Ready to go back to stock EX Cam!!! Help please.

[jbrooks26]

Hey guys, I need some input from someone who is running the YZ Hotcam with auto decompression in their WR426. My bike ran good before I put the hotcam in last weekend. After install, I started it in the garage and it idled well for about 1 minute before I shut it off and walked away. I got it out to do the break in ride and it didn't want to idle without having the idle screw set to high idle and the choke out. Tried a smaller pilot jet and that seemed to fix the idle other than sometimes it would just die like I had pulled the manual decomp lever while it was running. Started right back up though. I rode it around for about 45 minutes at a fairly leasurely pace, running through all the gears up and down several times. It seemed to be running very strong, and I was very happy. The next day I went out to start it and now my foot is bruised from kicking it over. Would not start, I put the 42 pilot back in and it would fire and die. Turned the idle up again and it would start and run for a few seconds and die. Choke, no choke, hotstart, no hotstart it didn't seem to matter. It will start and run for a few seconds and then die again. It sounds real blubbery, and when you try to give it some gas it acts like it is flooding out. If you pull the hotstart out while it is running it dies right away. I am at a loss, if I had bent a valve or something it wouldn't even run would it? Sorry for the long post, but I am at my wits end with this thing. I have double checked the timing, I currently have 13 pins between the timing marks on top of the cams. The timing marks on the outer edge are lined up with the top edge of the head/valve body with the I in "HI" lined up with the notches in the indexer and both cam lobes pointed to the outside of the head. Please help, any ideas are welcome.

Josh

[Indy_WR450]

You are not alone in the Hot cams issues:

"yfzguru" says:

well recently after installing a set of hotcams in my yzf 450 ever since the first time i installed them and tired to start it it just back fires out of the exhaust, choke doesnt help, the only way to make it start is 3-4 shots of throttle and hold it open slightyl and kick it over, but before the cams it started up find no throttle no choke, just one kick and bang she lit right up, so I thougth it was something to do with the hot cams so i installed the factory cams and it does the samething with these cams, so I tripple checked the valve timming, valve clearances, made sure its not flooded, wood ruff key on the flywheel isnt sheared off, still the only way to start it is 3 shots of throttle, then hold the throttle open slightly, till she warms up other wise it just dies, then drive it around and its perfect but wont idle cold or start up cold, if any body could please help i need it!

My Buddy "YZMan400" says this:

Those hot cam gears are bolted on and are slotted right?? Im bettin that the gear is indexed wrong with the cam. What you describe is exactly what happened to my yz400 when the intake cam gear spun. It would only start with a little gas and then ran horrible. Im bettin the cams are indexed wrong.

Look at your cam lobes. They should be horizontal meaning that you can almost put a straight edge across the tops of them.

They should look like this, at least stock cams should look like this that is.

not like this:

See how the intake cam is pointing straight back in the 2nd pict instead of slightly up in the 1st. they should be slightly up like in the 1st pict.

I think the cam lobes should be pointing 105 beyond max lift. Meaning that if max lift is the cams pointing straight down then they should be 15 deg above horizontal. This is an aproximation mind you. But may be enough to give you an idea of what is going on.

[Indy_WR450]

Based on my research I think your intake valve clearances are not right. Most likely the center valve!

YZFguru fixed his issue by re doing the valve clearances:

"YZFguru" says:

The problem is not the pilot jet I used a leak down tester to identify that I had leaking intake valve, so I checked the valve clearances again and found out I did not have any clearance at all, so I re-shimmed it put it all back together and half a kick later she lit right up also I noted this is a very hard bike to get a feller gauge in so lol I'am gonna try a dial guage next time and lift up and down on the bucket to determine valve clearance.

[jbrooks26]

I checked the vlave clearances while I was installing the ex cam and they were spot on. I found it pretty easy to get my feeler gauges in to the valves, and checked the clearances to my manual using a go no go method. Also, I didn't mess with the intake cam, didn't even break the cap bolt loose. I am able to get the ex cam in and out without taking the intake loose so I saw no need. I think I am going to put the stock cam back in and see what happens. I will double check the intake clearances while I have the cover off and post the results. Thanks Indy, I hope that I can make this cam work.

On another not, I am certain that my timing is correct, it looks exactly like the pictures and I currently have the timing marks lined up with the top of the head. This leaves 13 pins between marks, which would be correct for stock cams and WR timing. However, this is a YZ cam. I am also having a problem with Kickback that was not there with the stock cam. Slammed my knee into the handle bars twice, made me cuss. Anyway, I am just rambling now, so I will post back with my results. Anyone with any other ideas please feel free to let me have it. Thanks,

Josh

[jbrooks26]

I double checked when I got home today and I am working with a Hotcams EX cam with part number 4035-1E, YZ426 S-1. I am trying to install it into a 2002 WR426F. I originally thought it was for a YZ450F, but I was mistaken. Just wanted to clear that up. I guess this cam should fit right in and the timing marks should be lined up with the valve cover edge. Someone please correct me if I am wrong. This thing has got me pulling my hair out. Thanks,

Josh

[jbrooks26]

Ok, here is the latest diagnostic information.

I have verified TDC with the timing mark.

I have 13 pins between 12 o'clock timing marks.

Both outer timing marks line up with the top of the head.

All 3 intake valves are within specs, .102mm fits, .152 does not fit.

I can get a .203 mm feeler in on the left EX valve but a .229 mm does not fit.

My right EX valve is too loose, .330 mm fits and tolerance says .225 max.

Could this one loose valve be causing all of my problems?? Blubbering if it starts at all, dieing after several seconds of running when it does start, and the kickback problem. Please advise. Thanks,

Josh

[Indy_WR450]

Check out this post with another Hot Cams nightmare. Maybe you can both work togeather to find a solution or dump the cams on e-bay!

https://www.thumpertalk.com/forum/showthread.php?t=312483

[HotCams]

Check out this post with another Hot Cams nightmare. Maybe you can both work togeather to find a solution or dump the cams on e-bay!

https://www.thumpertalk.com/forum/showthread.php?t=312483

Indy_WR450,

I don't understand how you can label this a "Hot Cam nightmare", when you yourself post that it was a valve out of spec that caused the problem.

Based on my research I think your intake valve clearances are not right. Most likely the center valve!

YZFguru fixed his issue by re doing the valve clearances:

"YZFguru" says:

The problem is not the pilot jet I used a leak down tester to identify that I had leaking intake valve, so I checked the valve clearances again and found out I did not have any clearance at all, so I re-shimmed it put it all back together and half a kick later she lit right up also I noted this is a very hard bike to get a feller gauge in so lol I'am gonna try a dial guage next time and lift up and down on the bucket to determine valve clearance.

jbrooks26,

If you are still having a problem, I would be glad to help. If you have it figured out, please post what you have found.

[jbrooks26]

Indy_WR450,

I don't understand how you can label this a "Hot Cam nightmare", when you yourself post that it was a valve out of spec that caused the problem.

jbrooks26,

If you are still having a problem, I would be glad to help. If you have it figured out, please post what you have found.

Sean, I got your PM and yes I would welcome your help. I have an e-mail in to you guys at Hotcams waiting for reply, I sent it in last night sometime. I have not gone any further so all of the information above is accurate to date. I have copied it below. Thanks,

Josh

OK, here is the latest diagnostic information.

I have verified TDC with the timing mark.

I have 13 pins between 12 o'clock timing marks.

Both outer timing marks line up with the top of the head.

All 3 intake valves are within specs, .102mm fits, .152 does not fit.

I can get a .203 mm feeler in on the left EX valve but a .229 mm does not fit.

My right EX valve is too loose, .330 mm fits and tolerance says .225 max.

Could this one loose valve be causing all of my problems?? Blubbering if it starts at all, dieing after several seconds of running when it does start, and the kickback problem. Please advise. Thanks,

Josh

[Indy_WR450]

Hot Cams says on another CRF450X post:

Hi All,

Let me see if I can help. First off, we do not make a stage 3 cam for a CRF450, but that is beside the point. I am sorry if you feel you have received poor customer support. Sometimes it is hard to try to diagnose a problem on the phone, with someone other then the person who installed the cam. With that motor, it is very easy to get the cam timed off one tooth. If you are not looking from eye level at the timing mark, it is easy to get a parallax effect, where it looks dead on, but because you are above the mark looking down, it is actually off. Being that you said you installed the stock cam, and it started right away, that says it is probably not a timing issue. There are three things we check first on a hard starting bike. Timing, (which we have ruled out in this case), valve lash, or jetting. If a customer says that those things are correct, then we have no choice, but to take there word, and at that point we like to get the cam back, to see what could be wrong. If there is something wrong, then you would get a new cam, no questions asked. I hope that helps.

__________________

I guess that means you can PM him and send the cam back in for inspection!

I understand manufacturing process for cams and it may be possible that you have defective sprocket and lobe timing or other QC issues with the product.

[jbrooks26]

I have replied to a PM and this post from Hot Cams. It seems though that I need to correct my installation(shimming the exhaust valve) before I go any further with anything else. I will fix my clearances and if that does not work I will re-install the stock parts to be sure I am not fighting another problem. I will post back with an update when it is available. Thanks,

Josh

[jbrooks26]

OH, this is starting to piss me off!!! I have fixed all my clearances and quadruple checked them. They are all within tolerance. With the "I" lined up in the window, the 3 and 9 o'clock timing punch marks are split down the middle with the top of the case, both lobes pointing outward and matching each other. Now, the timing marks are lined up with the metal part on the head, not the top of the gasket. The bike seems harder to kick, as if the autodecomp is not engaging soon enough. I put a new plug in it thinking that it may be time after all the kicking without starting, and I hadn't replaced it in a while anyway. Now all I get is about 1 revolution per kick through and about every third kick or so I get a pop out of the exhaust. I wish I had a digital camera so I could post some pics. Can anyone who is running the Hotcams EX cam in their 426 with the stock intake please verify how many pins are between your timing marks for me?? If I can't get this verified by tonight I will put the stock cam back in it. I am so aggrivated right now that it isn't even funny!! This should not be that complicated. ?

[Indy_WR450]

Josh you probably have a defective Hot Cams product! ???????

Stop killing yourself and put the stock one back in. I dont want to even think how many hours you got into this nightmare installation! ?????

[HotCams]

Going back to your first post, it sure sounds like a fuel problem, like it needs some time for the carb to fill with fuel, run for a bit, run the card dry, and die again.

Turned the idle up again and it would start and run for a few seconds and die. Choke, no choke, hotstart, no hotstart it didn't seem to matter. It will start and run for a few seconds and then die again. It sounds real blubbery, and when you try to give it some gas it acts like it is flooding out. If you pull the hotstart out while it is running it dies right away.

I would put the stock exhaust cam in, just to see if you still have the same problem. If it is a fuel problem, it will still be there. Another possibility is a stretched cam chain, which would through the cam timing off, and by trying the stock cam, if it runs then you know that is not the problem.

[jbrooks26]

Ok, looks like a general consensus. Stock cam here I come. I will let you all know the results. It may be a few days before I get time though. Bear with me. Thanks,

Josh

[jbrooks26]

Ok, looks like I have another problem. Stock cam now installed with YZ timing as it was before. Now I can kick it through without pulling the decomp lever, even easier than when I had the autodecomp cam installed. However it is not as easy as if pulling the decomp lever. Verified that "I" is top dead center using an allen wrench. Timing, "I" lined up with notches in the window, Intake mark lined up with the top of the head, exhaust mark 1 tooth high from the head, 12 pins between 12 o'clock marks. Both lobes pointing out.

I never heard any noises after install of any cam positions, turned engine over several times each time I had the chain off of the cam with no piston contact or abnormal resistance of any kind. What is going on here? Any Ideas? Will I need to pull the head to get to the bottom of this? Does this mean pulling the motor, or can the head be removed without going that far? Thanks for the help guys, this has been and remains a nightmare for me.

Josh

[Indy_WR450]

Hey Josh, is your cam chain tensioner tight? Do you have the valve clearances reshimmed back to spec?

Will the bike start and run?

Is YZ timing 12 pins or 13 pins? I thought it was 13.

[jbrooks26]

Indy,

Using a stock WR cam you should count 12 pins for YZ and 13 pins for WR timing. I did not try too hard to start it after I noticed that the compression was not what it needed to be. Wanted to ask about it first, right now I have the valve cover off to check again, and all seems right to me. I also have verified that it is getting gas, as the plug was soaked when I removed it to verify TDC. Thanks,

Josh

[HotCams]

Does this mean pulling the motor, or can the head be removed without going that far?

Josh

Sure, you can take the head off with the motor still in the bike, no problem.

[jbrooks26]

Is there anything else to check before pulling the head? Do I need any special tools to re-install the head? What will I be looking for when I get it pulled? Thanks,

Josh