Cost for cylinder bore????

airmobile101

airmobile101

Active Members
Any idea how much it cost to have a cylinder bored out? Not needing much. Maybe 10 over if that. Just enought to remove the score marks on these little KTM 50 cylinders. The cylinder is straight aluminum with no nikasal coating or anything like that. Im thinking I can make my money back with these to cover the cost I spent buying my daughters bike.
 
ridingred

ridingred

New member
$60-$100

Try to take it to a shop that does those little cylinders everday. I took my 400ex to a guy that's used to boring larger cylinders, so i paid $100 for that because he had to set it up and it took a bit more time.

you shouldn't have to pay much more than $60 if you go to the right shop.

 
M

Mike400EX

New member
Airmobile,

Those cylinders are aluminum w/o coating but it's all in the way the bore is finished. Standard methods with a stone hone will probably get you to the end of your driveway. The cylinders are bored, honed and then lapped. The final stage by the OEM's is an etch process that eats away a very small amount of the aluminum on the surface, leaving the remaining silicone particles - which are much harder - for the rings to ride against. Rebuilders usually final honed using felt pads with a special compound to remove the Al. Haven't had the good fortune to take a little KTM apart lately but I'm sure you'll see the pistons are specifically coated to live against those bores. Google a Chevy Vega, Porsche 928 or MB for cylinder finishing. I'm really feeling my age now!

 
airmobile101

airmobile101

Active Members
Ok, I think Im gonna try a local lawn mower shop and see what they can do. Mike400EX, I just need it punched out, but I will do the honing myself. The problem Im having is the pistons I have (4 total) are all sized C or D and the jug is a A or B. So the clearances are kinda tight with a C or D piston. Im moreless trying to kill 2 birds with one stone. 1. to remove the score marks, and 2. get enough clearance for the C and D piston to fit with in the specs.
 
Loud450man

Loud450man

New member
sounds like your on the right track but ive been wanting pics of the cylinder marks since i read the last thread lol mind posting a few?
 
airmobile101

airmobile101

Active Members
sounds like your on the right track but ive been wanting pics of the cylinder marks since i read the last thread lol mind posting a few?
Click to expand...
Well.......... that might be hard to do since I have filled them with Thermo Steel. lol

 
airmobile101

airmobile101

Active Members
I have a unscored cylinder coming,but I would like to salvage those other two cylinders if possible, just don't feel like droping $100 a pop on each cylinder since I can buy a used dirtbike for 300-500 bucks. If I can get away with having the cylinders done right and toss in a new piston for each cylinder and sell them for $200 a pop shipped, that would be great. lol
 
airmobile101

airmobile101

Active Members
oh i thought maybe you took some befor that lol
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I was too lazy since I figured it wasn't gonna work. The problem Im having is the thermal steel is a course epoxy once it cures compared to JB WELD. I don't think the rings will like that very much! lol I have JB welded my Z400 cylinder before and it worked great. Just one problem that I failed to mention with that. The cylinder was scored at the bottom of the cylinder. Not near the top where the majority of the heat is.

 
airmobile101

airmobile101

Active Members
IDK......... I could see JB weld working on a 50cc cylinder if the temp was under 600 degrees. The problem is I don't know how hot those little 50 2T get. lol
 
ridingred

ridingred

New member
i wouldn't jb weld a cylinder ever. Jb weld is good for some things, but i've seen it go bad so many times, i know i wouldn't use it on engine internals. a good quality epoxy would work ,but again, i still dont' know about in the cylinder.
 
airmobile101

airmobile101

Active Members
Update.......... I slapped the engine together real quick for a good laugh to see what type of compression I got. I ended up with 120psi! lol I hand kicked the engine over multiple times to see if the piston rings were catching or not. Not at all. So I think Im gonna toss it together tomorrow with what I have and see what happens. lol
 
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