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Picked up a '99 yz250, project time.


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Hey everyone!

 

I'm a noob here and to YZ's but picked one up for next to nothing so I figured why not? It's a great winter project and I've really wanted to get out of the cage and off 4 wheels. I work at an Arctic Cat/Can-am dealer as a service writer and own a Wildcat SxS and come from a history of YFZ's, Raptor's and Arctic Cat Sleds. I still actually have a Raptor 350 with a high compression built. So as you can see I have no real history with dirt bikes, its never too late to learn something new!

 

So anyways to the bike. A guy from the neighboring town had it listed for cheap so I went and checked it out. Apparently it was too much bike for his kid and had some damage so he just wanted to get rid of it. It had a broken brake lever, missing clutch lever and some misc. damage from laying it over. He claimed it had the top end replaced in 2013ish and hadn't been ridden in a while, he also thought the plug was fouled because he couldn't get it to fire. Oh well, worst case scenario I'd have to rebuild the top end. The only changes I can see is the FMF pipe and silencer. 

 

Once I got it home I picked up a new brake and clutch levers, then I noticed the carb wasn't completely pushed in on the engine side. So I went ahead and pulled the carb completely out to get a good look at it. it was setup with a 172/48 combo but was very clean. Then I noticed the pilot screw was no where to be found. Once I got everything sorted I kicked it over and it fired right up but was idling pretty high, any adjustment on the choke/idle nob wouldn't change it (not sure why). 

 

Now on the first ride I had no power band in first and second gear, third to fifth pulled like crazy. So it came down to the power valve or compression. Compression it was, 62 psi after 4 hard kicks. 

 

So now on to some questions; 

 

If they rode this without that pilot screw in it would it have been the cause or was it just time for a fresh top end?

 

The plug looks rich (could just be lack of compression I suppose) but does that jet combo sound right for 4000ft+, I live in the high desert. 

 

Recommendation on new piston, I've heard Pro-X but some people have also told me to just go back with OEM.

 

I intend on fully rebuilding this bike so anything else I should do while I have the engine apart? We have snow on the ground so I want to take my time and get everything done right. Any recommendations are greatly appreciated!

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Hey buddy, looks to be a good bike. Im in. Pro x isnt bad, oem is good obviously. Namura top end kits are cheap and pretty good too. If you have the engine apart, you could port and polish. Plastics dont look to be that bad either. Ebay graphics kit and theyll look good. Nice truck btw, how long is the bed in that?

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Hey buddy, looks to be a good bike. Im in. Pro x isnt bad, oem is good obviously. Namura top end kits are cheap and pretty good too. If you have the engine apart, you could port and polish. Plastics dont look to be that bad either. Ebay graphics kit and theyll look good. Nice truck btw, how long is the bed in that?

 

I think I will go with the Pro-x, I personally haven't heard anything about the Namura kits other than I have seen them on my parts books. It really isn't in terrible shape, just needs some TLC and every bolt in the plastics is different. haha

 

Thanks! Its a long bed 4 door tacoma, I believe it measures 6 ft.

 

62psi is very low. You will definitely need a top-end, and it has to be done before attempting jetting.

 

Yes, I am going to pull it apart tomorrow and see how the cylinder looks before I get to ordering parts. 

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I think I will go with the Pro-x, I personally haven't heard anything about the Namura kits other than I have seen them on my parts books. It really isn't in terrible shape, just needs some TLC and every bolt in the plastics is different. haha

Thanks! Its a long bed 4 door tacoma, I believe it measures 6 ft.

Yes, I am going to pull it apart tomorrow and see how the cylinder looks before I get to ordering parts.

just get a bolts kit for the bike. Itll be soo much easier on you. And those are good trucks
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I will look up that bolts kit, sounds like a good thing to have around. 

 

Numbers are pulled off all the way now, it was actually 269 originally and then they pulled the 2 off. I plan on just doing a graphics kit on it which should clean it up a bit, although I'd like to do all white plastics but that will be later down the road maybe. 

 

I pulled the head, cylinder and piston today on my lunch break and found a couple pretty good grooves in the cylinder. Looks like I will need to send that off for sure, the piston appears to be a Wiseco and it looks pretty new. The bottom end looks good, no play in the crank but I haven't pulled off the cover to check the flywheel just to be sure. 

 

Any recommendations on where to send this cylinder or do an exchange program? I priced out a new one and its much cheaper to get it repaired than to buy a new one, even at cost. 

 

 

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I bought a cheap bike (99 YZ250) too for a project bike and have similar problems. I sent cylinder to Kustom Kraft to replate and bought a wiesco piston kit. I highly suggest wiesco piston kits, top quality stuff. Good luck with yours!

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I think I am just going to send it off to Millennium and have it fixed/coated. 

 

I bought a cheap bike (99 YZ250) too for a project bike and have similar problems. I sent cylinder to Kustom Kraft to replate and bought a wiesco piston kit. I highly suggest wiesco piston kits, top quality stuff. Good luck with yours!

 

What did Kustom Kraft charge you to replate your cylinder? Was it grooved as well?

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