Engine Blocks and cylinders

[Ricks]

I was doing a little prep work on an engine today when I came across something I had not seen before.  I recently had Wayne sleeve  a 150cc cylinder back to a 125cc size.  I was test fitting the cylinder to the block, but the cylinder was too big to fit in the block spigot!  WTF, I said to myself.  I then pulled out some other cylinders I had and started measuring.  Sure enough, the 150cc cylinders are cast larger at the bottom.  The two engine blocks I have are 125cc. Pictures below tell the story.  What I ended up doing was using a die grinder to open up the block to accept the cylinder.


Notice one of the blocks has a step cut, the other doesn't. 

[pd]

Interesting , Rick .

Do both the 125 and the 150 cylinders fit snugly into the blocks ?

Pete .

[Ricks]

Interesting , Rick .

Do both the 125 and the 150 cylinders fit snugly into the blocks ?

Pete .

The 125cc floats very loosely, not indexed at all.  I don't have a 150cc block, so I don't know for sure.  The 125cc block I clearanced for the 150cc cylinder, I left it tighter than the other, but still some room. The studs seem to provide all the indexing.

[pd]

I wondered what you have as my 125 cylinder is very loose . Almost too sloppy , but I think there is enough room on the wrist pin to make up for any misalignment . Still , I center the cylinder as close as I can using two sides at the base . So far that seems to be good enough .

Pete .

[Ricks]

I wondered what you have as my 125 cylinder is very loose . Almost too sloppy , but I think there is enough room on the wrist pin to make up for any misalignment . Still , I center the cylinder as close as I can using two sides at the base . So far that seems to be good enough .

Pete .

After installing the 2 bolts and 2 studs, there isn't much room for play.  Aligning to the outside of the base would just be for aesthetics, as far as I can see.

[pd]

Aesthetics or not , it works .

The bolts/studs seem to allow a pretty fair amount of play on my motor . Like I said , almost too sloppy . At least there's a lot more slop than I'm use to on other motors I've had apart .

The outside base alignment also insures the cylinder is mounted the same every time .

Pete .

[pd]

I wondered what you have as my 125 cylinder is very loose . Almost too sloppy , but I think there is enough room on the wrist pin to make up for any misalignment . Still , I center the cylinder as close as I can using two sides at the base . So far that seems to be good enough .

Pete .

After installing the 2 bolts and 2 studs, there isn't much room for play.  Aligning to the outside of the base would just be for aesthetics, as far as I can see.

Rick ,

I was thinking about cylinder 'fit' to the case . Being as your bolts/studs don't allow "much room for play" , I have to wonder exactly which fasteners you use .

Along with that , do you have to re-torque those fasteners after you run the motor for a bit , the first time after assembly ?

Pete .

[Ricks]

I use the stock studs with either a nylock fastener or steel locknut.  On the other 2, I use the stock size 5/16" fine bolt with the same fastener.

[pd]

OK . Thanks , Rick .

I'm using the original hardware and wondered if you found anything better .

Pete .

[Derek]

I've found this place, Albany County Fasteners to be good source of hardware.

albanycountyfasteners.com

[henrylr]

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Their material selection is also great. Many screws, bolts, nuts and washers are available in various non-ferrous and ferrous metals including two grades of stainless steel.

I've been restoring a wheel horse 1975 tractor and almost all nuts, bolts and washers are now stainless steel. I also used stainless hardware in restoration of my lathes and milling machine. I think their prices are very fair. I'm not connected with them in any way.