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SDP76

Piston doesn't fit, what should I do???

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Yeah 100% but the guy said he couldn’t find one and is a rush. That’s the only reason I gave him the advice to take the piston to the machine shop, cause he seemed to be trying to calculate the bore size, which-as you pointed out- the guy drilling the hole should do.

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2 hours ago, Adam Meyerson said:

Take the piston with you to the shop that is gonna bore it. They can then set the clearance up correctly. If you ask nice, they will set your ring gap for you too. They are also in a much better position to evaluate  the condition of your piston than we are. Good luck!

Thank you so much for your help! this sounds like the perfect idea!

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55 minutes ago, CDNSXV said:

So the advice here is to spend several hundred dollars on boring out a cylinder to fit a $50 piston that is full of scratches from bouncing around in a toolbox?  Yea, that makes PERFECT sense?  😲

OR

Maybe, and I'm just spitballing here, you go buy the correct piston to fit the new cylinder you just bought?  

Also, any machine shop that needs you to tell them how big to open up the bore to fit the supplied piston is a machine shop that should NOT be doing the work.

I was hearing that it would cost around $50 for it to be bored out, but you might be right.

I think I might just be lazy trying to make this work, but I also have not been able to find a stock sized wiseco piston for it yet so that is also a part of the problem. Thank you for your help. 

Edited by SDP76

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37 minutes ago, Adam Meyerson said:

Yeah 100% but the guy said he couldn’t find one and is a rush. That’s the only reason I gave him the advice to take the piston to the machine shop, cause he seemed to be trying to calculate the bore size, which-as you pointed out- the guy drilling the hole should do.

 Thank you for your help.

Edited by SDP76

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2 hours ago, RawbW said:

Probably just needs some foreplay. Try caressing the camshaft and crank.

Haha I wish that's all that it was, the piston is not connected right now and I have tried putting it in every which way, but it is just simply too big. Thanks for the suggestion tho!

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2 hours ago, Rod21 said:

Furthermore,  lots of variables here  ... not really familiar with Hondas  ... is it an XR 80 or possibly an XR 70?

Cylinder size should be stamped at base of cylinder. 

That could be clue 1 worth looking at.

It's an XR80R. The cylinder size is definitely something to look at, thanks for the help.

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46 minutes ago, Igomoto said:

This ^

Do it right, ditch that piston and get a new one at the correct size- going to be way more work, cost and trouble chasing that issue. 

Thinking you might be right, but I will do some more research on it, thank you.

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26 minutes ago, SDP76 said:

Thinking you might be right, but I will do some more research on it, thank you.

Measure the bore, and contact Wiseco- they sale an assortment of sizes and can tell you what's best- 

There are also 4 different OEM pistons made for that motor- starting at standard and working up in increments of .25. 

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2 hours ago, CDNSXV said:

So the advice here is to spend several hundred dollars on boring out a cylinder to fit a $50 piston that is full of scratches from bouncing around in a toolbox?  Yea, that makes PERFECT sense?  😲

OR

Maybe, and I'm just spitballing here, you go buy the correct piston to fit the new cylinder you just bought?  

Also, any machine shop that needs you to tell them how big to open up the bore to fit the supplied piston is a machine shop that should NOT be doing the work.

99% sure the XR has a steel liner, and will be cheap as to bore. Much cheaper than another piston.

 

3 hours ago, Adam Meyerson said:

Take the piston with you to the shop that is gonna bore it. They can then set the clearance up correctly. If you ask nice, they will set your ring gap for you too. They are also in a much better position to evaluate  the condition of your piston than we are. Good luck!

What he said.

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1 hour ago, SDP76 said:

Thinking you might be right, but I will do some more research on it, thank you.

There's a bunch of threads in the xr80 section that mention bigger pistons you can use to big-bore it if you wish, otherwise quit messing about and take the piston/ring/barrel to your favorite machine shop and get 'er done. There's a couple of smaller sizes on e-bay if you're worried about having some more oversizes left. All around $150.

Edit; You can use a stock 51mm CB400F piston to get 92cc if you wanna get carried away. It goes straight in from what I found (after boring) but you'll probably have to mess around rejetting etc. Like I said though, ask over on the xr80 forum. https://thumpertalk.com/forums/forum/23-xrcrf80-200/

Edited by DEATH_INC.
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8 hours ago, Igomoto said:

Measure the bore, and contact Wiseco- they sale an assortment of sizes and can tell you what's best- 

There are also 4 different OEM pistons made for that motor- starting at standard and working up in increments of .25. 

I know, I just don't really want to wait 2 weeks for a piston, but if it comes to that I will.

7 hours ago, DEATH_INC. said:

99% sure the XR has a steel liner, and will be cheap as to bore. Much cheaper than another piston.

 

What he said.

Alright, sounds like the right thing to do, I will call up the shop and get some info, thank you for your help.

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7 hours ago, DEATH_INC. said:

There's a bunch of threads in the xr80 section that mention bigger pistons you can use to big-bore it if you wish, otherwise quit messing about and take the piston/ring/barrel to your favorite machine shop and get 'er done. There's a couple of smaller sizes on e-bay if you're worried about having some more oversizes left. All around $150.

Edit; You can use a stock 51mm CB400F piston to get 92cc if you wanna get carried away. It goes straight in from what I found (after boring) but you'll probably have to mess around rejetting etc. Like I said though, ask over on the xr80 forum. https://thumpertalk.com/forums/forum/23-xrcrf80-200/

I will take a look at those forums, thank you.

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1 minute ago, mixxer said:

Best $$$ ever spent is on an OEM service manual for your bike....

 

Yup, I downloaded one online and it is a life saver. Thanks for the suggestion. 

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The fun continues lol. I have called over 20 machine shops and they either don’t bore cylinders this size or they are way too expensive. Time to return everything and somehow find a 4 stroke 47.5mm piston kit for this thing. On the other hand does anyone want to buy a wiseco 49mm as you see in the above pictures 😂?

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