Another WR450 wont start after using a yz cam.. Please help...........

hey guys, can someone please help me out? I just put a 05 YZ450 cam (PN 5TA-12180-000) in my 06 Wr450 and it won't start, just cranks over with the electric start and sputters a bit. I followed the book, removed the cover and double checked all my timing marks, all seem ok to me, what could be the problem? I did notice however there is one stand alone timing mark on the flywheel, then a few mm counter clockwise from that there are two more marks with a dash between them, I used the single mark for my timing, and even verified this at stock as when i used this mark the two cam marks were right on the top of the head and the other two cam marks were closer to verticle, just like the pic in the manual states, By looking at the cam i found the tmiing mark looks about one tooth off the wr cam. so what could I have done wrong? please help.........

I have attached a pic and it may look like the exhaust cam mark is up a little from the head but that's the angle i took the pic at so the flash woulnd't reflect back, both marks are even with the top of the head when looking straight on to it. Also I count 13 pins between the top two marks, is this right? normal?


Sounds like and looks like you have the timing correct. When I did mine on my '01, I lined up the single mark on the crank and installed the cams from that. Stock they were both lined up with the out side of the head just like your pic, but I just turned mine one click clockwise for the yz timing and had no problems. But sense you have the yz cam, the marks look right where there suppose to be, except I cant see the third cam marks. Mine had 3 timing marks. One on the out side(use this one), one on top, and one on the inside. Your cam lobes should be facing out(away from each other).

If your timing still looks correct, install your old cams and see if she wont fire. But first always do the flood starting routine to make sure its not flooded/fouled. good luck

I haven't got my manual handy, did you use yours?

Did you check the valve clearances, I have read that they will be about .1 out.

Post a pic of the other side (the cam lobes).

A good way to verify if you are on the correct timing mark if to remove the plug and drop a long screwdriver down the hole so it's resting on top of the piston. Rotate the crank CCW until the screwdriver is at it's highest point (TDC). The mark you see on the crank in the window now is the correct timing mark. Remember, you have two TDCs per combustion cycle. You want the TDC of the compression stroke when all the valves are closed.

Well I pulled everything apart AGAIN, double and triple checked everything, put it together and the marks still all look the same, I used the I mark instead of the H mark as the manual states, same mark i used to verify the stock timing before swapping out the cams. then i looked at the back side of the cams, both seem almost perfectly even like a pic i found here under a search. put it all back together and tried it again, same thing, just stubling. I counted 13 pins between my pins, this is also correct is it? Will the jetting need to be changed, am i now too rich or too lean to start? I never had any troubles with my current jetting as per indys specs

I can't give the exact answer, but I believe if you do not have the carb spot on you will be SOL. I built a WR450 with the works except for using stock YZ cams and it did start with the electric starter, but barely. That was in a SuperKart application with a 45mm Mikuni. I recently built another and changed the lobe centers, but still used the stock YZ cams. It starts great with the remote starter off of the crank, but will not fire with the onboard starter. I tried different starters, a straight shot from a second battery, HD and shorter cable, added a second compression release (from a WR426),etc. No fire. I am certain that the answer is the speed of the starter. When we use both compression releases, spin the remote starter up, and release the 426 lever, it fires instantly and runs like a scalded ape. The top end on this mild engine was just under 130 mph at Elkhart Lake 2 weeks ago.

I have inquired about upgraded starters. I have on hand the larger YFZ starters and a left cover, but it will take some serious mods to get it to fit. I checked with several starter experts and they tell me that the Yamaha and Honda starters are the latest tech for their size, but they would need a thousand orders to develope a better replacement. I believe that less windings can result in higher starter RPM's, but I am no expert in this area.

The bottom line is that Yamaha designed the WR for a specific purpose and went to the trouble to minimize the starter weight. It is no accident that the cam timing comes the way it does.

Don E

You should be able to kick start it if the starter is actually turning too slow. However, this is the first I have heard about it. I had to richen up my start jet to get mine started reliably after a Hotcam install. You can also test this by giving it one twist of the throttle and then try to start again. I went with the largest start jet available for my 426 which was a 72. Hope this helps.


I had the same problem, It turned out to be a valve shim that had shifted and caused one of my valves(far right intake valve) to stick open just enough to keep it from starting.

Good Luck,


Thanks for the Info guys, you are right, she started right up fine with the foot starter. I took her out for a ride and found I definately need to rejet again. I did notice the sound is very different, I already had a YZ muffler on there and now she's not as deep sounding, untill you crack her wide open. The power is also different, I have read lots of people saying how the power is better down low, others say better up high, others say it's all over, well Im kinda disapointed, I use to be able to be in third gear and slowly roll the throttle to full and as the bike accelerated she would pull a wheelie, and she will NOT do this now, so bottom end/midrange seems to have suffered, however when I rev up high the power cuts in again more then ever on top end. Maybe after I up my starter jet I may have better luck with the magic button.

Sounds like you have some jetting to do.

Yup, almost done, I upped the pilot jet and the starter jet one size each, Im now trying to time the accelerator pump as per the manual, but i can't seem to find any free play while adjusting the screw either way, right now it's set as per the Boyaseen spec (their tool) but i have a bad bog off idle if i acclerate hard, good time to fix it now the carb is off...

Update, Was out for a ride today, she starts fine with the estart when cold using the choke, other then that, she just won't start with it, only one kick from the manual start and she goes perfect, I tried to hit the lean hot start lever too and she just backfires and not start, but if i crank her over when warm and slowly roll the throttle she will fire up most of the times........ I guess I may have to live with this or change cams back again.

From my point of view the best solution is to get the original starter to spin faster. If yours is like mine, it cranks fine...just not fast enough. I did some research with various motorcycle starter/electronics experts such as...

Ricks Motorcycle Enterprises in Boston (800) 521-0217

Larry at GOKI (818) 998-0852


Elwood at Stocker Starters (888) 786-2537

Larry thought it would be interesting to shoot 18 Volts to the starter, but that would require an additional 6V battery in series for the starter only and another rectifier to charge it, etc. Elwood said that he would love to improve the starter because of a lot of issues with them even in stock bikes, but it would take a thousand orders to make it worth while.

As I indicated earlier, perhaps less windings could help the speed at the expense of some starter power. Changes to the starter gearing would require major mods and size/weight restrictions point to a solution based on the original unit. Apparently, the OEM starter is state of the art using modern materials, so........

We could all benefit from a realistic solution, but I am out of my league at this point. Any "rocket scientists" out there that have thoughts about a realistic solution???


Don E

Yeah, a faster starter would be nice, however why does it start when cold with the e start and not when warm? it's strange, If i knew this would have hapened I would not of bought the cam forsure, I read may sayd they had no problems getting it to work, i must have missed the talk about the magic button not working after doing it though.

I bought a set of Hot Cams for my YZ. They accidentally sent me an exhaust cam for a WR/YFZ. The intake is the same for the YZ/WR/YFZ but the exhaust is Specific for the YZ and they have a different cam for the WR/YFZ. I asked why the different cams for the exhaust and the answer was that the cams are the same just the decompression pins are different lengths. I was told that if you put the YZ cam in the WR it would have trouble starting with the electric starter because the pin is to long and it would not have enough compression to fire and would just keep cranking. Also if you put the WR cam in the YZ it would be harder to kickstart because the pin is shorter and would not bleed off enough compression. I did verify that the pin is a hair shorter on the WR Hotcam than the stock YZ cam.

So does this mean I am better off keeping my 06 wr cam and doing the cam mod than going to a yz cam? I want to see gains from a different exhaust cam since I just bought a Crower intake stage or Gen 3 cam. Anyone know what I shold get or maybe stay stock? Thanks, Jeff

Well if i had my time back, I don't think I would have changed mine out, I may even change her back again, I lost some bottom end that i liked, still undecided yet.....

I dont care for bottom end on my machine so it could work for me, but if you decide you dont want the cam, I will buy it off you. Let me know. Thanks, Jeff

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