Help - Need Advice (warning long)

Hi Ya,

First up I just wanna say a couple of friends put me onto this site a few weeks ago and I have been lurking here since then and I have to say hats off to everyone for such an awesome online community.

Now down to business. I own a 2001 WR426F, and have owned the bike for 10 months now. It was bone stock when I bought and I have gradually been building it up as an Enduro race bike. I finally bit the bullet last week and had the YZ450F Cam installed. I am not overly technically minded and I don't have the best collection of tools at the moment so I decided it was probably best to pay someone who knew what they were doing to install the cam. The local Yamaha dealer flat out refused to install the cam for me :D. The local Honda Dealer agreed to install the cam (they apparently have an ex-Yamaha mechanic working for them which made me a little more confident). I even gave them my workshop manual and the installation instructions off this site to help them along. I dropped the bike in to have the cam installed and valve clearances re-set and picked it up the next day.

They told me it took them 8 hours to do the work ($690 Australian :D) and that they had to rejet the bike. I almost fell over backwards at the price. I took the bike out for a run and it just didn't seem right, the midrange seemed really flat. Then after about 20 mins of riding the bike started spluttering and losing power under acceleration, almost like it was running out of fuel. I shut the bike down, gave it a look over and then started it up again. The bike went fine for another 10 mins or so and then did exactly the same thing. I rode the bike back to the bike shop and told them what was happening. At first they tried to blame the cam itself saying that it was probably incompatible, but I told them that quite a few people has successfully performed this mod (right guys?). Unfortunately, the mechanic that actually worked on my bike was not there, so a different mechanic went to work on it. I sat there for 3 hours while they messed with the jetting, took the bike out, came back, messed with the jetting some more etc.... And at the end of it all they wanted to charge me even more money, but I flat out refused. So I took the bike out again and it seemed to go fine for the first 20 mins or so and then the same thing started happening - only this time it seemed worse - sputtering, no power and some popping from the exhaust :). I nursed the bike home, shut it down, let it sit for 15 mins and then took it for a run a round the block and the problem is still there. I really don't want to ride it in case I am doing some sort of damage to it. Now I am at a loss what to do. If I take it back to the bike shop, I know they will blame the YZ450F cam as they tried to blame it the first time I took it back. Since they spent hours on the jetting, I am starting to wonder if it is really this (unless they didn't really know what they were doing). I live in Canberra Australia and we are at 1888 feet altitude (I know this because I get flying lessons on the weekend :D) . The guys at the shop said they put a #175 main jet and a #45 Slow Jet in. I'm guessing everything else is stock. I will be the first to admit that I don't know a lot about jetting, but maybe this will help you guys try ad give me some suggestions as to what the prolem might be. The bike ran like a dream before I had the cam installed, but I suspect the cam itself isn't the problem, but the work that these guys did on it. Given the amount of money I have already spent I don't really wanna go back to the the dealer until I have some suggestions as to what it might be (other than jetting). Apologies for the long winded e-mail, but I guess the more info I give you guys, the easier it will be for you guys to help me.

Oh, and the only other engine mod the bike has is PowerNow. The exhaust is a stocker (next upgrade :D)

Any advice you guys may have would be much appreciated.

i think it sounds like they installed the cam incorrectly and got the timing wrong. you need to check with them that they have aligned the timing marks as shown in the instructions from this site. i have the 450 cam in my 426 which i installed myself and it was a pretty simple switch which did not require any jetting changes what so ever. my bike was jetted right and ran great before the mod and now ive had the 450 cam in for about 5 months and its ran great since (only now it starts a lot easier). if i were you i'd pull the cam cover off yourself and check that they got the timing marks the same as in the picture on the instructions with 14 pins on the chain between the centre timing marks on each cam. and i also think you'd probly be kickin yourself that you paid so much for them to do the install and stuff it if you had of realised how simple it is. good luck getting it right :)

8 hours?

You got hosed but good. It does sound like the cam incorrectly phased. I started doing my own work after getting a bill like you got. Your WR came with a good shop manual, I would read it and buy some tools.

Ricko, I have to agree with the other guys here. It definitely sounds like they messed up the timing. I also don't think a 175 main jet would be helping, or the 45 pilot for that matter. When it is confirmed that the timing is correct, I would start with a 165 main, and the 42 pilot. That is what your bike should have had stock. Also the needle will probably need to be lowered one notch from stock (raise clip one clip position). Make certain that the timing is right before trying to sort the jetting though. PM me if I haven't explained anything clearly, or if I can help to fix your problem. :)

I thought that the timing chain would wear out prematurely if a 450 cam was placed in a 426. I hear that the chain pitch is slightly smaller by a fraction and is not recommeded. I would research the YZ450 forum and see what the posts say there. :)


Its raining here today, can't ride so I decided to change to YZ timing and give it a try. The whole process start to finish was 75 minutes. Changing the cam timing and replacing the cam are essentially the same process (time wise). I am not a mechanic, I did not race to finish. Anything over 2 hours labor and you got peeled.

Hey Guys, thanks for all of the replies. After they spent ages on the jetting and the problem persisted I suspected that they may have installed the cam incorrectly, but just wanted to run it past you guys. I am kickin' myself over the cost and know I got hosed and I argued the point when i first picked the bike up, but they wouldn't budge on the price and wouldn't let me take my bike unless I paid :D. Basically I could have bought a new exhaust with that money :D. I usually do minor repairs myself but am not overly confident with jetting and issues involving timing, but do want to get into it more. Unfortunately I'm doing the Air Force thing at the moment, and I had my bike sent to Canberra with me, but no tools as these are still sitting up in Queensland. One of my MX racing pals here usually helps me out with repairs, but he has taken off overseas for a couple of months, so I figured I would pay someone to do it. I guess you live and you learn :)

Hey Indy, from what I can tell Yamaha does not recommend installing the 450 cam in a 426 because there are slight differences. This has been thoroughly debated by a lot of the guys in this forum and the YZ forum. I was satisfied that enough people (who ride their bikes a lot harder and more frequently than I do) have installed the cam without problems that it was a relatively safe mod (ie the chances of catastrophic failure are minimal). Regardless, I am confident that it isn't the cam itself causing the problems.

Well the bad news (depending on how you look at things) is that the timing on the 426 looks okay (I think). I went next door and borrowed my neighbours tools and cracked the top off the engine and this is what I can see:

I marked the timing marks in red. It appears that there is 14 pins between the timing marks. Does this look okay to you guys?

If anyone is intersted, this is what she looks like in one piece :)

If the timing does look okay, do you guys have any other suggestion as to what might be causing this problem.



i cant get your picture to load. make sure you check that with the engine at TDC, when looking from the left side the cam lobes line up as they do in the picture from the instructions. if the timing is correct then the problem would have to be caused by something else the mechanic has done during that 8 hours he wasted on your bike :D, so you'l have to go back and speak to him. im no mechanic either and i spent no more than 1 and a half hours doing my swap. i have a feeling this will be the last time you trust a dealer to perform work on your bike


I think you need to pull the alignment plug and make sure the cams are aligned using the mark.

If they pulled both cams, they may not have gotten them back in correctly and they could both be a little off.

The reason I'm asking this is because your bill was pretty high. Like they dropped the cam chain into the engine and had to do a lot more work on the bike. What is the exchange rate?

Not sure what the go with the pics are, will have to try and figure that one out later. The exchange rate is about 67 cents, so I paid the equivalent to $460US to have the cam installed and valve clearances reset, as well as rejetting the bike when it was running fine prior to the mods. I am taking the bike back to the dealer tomorrow. When I cracked the engine open, there was definately 14 pins between the timing marks. The lobes at the back (throttle side) seem to match the pic when at TDC.

The problem is, now the bike won't start at all. I put it back together and spent about half an hour last night kicking that thing over and over. It started okay before I pulled the engine cover. I triple checked the spark plug and fuel.....but the bikes got nothing....arghhhhh!!! :D It's not my week when it comes to bikes!!!! Nothing a beer won't fix though! :)

Man, if that were my bike, it would take more than one beer to make me feel better! Not that that makes you feel better, sorry. From what you say, the dealer musta screwed something up, they better stand behind it.

Good luck!


Are they timed to the piston correctly? Is your piston at TDC when you check cam to cam alignment? I have work on a 98WR400 and it was hard to keep the piston at TDC while I was reinstalling my cams/chain...


Thanks you guys for all of the advice and suggestions. The bike goes to the dealer in the morning and I am gonna pass all of your suggestions onto them. They said they would fix it no charge, which is somethingI guess. I am gonna have a crack at starting it again tonight before I take it in. And after that I will have a number of beers (probably one for each kick I have to give it to try and start it!). :).....I want my 426 back !!!! :D I will let you guys know how it pans out.

Moral of the your own work if you can !!

BTW I installed the 450 YZ cam on my WR400 and it works flawlessly, especially now I have put in the JD jetting jets.

Point to note on valve clearance....make sure they/you measure the valve clearance with the auto decompression bump completely disengaged. Took me a while to figure that one out - if you are not careful it depresses the valve slightly when measuring, throwing off the clearance measurement.

Just thought I'd let you guys know before I have my beers.....I pulled the plug on my bike after trying to kick it some more(with VERY minimal tools mind you. I only had a plug socket, but no socket wrench. So I shoved the plug socket in there, then jammed a small wrench into the socket and the used multigrips to turn's the for ingenuity?! :) ) You wouldn't believe how black the plug was. I guess the 175 jet they put in certainly wasn't helping. The bike wouldn't start because the plug was mega-fouled! I stuck my finger in the exhaust tip and heaps sooty there too. So I whacked a new plug in and it started first kick. Hopefully it will run long enough for me to nurse the bike back to the shop tomorrow. They are way off the mark with the jetting. not sure where these guys learnt there trade. I will get them to check all of the cam and timing stuff and return the jetting back to stock. Hopefully after that she will be sweet again. I certainly have learnt my lesson from this. I thought I was taking the wise path by getting the dealer to do the work - obviusly this is not always the case. Others take heed! Anyways time for beer.....I'll have a couple for you blokes too given that Australia is the second largest beer drinking country per capita behind Germany.....AND PROUD OF IT! :D :D :D :D :D

Moral of the your own work if you can !!

BTW I installed the 450 YZ cam on my WR400 and it works flawlessly, especially now I have put in the JD jetting jets.

Point to note on valve clearance....make sure they/you measure the valve clearance with the auto decompression bump completely disengaged. Took me a while to figure that one out - if you are not careful it depresses the valve slightly when measuring, throwing off the clearance measurement.

Cheers for the advice Missile. I usually do some work myself - but unfortunately I have no tools with me at the moment as I am away from home. But having learnt the hard way I couldn't agree with you more. Another learning point for me is don't take my bike away from home without my tool bag. I don't know what I was thinking! :) Hopefully it will all get sorted tomorrow. I have a big ride on the weekend, so it better.

i forgot to ask before, but did you also check your valve clearance when you had the cover off. they may not have used the right shims :)

Just got off the phone to the dealer. They have now said that the problems may be caused because I installed a YZ cam and left the stock WR ignition? &%$#@!? Have you guys heard anything about this. I am suspecting they have no idea. I think I am reaching boiling point.

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