CB250 Engine rebuild

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fastbob
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Re: CB250 Engine rebuild

#31 Post by fastbob » Sun Dec 09, 2018 7:37 pm

We'll I've had another look at your picture of the cylinder where you say " oh shiiit " and although I completely take your word for it that its knackered I can't quite make anything out from the photo. So a light hone obviously won't save the day . Regarding the engine bolt holes , they could possibly be drilled over size and then sleeved down to match the bolts . Failing that, you could simply insert some strips of metal alongside the bolts and tighten everything up with a few friction washers for good measure. As long as the engine can't move it'll be ok plus nothing will be visible.

Snod Blatter
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Re: CB250 Engine rebuild

#32 Post by Snod Blatter » Sun Dec 09, 2018 8:06 pm

Here's the photo again, edited just for bob!
Image
I can only guess this happened either when it was stood outside after it was found to be right mega broke, or perhaps something fell in from a plug changing session and broke the surface which has then be worn away more and more. In time I'll also check if the bores are oval, that will be a good way to find if they can even be rebored or if a replacement cylinder is the only option.

Drilling out the holes and putting in sleeves is the plan, but from the "inside" so that I can be fairly sure they're in the right place.
Image

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Speedy23
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Re: CB250 Engine rebuild

#33 Post by Speedy23 » Sun Dec 09, 2018 8:15 pm

Snod Blatter wrote:
Sun Dec 09, 2018 8:06 pm
Here's the photo again, edited just for bob!
Image
I can only guess this happened either when it was stood outside after it was found to be right mega broke, or perhaps something fell in from a plug changing session and broke the surface which has then be worn away more and more. In time I'll also check if the bores are oval, that will be a good way to find if they can even be rebored or if a replacement cylinder is the only option.

Drilling out the holes and putting in sleeves is the plan, but from the "inside" so that I can be fairly sure they're in the right place.
Resleeve it? Possible?
Oh my God, what's happened? I don't know man...I just got here myself!

Snod Blatter
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Re: CB250 Engine rebuild

#34 Post by Snod Blatter » Sun Dec 09, 2018 9:41 pm

If by resleeve you mean replace the liner then I'm sure it is possible but why bother when there are so many decent blocks around?

If you mean resleeve as in sleeving the engine mount holes with steel after drilling them out, anything is possible. There are no problems, only opportunities to improve!
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Speedy23
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Re: CB250 Engine rebuild

#35 Post by Speedy23 » Sun Dec 09, 2018 10:10 pm

Snod Blatter wrote:
Sun Dec 09, 2018 9:41 pm
If by resleeve you mean replace the liner then I'm sure it is possible but why bother when there are so many decent blocks around?

If you mean resleeve as in sleeving the engine mount holes with steel after drilling them out, anything is possible. There are no problems, only opportunities to improve!
I was on about pressing new liners into the block, but, as you say, if there are loads of s/h blocks out there, then probably not worth it. But keep us posted - interested to see how it's going.
Oh my God, what's happened? I don't know man...I just got here myself!