HEADS UP!!!

Site upgrade in progress... Core site functions are working, but some non-critical features/functions will be temporarily unavailable while we work to restore them over the next couple of weeks.

Please post any bugs you encounter, but before you do, check to see if it's already listed.

Thanks for your patience while we work to improve the community.

Sign in to follow this  
Followers 0
silverblackdak

new to 426

14 posts in this topic

I purchased this wr 426 a couple months ago. It has had 4 year old gas in it, so starting it was nearly impossible until I cleaned the carb and rejetted with a 168 main and 45 pilot. starting became much easier, but i was a little baffled by the fact that the choke was unusable, even at 60 degrees completely cold. is this normal?

The bike is now unstartable again. recently it has begun pissing fuel while it sits, float problem i believe. went to check my valve clearences today, i followed the manuals directions lining up the I with the marks on the timing plug. my issue is that the I and E on the camshaft gears were upside down and the lobes were facing inward instead of out.:eek: I know this bike has had the yz timing done, thanks to the original owner. I rotated the crank and lined up the punch marks on the cams to get my measurements.

I would like to know what is going on with the marks and how i should go about getting the correct measurment? Thanks TTer's

Edited by silverblackdak

Share this post


Link to post
Share on other sites

I think your engine was not on the compression stroke, so you were 180 degrees out from TDCC. Continue turning the engine over in the correct direction until the lobes on the cam face outward and you will start to come up on Top Dead Center Compression (TDCC), and your marks should be good. Hope this helps. Maniac

Share this post


Link to post
Share on other sites
....but i was a little baffled by the fact that the choke was unusable, even at 60 degrees completely cold. is this normal?

.....I rotated the crank and lined up the punch marks on the cams to get my measurements.

I would like to know what is going on with the marks and how i should go about getting the correct measurment? Thanks TTer's

What happens when you use the choke?

Did you clean the fuel tank? The new pilot may well be clogged again. You most likely have dirt around the needle & seat.

Are the cam dots lining up with the head, are the lobes at '10' to '2', TDC on the compression stroke?

Share this post


Link to post
Share on other sites
What happens when you use the choke?

Did you clean the fuel tank? The new pilot may well be clogged again. You most likely have dirt around the needle & seat.

Are the cam dots lining up with the head, are the lobes at '10' to '2', TDC on the compression stroke?

when i am kicking the bike normally with no choke it attemps to start or will start for a couple seconds then stall. turning the choke on negates any fire the motor has until the choke is shut off again. then the same, will start for a few seconds then stall unless i catch it with the throttle. a few revs then it idles fine.

i did not clean the tank, the previous owner emptied the old gas when he was getting ready to sell. i did have dirt around the float needle and seat, thought for sure cleaning it would stop the leaking gas, but no.

The cam dots do line up with the head, but no mark can be seen through the timing plug. not sure if that matters. the lobes appeared to be at 10 and 2.

Share this post


Link to post
Share on other sites

Sounds like you need to clean and adjust the idle circut in the carburetor. you will have nothing but trouble starting this bike until it idles perfect. I recommend an Iridium spark plug or one of those "Fine Wire" spark plugs to help with initial starting.

Set the float level slightly lower than the manual says. The spring in the needle gets soft and allows the float to move higher (float level also) and leak out fuel.

Share this post


Link to post
Share on other sites
The cam dots do line up with the head, but no mark can be seen through the timing plug. not sure if that matters. the lobes appeared to be at 10 and 2.
If memory serves you should see "H" and "I" through the timing hole. With the cams aligned correctly you should see the "I" mark. The "H" is for timing with a timing light.

Share this post


Link to post
Share on other sites
If memory serves you should see "H" and "I" through the timing hole. With the cams aligned correctly you should see the "I" mark. The "H" is for timing with a timing light.

Thats the thing, when the "I" is aligned with the timing plug marks the cams are completely opposite what they should be, lobes facing in. Its a wr with yz timing, could this effect where the marks through the timing plug appear?

I did manage to get a measurment, i think, with the cams in the correct position, lined up the cam marks with the head. 4 out of 5 valves are out of spec.

I also cleaned the carb out again, no clogged jets this time. Havent had a chance to check the float adjustment yet.

Thank you for the replies

Share this post


Link to post
Share on other sites
completely opposite what they should be, lobes facing in
That sounds like "180 out". Rotate the crank until the "I" shows up again. For every one revolution of the cams the crank turns twice. This FAQ will help you confirm YZ timing.

Q: How many link pins are between the cam marks for YZ timing?

A: If you have a 400 or 426, you will need to rotate the exhaust cam sprocket 1 tooth clockwise at TDC. This will give you 12 pins between the marks, stock is 13. If you have a 450, you will need to buy a YZ exhaust cam as the rotation method does not work due to the decomp pin.

Share this post


Link to post
Share on other sites

I don't think this is the float. It sounds more like the O-ring around the float valve assembly. It is making your carb super rich all the time because it is continually leaking fuel into (and out of) the bowl, which is why choke won't work. Turn off the gas, let it sit and/or lean it over a little to dump excess fuel and then try to start.

Share this post


Link to post
Share on other sites
I don't think this is the float. It sounds more like the O-ring around the float valve assembly. It is making your carb super rich all the time because it is continually leaking fuel into (and out of) the bowl, which is why choke won't work. Turn off the gas, let it sit and/or lean it over a little to dump excess fuel and then try to start.

Actually, the problem could really be the float valve/needle. That wears out over time and will not shut off the fuel. You'll have too much fuel in the bowl, it will run out the bottom and also flood the engine at times, making it harder to start.

Everyone should keep an extra one of those around for when this happens

Share this post


Link to post
Share on other sites
Actually, the problem could really be the float valve/needle. That wears out over time and will not shut off the fuel. You'll have too much fuel in the bowl, it will run out the bottom and also flood the engine at times, making it harder to start.

Everyone should keep an extra one of those around for when this happens

This is the first place to start. Last year my 426 started leaking and after pulling the carb apart I found the O-ring to be hard as a rock. Replaced it with a new one and my problems went away. This is the part # for my '02 -

5BE-14107-00-00

You will love your 426 once you get it sorted out. I bought mine new and it has been such a great bike I kept it even after moving on to a 450. Mine is jetted with a JD jet kit, stock YZ exhaust and the "free mods". It is a 1 or 2 kick bike and to this day has yet to need a valve adjustment. Good luck:thumbsup:

Share this post


Link to post
Share on other sites

Thanks for the replies fellas.

I finally got it to TDC, all the vavles are still in spec. Ive got a float valve on the way. Definetly makes sense that it is making the bike run rich.

In the few rides Ive had, I already love the bike. I did have it starting in 2 or 3 kicks until it started leaking gas. Im really hoping that the valve solves the problem. Im leaving for the U P friday, so Im cutting it close.

Share this post


Link to post
Share on other sites

You would be doing yourself a favor if you very carfuly went through the whole carburetor very carfully and check the manual and the Jetting Database at the top of this forum . Then set your idle as best as possible.

You should be able make that bike a one kick every time (except maybe when very cold)

Trust me you will kill yourself on a long technical trail ride if you have to kick that thing three times every time you drop it or turn off the motor.

The extra time you spend tuning it will pay off huge on a hard ride.

You will also save money by not breaking the kick starter.

Share this post


Link to post
Share on other sites

The bike ran great after i replaced the needle valve set. The O-ring on the old one was hard as a rock, so ill be getting a new one for it as a backup. I was running it without the baffle, but it is a little loud, and tends to scare the wildlife away. put the baffle back in and with a little tweaking of the fuel mixture it starts in one kick 90% percent of the time. Im glad i made the choice to go blue.

Share this post


Link to post
Share on other sites

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
Sign in to follow this  
Followers 0