Cylinder Repair for CR250 and Big Bore?

[CR2FIFTYR]

I was wondering what is the recommended work for repairing a cylinder with 2 small hairlines near the exhaust port.I believe the cylinder is plated so if I have collected the right info I would guess that I have to get it bored out to the next size, then get it welded if there was any signs of the crack left,then get it plated?Another problem I have is that one of the head studs must have pulled or something before I had it so someone put in one bigger stud and drilled out a little more of the bolt hole on the head.Does this pose a threat to my engine at all?I was recommended in another section to just torque it to the same specs as the others and put thread locker on it?

Also I was wondering if I did a big bore if it would cut down the top end and midrange at all.What I really think I want is a good amount of bottom end and an abundance of mid and top end.BTW this is the 1995 that I have been totally redoing.Thanks.

Oh and I forgot who would be recommended to do the work if Eric isnt going to open back up or is he???

 

[robwbright]

You can have a big bore ported for whatever spread of power you want - within reason.

Eric's choices are low/mid, mo betta everywhere, and mid/top.

 

[CR2FIFTYR]

I dont know then.After looking at the site it seems like mo betta is the choice for my bike since it says midrange hits hard on the 250's and 500's but they are flat on top and bottom.Plus I trail ride and road ride alot so it would probally work out good.I would like to do the 265 big bore then by Eric Gorr but does anyone know when he is going to be back?I have seen he is doing some work out of a different shop right now but I am in no rush since the frames just getting painted and I need bearings and other misc. parts.I dont think the cylinder fix would be included in the price though.I will try to put together a list of everything I want then if I can find a link to his old site.Thanks for the help so far!

 

[CR2FIFTYR]

Ok.I think what I want to do is get the crank rod kit and send it to Eric just for installation along with my other parts.($50)Also I want the big bore kit which includes the mo betta porting and I guess from what I read it includes the piston assembly.($550)Another thing I would most likely need is the cylinder welding because the cracks probally go deep as the bore would?($600)And finally I got thinking, why couldent I just take the big stud for the head out and have Eric put a heli coil in it so i could run a stock stud there?That brings my total up to $615 which doesnt sound bad to me at all.One other thing I was wondering though is can I send the clutch basket to get polished or can you only have that done with the lower end rebuild?If you can send it how much would it be?Thanks again all!

 

[Eric Gorr]

Cracks in Honda cylinder castings are terminal. I've tried all sorts of geometric heli-arc weldments, including preparation of degreasing and soda blasting, and pre-heating to 400 degrees F. After welding a company named FPM stress relieved the cylinders to make the weldment and parent metal the same hardness. There is just no way to repair a CR250 cylinder with cracks between the sub and main exhausts.
Its best to just buy a new cylinder from Service Honda. Most of the time its cheaper than any of the popular aftermarket plating companys' price.

 

[Eric Gorr]

Oh and a 99 cylinder is a better replacement for your model, and all the parts swap over to the 99 cylinder. However don't use a 99 piston, use the piston for a 95 model and the Wiseco number is 614MO6640

 

[CR2FIFTYR]

Thanks alot for the info.I am honored just to have you respond to my question.:)So I guess I will start looking for a 1999 cylinder and then that way I wont have to repair the big stud.I was reading about the 1999 cylinder on your site last night but was wondering do the smaller ports make the air move faster or something?Thanks again!

 

[Rhein]

Eric, can you do work on my cylinder?

(sorry to thread jack OP)

 

[Rich Rohrich]

Eric, can you do work on my cylinder?

(sorry to thread jack OP)

Eric won't see this. If you want to contact him send him an e-mail : ericgorr @ hotmail.com

 

[skipn8r]

However don't use a 99 piston, use the piston for a 95 model and the Wiseco number is 614MO6640

Does Rich or anyone else know why Eric made this recommendation and whether it applies to all '92 - '01 CR250 engines?

 

[Rich Rohrich]

I don't remember the specifics of that one. Best bet would be to contact Eric and ask him.

 

[Faded]

Does Rich or anyone else know why Eric made this recommendation and whether it applies to all '92 - '01 CR250 engines?

IIRC, '96 and earlier CR's used domed pistons which won't work with the '97 on up heads designed for flat top pistons.