o7 WR450 sick after first valve service

I never did a valve adjustment on anything without rockerarms,so I thought I would let the dealer do the first valve service. (600 miles) Now it misses and bogs down up to1/4 throttle with no load on the engine. IT seems ok when you are under hard acceleration though. Ran great before.! What the :prof: could they have done to it? I'm half afraid to take it back to them.

Doesn't sound like a valve issue...what else did they work on? Unless they did actually adjust them and messed up the valve timing, but at 600 miles I doubt you would need them adjusted. Did they mess with your carburetor? Jetting, fuel screw? Did the weather/temp. change significantly since you rode it last?

The last time I rode it before the service the temp. was in the 50s it was fine.Today it was 61 ran bad. They were only supposed to do the valve service and they did change one intake and one exhaust setting.

Sounds like they messed up the timing...

Really easy to do yourself too...without messing up the timing:thumbsup:

Yep, that's all I can think of is that they messed up the valve timing.

my 08 was out of adjustment at 600miles. :prof:

but I have to agree that it is very possible to skip a tooth on the timing chain.

one thing that bugged me when I did mine was the alignment mark on the exhuast cam. there is one mark at 9 o clock and another at about 11 o clock. in contrast the intake cam has marks at 12 and 3. with my exhaust cam I ignored the mark at 11 and just alighed to the 9 o clock. it also helped me that I marked the chain and gear with a sharpe.

that 11 O clock mark on the exhuast cam makes me wonder...

what would happen if I had aligned that 11 o clock mark to 12, when I assembled it???? is it YZ timing or bust?

(this post is probably un readable. sorry)

Wow, I have 2k on mine and it runs like it was new. I MIGHT adjust them this winter after another K or so. Several friends who did not adjust theirs until over 3K and they were not out enough to worry about. I think you can tinker something until it falls apart. JMO

It is very common that the valves need adjusted after the break-in period of 200-800 miles. It's after this initial adjustment that they stay within spec for a long time.

I think the best way to make sure the cams line up is to take a digital picture of how the dots align with head at TDC before removing them then refer to the picture when re-installing. I remember my cams were not exactly at 3 o'clock and 9 o'clock but were still timed correctly.

When I did mine I used a white paint pen to align mark both cams with the cam chain. No problems at all! The digital camera pictures is also a great idea too.

From left field here...they could have fooled with your jetting under the assumption that you would be back for more shop labor. Check the bowl bolts and see of it seems they have been turned. Ok so that was the devil's advocate...On the other hand...If the missing and bogging (particularly missing) to 1\4 throttle are significantly rough I suspect a missed timing mark while putting they back together. I would talk to the service manager first. If that doesn't get you there then just lift the valve cover off, rotate the crank to the point where the marks are SUPPOSED to be at TDC, and see if the marks look good...if thats OK then check the jets. I mean, thats the only way that you are really gonna know.

:prof: I guess I will check the timming myself. Should I follow the manual,or can it be set to YZ spec. and would there be any noticeable improvement to do so? Im also going to do the performance mods I've read about here. Lots of great information.:bonk:

Just follow the manual and take your time....

The days of setting to YZ spec are gone (starting in 05 I think). The newer WRs have the Auto-Decomp Exhaust cam and if you don't line it up right it won't start.

Yup, just follow the manual. Before you break it down see if you can locate the fuel screw on the bottom of the bowl. You will need a small short screwdriver so you can check to be sure that it is good. You should be able to tun it in a turn and a half to two turns. Set a reference however you want to and then count the turns to get it all of the way in. I think (somebody catch me here if I am off) it should be turned out 1 and 1/2 turns or thereabout. So check that then back it back out. Try it at 2 out if you still get bad results. If this doesn't fix it then you may have trash in your pilot jet. These are just possibilities. I am mentioning them because they may be easier to check than the timing for you. Plus the fact that the bike misses only to a quarter throttle and then runs fine makes me doubt my original assumption that the timing is off. The carb goes through several different circuits as you turn the throttle back. In general I have taken in from others that the carb goes Pilot to 1/4 then Needle to about 3/4 then Main to WOT. Drain the bowl then pull it off. You might wanna see whats in there anyway. Check the Pilot and see if its clogged. Keep in mind that all of this is just a suggestion and will not harm your bike and will only get you more familiar with it. Good luck dude

I think you are right about the timing,it would run bad all the time.I have new jets and the ais removal kit ordered ,so i'll be finding out for sure. Im still going to check the timing I really should get more familiar with this bike.

If you don't already have a manual, get one! They have all the info you need to check the valves, and go as far as rebuilding the entire bike.

Take it back to the shop. If was fine before and they so called fixed it. ***. Whats up now? Take it back as fast as you can, they did something.

:thumbsup: Well I checked the valve timing and the exhaust was off one tooth. Also checked the clearances,they were all in spec.Thanks for all the advise

You should go back and demand your money back. That was the shops fault not yours. You shouldnt have to go back and fix what you paid someone to do.

Sorry, just burns me up when a shop screws up and the customer has to waste time to get it right.

Oh I intend to let them know about it. We'll see where it goes from there. My question is don't they test ride after they service these bikes. IT was so obvious the could not have missed it. The steering was also to tight.

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now