Cylinder measuring

[Dan Paull]

So just about to attempt my first rebuild. I've been told I need to measure the bore before ordering piston and rings. I was going to go a Vertex piston or OEM. The OEM doesn't have different sizes (ordering off bto sports) however the Vertex has A, B and C. So my question is how do i measure the bore and how do i know if the OEM one will fit or how do I choose which vertex one to choose.

[dirteta]

Have a machine shop measure the cylinder for out of round before you do anything imo.

[Jdrost72]

U need to measure it with tel. Gauge and a micrometer. If u don't know how to do it u could go to a machine shop. But not all r set up for small engines. And if u want to know how to do it your self. Check the internet. Or if u have a vo-tech. Small engine. Ask the instructor. Most dealers don't bore or mic. They send it to a vo-tech or a machine shop and charge u more

[casualrider1994]

Have a machine shop measure the cylinder for out of round before you do anything imo.

i'm curious. do most machine shops have the equipment to do this or is it only specialty shops?

[motoxvet]

i'm curious. do most machine shops have the equipment to do this or is it only specialty shops?

Your best bet is to find a motorsports machine shop and have them do the measuring.  A lot will do it for free or maybe $5.   I have micrometers and telescoping gauges at home but with something as important as a top end, I'll take it somewhere and have them do it.   The type of motorsports machine shop I'm speaking of is one that does boat, cycle, ATV, snow machine, etc., not necessarily automotive race machining, but depending on where you are, you may have to trust them.   Note that like someone hinted at, MOST dealers don't do their own machine work.  They send it out.  See if you can find out where they send it to.  It's probably the closest, most convent location for them AND for you.

[LovingOffroadPain]

Check out this thread, gets pretty detailed for you.

 

https://www.thumpertalk.com/topic/831082-how-to-mic-a-cylinder/#!GIGz9

[Dan Paull]

Check out this thread, gets pretty detailed for you.

 

https://www.thumpertalk.com/topic/831082-how-to-mic-a-cylinder/#!GIGz9

Thanks, I read that. Kinda just confused me more haha. Someone said on there that I don't need to hone my cylinder, is this true? Also my oem parts from bto sports doesn't have different sizes?

 

Here is where i was gonna order the oem one from

http://partsfinder.onlinemicrofiche.com/btosports/showmodel.asp?Type=13&make=kawasakidb&a=28&b=5&c=0&d=-CYLINDER/PISTON(S) 

[Beau 88]

Thanks, I read that. Kinda just confused me more haha. Someone said on there that I don't need to hone my cylinder, is this true? Also my oem parts from bto sports doesn't have different sizes?

 

Here is where i was gonna order the oem one from

http://partsfinder.onlinemicrofiche.com/btosports/showmodel.asp?Type=13&make=kawasakidb&a=28&b=5&c=0&d=-CYLINDER/PISTON(S) 

You can't hone a nikasil coated cylinder is what they were probably refering to they are diamond honed stones will just ruin them .

[Flagstaff]

I use a bore gauge, both or many directions, and read it off the same mic. I use to measure the piston.

 

Mike

 

Or Mic

[Dan Paull]

You can't hone a nikasil coated cylinder is what they were probably refering to they are diamond honed stones will just ruin them .

ahh yeah I have read that before so I wont hone mine. My bike has done 50hours and I don't have the tools to measure the bore if i just bought the oem piston would it be the right size or should i take it somewhere to be measured?

[Beau 88]

ahh yeah I have read that before so I wont hone mine. My bike has done 50hours and I don't have the tools to measure the bore if i just bought the oem piston would it be the right size or should i take it somewhere to be measured?

Take the cylinder to a local machine shop to have it checked for roundness and wear , take all your info with you of OEM bore size they won't know what it is supposed to be without it. For example i have a 2001 cr250 stock cylinder bore size is 66.40 mm stock piston size is 66.34 mm and i need .002 of piston to cylinder wall clearance with that kind of info they can fix you up . At least tell you if the cylinder is usable or if you'd be wasting money just putting a piston in .

[Dan Paull]

Take the cylinder to a local machine shop to have it checked for roundness and wear , take all your info with you of OEM bore size they won't know what it is supposed to be without it. For example i have a 2001 cr250 stock cylinder bore size is 66.40 mm stock piston size is 66.34 mm and i need .002 of piston to cylinder wall clearance with that kind of info they can fix you up . At least tell you if the cylinder is usable or if you'd be wasting money just putting a piston in .

Yeah, okay will definitely get it measured 

[Beau 88]

Yeah, okay will definitely get it measured 

If it's nikasil with just a little wear you can go to a B or even a C piston if needed you don't need to resurface unless it's worn through or peeling.  ?

[Dan Paull]

If it's nikasil with just a little wear you can go to a B or even a C piston if needed you don't need to resurface unless it's worn through or peeling.  ?

it hasnt worn through or peeling. The engine is only 50 hours old