I hate it when this happens

[scotty dog]

Well, I have done some research, and come to three options; Option one is that I go to bikebandit.com and buy every OEM part(top and bottom, because it turns out that I also detonated the piston), which, I am not sure I want to do. I can also go to motosport.com and order a wiseco top and bottom end kit which includes everything(has anyone had any experience with this kit?), or I can look for a used engine and swap the engine out(Does anyone know if other brand engines will easily fit in my frame? Like a 250 2 stroke RM?). Now, I think that wiseco probably has the best performance parts, but isn't OEM more reliable? Also, would the wiseco set come with the bottom end put together already, because I don't have the machinery to put it together otherwise, if so, does anyone know of a place that can help me out? Also, is a 2001 cr250 engine interchangeable with a cr125 frame, I heard that the 2001 was the best year. Any advice would be appreciated, 2 strokes still rule, but believe me, I got hassled about it from my 250f friends, although their bikes are only 2 years old, and mine is a 2001, and as far as I know hasn't had a top end until last week. Well, I suppose it is time to take the old fart out of the shed(1984 xr 200), say hello to good gas mileage, and heavy weight, no power riding, at least it isn't a loud four stroke...

I would go the Wiseco kit, the crank should come complete from what i can tell, ya still need some special tools to put it together and pull it apart but having a complete crank is half the battle.

[JohnN]

While I would look into a Wiseco crank, I have heard way too many folks having problems with the pistons to ever recommend one. Either OEM or Wossner... whichever you can afford.

Make sure that you replace all the bearings and seals as well... it's cheap "insurance" since you have the bike apart already. I've heard quite a few stories of guys cheaping out on this stage only to have the bike seize a bearing or tear up a seal. Then the whole thing has to come apart again. Sometimes having to replace EVERYTHING again.

No that would be heart breaking.

Oh and another thing, the gas/oil mixture is not as important as having an ultra-clean air-filter! With gas/oil mixture once you choose and oil and mixture stick to that. Don't swap then around all the time. And learn how to properly jet your machine, it will run better and last longer.

Let us know how you do...

[ford832]

Twice the horsepower?  What about Maico's air-cooled 250 in 1981, which made 42 horsepower?  And I know the 490 gained a lot of power when they made the new '83+ engines, so I wouldn't be surprised if the '83 250 (also air-cooled) made more than 42, but of course I don't have a number to post on that.  Yes, the '81 is four horses down on a new YZ, which also has a powervalve, but you can't say they've got double, unless you look at a 250 that doesn't have an expansion chamber, or something.  And remember, all my bikes, as well as my dad's and my uncles', are air-cooled and running 50:1 ratios, and they haven't had lubrication-related failures.  I'd probably put more oil than that if I were to go actually racing, but still, anything that can last thirty years on 50:1 probably doesn't mind lean ratios.

I don't want to start another new vs old debate, I'm just saying, don't short-sell the fins.

Don't get me wrong,I like the old bikes,but as for those power figures-well,as always,you can talk rear wheel hp,shaft hp,or in the case of Maicos of that era,I believe the hp was measured at the sales brochure.
As for the CR,that's too bad.Likely you did nothing wrong but the crank was just due.Sometimes when you smoke a piston bits will end up in the crank bearing area which is usually then a ticking time bomb.

[TMKIWI]

Well put ford. !!!

[JETZcorp]

Oh yes, because we all know that the marketing departments today are far more honest than they were before.  Although, I notice that no one really seems to be talking about horsepower.  When I was writing my paper, it took me an hour and a half to find how much power a 250F made, and I ended up finding it here at TSM.

[TMKIWI]

Ok i will bite.
Torque governs acceleration not horsepower.
Pasted below are figues out of Suzuki brochures.
Dont worry if they are brochure figures or true figures.
Just look at the increase in torque over the years.
RM 250 B 1977
Overall Length: 2,140 mm (84.3 in)
Overall Width: 885 mm (34.8 in)
Overall Height: 1,220 mm (48.0 in)
Ground Clearance: 280 mm (11.0 in)
Wheelbase: 1,450 mm (57.1 in)
Dry Weight: 101 kg (223 lbs)
Engine type: Air-cooled 246 cc single-cylinder 2-stroke. Piston and reed valve. 35 hp/ 7,500 rpm,35Nm 3.6 kg-m (2.61 ft-lbs)/ 6,500 rpm.
RM 250 S 1995
Overall Length: 2 167 mm (85.3 in)
Overall Width: 815 mm (32.1 in)
Overall Height: 1 250 mm (49.2 in)
Seat Height: 955 mm (37.6 in)
Ground Clearance: 360 mm (14.2 in)
Wheelbase: 1 467 mm (57.8 in)
Dry Weight: 98 kg (215 lbs)
Engine type: Water-cooled 249 cc single-cylinder 2-stroke, AETC. 51 hp (37,5 kW)/ 8,000 rpm, 47,5 Nm/ 7,000 rpm. 5-speed transmission.

RM 250 2004
Overall Length: 2,175 mm (85.6 in)
Overall Width: 840 mm (33.1 in)
Overall Height: 1,280 mm (50.4 in)
Seat Height: 950 mm (37.4 in)
Ground Clearance: 350 mm (13.8 in)
Wheelbase: 1,470 mm (57.9 in)
Dry Weight: 96 kg (211 lbs)
Engine type: Water-cooled 249 cc single cylinder 2-stroke. 55 hp (40.5 kW)/ 8,000 rpm, 50 Nm/ 7,500 rpm.

I dont know why you feel the need to defend the old bikes when no one is putting them down.
They are what they are and technology has moved on.
So enjoy your Maico and have fun but please don't sugest it will keep up with a new bike.

[JETZcorp]

Well wait a minute, what you've shown is that an RM in 1995 makes five horsepower more than a brand new YZ250 on the showroom today...

Besides, I've never said that they've got as much horsepower as today, or that they're as fast as a new bike on a modern track.  I just don't want people thinking that bikes from the '80s were so bad that you might as well run a Model-T against the latest LMPs at Sebring.  There seems to be a lot of that conception floating around, even if it's just subconscious.  Like when nobody doubts that a new Yamaha will make 46hp, but when 42 is quoted for an '81, oh, that's gotta be from rectal extraction.  I really don't want to turn this into another argument, but I also don't want to let people go away from a discussion with the notion that an "old" bike can barely move under its own power or that they'll rattle apart as soon as you hit a bump.  I still maintain than a mid-80s bike (and NOT a mid-70s bike) could be competitive (and NOT superior) in amateur-class racing.  No one can use their bike to the fullest until they get very good indeed, so there's a shit-ton of wiggle-room.  The comment that started this (that new bikes make twice the horsepower) is an excellent example.  Horsepower hasn't been doubled in any displacement class since the original two-stroke revolution, and all I'm out to do is make sure that people know that.  When we start assuming that newer instantly makes things better, then we've got a really easy segue into the assumption that an "outdated" YZ must intrinsically be slower than a YZF, and I think we can agree that's dangerous.

[TMKIWI]

Jetz no one is saying the bikes from the 80's are crap.
You miss the point again.
The twice the horsepower comment was about the PE done on the dyno. NOT an 80,s bike. It was a 78.
The horsepower figues in the Suzuki brochures are crap.
The point i was trying to make is that torque has increased over the years.
Not only has the torque increased but the torque spread is over a greater RPM range now then in the past.
That is why the newer YZ engines gets great praise as it has a lot of power over a wide RPM range.
That does make the bike quicker and easier to ride.

Maybe i should have used the word performance not horsepower.

I am not slamming the old bikes at all but real world performance has improved.

By the way. I own a mid 80s bike but it has too many strokes so wont mention it here.

[JETZcorp]

If there's one thing I think everyone can agree on, it's that old four-strokes really do have troubles in terms of raw performance.  This was a time in which nobody was crazy enough to make the engine as fragile as a vase and running 400 strokes a second.  Thus, they tended to be relatively reliable (relative to today's 4Ts, which disintegrate when breathed on) and had a pretty fair following by guys who liked big, gnarly pieces of craziness forged out of a single piece of granite.

[TotalNZ]

I think those figures are probably at the crank aren't they?
Sorry to hear about your bike hondacr. Sounds like it was just her time.