Cylinder Identification help needed......

As I continue to get parts for my now basket case 500XC project build up, I got a cylinder today that was suppose to be a 1987 500 cylinder. Only I already have what I thought is an 85/86 500 cylinder, and this new one I just got is way to short for me to believe it's a 500 cylinder. Unless they really changed the cases for 87, for a much higher base gasket surface. Bore size is real close between the two.

Sure would appreciate if anyone could help me ID what forsure each of these cylinders are. I looked in my pdf manuals, and had no luck finding the part numbers from the sides of the cylinders. Made me think they were perhaps casting numbers, and off some from an acual PN, like vintage mopar parts are.

Here's some pics I uploaded to my photobucket album in the hopes of getting some ID help on these. Thank you.........

Newer short one is on top.


Bottom cylinder from pic above, and one I have been sure was a 500 cylinder.


Top one from above pic.

Intake side port differences.

It should be pretty ease to ID them, it will just take a bit of searching. Look up the part numbers in the parts book.

Well, that's what I thought. I have the parts manuals I found online in pdf form, that cover the 84, 86, and 87 model years, and I'm not seeing these numbers.

Bore size is very similar, but I haven't pulled out my calipers to get that specific number. Just can tell they are both roughly 500 bore dia.

The cylinder I got today, is like .750" shorter from base gasket surface to head surface. I'm kinda assuming the short cylinder must in fact be a 430 cylinder, or perhaps even a 400 cylinder. Though I don't know the 400's bore size.

Not being able to ID forsure the one, left me then wanting to also nail down the one I've been accepting as being a 500 cylinder.

1Tuff

The tall barrel 16 14 582 is the 500 barrel. The other is 400-430. Bore on 500 and 430 same, pistons very different and so rod length. On aircooleds the 430 and 500 had cylinderheads with different squish, dome, designs and I'd bet it's also the case with LC engines. don't mix these heads up.!

Port design (at the sleeve) on AC and LC 430s same, as is case with 500s. Exhaust exit angle differ between AC and LC.

The lower one you show the inside ports on is like husqhamm says the 430 if the bore is 86mm or an oversize there of. The 500 cylinder has that L shaped port in front of the carb broken into two seperate ports and is longer. I find the 500 head with it's much bigger dome works pretty well on the 430. Actually the cylinder studs are the same the head "nuts" are different and the gasket difference seems to be to accomidate those longer "nuts" with bigger holes on the four main hold down points.

I find often folks have ground on the cylinder near the top of that port in front of the carb often to the extent I consider the liner undermined too much. Quite often find that. The new stuff is quite polished and smoothed compared to the rough transiton from liner to bumpy cast aluminum.

Water cooled ones have a divider in the transfer port while the air cooled ones don't have that. The water cooled ones do have significantly more transfer port passage area or volume as opposed to the air cooled ones even if they seem to share the case design at the cylinder base and gasket.

Laurence,
The shorter one is a 400cc, it has the same part # of my 1986 XC400 lump.

Hope this helps.

Fantastic help and clarrification guys, really appreciate it.


So in '87, would the 500 cylinder be identical to the one I have???? Or any changes by that point?


Also curious what you guys consider the going rate/cost for a good cylinder on the used market????

Good point. I had snagged an 87 430 head, actually only because I thought it was a match and the same as an 87 500 cylinder. I was thinking that in 87 they had revised the long shank nuts that hold the cylinder down, to being a shorter design now seating in shallower counterbored holes in the head. I could see that difference in some pics. Guess while it was good that I noticed the small difference, I was way off on the reason for the difference, and that it has nothing to do with anything other than the head being for a shorter cylinder.

Now since I'm always looking for an edge, or as many as I can come up with, your statement made me take a look at this other "87" head, and compare it to the head I'd gotten with my 500 cylinder. Sure enough, while the squish band looks identical, the chamber size it's self is smaller. Just looks a touch shallower chamber dome depth when looking at the head upside down. Perhaps an 1/8 of an inch or less, shallower. I'll have to grab my calipers for an more accurate depth diff. measurment.

So, being an ex Mopar drag racer, this leaves me wondering about raising the compression on a 2 stroke. Because 4 stroke V8's really wake up with compression increases. If I simply open the counterbore cylinder nut holes up on this 430 head, it'd go right on the 500 cylinder, but allow for a compression increase. Not sure how much, but I'm guessing a noticeable one, considering how small the chamber volume is to begin with on the 500 head.

Hmm, compression increase worth any gains, or should I just re-sell this 430 head????

Exactly what a good cylinder still on the origional bore and not tampered on with dremmel tools or their air powered equivelant die grinder probably should be approximately equal to the cost of a piston to re bore it to, a new one. However I think most are sold on ebay in such a manner the buyer has to low ball it as more often than not they will get something less than what I described in the first sentence. Perhaps $50 in reality but don't ask me to sell one this year.

As to your raising the compression on your 500. If you deck the cylinder meaning cut some off the bottom and then mount the head on a plate on a lathe and sculpt the squish you desire you could end up with gains in torque on the low end of the revolution per minute range. I have a 360 this has been done to. It is quite enjoyable to ride, the steel kick starter has been lengthened. Generally on two strokes going too high on the compression leads to pumping losses and no real gains if you are after high rpm power and higher total horsepower. Some of the 400 heads at least one off of a water cooled dual shocker have higher compression than a 430 head when put on a 430, some seem to be the same as a 430 head just not stamped 430. I have tried the higher compression head on the 430 head and it didn't seem to make any gains, the 500 head makes it fun to ride harder to stall and easier to start, Probably not as good out in the open areas of the rocky mountains or west near the grand canyon or such or even a local gravel pit but certainly pounding through rock gardens it works good.

Fran

I would say the porting of guys whose race these little carts with two stroke motorcycle engines and much larger exhaust systems would be what to examine to get ideas.

I havn't done it but I hear you can add passages connecting from the reed cage area to the transfer port in the cylinder. This would be like an external passage going around the cylinder stud. I was thinking of adding an exhaust port above the front transfer port and going around the other stud to the exhaust somehow like in a power valve engine with the boost ports above the most forward transfer ones. No one has told me they have seen that attempted but the first description in this paragraph apparently has been done with some though I don't think a lot of improvement.

I used to subscribe to dirt bike magazine and they tested the ktm 440 and put it on the dyno and discovered it came within one horsepower of the 550. You could figure out what year it was as the 500 class model kept getting different numbers. Husky is basically the same situation with the 430 and 500 same bore different stroke. Might I wonder aloud could one get just as much power out of a 430 as a 500? You have a much lighter piston the same exhaust and transfer port cross section. I sure don't drag race however at least with Ford I am under the impression a 429 has as much racing ability as a 460, here the same thing same bore different stroke.
Fran

Ah hmm, OK, where to start.

All things being equal, stroke, equals torque, especially at lower rpm's.

Oh man, huh, OK, I think I'm interpreting this correctly. 50 bucks lol. Not what do we wish they cost, which in my case would be ohh, 5 bucks lol. But what is the fair market value tending to bring on used ones. Maybe I'm already fairly equipped to answer my own question, since I watch ebay with such consistency. I paid $125 for the good standard bore 500 cylinder and head. See plenty of numb nuts put them on there for 2 and 300 bucks, in much worse shape. Have noted one slightly rougher looking bore 500 cylinder alone go for 35 bucks a while back, and have been kicking myself for not grabbing that one every since. Got my NOS Mahle standard bore piston, ring, wrist pin, and circlips kit for 120 shipped. While I wish they were cheaper, I'd say a fair average price, from what I've seen watching just ebay (my only barometer), is probably right around what I paid. As always, with so many popping up way over priced, just because they are "500" cylinders, you do have to be quick to assess ones down in the 150 and below price range. Still kicking myself over that 35 dollar one. Think it needed an overbore from standard, but have seen NOS overbore pistons on occasion.......

Anybody else have any observations on cylinder pricing???? Perhaps from markets other than ebay?

Great info Fran. The compression increase debate on 2 strokes I have seen in other forums, and is often filled with those completely against the concept as having any place in the 2 stroke world. I was just curious what the concensous in here might be.

Back in '94 I grabbed a basket case '85 Red CR250, and dug out all my old MX mags and pulled every privateer punch I could find on what was done when new, to run with the factory bikes. However, not knowing any better, and it being such an automatic gain mod on V8's, I had the head milled. Don't recall the specs, but between myself and the machinist we tried a what we thought was a small safe amount, that should show something, if it was going to. I wish I would have done it separately, because the bike wound up being an absolute hotrod of a 250. Was a bit tough to start, and needed high octane gas, but neither were an issue for me at the time. Despite my porting mods, it was still a low rpm animal, but did carry over into a stronger midrange powerband. The bike would easily run down 92 & 93 250's I'd often practice with. I mean like obvious big hp advantage, on short straits. Everytime I had the bike out, I seemed to have fathers that were timing their sons coming right over to me when I'd be taking a break, and asking me all about the bike, because they couldn't believe how easily it seemed to be out horsepowering the newer bikes. Always would get the "what year is this thing, wow it looks like new, and what the heck did I do to the motor". I could never help but think that the raised compression played some part in the power advantage.

I need to delve into it further, perhaps in the karting arena as well, or snowmobile, etc. I know it's a guaranteed big power increaser on V8's, and great there especially if taking a low compression mill, with room to spare before race gas comes into the picture. No other changes, and it yields big smiles. The 2 strokes are just such a different animal I come to realize, I really want a better understanding of modding them this time around.



Oh, and yes, forsure there are gains to be had if all things are equal and you can start nocking grams out of the reciprocating assembly on a V8. Hence a 347 stroked sbf, often running a touch stronger than say a stock bottom end 351w. The stroked 302 has much shorter rods, and much much shorter compression height (mass) on the pistons. Equaling free revs as it were. Though the shorter rod to stroke ratio has it's cons as well, being much increased frictionional piston/cylinder sidewall loading and thus dramatically increased wear rates.

So I can see how some 430's could be real hotrods motor wise, with the same port area, and lighter reciprocating assembly. Less leverage always equals less torque though. Always a trade-off somewhere.