New YFZ450 owner...what do you think of my new project?

[IQRaceworks]

Well...it looks like I'm finally a Yahama owner after owning Hondas and Suzukis all my life. I picked up this 2005 YFZ450 because I though it would be a fun project. Supposedly it's got a bad crank, or bearings...or worse. Hard to tell...the kid I bought it from didn't really know. He just knew that is locked up on him. It will crank...but not very smooth...it's really laboring. He said a shop told him it was a bad crank. So I decided to go and look at it. I went and gave it a looking over, and after talking him down quite a bit from what he originally wanted for it, I paid the kid $1000 for it. I think it's a good deal, even though it's going to need a little TLC (and motor work) to get it up and going.

The kid that I bought it from said he only had it for 8 months before the crank went out on him. He said the guy he bought it from was the one who did all the mods to it. I'm sure it was pretty nice before this kid got to it. He kept it out side, and that never really keeps them looking nice. I doubt he ever did any maintenance on it at all. I haven't broke in to the motor yet, but I will do it tonight so I can see what's going on inside of it.

Right off the bat I can see several things that are going to need to be replaced (rear rotor/pads, front pads, sprockets & chain, chain roller/idler, front tires, rear skid plate, and get rid of the stupid lowering brackets the kid made and return the quad back to a normal ride height in the front. I'm also going to need to get some lower shock mounting bolts....it looks like it just threw some 1/4 bolts in there.......some people have no common sense. Hopefully the G-Force axle can be cleaned up. Is that big nut supposed to be loose on the side?? At least all of the plastics are nice on it.

As far as the motor goes....I've heard that the early model years of the YFZ's are only 440 cc and not 450. What do I need to do to get it up to 450? Any info would be great! Thanks!!

Well, here are some pics...what do you think?? Did I get a decent deal on the bike? Any tips or suggestions on things I should do if I'm going to have it all apart and the motor out? I want to keep it pretty mild...just a bike to ride woods trails with...not race.

http://i208.photobucket.com/albums/bb241/iqraceworks/IMG_0585.jpg

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:huh

To get the bike to 449cc you will need an '06-up jug, piston & crank.

[yamahahaha]

that "lowering kit" is the most retarted, crappy funny thing i have seen, just a joke. but what u got for the price its great. keep us posted with the motor problem, im curious to see whats up

[IQRaceworks]

Well, I pulled the motor out and I managed to get the head and cylinder off tonight. Everything up in the head looks really good, the cylinder looks perfect except for a small spot that is just a little rough, and the piston looks the same. The probably is definilty the main rod bearing. The crank spins night and smooth, but as the rod go around it gets tight and almost locks up.

Would it be better to replace the entire crank/rod assembly....or have someone pretty out the pin and install an new rod in my crank? Also...what about a piston? I'm assuming that my best bet would be to replace it with the stock size, and then just hone out the cylinder a little to smooth it back out. Should I replace the timing chain while I'm at it, or just leave it be? The adjuster still has about 1/4" of travel left before it can't tension the chain any more.

The head looked great, but I did notice some pretty thick shims under the valve caps. I haven't measured any, but I will. I guess if they are within spec I'll just leave them....if not, maybe new valves?

Any info would be great....Thanks!

[400cc]

sweet ride man, i've been thinking about getting a yammi for another ride

i picked up my trx450r off ebay for 1600 with a cracked case

[BakerRacing40]

to make it a 449cc you have to change the crank and get a piston.

for your engine build, if nothing is damaged other than rod bearing. i would put the hot rods crank, new crank bearings, medium compression piston 12.5 or 12.75 to one at the highest for you, do the oil mod, change the cam chain, valve springs, shift shaft, and you should have a reliable engine making decent power...

[IQRaceworks]

Thanks for the info...

What's wrong with the shift shafts? Do they wear out? Should I replace it with another factory one, or aftermarket?

[squadie]

When mine was rebuilt after the crank bearings seized, they put an 06+ OEM crank in it. This bumps it to the 449. The 06+ crank is better as I recall -- stronger wrist pin I think. Don't know how the OEM price compares to the Hot Rods.

[IQRaceworks]

Well, here are some pics of the inside of the cylinder walls. When the rod bearing locked up, I think it put a lot of stress on the front and rear of the piston. The piston skirt is pretty chewed up.

You can barely feel the marks with your fingers. There are no rough spots or gouges, but you can definilty feel some smooth marks down in there.

I know it's hard to tell from the pics....but could I get away with a light hone and a new piston and rings...or do I 110% need a new cylinder also??

Thanks!

http://i208.photobucket.com/albums/bb241/iqraceworks/IMG_0630.jpg

http://i208.photobucket.com/albums/bb241/iqraceworks/IMG_0629.jpg

If it was me I would either get a new cylinder or bore it. You can do a small bore and be safe.

[IQRaceworks]

Originally posted by YFZ-DunerUtah
If it was me I would either get a new cylinder or bore it. You can do a small bore and be safe.

When you say "do a small bore and be safe".....do you mean to just run a ball hone through it to clean it up a little?

From everything that I've ever read about Nikasil plated cylinders....boring them in a NO NO.

Can you give me some more info?

[IQRaceworks]

Well, I finally finished my project "basket case" of a YFZ450 that I picked up for dirt cheap. The motor was locked up (rod bearings), the chain and sprockets were shot, brakes were all shot, the previous owner engineered his own front end lowering kit, and the thing was just not taken care of.

I stripped it down to the frame, rebuild the motor with a new crank, bearings, piston, and a nice used cylinder that I picked up. I also replaced the timing chain since I was already in the motor, and also did the oil and cam mod to the motor.

I also ended up replacing the chain, sprockets, rear rotor and pads, and cleaning the axle up and getting all of the rush off of it. I also picked up some other used parts off of ebay (skid plate, rear wheel hub, bearings...).

It was a real mess.....but it's all finished now. It runs great, looks decent, and should be a great quad! It was a fun project, and I'm glad I was able to do it all myself....and do it right. I figured that I have around $600 in parts in it, and I paid $1000 for the quad....so all in all I have a pretty nice quad for $1600 :)

*** WHEN I GOT IT *****

http://i208.photobucket.com/albums/bb241/iqraceworks/IMG_0585.jpg

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http://i208.photobucket.com/albums/bb241/iqraceworks/IMG_0603.jpg

*** ALL FINISHED!! ***

http://i208.photobucket.com/albums/bb241/iqraceworks/IMG_0907s.jpg

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http://i208.photobucket.com/albums/bb241/iqraceworks/IMG_0903s.jpg

[400cc]

sweet, glad to hear you got it all done

now you just need a video of you rippin **** up