regular or high test

KZ750B twin, 1979 model. Anyone notice any difference in using high test rather than regular grade gasoline?

Oh boy! Here we go... :laugh:

Start with the cheap stuff and watch your mileage.

Then do a tank of mid, then a tank of high.

Repeat this process a couple times to eliminate varience, and compare: Whichever yields the highest mileage for you, is the one to use.

Depends on riding styles, engine setup, climate, etc.

GL!

My 79 750 twin runs fine on regular unleaded so I never saw any reason to send more money on the expensive stuff.

Thanks. I've been running regular for the past 31 years, but thought I might have been missing something as far as performance.

When mine was new I noticed it would miss a bit on regular but it's a California model that was jetted way too lean. I suspect a correctly tuned bike does not need it.

If engine does not ping on 87 no use to use high test,the lower the octane with out pinging the better.

With age, there is carbon that builds up inside the combustion chamber and on top of the piston crowns. This will raise your compression quite a bit. plus it can cause pre-ignition due to the fact that the carbon holds heat. The best thing to do is to remove that "Crud' with combustion chamber cleaner. This can be bought from either Yamaha dealers or at any Mopar dealer. Here is a link to a previous discussion.
kzrider.com/index.php?option=com_kunena&...ew&catid=2&id=369254