Ignition timing advance to improve MPG

650 Transalp

[FatFergie]

That's interesting Activmoto. 4 degrees is quite a lot so how did you do it. I played around with a 125's ignition years back with mixed results but never really understood how I was altering the timing curve because I didn't have the gear to measure it at different revs.
Is it all your own work?

[raymo]

what you set it too?

I think its 27advance max, which folk think is low ( 35 on some engines,)
but I recall reading somewhere that the Honda Three valve head setup is designed to lower the requirement for significant ignition advance...

remember that Hondas run rich

will watch with interest..

how did you advance it?


cheers

Raymo

[Alba]

Technical point, but still on topic , what does advancing the ignition involve? Is it giving the spark for fuel ignition sooner?

Raymo by saying Honda's run rich does that imply greater fuel use than necessary

[raymo]

Originally Posted by Alba

Technical point, but still on topic , what does advancing the ignition involve? Is it giving the spark for fuel ignition sooner?

Raymo by saying Honda's run rich does that imply greater fuel use than necessary

Hi Alba,

Advancing the ignition means that that you ignite the fuel air mix earlier, so giving it more time to completely burn.. The time is measured in degrees before top dead centre ( TDC the piston is at the top of its stroke ), the ignition timing advances through the rev range to a set maximum, at about 4000 to 5000 rpm, depending on the engine)


The 4 degrees and be added mechanically ( usually involves moving the rotor that triggers the pulse coils or moving the pulse coils, by extending the mounting slots, ) or electronically if the CDI is programmable..

The optimum air to fuel volume mix is about 15 to 1 but this is idea Transalps et al are usually 12-13 to one.. the additional fuel helps with cooling.. if you leaned it out you may get better mpg, but I suspect you would get overheating and mechanical problems...


This is why some folk find that they can fit a less restrictive air cleaner and more free flowing exhaust and fined they do not have to re jet the carbs, get better power and more MPG.. they are leaning out the engine slightly

Mr Honda put a lot of though into these engines.. they can be tweaked a little but you need to change one thing at a time and then road test / dyno

Do a search.. think Kymmy posted some good stuff a while back
will see if I can find the article I was reading

[raymo]

Thanks

I have a 600 TA .. know what you mean about the oil facial ( folks pay good money for that ), I was checking the timing on my XLV..tried cling film over the timing access hole .. ( good fun as it look like the engine has a heart beat as it throbs with crank case pressure dont work though..

afraid it was a face full of oil as the XLV max advance is 27deg @4000rpm and at 4000rpm you get a good oil facial teatment

keep us posted

[StumpyFingers]

Why not just add a tooth to the Front sprocket?
It has got to be cheaper overall than the chance of a broken engine.

[Alba]

Cheers raymo, does sound like activmoto is trying to improve on Mr Honda good luck....

[raymo]

Originally Posted by Alba

Cheers raymo, does sound like activmoto is trying to improve on Mr Honda good luck....

no probs may have a week end free soon .. feel an applecross moment coming on

[piguglyshandydrinker]

Good luck with the tinkering Steve.

I have looked into all kinds of ways to improve fuel consumption (further), and still cannot understand how my mid '90s Alp 600 could get close to 70mpg when pootling, 58-60 regularly and low 50 with 'spirited' riding (trying to keep up with mates' CBR600s etc....).

I've looked at carburation, ignition timing and valve timing/lift etc.

I have yet to find the answer as to why!

Phil