Posts
5819
Joined
10/1/2013
Location
Davis, CA, USA
Edited Date/Time
2/1/2017 3:53pm
Here's something a little different for ya. I've been running pro hillclimbs for about four years now, some of you might have seen the GoPro videos I post after the race weekends, and I ride a 11 YZ450F and a 01 CR500. Over the last season it became painfully obvious to me that stock motors just weren't going to cut it against the $10k+ nitro burning motors I was racing against. I've been stuck around 10-20 place and to be totally honest I'm sick of it, I feel like I have the skill to win since I have once before, but everyone has elevated their game to the point where I just can't compete on stock equipment and I've kind of been slipping backward, even though I'm much better then I was even last season. In the words of Chad Reed, "if you're going to bet on anyone bet on yourself", so I'm making the investment in some motor work.
Here's the breakdown by bike:
450: My parents helped me out big time this Christmas with a beyond killer GYTR cylinder head. This thing is just so cool, CNC ported at the Cosworth factory, comes with cams, and the valves are already installed and ready to go! 13.5:1 high compression piston will also be going in as that is what the head is designed to run with, so it will now be a 100 octane bike only. I'm planning to keep the stock exhaust to keep the cost down, but I think the head, piston, and a correct map will make a big difference. Here is where I'm at so far, the bike is disassembled and I'm currently waiting for head and base gaskets so my dad and I can put everything back together.
500: The stock cylinder on these bikes is pretty rough, so I went ahead and cleaned up all the ports and just generally smoothed everything out. It will also be getting a very high compression head that will require 110 octane fuel. I'm keeping my stock head just so I can throw it on and ride the bike for fun, the high compression head will be for racing only. Currently, the bike is disassembled and the cylinder is getting a fresh 89.25 mm bore.
Here is a comparison of the 450 head ports, it's crazy how different they are!
The 500 cylinder before I cleaned things up. I thought I had pictures of when I was done but I guess I'll have to get some when I get the cylinder back.
That's where I'm at so far, hopefully next weekend I'll be able to have an update and I should have all of the parts needed. I'm basically just going for two common sense builds that keep the costs down but hopefully close the gap in performance just a bit so I can start cracking the podium. If anyone has some cheap suggestions for either bike please let me know, anything I can do to drop weight or update things would be great.
Here's the breakdown by bike:
450: My parents helped me out big time this Christmas with a beyond killer GYTR cylinder head. This thing is just so cool, CNC ported at the Cosworth factory, comes with cams, and the valves are already installed and ready to go! 13.5:1 high compression piston will also be going in as that is what the head is designed to run with, so it will now be a 100 octane bike only. I'm planning to keep the stock exhaust to keep the cost down, but I think the head, piston, and a correct map will make a big difference. Here is where I'm at so far, the bike is disassembled and I'm currently waiting for head and base gaskets so my dad and I can put everything back together.
500: The stock cylinder on these bikes is pretty rough, so I went ahead and cleaned up all the ports and just generally smoothed everything out. It will also be getting a very high compression head that will require 110 octane fuel. I'm keeping my stock head just so I can throw it on and ride the bike for fun, the high compression head will be for racing only. Currently, the bike is disassembled and the cylinder is getting a fresh 89.25 mm bore.
Here is a comparison of the 450 head ports, it's crazy how different they are!
The 500 cylinder before I cleaned things up. I thought I had pictures of when I was done but I guess I'll have to get some when I get the cylinder back.
That's where I'm at so far, hopefully next weekend I'll be able to have an update and I should have all of the parts needed. I'm basically just going for two common sense builds that keep the costs down but hopefully close the gap in performance just a bit so I can start cracking the podium. If anyone has some cheap suggestions for either bike please let me know, anything I can do to drop weight or update things would be great.
Great start to a build thread, I like a good run down with detailed pics, keep up the good work!
I'm not very familiar with Hillclimb, do you ride both bikes in the same class or separate?
And someones got to ask it.... which bike is better?
In terms of weight savings, an aluminium bolt pack can save a surprising amount. I don't know what the YZF's are like but my RMZ had loads of steel M6 bolts under the tank, holding on the fuel pump, wiring harness, electrics etc. You can safely replace all of these along with some body work bolts with ally and drop a good few g's for less than £20
Dont know so much about hillclimb, but my guess its all about mid - high power.
If it was my bike and on a budget i would look up that cpi pipe so it is made for the power range i want, then port the cylinder to match the pipe, maby cpi have the optimal ex.duration numbers, If you are skilled with the rotary file, it will only cost you hours of work, if not you can destroy it.
Another choise is to send it to Gorr or some other reputable tuner and get the work done.
There are plenty of knowledge around the world of how to make CR500 scream.
Cool project, i will follow this..
Thanks for the heads up on the bolt kit, I'll have to look around and see if it's worth the money for me to swap some of them out. I probably won't have an update until this weekend since I'm up at school for the week now, but I'm hoping things will go together smoothly and steadily here soon.
As for the CPI pipe, I actually have one for the bike but I kind of have mixed feelings about it. I've noticed that for the hills we generally run, which are much more technical then the AMA style hills on the east coast, the CPI gives up too much bottom end for me. In an ideal run I would never have to worry about falling off the pipe, but in reality the hills are just too technical for me to consistently keep it there every time. That said, I've gone back to my FMF. However, I was only running the CPI on a completely stock motor on the stock 89mm bore, so I have a feeling with the cleaned up ports and higher compression I may have a different experience with the CPI now then I did before anything was modified. Our next race is in April so I'm trying to get everything together with plenty of time to try everything out and get a feel for both bikes, at that point I should be able to decide which pipe works best for me.
The Shop
DeCal Works Huge Plastic Inventory of UFO and Polisport kits.
Luxon 4-Post Bar Mounts
$189.95 - $239.95
Cool projects for sure
Here's a cool trick I learned from someone on here. Ironically, cr500s are pretty cramped for taller guys like me (6 feet), so I cut the spacer off of each foot ped and reversed them around. Then they were welded back on and presto, lowered foot pegs. If I remember right I just had to use the opposite side springs and that was it, simple and very effective on the bike.
I'm thinking of replacing the rear master cylinder with a newer unit just to get rid of the remote reservoir, just seems like a waist of space and weight, as well as just another thing to get ripped off. If I can find one cheap or if someone here has one they would sell I'll swap it out, I believe it should bolt right up.
A cool tip my dad taught me was to always mark the head nuts with a sharpie, that way you can easily tell if they start to come loose for some reason. Obviously everything is torqued to spec, but you just never know.
Here is the 450 all torn down, waiting on a cam chain and head and base gaskets.
Before assembly I measured everything out for the 450 and the cylinder was well within spec, giving me .002 clearance if I remember correctly. I found a map online for the ported head and new cams so I downloaded that into the bike as well. Assembly really wasn't too bad, this was my first time rebuilding a fuel injected bike and everything went slowly and smoothly. We just kind of took our time and measured everything, making sure everything was in spec and torqued down correctly. I was a little pissed off that the valves came about .001 too tight, so we had to shim the brand new head...
Took a few kicks to get it going but after that it ran great! Went up and down the street a few times to get the first heat cycle done, didn't want to let it idle since the cams needed to break in as well. I can't wait to try this thing in the dirt and see how it rides, felt very smooth revving on the street and didn't have the jerky bottom that the old setup had.
Started the 500 for the first time today as well, it also sounded great! The exhaust flange I have that converts it to an O-ring system really made a difference in sound, no more exhaust leak or rattle. We'll see if my port smoothing helped anything when I ride it for the first time, too much rain this weekend unfortunately.
Now, keep in mind all of this was done with the bike as stock length, but I feel like I have been at more of a disadvantage over the years then I realized. I know I'm still not even close to the power other guys are putting out, but for a relatively low cost and without much, if any, sacrifice in reliability I think I've tightened the gap significantly. I've put about two hours on the bike so I'm planning on rechecking the valves and changing the oil and filter, but as of now it seems like it's ready to rip!
Here is some gopro footage. Some of it is from breaking it in on a trail ride, and some of it is testing it out on some decent sized hills.
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