YZ426 "EX" Hybrid build

[Big Red Hammer]

Whats going on everyone, I have been contemplating for a while to build a hybrid. I bought a yz426f with a built motor earlier this year. I enjoyed it for a while until I had a bad landing and blew out my acl, mcl, and pcl in my left knee. After a month of healing I got back to riding with the help of a brace, but I cant handle riding the dirt bike anymore. So long story short I keep to riding quads my knee is still jacked up since I haven't been able to have surgery. But it hasn't slowed me down yet, I still make it to the track as often as possible and I just got back from the dunes where I managed to destroy second gear on the old 440ex Instead of just fixing the trans i'm going to swap in a monster of a motor. Anyways I've decided to start a little thread on my build.

Here's what I'm starting with, an '02 400ex with a beefed up 440 big bore. and an '02 YZ426F with a high comp piston, stage 2 cams, p&P, and a few other goodies.

[Big Red Hammer]

After tonight's tear down I've found I need to replace the swing arm pivot bearings and bolt.

I'm on a limited budget on this build so any tips or tricks to make things go smother feel free to step in. I've also been reading through the old hybrid threads soaking up as much info as I can.

[Big Red Hammer]

Here's ol' 440 at the dunes last weekend gotta love action shots.

[blacknblue#2]

I learned fast that a limited budget and a hybrid dont work well together...But your into it now...ill be checking for updates...Carry on lol

[Big Red Hammer]

I know that but I have unlimited time, so hopefully it will offset the limited budget. I see you have a hybrid, what radiator and style of kicker are you running?

[Groves187]

I would find a after market duel pass 250r radiator or a stock Trx450 radiator at the least. And run good coolant in it. I use a fluidine duel pass 250r radiator and engine ice on my CRF hybrid.

[Big Red Hammer]

I will look into that, I have found a yfz oversize radiator on ebay I might order. I've also thought if I have a problem controlling heat I can add an wr426 stator and yfz fan.

[Groves187]

Yeah I'm sure that would work. You might want to get everything in place and take a measurement of how much open space you have left and see where you can put it. Nothing worse than your radiator being to tall or to wide and won't fit. Haha

[Big Red Hammer]

Good point. another thing should I keep the twist throttle from the dirt bike or convert it to a thumb throttle?

[ss440ex]

Need any engine mounts?

I think I have a set left over....let them go real cheap!
Also have a spacer for the rear of the YZ engine, you will need to get a bushing made.The YZ piviot bolt hole is .095 larger.

That will get you started and align the sprockets.

You will also need an oil tank, or go to a wet sump system.

[Big Red Hammer]

That would save me a quite a bit of fab work. send me a pm on the details. Any Idea where I can get the water pump outlet?

[Big Red Hammer]

I seen a cool see through oil tank on here a while back. I will fab something similar to that once I have the motor and radiator mounted in.

[zyoung04]

Originally posted by Big Red Hammer
I know that but I have unlimited time, so hopefully it will offset the limited budget. I see you have a hybrid, what radiator and style of kicker are you running?

Since he won't answer u back lol ull see we are from the same town and I had a in putting his together he had an aftermarket honda quad 450 radiator with no fan or anything like that. The kicker another guy who had a hand in putting it together made a spacer for the stock kicker other than a lil custom body work it works fine

[Big Red Hammer]

I will see what I can do about a kicker extension. Do you know if that quad has had any issues with overheating?

[Big Red Hammer]

Thanks to ss440ex motor mounts are on the way and this project is back on track.

[ss440ex]

If you have any questions just ask...

Thank you and good luck.

[Big Red Hammer]

I just took my yz426f dirt bike for its last ride today, I forgot how much fun it is to ride I almost feel bad for getting ready to take it apart. Anyone know if a yz250 4 stroke or a yz 125 2 stroke motor will swap into this 426 frame? And more good/ bad news. I was just told im going for knee surgery on Halloween so this project is going to slow down for a month or so. And I have decided on a color scheme, I will be using my fullbore red plastics with a bright yellow frame. The sub frame is already finished.

[Big Red Hammer]

heres a pic

[Big Red Hammer]

Not to mention this is my new trailer I just finished this morning. do not attempt to adjust your screen that is bright blue.

[Big Red Hammer]

I finally got the motor mounted, I still need to fab up a head stay, The only issue I have ran into is There doesn't seam to be enough clearance for the carb. Could someone post a pick of how they solved this.

[Big Red Hammer]

I finished the exhaust tonight, I used almost the entire pipe I had on the bike. Using a white bros head pipe and I believe a motoworks slip on with a few more cuts and welds. I will be header wrapping the entire pipe once im done with the frame.

[Big Red Hammer]

I started on the intake today. I used the factory 400ex intake boot and reamed out the inside to fit the yz carb. I also had to notch out the frame in a small spot. I will be rewelding and gusseting once im able to walk again.

[Big Red Hammer]

I also decided to throw the tank and plastics and check for clearance I must say this thing looks way more bad *** than the old 440 ever looked.

[quadcrazy02]

Not trying to get into your bidness but you might concider gusseting your frame really good because i had a buddy that did this but with a crf motor and his frame broke in several places, mainly around the motor mounts. this happened in one season of mx racing, just letting you know, other than that your build is starting to come together, good luck with your surgery and keep us posted.

[Big Red Hammer]

I will be doing that before paint, Its just going to take me a while I had surgery today it went will but it turns out my pcl is completely gone, but the doc has assured me that I don't really need it, so it it will be a week or two before Im able to walk without crutches. iv still got several parts coming. Do you know where I can get a gusset kit or is that another thing Im going to have to fab?

[quadcrazy02]

not sure you might call JB Racing or talk to Jerry (leager400) im sure either onbe of them could make u one

[Big Red Hammer]

I received my radiator, hoses, and oil tank today. I still need a kicker extender and gusset kit, and I should have everything I need to finish the monster. I did also find a 523 big bore/ stoker kit that I might have to get next winter.

http://www.maxrpms.net/shop/index.php/motorcycle-kits/mk-yamaha/yzf450/yz523f-stroker.html

More pics to come once im moving around better.

[beastlywarrior]

Bare performance makes a good gusset kit

[J51S]

^Ya what he said. Even with the frame gusseted my upper frame rails still cracked in 3 different spots, as well as the subframe. That was after one mx season also. I almost compare the steel they used on the 400ex frame to a hard copper pipe lol.

Build looks great tho! Deff looks more badass now.

[Big Red Hammer]

Ill be gusseting the frame after I finish mocking everything up. I had surgery last week so I'm not entirely up and moving too well yet. But as soon as I'm better Ill be getting back on this project. I still need a kicker spacer and a good gusset kit. I have not heard back from leager400 yet. most places are selling the gusset kits for 75 to 80 bucks a kit. teixeira makes a 20 piece kit but I'm not ready to dump the cash on it until I'm back on my feet, unless I get a good deal.

[Big Red Hammer]

I managed to finish the head stay today before my knee had enough. I've also order a gusset kit and a 125 shorty kicker with a knuckle, so I can build an extension.

[Big Red Hammer]

Got the radiator mounted up and hose cut and in place. I also found the oil tank I picked up is too big so I need to find a smaller one. oh well im only out 10 bucks.

[Groves187]

You can always do the Oil sump conversion so you don't need a oil tank. A lot of people don't like the idea because the Yamaha shares the engine and trans oil and only holds a quart or two.

[Big Red Hammer]

Ya Id rather keep an oil tank, just to be safe. the case just don't hold enough oil for my liking. I'm wondering if the kfx400 oil tank would fit, but I'm not finding any dimensions online.

[Groves187]

What kind of oil tank did you buy for it originally? Another thing you might be able to do is use a oil cooler from a trx450. You will get more oil capacity and cooling from the cooler and some more capacity from the lines. Plus it's small. I might know someone with one laying around if your interested.

[Big Red Hammer]

originally I picked up a yfz oil tank for dirt cheap, I guess its not a total loss since I got the hose ends I needed. And that oil cooler might work, but I need a way to check and add oil.

[Groves187]

Does the 426 have a sight glass on it? I don't remember. If so just use that and over fill and check it by the sight glass.

[Big Red Hammer]

there is no sight glass and no way to get oil into the motor.

[bansheebc]

I've got a 400ex oil tank on my Walsh hybrid. Pain in the butt to put oil in. Have To turn on side but fits well

[Big Red Hammer]

I had thought about using the stock tank, but it did not fit right or look clean in the frame. I'm going to mock up a pill style oil tank out of some 3 inch pipe. hopefully I can get enough capacity out of that.

[Groves187]

You can take the stator plug out and put the oil in that way. Pretty sure that's how they do it with the sump conversion. If your going to have some thing fabricated why not try and take the trx450 oil cooler and cut a round hole in the top and have a bung welded on so you can add oil.

[ytman]

I made one from a piece of 4" alum tubing for my 650 a long time ago. I think I got the weld in cap from fuel safe. ...i think..

[Groves187]

Originally posted by ytman
I made one from a piece of 4" alum tubing for my 650 a long time ago. I think I got the weld in cap from fuel safe. ...i think..


That looks pretty good.

[Big Red Hammer]

That looks good. I'm going to build one today. I figure if I make it 3 inch diameter and 12 inches long it will hold about 1.5 quarts. I can also mount it under the radiator between the frame rails, or behind the radiator on top of the lower frame rails.

[ytman]

This ones cool.

[Big Red Hammer]

That would look good for a filler cap, i was just going to use a large bolt

[ytman]

check the boyd's site. that ones $44. Make it sweet. I'm looking for others.

[ytman]

haha. Check out www.bungking.com great name

[Big Red Hammer]

They have everything i need. I wonder if they would send me some stickers too. How great would it be having the announcer shouting out "here comes the bung king hybrid coming from behind." I havent even started working on the tank yet, its pritty cold here and my shop dont have heat yet.

[ytman]

Stay in the house, light a fire and let the fire of inspiration warm you...what a crock. I live in So. Cal. It's 50 deg. and I'm ready to make a fire.
I hope I've helped in some way BRH. Good luck with your oil tank.

[Big Red Hammer]

Ill have this thing done soon, even though i cant ride for another 2 or 3 months before i can ride again.

[Big Red Hammer]

I started making an oil tank tonight, it didn't turn out to my liking so I went back to playing with the original tank I got for the bike. after I trimmed 1/4 inch off of each side of the tank, and what do you know it fit down in the frame rails. Now all I have to do is fab up some mounts and I'm golden.

[Big Red Hammer]

I finished the kicker last night, using a rm125 kicker

[Big Red Hammer]

I finished the lower motor mount tonight. Id rather have too much than not enough. If you look closely I used the factory 400ex motor mounts and moved them to where I need them.

[Big Red Hammer]

All I have left to do is mount the oil tank, gusset and pc the frame, then I can ride. until I have the coin for some long travel +3s and shocks. Im also debating on building a dual pipe for this bike.

[Big Red Hammer]

Update time!


I've finished the frame, fully gusseted. I will be cleaning the frame and taking it in for a pc quote tomorrow, if its too much Ill will paint it and get it pc'd after next session.

[Big Red Hammer]

Good news everyone, I have completed the monster

[Big Red Hammer]

All finished I will be starting it up tomorrow

[Big Red Hammer]

and another shot

[yfzttracer76]

nice!

[Big Red Hammer]

I took her out on her maiden voyage today. she sounds amazing, and is retardly fast. I quickly found out the gearing was too tall with the 15-38 gears and 20s. I'll to drop a tooth in the front until I get some 18s. Also even with trimmed fenders my foot hits when I kick it over, looks like ill have to do some more cutting. Overall Im happy with the way this franken quad turned out. I still have the twist throttle on for now, but I will be changing it out for a thumb throttle as soon as I get a new cable.

[Big Red Hammer]

Well I rode the piss out of it today, 5 hours straight of trails and sand at the sand bar. By the end of the day I was still able to hold my hand on the head without burning myself. The day was going great until I found a wet spot in the old pond out here and endowed. After getting it flipped back on its wheels, it fired right up second kick. At the end of the day this thing has exceeded all of my expectations. I was a little worried about using the twist throttle on a quad but after a couple of hours it felt natural.

[ytman]

Way to go Hammer (not the endo part). You set out to build your own machine and you did it. Maiden voyages don't usually go that well. You obviously lined everything up correctly. You must be proud. Congrats.

[Big Red Hammer]

thanks, im not going to lie i had my doubts I could finish it. I have to thank everyone on here for their help and support. especially since most of my friends and family thought i was crazy for taking on such a project.

[beastlywarrior]

awesome build

[Big Red Hammer]

Looks like its been a while since I've done an update, so far I've added +2 Laeger's a-arms, um bumper and ims roll nerf bars. This thing is still fast as hell and my friends refuse to ride it. I'm about to upgrade the shocks to triple rate fronts and dual rate rear.

That's all for now