500 big bore

[Bryanj]

I have just finished boring out a set of 500 barrells to take 550 +0.25 pistons and if anybody is interested in buying these, with piston kits, before i bolt them into one of my engines please get in touch.
In the next few weeks i will also have barrells at 0.25, 0.5, 0.75 and 1.0 mm oversize along with kits if anybody is interested.

I have been busy using my boring bar and sorting out piston kits purchased over time..

There is a possibility of a set bored to a rare set of Yoshimura pistons at 59mm which is the maximum a 500 liner can go to.

Keep it dirty side down

Bryan

[Oddjob]

Wouldn't you be better using a set of 550 barrels with the Yoshi pistons Bryan, the liners were thicker to start with.

May pop down there over summer with some barrels for you to do if that's ok. Will need to be same day though, pop down and pop back same day etc.

[Bryanj]

Ken, that depend on the cases as 550 liners will not fit in some 500 but will in others, i am working on dropping a set of 550 liners into a 500 block to see.
I would happily do some blocks for you but it is wearher and work dependant as i have to set up outside!

[Oddjob]

As you know I intended to do the 550 liners into a 500 block myself. However I also found that the recess in the surface where the top hat lip on the liner sits is different between the 500 and 550. You could either get them machined bigger or reduce the size of the lip on the 550 liner. I experimented with reducing the lip. Got a mate with a lathe to turn down a 550 liner lip to fit the 500 lip recess. Just did one liner to see if it worked. You’d also of course need to bore out the 500 block to accommodate the bigger size of the 550 liner.
I was really only doing this as I had 2 sets of 500 barrels with ruined liners but good fins etc and 2 sets of 550 barrels with good liners but masses of fin damage. After giving some liners away to help out a fellow member I ended up with one set of barrels and pistons worth trying to salvage. In the end I found a NOS set of 550 barrels in superb condition and dropped the idea for a later date.

[Rozabikes Tim]

Ken, that depend on the cases as 550 liners will not fit in some 500 but will in others, i am working on dropping a set of 550 liners into a 500 block to see.
I would happily do some blocks for you but it is wearher and work dependant as i have to set up outside!

I had the experience of this not working when I had a 500 in my early 20's. Put 550 barrels and pistons on it.  It would run but when warm, not good! Put the 500 barrels back on, it was fine....
Always assumed some heat seizure happening?
May have been my Muppet "gung ho gove it a go" mechanicing skills then?

[Oddjob]

It’s the reinforcement pillars around the bore holes in the crankcases that cause the problem Tim from what I understand, the liners being bigger don’t have the clearance to operate or even fit in some cases. After a certain engine number Honda addressed it and reduced the pillar sizes to allow the 550 barrels to fit.

As yet I don’t know if my 550 barrels will drop onto to my 500 cases as the engine is still all in one piece and will be the last thing I do on my restoration. If it’s a problem I’ll try and fix it. If I can’t I’ll revert back to my 500 barrels.