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Old 10-03-2016, 06:31 PM
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Default NEED ADVICE, To replate, or still rideable?

     

Alright, so I've had a 1996 Cr250 for a few years now, rebuild it from top to bottom and have ridden it thoroughly since.
Unfortunately due to a bolt coming off I lost all my coolant, overheated and blew the top end. The motor did not dead seize, but has a score mark on the cylinder wall. It looks much worse in the photo than it actually is, but just barely catches a finger nail.




I already know what the answer would be for replating, yes it needs a replate. But can I get away with putting another piston and rings in and running it for a little while? I plan on buying a brand new 2001 cr250 cylinder/head/piston when the funds come by, but if I could get a while out of the current cylinder without damaging anything else than I would like to.
(no track riding, only trails and ice riding in the winter.)

I don't want to put a fresh top end in to only get like 2 hours, but if I can get 10 than I'll do it.
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Old 10-04-2016, 08:43 AM
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What is going on with this desire to bolt a 2001 top end on a steelie bottom end? I'm getting inquiries about this all the time now. Is somebody on the internet saying this is a good idea? because it's not.

The reasons the 2000 and 2001 are so potent goes beyond port timing. Putting a 2001 cylinder, piston and head on a pre 97 nets you an engine with an analog vs digital ignition with the wrong mapping for that cylinder. It also has the wrong power valve governor (PV opens at less than optimal RPM). Smaller reed valve surface, wrong shape pipe, not as efficient cooling. Also the head stay boss is slightly different so the head stays won't fit without modification. Basically you get an engine that will be a big disappointment.

I've said this before but unless you have a big supply of parts to pick from, you're better off keeping your engine parts swapping limited to "in generation": 92-96, 97-99, 00-01.

As for your question, you can try to hone the cylinder with a ball hone to clean up that carnage, but unplated Aluminum (where the damage is), will wear like gangbusters and may bite you in the butt at a very inopportune moment, so ride at your own risk.

When it comes time to replace it, don't. Send the cylinder off to Millinneum Technologies and have it replated. If you want more power, have your cylinder ported and the head milled. It will be every bit as fast as an 01.

My two cents.
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Old 10-04-2016, 11:34 AM
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Quote:
Originally Posted by dogger315 View Post
What is going on with this desire to bolt a 2001 top end on a steelie bottom end? I'm getting inquiries about this all the time now. Is somebody on the internet saying this is a good idea? because it's not.

The reasons the 2000 and 2001 are so potent goes beyond port timing. Putting a 2001 cylinder, piston and head on a pre 97 nets you an engine with an analog vs digital ignition with the wrong mapping for that cylinder. It also has the wrong power valve governor (PV opens at less than optimal RPM). Smaller reed valve surface, wrong shape pipe, not as efficient cooling. Also the head stay boss is slightly different so the head stays won't fit without modification. Basically you get an engine that will be a big disappointment.

I've said this before but unless you have a big supply of parts to pick from, you're better off keeping your engine parts swapping limited to "in generation": 92-96, 97-99, 00-01.

As for your question, you can try to hone the cylinder with a ball hone to clean up that carnage, but unplated Aluminum (where the damage is), will wear like gangbusters and may bite you in the butt at a very inopportune moment, so ride at your own risk.

When it comes time to replace it, don't. Send the cylinder off to Millinneum Technologies and have it replated. If you want more power, have your cylinder ported and the head milled. It will be every bit as fast as an 01.

My two cents.
Thank you for the response dogger. Your two cents is very valued to me. I'm honestly not looking for any more power out of my motor, I was happy where it was at. The only reason I was looking at the 01 cylinder, was that they are still available brand new, as is the head. The 96 are NLA. I didn't realise there were fitment and running issues.
I figured I would be better off with a brand new cylinder, as I realised mine was ported by god knows who. But in retrospect, the power delivery was always great. So I Guess with all the things you have pointed out, I think I will go with a replate.
Any thoughts on sleeved cylinders? advantage/disadvantage.
I know some say they run hotter, and don't last as long.

I guess it just isn't worth the headache of a breakdown to postpone a little money spending to run it in non optimal shape.
Thanks again for the advice!
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Old 10-04-2016, 02:30 PM
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I didn't know your cylinder had been ported. In your case, re-sleeving is an excellent option.

I re-sleeve CR500 cylinders all the time. You can avoid the heat and durability issues by going with an Aluminum sleeve and having it NIKASILed. Going this route will yield a cylinder structurally and dimensionally identical to a brand new cylinder from Honda.

I get my Aluminum sleeves from Advanced Sleeves and send it along with the cylinder, piston/rings to Millennium Technologies. MT removes the old sleeve, installs the new one, blends and matches the ports, finish bores and hones for the supplied piston then plates it. The plating used by MT is superior to the NIKASIL used by the OEMs. I actually send new cylinders to MT to have the NIKASIL removed and their NSC applied for engines I'm trying to squeeze every ounce of performance out of.

This is not the cheapest route, but since your cylinder is NLA from Honda, it's part of the "fun" of owning a steelie.

Good luck with it.
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Old 10-05-2016, 09:48 PM
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Thumbs up Consider the possibilities

The plating on the cylinder in the TDC area is going, going, gone? You need a sleeve or a replate job. Iím the cylinder repair guy. Most of the posts so far are about a replate job. A new iron liner will add strength & stability to your cylinder. There are a bunch of different pistons available to around 2mm over. Porting is much easier with a liner either installed or removed. Consider a sleeve, consider the possibilities.

JT
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Old 10-06-2016, 12:56 PM
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Quote:
Originally Posted by John Tice View Post
The plating on the cylinder in the TDC area is going, going, gone? You need a sleeve or a replate job. Iím the cylinder repair guy. Most of the posts so far are about a replate job. A new iron liner will add strength & stability to your cylinder. There are a bunch of different pistons available to around 2mm over. Porting is much easier with a liner either installed or removed. Consider a sleeve, consider the possibilities.

JT
thank you for the post John, I think I'm going to go with a replate though being that the original plating seems to have lasted around 20 years.
Now the question is, wiseco forged piston (like I had) or OEM?
I've actually never ridden an oem in this bike.
I'm leaning towards oem to try it, any positive/negative feedback??
Care to shed some light dogger?

thanks!
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Old 10-06-2016, 02:38 PM
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I recommend an OE Honda cast piston in all cases except for the most
extreme build ups where a switch to a single ring HRC or Wiseco piston
will yield a little more power (albeit at the expense of durability).
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Old 10-08-2016, 07:24 AM
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A Wiesco piston is at least 4 times stronger than an OEM piston; I tested Wiesco & OEM pistons in my press. For a piston choice itís sometimes a case of availability rather than a preference of brands & types. Many times a person will shop on EBay for the best price on anything especially pistons. At times a dealer will sell pistons at a lower price to reduce their inventories.

Wiesco piston


OEM piston

For honing your plated cylinder; a diamond hone is needed if you wish to replace your crosshatch in the bore. Ball hones although handy for port champhering donít do much for plated cylinders. Your main concern should be if your cylinder is round & straight. I use the Sunnen brand of hone heads for all of the final sizing. Sunnen is the best honing equipment for sizing small engine bores. The smaller Sunnen hones are longer than the cylinders which they size; This particular feature gurentees a round & straight bore.


JT


Last edited by John Tice; 10-17-2016 at 06:40 PM.
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