Recent content by John Murray

14v - 16v can give more spark energy with an inductive ignition, but as mentioned before inductive isn't the best choice if battery life is important. CD isn't normally fussy about supply voltage as it steps the primary voltage up to 400v or so anyway. I run Turnigys on a Bultaco.

Interesting thread. The secret to getting good battery life out of a total loss system is to use a CD ignition rather than inductive. I've run both types and the CD runs much longer. A CD ignition will only draw a fraction of the current of an inductive ignition of a similar energy level - you...

I've seen some engines using variations of the variable length chamber - mainly karts and outboards. Which kinda makes sense with applications like these that lack a sufficient spread of gear ratios, or any at all. It's not something I'd want to do unless there were no better alternatives. It...

Alex demonstrates how to launch. Bill is smiling and gracious. You're a lucky man, Pat.

You gotta let the Busa guys win one occasionally, it's good for their self-esteem..

I think I'm almost as thrilled as you are with the performance Pat :D I'm sure there's more in it, enough to get you well into the sevens at least. Keep in mind that a dyno tune will only get you into the ballpark, and it's a pretty big ballpark at that. I'd plan on making quite a few runs at...

Good to see the clutch held up. I wouldn't worry too much about the grey sludge, it's normal for an all-steel clutch and doesn't seem to hurt anything. If the current setup is working I'd stick with it for the time being rather than introduce a new unknown. Finish tuning first.

Don't be surprised if you find it wants more jet at the track than it does on the dyno.

Some good numbers there - I'd better start work on the 2021 NFI Racing T-shirt design...

No, the BMW is irrelevant to the N/A Bul engine.

Teazer said this earlier: Bill is correct that lambda results can be misleading. As John points out, give the motor what it wants for max power and keep that record as a baseline. Lambda isn't actually what is read by the O2 sensor. It supposedly measures unburned oxygen, so a high O2 number...

No, I use Shell M with methanol and also with gas. I was using an ester with the air cooled engine on gas but had piston scuffing issues because the rear (thrust) wall consisted mainly of intake port. Switching to the castor blend eliminated the scuffing completely and gave a small hp increase...

https://www.eshifterkart.com/Elf-HTX-909-Kart-Racing-Oil-1-ltr-HTX909.htm https://www.accelerationkarting.com/ElfHTX909Oil There may be other suppliers closer to you.

Not too bad here, only 34C. My son was working in Cobar that day where it hit 47C.

I dunno Teaz, I live in Orange NSW where the winters are long and frosty and sometimes snowy. Overnight temps below freezing aren't unusual. On the positive side the summers are bearable. I follow a particular forum purely because two guys, Frits Overmars and Jan Thiel, also go there. These...