|
|
Post by Karterdude! on Jun 21, 2009 11:13:43 GMT 9.5
I was told and read on another forum if you want to save a little bit of money on rebuilds, then do rebuilds on your engine as soon as feel drop in RPM's
Is that true.
My last rebuild was about 8 hours ago but my RPM has not dropped yet.
Just was wonder what do you guys think?
|
|
|
|
Post by Kart61 on Jun 21, 2009 11:17:02 GMT 9.5
Remember reading something about acompression gauge. Measure the compression or something like that when you have finished running the motor in, then measure after each meeting. Sorry mate I can't quiet remember how to do it exactly someone told me how to do it a while back at the Bitchemen. Sorry Again
|
|
|
|
Post by tom on Jun 21, 2009 23:55:09 GMT 9.5
I always rebuild the top-end of my motors according to compression loss..
It's quite straightforward, but you have to be very careful to follow the same procedure when you do this.. There are many ways, but to get a repeatable result, you need to always do it the same way.
This is how i do it:
-Run in the motor as per engine builders recommendations.
-Wait until the next day (engine cool)
-Remove carburettor (prevent fuel entering motor, and ensures consistent air intake to engine)
-Remove spark plug and zip-tie it so it is touching engine (prevent ignition damage)
-Fit compression gauge
-Use external starter to crank motor for a few seconds
Obviously with no carby you don't want to crank it for long or you will be wearing the top end.. Some oil is still transferred from the bottom end, but if you always do it the same way it is repeatable.
It doesn't matter what compression you see, write it down, and then test the motor the same way after each meeting..
When the drop is approaching 10psi, fit a new ring and measure the piston-bore clearance. Depending on what piston clearance you like to run you might fit 5 rings before you need a new piston fitted.
The main reason i started doing this was because some engine builders aren't too fussy with the way they build their motors, and i was getting inconsistent performance after a re-build.. Once i started doing my own engines i found that after running them in the compression was always very similar..
Good luck!
PS if your motor has done 8 hours, there is no way the ring is still OK. Typically on a Yamaha KT100S the ring will perform well for about 30mins. Racing dirt karts i rarely made 3 meetings on a ring.
|
|
