Hours on motor vs. Tanks of gas

Brian Garfield · Posted: Fri Mar 10, 2006 8:42 pm Post subject: Hours on motor vs. Tanks of gas

Since we autocross, it tends to be more difficult to estimate the amount of time on the motor.
Does anyone have an idea of the number of tanks of gas, say, before a top end and bottom end rebuild?

I can easily tell you how many tanks or gallons of gas (or approximately) but have no idea of how much time is on the motor.

Thanks,
Brian

Danny Lerner · Posted: Fri Mar 10, 2006 10:44 pm Post subject:

I never use more than like a 10th of a tank when I auto-x. You should probably base rebuilds on the # of events you attend. I know I only have the kart running for about 10-15 mins per event - including all my runs and short warm up time.

Personally, I feel the once a season I plan on doing the top end on my cr80 shifter is even overkill.

Danny
_________________
http://community.webshots.com/user/gto7419

Jim Russell, Jr. · Advertiser Joined: 03 Oct 2001 Posts: 1535

I use up 9L of fuel during a 30 minute road race. I rebuild at 3-5 hours run time. This would be 15-20 gallons of fuel. For Auto-X this would be 1-2 seasons of run time.
_________________
Russell Karting
888-KARTING

Larry Andrews · Posted: Sat Mar 11, 2006 2:32 pm Post subject:

Mike Speed makes a nifty little gizmo that tracks engine hours. His algorithm doesn't track time spend under some rpm (3k?) that exceeds a threshold duration. So it basically ignores time spent idling in the pits.

I'd have to guess that you can too. <shrug>

By that calculation method and working on the 5 hour rebuild time and one minute per run and three runs per day assumptions, it's going to be 100 autocross days before a rebuild is needed. Shocked

ymmv, hth, la

Bob Monday · Joined: 21 May 2004 Posts: 91

Can you put a TinyTach on a kart? It is as self-contained as any device can be, using a loop around the spark plug wire to sense "running". I just don't know if you can put it on a 2-cycle. I think that you can, though, because I put one on a Briggs motor, and as I recall, it fires the plug every revolution, too. Still, that would only affect the tach side, not the "hours" side. Cost is about $37.

Bob

Andrew. james · Posted: Sun Mar 12, 2006 8:24 pm Post subject:

Doesn't the mycron give you a reading of how long the motor is in use?
I do the ring at 1.5 hour or 3 tanks of gas or when ever I feel it starting to get slower which ever comes first. A complete top at 4-5 hour.
Bottom end I have not done myself, the builder said 5-8 so I'm going with that.

Vernon Head · Posted: Mon Mar 13, 2006 10:58 am Post subject:

Greg Bell at Leading Edge says to take off the pipe and look at the piston. You can see the blowby start to develop below the ring on the exhaust side. There's always a little bit of brown, but when it starts to get black and begins to spread down the side of the piston he says its time for a new ring.

Brian Garfield · Posted: Mon Mar 13, 2006 11:12 am Post subject:

Good info on that Vernon, sounds like a great way for Soloists to tell since we loose track of time.

Brian

John Denman · Posted: Tue Mar 14, 2006 1:18 pm Post subject:

Another way to check for piston/ring wear is to carnk over the motro backwards - disconnect the coil wire since it may start.

If the motor has a noticable difference in compression (less) backwards then forwards it needs a ring. Don't ask me why this works. Shocked

_________________
John Denman
Producer for RTMP
http://www.kartweb.com