hand to turn the advance control don't we!??!? I think I'll leave mine as it is!

[strom]

Thanx TC... now I'll have to decide between a GSXR and GPZ600R
pick-ups....

LP