Dyno Test

[Dan Hodges]

I tried to modify my last post but could not so I will finish with a new one. The needles are in the stock location and the plugs look good. I use one step colder plug on the center two cylinders. I have had this thing since it was new and have tried every carb modification known to man. Those dyno jet kits are a waste of money and I have a spare set of carburetors to prove it. I tried a set of FJ 1200 carbs a few years back which required a lot of fiddling to get them to fit properly, but I concluded they were to big for my combination. You, Jeremy, said your motor had 170-180 psi @wot. The book says 145psi @sea level and I have 150 with a 3% leak down rate which means you have a bunch. The best reference I have ever read about the internal combustion engine, is a book called, The Internal Combustion Engine In Theory And Practice by Charles Fayette Taylor. It has been my bible no matter if I was building a 540 c.i. rat motor for my race car or working on my old Yamadog.

[Dan Hodges]

Dyno Test

Thanks Ratbyk for leading me to Jeremy's dyno work.

[Jeremy_Sells]

Hello there Dan,

Nice to see this thread still lives on after a year or so. If you saw the charts, you'll see that I had a bit of a rich mix fed by the idle jets. After that post died off, I ended up going from 42.5 to 40.0 on the idle jets and that eliminated the richness and hesitation off idle. In addition to better power and rideability, I have been able to squeeze over 40mpg out of this thing on numerous occasions, amazing!! Welcome to the forum and if you get a chance to get your bike on a dyno, show us the results so that we can build on this whole jet tuning theory.

Take care,