YFZ Central banner
1 - 20 of 22 Posts

·
Registered
Joined
·
10 Posts
Discussion Starter · #1 ·
so guys i joined just a little while ago and i have been about 3 months on my yfz build. (paychecks cant get here fast enough lol) i am about 75% complete and just wanted to share some eye candy with everyone.

we will start with the blown up piece of crap and go from there. i got it blown up and didn't know it. The guy said the piston needed replaced and i didn't try to start it for fear of screwing it up. so i opened her up and this is what i found.

total bottom end failure:
seized lower rod bearing
cracked connecting rod at the wrist pin
oil pump gears stripped
crank bearings seized
waterpump impeller blades broken
waterpump shaft sheared off
oil screen collapsed and sucked up in to itself
tons of debris all through the bottom end

Total top end failure:
valve bent
piston gouged and scarred
jug plating completely gone

some just off the truck the day i brought my baby home pics












Starting Tear down. here are a few carnage pics of the devastation that i found when i opened it up












 

·
Registered
Joined
·
10 Posts
Discussion Starter · #2 ·
Starting to paint and reassymble everything after completely draining my wallet


























and those pics are from yesterday. fastest thing ive ever sat my a$$ on.

101mm BB
ported and polished head
+1 valves
cam mod exhaust
stage 2 cam intake
4.4+ stroke
oil mod
fluidine radiator
carb bored to 40 mm and 175 main 48 pilot
no air box lid
and slip on pipe that i took apart and emptied the guts out of so it's basically a drag pipe.

need to get the front A arms painted and graphics kit and seatcover. but that's where i'm at as of today. Enjoy!
 

·
Registered
Joined
·
10 Posts
Discussion Starter · #7 ·
I like the dasa pipes but I would want the most bang for the buck. Dmc makes a full setup under 500$ but I havent been able to find any reviews on them. I have even thought about making a custom setup. I am an electrician by trade and bending tubing is what I do all day. I have considered buying stainless tubing and making my own exhaust from headder to muffler. I think true duals in 2" would be sick if I did it in chrome or stainless. I could even make my own cherry bombs for it. Just an idea I have been throwing around in my head. I ran it on my buddys dyno that he has at his race shop and even with my crappy setup I have nearly doubled the stock hp. Just need to find the cut away views of a high performance exhaust and I can make it once I know what the internals look like. I may make my own intake too. The fci looks simple
 

·
Registered
Joined
·
105 Posts
Don't get me wrong, we are all riding on a budget these days. This is what makes these forums so great is the info and supply of used parts for sale. With that said you are really wasting those engine mods by not giving it enough air in or out. I run an fci with an airbox and outerwear in the trails and have no issues unless the box goes under water.

Also not all exhaust are created equal. Some are made for a mostly stock engine and help create more back pressure for bottom end ie: dr d
Then others are much more wide open for built engines. I'm personally partial to the Dasa and a site sponsor kb motorsports sales them for 569 but with an instant rebate option so you can get it for 484 plus shipping.

In the end it's your bike and your money and you need to be happy with it. So don't work too hard and ride a lot more lol.
 

·
Registered
Joined
·
10 Posts
Discussion Starter · #12 · (Edited)
The setup is from ike wolf from a little machine shop down the road from me. For 300$ he shaved/bored the case so the sleeve fit and some other work on the piston. Id have to call him to find out for sure but I believe it is a trx 450r piston thats been modified for the crank clearance and deck height. He put the top end in for me and the pic is when I brought it back from his shop to start final assembly. I havent plut it on the dyno yet but plan on it when I finish my work. He also had to rechamber the head due to the piston being wider than the head chamber for combustion issues. He has built a few of these for hill shooters and drag guys and swears it will run with a cub banshee or quadzilla all day long. The cost was just labor and I had to buy the parts, which he bought and showed me the recipts and I reimbursed him. It is also the reason I have to run the fluidine radiator with the fan over ridden to stay on constantly. Something about the water ports being smaller for heat and blah blah. Not my cup of tea when it gets in to all that stuff. I like to turn wrenches but I am no machinist. He used to work for yamaha in the research and development department on the motor end for the atvs and dirt bikes. He retired a few years ago and got bored so he takes on a few prodjects here and there to pass the time and boredom. Ive seen some crazy stuff in the pictures on the wall in his shop/garage. I wish yamaha would have released half the stuff he has told me about. But I am getting off subject. If you want you can pm me and I would be happy to discuss it further.
 

·
Registered
Joined
·
453 Posts
Looks good!! I personally have been in your situation, I just recently tore down one to find the same horror. The previous owner thought it had a cracked piston and had no idea on the internal mods, To find out it was a MAXRPM 501 kit, someone had tightened the cam cover too tight trying the cam mod and scarred the journal bad luckily no other issues. Cant wait to see yours progress as time goes by, Buying parts a little at a time keeps the builds interesting.
 
1 - 20 of 22 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top