Best way to enlarge small ends

[jensen]

Hi Jerry,

Thanks, the reason I had to be more specific then a yes or a no, is that I have seen too many wasted cranks, and nobody is going to re pop cranks in a short term at a reasonable price,

Jensen

[conbs]

Well...... I have read this thread and thought through it over and over. I see both sides of the discussion. I think the answer to 48's question is: it depends.

If you are building a race bike or looking to build a bike that is sure to give you years of trouble free riding, Jensen and Jerry are spot on. On the other hand, if you are looking to get your bike up and running at the least cost for a rider - and have a great story about the experience, no matter what, then why not give the 48lesco proposal a try.

It will be difficult to keep things aligned, there is no doubt, but 48 make a very stong point that not that much material is being removed and you do have the current alignment (though it is worn) to help out. Without enlarging the bushing too much, there is just not that much room to create an issue. That said, if you do create an issue, the joy of riding your Honda will be shortened as Jensen has described.

So, what if it does? You will have to buy new pistons, rings and perhaps liners (assuming you do not have a catastrophic failure). It will probably still be cheaper than getting your crank rebuilt right now (though you will still face the expense of resolving your crank issues if Jensen is right). It is basically a bet of spending less money now. If you win you are back on the road with money left in your pocket. If you lose, you will spend the same money to fix the crank "rignt" plus more on pistons, etc.

But, what if 48 is successful? He will have done the impossible and have had a great life experience along the way. To me, that is worth way more than rebuilding the engine the same way any Tom, Dick or Harry can (though I am currently doing that, too). If the HD guys can ream their rods in place, 48 can see how they do it. They probably have some tricks that help give their effort the best shot at success. There is also 48's defining question of what Honda did back in the day. If Honda took the crank apart to fix a bad small end, wouldn't they just have replaced the rods? Why go to the trouble and expense of creating oversized wrist pins?

But, even if Jensen's prediction of premature piston wear bears out, it will be a GREAT story to share over a beer (hopefully with Jensen). On the other hand if the 48 method bears out, that "story" will not really be known for sure for a number of years. It will add a drama to 48's riding like few other things can. Just don't plan any long road trips.

When I was young I knew a guy who built a '58 ford Y block with twin turbo chargers. He turned his own cams on a lathe and finished them by hand. He didn't finish elementary school and was self taught. He had more mechanical ability than anyone I have ever even heard of. I watched him do "the impossible" over and over. It was an inspiration to me and taught me to always think outside of the box.

I concede that my post goes against convention and Jensen and Jerry are absolutely correct in their thinking - if you want to do it "right". Still, I hope 48 will give it a try. For anyone who disagrees, I urge you to watch The World's Fastest Indian before you post.

48, please take lots of pictures if you do give it a try.

[48lesco]

Didn't mean to start a controversy - I had already decided to do it in-place and was just asking what others had used.

World's Fastest Indian HA! I forgot about that; gives me hope - Didn't the Six-Million Dollar Man grind airplane pistons by hand in that one episode?

[G-Man]

48

Just because I am a contrary old bloke who likes to go against the flow, I would look at using up some old scrap barrels (I have plenty) and piston(s) to make an alignment tool from which you could guide a home made lapping tool through the rod end.

Bolt the cases together around the crank and use the 'jig' to align the lapping tool to the con rod eye.

Now I have no idea whether this would work, but I just love it when people tell me things are impossible........ :-) Yes I know it's not official Honda practice but discovering that one of the dampers I rebuilt recently had never ever worked properly because of an error in manufacture reminded me that nobody's perfect..

As Jerry's compatriots would say. No dramas, mate! It's only an old engine, after all...

Have some fun!

G

[48lesco]

Thanks for the input and interesting suggestion G! You hit on an interesting point - what was the official Honda procedure for using their oversize pins??? Service bulletin anyone?

[jensen]

Hi,

The procedure was reaming with the factory reamer (special tool).
I completely agree with G, Honda made mistakes, and this oversize piston pin was one.
After the 250 /305 Honda abandoned the "technique"and never tried it again.

Many people would love to see oversized CB450 piston pins, but Honda made a wise decision.

btw G, I never mentioned anything about being this method impossible, it's just not what I should do, and that's what exactly what I wrote.

Conbs, I see where you coming from, and I appreciate your input and thoughts, but what can I say ? I have enough evidence lying around in my shed that other methods then I described are not working in the end. But one can always be lucky.......,

Jensen

[conbs]

So, after my post yesterday, I couldn't stop thinking about that movie. It turns out my wife loves Sir Anthony Hopkins and we watched it again last night - for her birthday! What a gal! It is "Hollywoodized", no doubt, but the basic story is truly inspiring.

Thank you Jensen for the info on the Honda hand reamer.

Any one have a Honda reamer they would loan 48 to help out? A hand reamer would definitely require some finesse to avoid creating the problems Jensen described, but it is a machinists tool and they can be used effectively with the right touch. And, ...... perhaps a little luck as Jensen has suggested

I know I have seen discussion on this forum regarding oversize wrist pins. I know people have purchased them, but has anyone ever actually put them in their bike? If you did, how did you deal with the small end? Was it successful? Is your bike still running or are the remains in a place like Jensen's shed?

48, I don't think you have created a controversey. Iron sharpens iron. It may cause a few sparks, but in the end we all become a little sharper. May your hands be filled with finesse, touch and good fortune as you proceed.