Planet Minis

five21racing

2003 YZ85

I got it in a trade + cash for my 250f.

Well a month later (today) I decide to tear into it. We made the trade right after I got done racing a hare scramble so I wasn't paying much attention. So right there I miss all the things that were wrong with it.

Whatever, I'm over that, the kid who had it is just a complete idiot.

I noticed it leaked oil from the ignition cover. I poped that off and I'm just guessing it needs a new gasket.

Here's the question though. I grabbed the flywheel with my hand and turned it without much effort. I'm guessing that's a pretty good sign it needs a new top end? Should I install a top + bottom end too? I would rather not stick a ton of money into this since I'm just going to sell it as soon as I get everything done. I do not want to hand someone else a bunch of head aches and problems though. I hate when that hand is delt to me and I would pass it along.

I should have a pretty nice little 85 after I'm done going through it 100%.

Thanks for any help.

xr1million

Why not pull it apart, examine it all... then see what it needs!!!!!

and decide what you want to put into it!

five21racing

I'm exactly high up on the food chain when it comes to engines. Adjusting valves and such - no problem. That's really about it though.

SUZUKIRM12594

Its as simple as knowing how to work a wrench...Take off the cylinder, and check for cracks, scuffs, and the usual ware... If the piston is in bad shape, buy a new one and throw it on and put your engine back together...2 stroke engines are alot easier to work with than 4 strokes. You can probably whip that up in 30minutes if you dont find any other probs on the way. (Remember: Any case that is removed on the bottom or top end needs new gaskets and must be evenly torqued with a torque wrench)

five21racing

Ah, the obvious stuff... Yes I know if there's a crack; there's something wrong. I was talking about how much of a gap there should be between parts and such.

Thanks, I'll tear the bike down and pull the motor.

SUZUKIRM12594

You can start off by buying a YZ85 service/mechanics manual...It will explain everything you need to do in detail. Including specific measurements and torques.

Luckystar64

Pull the top end off and see if there is any up and down play in the crank. If it feels tight, and the connecting rod isn't all scored up where the wristpin bearing rides. Then I'd inspect, and maybe hone the cylinder-- slap it back together with new top end parts, and call it a day. You don't want to put crazy $ into a YZ85. They're everywhere, and cheap. That '03 couldn't be worth more than $1400 if it were immaculate. ---L*64

five21racing

$1400...damn

I took $1000 off the price I was asking on my bike so he could put the 85 towards my 250f.

I'll have her up to spec. by the time I'm done though. I'm glad an able person is attempting to save this poor little bike.

I worked a little too long tonight to get the top end pulled. I'm going out now to get the motor out though.

Thanks

Luckystar64

Yeah... Unfortunately there are a whole bunch of YZ, CR, KX, RM, KTM 85's out there that haven't changed much since '02 or so. Not only that, but kids ride/race those things for a couple of years, then move up to something else, so they're always for sale.

I'm almost positive that all the manufacturers will bust out a 4 stroke 150 in 2010-- then the $ will come down a little more yet. You'd have been better off selling the 250F. If you have only $1000 in it, and it doesn't need a crank or cylinder, you should still be OK. The motor is damn easy to work on at least. --L*64

five21racing

2 strokes are dieing and I have 2 of them in my garage.

It sure doesn't look good for me. Oh well...

Selling the 250f on it's own wasn't really much of an option. If I was to sell it on it's own; I would have been required to drop the price, big time. Plus it had 60+ hours on the stock engine.

Granted my bike was in excellent condition..

Update for tonight:

I finally got the engine mount bolts broke loose and oil came out of both of them, great...

I think it might be the best to just find a bottom end on ebay.

Let me know if anyone has one they would sell.

firepower354

Nice safe home for an XR100 motor...

five21racing

If I only learned how to weld when I had a $2000 welder in my dad's shop....

What would someone give for the roller anyways?

I guess I should really consider my options before I start dumping money into it.

punkguitarist

you could probably get a good amount of money for the roller because lots of people want them for xr100/ttr125 conversions.

go over to thumpertalk on the xr80-200 section or the ttr section and tell them you have a roller for sale. im sure someone would be interested

Luckystar64

Whoa! Whoa! First of all-- I've never seen a TTR125/YZ85 conversion, --- I'd like to though! Anyone have a pic? I did see a YZ85/XR100 conversion. Why would somebody monkey with that (TTR/YZ85) when you could get either a 150R if you weren't going to race it, or I just saw a really nice DMC conversion with a $2900 asking price on Thumpertalks' classifieds?

If that 85 has a set of good cases, a good crank, tranny, and cylinder, it won't cost that much to freshen the top end, and get it running right, then sell it! The whole engine can't be jacked. Get it apart, make a list of what it needs, get the parts, put it together and sell the dog gone thing, or just ride it.

I love two strokes, and I have a feeling that they'll be back. I think it would be cool to find a way to recirculate the top end lubrication to clean them up-- kinda like how a Honda 4 stroke has two sets of oil for the top and bottom ends. ---L*64

kman153

hey i rebuilt my yz85 frame up its pretty simple engine build id do a top and bottom end change incase the crankshaft bearings and the bike doesnt have any exhaust valves like bigger 2 stroke motors

kman153

some one buy my 85 its an 03 with a rebuilt motor and paointed frame and i went through all the bearings its ready to race

five21racing

don't try and push that in here... make your own ad if you want.

I was reading somewhere that some remove the power valves in the YZ85 motor??? It sounded a little off the wall..

BlackBeard

i didnt know the yz's had power valves. it wouldnt matter either way on that small of a bore the valve doesnt do much , if any regulation

stevec

YZ85 and CR85 has no power valve. It's the KX85 and RM85 that has PV.

stevec

It can add up. Piston kit $90, gasket set with oil seals $50, Hot Rod crank and rod kit $150. If the cylinder wall is scored, it'll need replating $180.