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What piston in 06 cr85?

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Did some searching on this and have some questions. One member dirlled hole in the piston for bridge lubrication, is this needed? Looking at the Wiseco kits on ebay. Any model better than the other? This is my sons last season on this bike and I want to freshen it up one more time. It is the stock 47.5 bore. Also I see many kits come with out the pin bearing, I figure it should be repalced at the same time.? Thanks

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none of them come with wrist bearings and yes its good to replace them. the pro lite is what I would order. does the 85 even have an exhaust bridge?

edited..nvm...just looked and yes it has the bridge. the wiseco should come already drilled.

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no they dont come pre drilled you need to drill them i would recommend it. we had 2 of them we raced for 4 years 1 stock and the other built for supermini. always ran the weiscos and never had a problem except for the one that i didnt drill it came apart within 5 hours. also yes we always replaced the wrist pin bearing cheap insurance.

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no they dont come pre drilled you need to drill them i would recommend it. we had 2 of them we raced for 4 years 1 stock and the other built for supermini. always ran the weiscos and never had a problem except for the one that i didnt drill it came apart within 5 hours. also yes we always replaced the wrist pin bearing cheap insurance.

Here is a link for a complete wiseco top end kit that comes with all the top end gaskets, piston, piston pins, wrist pin, and wrist pin bearing. Nice complete kit.

http://www.oemcycle.com/Item/product/5536/

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Anyone have a pix of the drilled piston? I put a stock piston in last year and didnt have to worry about it and i am not sure where or what size.

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Anyone have a pix of the drilled piston? I put a stock piston in last year and didnt have to worry about it and i am not sure where or what size.

I don't have pics but drilling the holes is easy peasy. Required tools: Pencil, 1/16 size drill bit, Punch and hammer, and a drill. You basicly put the piston on the rod without the ring, slide the cylinder over the piston so it is resting on the base, lower it slightly so that the ring groove is not showing in the exhaust port. take your pencil and trace the exhaust bridge on the side of the piston. Pull the cylinder and piston. I usually take a clamp with some rags and clamp the piston so it is still. Make 2 punch marks on the side of the piston directly in the middle of your exhaust bridge trace marks. I usually make one about 1/4 inch below the ring groove and another about 1/4 inch below that. I don't think that the holes need to be absolutely precise as far as where they are, a good rule of thumb is to center both holes in the middle of your trace marks and center them as close as you can estimate them in the center of the exhaust bridge (up and down). Drill the holes with the 1/16 size drill bit, take a larger drill bit and chamfer the holes. take some sand paper and sand down the holes on the inside of the piston to make sure there is no loose aluminum on the inside of the piston and you are ready to go. By the way, if you get a cylinder worked by Eric Gorr, he releaves the exhaust bridge so you don't have to drill the holes.

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Ok thanks for the tips! One more stupid question- cyl. looks good so does piston (oem) should/could I just ring it to get through the season? He will be moving to 125 sooner than later and I dont want too much hassle. Thanks all.

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The stock OEM piston has served you well and you can buy a new one for $28. Why change?

Edited by CamP

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The stock OEM piston has served you well and you can buy a new one for $28. Why change?

If you are looking to rebuild it on the cheap, I would agree with this. If you have a stock piston I would recommend replacing the piston too unless you know exactly how many hours are on it. It would suck to have the piston come apart on you during the season. If it were a wiseco piston, then you could probably get away with putting a new ring on it and riding for another season.

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My son races a 2007 and we use only the Honda OEM stuff and it works well. The first top end I took apart looked really good too so I just put in a new ring and off we went. He was smaller and slower then. The second was a complete job including pin and bearing. If your son is getting on the larger side I'd suggest the whole thing as there will be more strain on that little motor. Again the cost of the Honda parts are minimal and you don't have to worry about sizing. You can buy complete kits from Honda of Toledo an they are very reasonable.

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Where can I get a oem piston and rings for $28.00?

He actually said that a new piston was $28. You still have to buy the ring. I found one at this place for $29

http://partsfinder.onlinemicrofiche.com/hondaeasttoledo/Honda_OEM/HondaDB.asp?Type=13&A=299&B=9'>

http://partsfinder.onlinemicrofiche.com/hondaeasttoledo/Honda_OEM/HondaDB.asp?Type=13&A=299&B=9

Edited by frdbtr
Added info

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Sweet. Thanks all! I can get everything for $62 delivered. Thanks for the tip!

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