86 / 88 CR / WR 250 cylinder liner compatibility

[RTM]

My 88 WR250 has spat it’s dummy and in doing so ripped the rim of the cylinder liner. I have obtained an 86 CR250 cylinder with piston I hope to be able to modify to fit.



In the photo it appears to have additional transfer ports but I’ll not worry about that.



I know the 88 has a 66.5mm bore x 70.8mm stroke and the 86 has a 70mm bore x 66mm stroke (roughly)



I plan on fitting the 86 liner into the 88 cylinder and seeing how things line up port wise modifying things as necessary (if possible)



Spacers / skimming etc.



Has anyone been here before and can give sound advise?



I know LA sleeve do a liner but its more than I paid for the bike, so failing the above I’ll be machining my own but want to explore the above option first.

 

[2premo]

the cylinders are so different I have no idea how you will overcome the different bore and stroke or the port timing, so when it's sleeved who will make the custom piston that will cost a fortune

find a good used cylinder with a piston

 

[fran...k.]

I don't see any pictures.

Why don't you put your location so it shows up next to the avatar. I know a guy who has sleeved down suzuki 465 to run in 450 class and made reed cage butlaco. There are ways to get blank sleeves and do whatever is needed or desired.I don't really know but the dealer price for the sleeve might be a lot less than you were quoted enough so that you could get one installed. I think it takes over two parts bikes to put together one ridable one without buying a lot of parts and it helps to keep 85-86 seperate from 87-88.

Getting another similar cylinder, would be logical to me. I would rather swap out for an 86 crank than do what you have in mind. Maybe even an air cooled crank could have the water pump slot cut.

 

[RTM]

Finding a good used cylinder is the ideal option but the parts are rare / expensive and an 88 husky even with the most rosey coloured spectacles on is worthless.



Are you saying that the ports are way out? And that I cannot cut them to match? Adding metal is could be more of a challenge, I’ll give it a go though – that’s what a power valve does in essence.



The 86 cylinder the ports look remarkably similar radially, vertically I cannot tell but that is where is matters timing wise. My guess is that due to the stroke difference, the ports on the 86 cylinder will be further up the liner and I will have to drop it down to line the original ports up. This would mean adding a ring of cast iron to the top of the liner to make up the difference – not tried that before but willing to give it a shot.



No idea on the pin to crown height etc just yet as I don’t have the parts in hand.



I’m in the UK by the way.



If this was my 83 husky – I’d throw money at it !

 

[2premo]

a friend bought an 87 250 someone tried to do something like you are discussing
by the way it was apart when it arrived with a potpourri of different 250 parts
we looked at many options and ended up putting a stock top end on it

 

[RTM]

Just spent an hour scaling off the port dims from the photographs. All pretty approximate stuff but the exhaust actually seems to be lower in the earlier cylinder. Which would be a result. Meaning I could skim the top of the liner and using a spacer under the liner rim lift the exhaust up to the correct level - or just bring it up with a file. All guess work till the real thing arrives of course.

The older liner is much much shorter (20mm or so) should be plenty left in there at the bottom of the stroke I hope.

 

[RTM]

1985 cylinder showing exhaust port

You can see the two additional transfer ports to either side of the exhaust port. The 88 WR alloy cylinder has no recess for these so I'll just leave them blanked off with the alloy behind.

 

[RTM]

85 inlet port

 

[RTM]

88 cylinder liner (the line at the top is the cracked off rim)

 

[RTM]

88 Inlet Ports - there is a massive difference between the induction port as you can see - but ts reed valved so I doubt it will make all that much difference.

 

[snfpagp]

I have a 86 Wr 250 That i need to rebuilt my cylinder any ideas where can i get it rebuilt in the US ?

 

[snfpagp]

I have a 86 Wr 250 That i need to rebuilt my cylinder any ideas where can i get it rebuilt in the US ?

 

[2premo]

I have a 86 Wr 250 That i need to rebuilt my cylinder any ideas where can i get it rebuilt in the US ?

there are a number of used 85 86 250 cylinders available for pretty cheap, you might want to look at those as an option, I probably have one laying around but am moving so I can't look, as they are packed
they used to come up regular on flea bay

 

[fran...k.]

If this was my 83 husky – I’d throw money at it !

Probably making some custom inserts for a 12mm swingarm pivot rod, changing the cylinder stud/rods and using an 1983 top end will get you an engine with a few more modern features. If this liner problem put this lower end out of action early in it's designed for lifespan It could be rather handy to have. At least in the 500 what I listed above has worked for me. You would need the proper stroke crank though I don't think the crank will be the hard to deal with issue as time goes by.

I have little experience with the 250 I bought a few lower ends off ebay when I was diseased years back and no one else bid much but the only one with a top end I sold off that. It was an 88 wr actually I think I bought the whole bike, There was a semi circle cut out on the back of the piston down low. The cr of that year or close had a powervalve with those extra exhaust ports I would imagine. The dimention from the top of the cylinder to the top of the exhaust port is probably a key one.

 

[2premo]

Probably making some custom inserts for a 12mm swingarm pivot rod, changing the cylinder stud/rods and using an 1983 top end will get you an engine with a few more modern features. If this liner problem put this lower end out of action early in it's designed for lifespan It could be rather handy to have. At least in the 500 what I listed above has worked for me. You would need the proper stroke crank though I don't think the crank will be the hard to deal with issue as time goes by.

I have little experience with the 250 I bought a few lower ends off ebay when I was diseased years back and no one else bid much but the only one with a top end I sold off that. It was an 88 wr actually I think I bought the whole bike, There was a semi circle cut out on the back of the piston down low. The cr of that year or close had a powervalve with those extra exhaust ports I would imagine. The dimention from the top of the cylinder to the top of the exhaust port is probably a key one.

the piston is a different skirt design in that the intake side is shorter than the exhaust side, can't remember if my CR had the cut-out like my XC, I took the CR apart about 8 years ago to inspect and I put a ring in while it was open but don't remember what it looked like

 

[RTM]

I have a 86 Wr 250 That i need to rebuilt my cylinder any ideas where can i get it rebuilt in the US ?

Can you do me a real big favour - I need the dimension from the top of the piston ring to the gudgeon pin Centre line & the top of the exhaust port to the top of the cylinder. + any other dims you can tell me . Would be eternally gratefull.

 

[snfpagp]

Hey RTMi decided to sale it as is I have no mechanical experience could not tell you where to start measuring

 

[RTM]

Thanks guys, I have now managed to purchase a couple of 88 barrels one with a power valve and one without, the liners are identical even with the power valve which surprised me no end.



Very lucky to find one let alone two as there were only a few hundred manufactured in 88.



Now to work out why it seized – a classic four point seizer, so it got a bit hot. The plug was correct and as far as I know the carb is stock, maybe the water pump failed? But it didn’t lose a drop of water.



However the bike was a pain to start earlier that day as I had to bump it off initially. I wonder if there in is the clue.

 

[auto]

I thought that only the 88 CR had long stroke motor.Your saying,at least in Europe the wr(no power valve) also was a long stroke motor

 

[RTM]

The 87 & 88 have the longer stroke 70.8mm with a 66.5mm bore. Yes the WR also has exactly the same liner as the CR. I have just swapped them over and they are identical. Other than having no power valve.

If you look at the photo above of my WR liner (the one removed from the jug) you can clearly see the notches which are cut out of the bottom of it to allow the con rob to clear. The longer stroke motors needed this feature.