hone or bore?

spincycle

Member
stock kt100 stuck piston, cylinder wall doesn't look too bad, bore was at 52.0, thinking maybe going to 52.05 or 52.10, typically, how much of a cut should you go to boring instead of honing it out?
 
First hone the cylinder then measure. Calculate the size piston you want for clearance then call the kart shop and ask them to measure some pistons for you. The marked size can be off 2-3 thou. Allot of times you can find a piston that's marked the same size as the one you have but is a little bit bigger or maybe the next size piston that's a little bit smaller. You can re-fresh the engine 2-3 times on the same (marked) piston size. If you just order the next size piston you'll be there honing all day.

The only time you bore is for major damage or if you want max piston size now.

Sundog
 
Thanks for the info, trying to avoid boring...but at the same time, trying to maintain perpendicular cylinder, im being told honing (or the person doing the work) sometimes can end up distorting the trueness of the bore when using honing to take more out than you should...true?
 
Thanks for the info, trying to avoid boring...but at the same time, trying to maintain perpendicular cylinder, im being told honing (or the person doing the work) sometimes can end up distorting the trueness of the bore when using honing to take more out than you should...true?
From my flathead days, you can tease the bore to one side based on wear in the bore, laying the cylinder on its side, etc.
Have made a measurable difference in bore location by laying cylinder on its side.
Might be the reason machine shop honing is done with bore vertical.

If only removing .002 to .004 inches, honing won't make a noticeable difference.

The precision of the person doing the bore work can affect as much, or more, depending on their goal.
The lathe man can affect these things based on his precision.
As always, precision costs money.
 
An experienced technician will not distort the bore but I have seen some beginners that did a very bad job. What kind of hone do you have?
 
Spincycle,

Good advice for you from everyone here, especially Sundog's comment about sorting pistons. When I was building a lot of Yamahas back 20-30 years ago, I would typically stock 50+ pistons, and I kept them all sorted on actual/measured size, not "marked" size. They do wander up and down a bit (and also vary in taper as well, which can be just as important). And it's totally possible to freshen an engine a number of times and stay on the same pistons size!

As far as the quality of the bore -- as long as you go to someone that has experience honing (and preferably uses a floor model Sunnen hone and uses a "keyway mandrel"), you can and should get excellent results. It's *always* good to have the header (or a dummy header), and a top deck torque plate on the cylinder while honing. Tightening the header will distort the cylinder out of round, and the top plate (fake cylinder head) will turn the top of the bore into a bit of a "stop-sign" shape. Don't over-tighten header! Keep the torque very low, and double nut them to keep things from coming loose.

PM
 
An experienced technician will not distort the bore but I have seen some beginners that did a very bad job. What kind of hone do you have?
None....just trying to get opinions on which way is best to go, got a couple local engine shops that can handle it...thx!
 
on the subject of hone.... I have a set of three Tennessee hones, will do 80cc-500cc bores.... with mandrel for use in lathe or mill.. .800.00
I found best results using top and bottom plates as well as having exhaust manifold bolted on.....
 
Ok, got my hands on a much better inside mic, cylinder measures 52.03, cylinder wall looks pretty good but in need of a clean up/good hone to let's say 52.05, unless by anyones recommendation to go one/two more thousandths maybe? If going to 52.05 bore after honing, does anyone happen to have a 52.02 piston/ring laying around they might be willing to part with? Thx! Don
 
i saw on your profile that your from Omaha NE. you a little over a 100 miles away from one of the smartest 2 cycle engine builders in the country. he is also very helpfull, contact Kermit Buller at Buller Built. The money you spend to get a correct setup is worth a ton of mistakes by the unqualified,

https://www.buller.net/splash
 
i saw on your profile that your from Omaha NE. you a little over a 100 miles away from one of the smartest 2 cycle engine builders in the country. he is also very helpfull, contact Kermit Buller at Buller Built. The money you spend to get a correct setup is worth a ton of mistakes by the unqualified,

https://www.buller.net/splash
im acquainted with him, actually buy quite a bit of stuff from them, but, i'm kinda hands on kinda guy, I try to learn as much as I can and try to use that knowledge to do as much of the work on my karts on my own as I can....;)
 
You can sometimes ask the kart shop to measure a couple piston sizes for you. I just asked Comet Kart to measure the size I wanted to buy & they sent me the measurement.

But, I actually have a spread sheet with several brands, sizes & weights of pistons I have kept & added to for a long time to help me make a decision on what size I want to purchase. I confirmed that when I asked Comet Kart Sales if they would measure the piston for me before the purchase.

Brian #89
 
I prefer KSI pistons in the black box. They're more uniform in size and coated pistons are readily available in most sizes above .50.
 
Back
Top