KT100 rebuild


(Dan Dedering) #21

Got the crank and cylinder back. Cylinder hone to fit new 52.20 piston ($25). New rod bearing installed on trued-up crank ($40). Started rebuild.


New seals installed. Used Threebond 1184 for the case.

New .020" base gasket and cylinder installed. Ready for cylinder head. Carb cleaned and rebuilt. Pop-off set to 10psi @ .040" fulcrum height without gasket. I used my dial caliper as a depth gauge across a straight edge when setting the fulcrum height. Once the caliper contacted arm and released pop pressure, measurement was recorded. This worked great!


(James McMahon) #22

Thanks for documenting this and sharing it.
Was the rod checked for true and ovality?


(Dan Dedering) #23

Combustion chamber cleaned up very nice, no pitting from detonation.

After cleaning chamber I found that the S/P hole was helicoiled. Interesting that the heli depth is only .435" of the available .680" of overall thread depth. I think heat transfer would suffer from this lessened thread engagement. Also, looks like heli threads are getting old. Wonder if a second up-size heli is available? Something for doing a Heli a second time?
Notice thread condition…


(Dan Dedering) #24

Yes, rod was check. And crank was trued on centers.


(Dan Dedering) #25

Also, after I complete the assemble I’ll have the same engine builder run break-in and dyno pull.
I’ll share that too.


(Dan Dedering) #26

Thread repair inserts are out there.


(Dan Dedering) #27

http://www.timesert.com/html/bigsert_sparkplug.html


(Andy Kutscher) #28

Great progress, I’m putting my backup KT100 together this week so going through much of this myself.

Timeserts are a MUCH better solution than helicoil, I wouldn’t hesitate to use them. I installed timeserts in the aluminum wheel uprights on my GT3 where the radial mount calipers mount because it’s a know weak point that can strip out easily. They have been in there for 4 years now and are holding up great.


(Dan Dedering) #29

Thanks and Andy. Check out this video link I posted.


(Dan Dedering) #30

I’m going to call the engine builder today and get he’s thoughts on this today. I can do the machine work myself in a mill at work. Pretty straight forward job, plunge mill out the old heli, drill and tap M18 x 1.5. Spotface & countersink for washer surface of insert. Use 266 loctite, good to go.
Only concern is if the installation tool is really needed for installing insert, if it’s tri-lobed to expand the bottom portion of the insert.


(Dan Dedering) #31

This is the old crank pin bearing and thrust washers.


The old seals had grooves around the O.D. I like that idea with RTV. They also had the tension springs removed, probably to reduce drag.


(Dan Dedering) #32

Everything looked good during disassembly. No red flags.
A name drop to Scott at Two Cycle Technology for the crank, cylinder work and parts.
I’ll report back with more, either dyno or head work (ordered Big-Sert inserts).