Cam cover bolts, torque wrench?

Thanks for all the feedback on the torque wrench's I haven't bought one yet but I definitly know what I WONT get! I was even at FB earlier today and passed on the one they had on sale. I'd rather pay $50 or so for a good reliable one then $$$$ on a head that has been trashed / cracked/ stripped by a crappy inacurate wrench.

So do those pics I posted look good to you guys??? Everything look like it should? maybe another feedback or two about turning the crank the wrong way will set my mind at ease. I'm stopping for tonight, tomorrow I'll pull the cams and get the right shims.

Also, lastly... I put a 50 pilot jet in there to stop the backfiring and popping... now that I see how far off the valves are once everything is back in spec should I go back to the stock 45 pilot for the initial tune?

.. now that I see how far off the valves are once everything is back in spec should I go back to the stock 45 pilot for the initial tune?


Gray, any harm done by rotating the crank shaft clockwise? Not sure if you saw that. Also please look at the second page of the thread with the pics I posted and tell me if that looks normal to you. My service manual says that the timing marks on the cam gears should be on the outside of the gears but I'm seeing the outside on the exhaust and the inside on the intake... but the cam lobes are both pointing away (out)

If the tensioner is in place and the cams timed, there's no harm in it. With the tensioner slackened or removed, you should avoid turning the crank either way from TDC more than about 20 degrees unless the cams are disconnected. You can cause it to skip time.

While setting the timing, you should turn the crank slightly backward (clockwise) from TDC until it moves the cams clockwise out of place, then turn it slowly forward (counterclockwise) to TDC. This pulls the front and top runs of chain into tension as they are when everything is running, and shows what the timing is really like. Checking it while turned backward can give you a one tooth error.

Your timing is wrong. Look again at the picture KJR put up:


Note the mark at 9:00 o'clock on the exhaust, and 3:00 on the intake, with another pair of marks more or less at 12:00. That is correct. Now look at yours:


What I want you to notice about this is that because you have a pre-'03 engine, your cam sprockets are different. The same sprocket is used on both cams, and both of them have THREE marks, not two. On the web of the sprocket you see a stamped "E" and an "I" opposite that. The mark adjacent to the "E" is used to align the exhaust cam, which you have done correctly. However, the mark near the "I" is the one used to align the intake cam, and that's where you screwed up.

What year/size engine is that?

Hey Gray,

Well I haven't screwed up anything yet :-) This is exactly how I got the bike. I have not removed any of the cams, or sprockets or chains yet.

It's a 1999 YZ400FL so someone else must have tinkered in here.. :-(

ok a few things, first I went down and bent all my little flat feeler gauges so that they would easily slide in and out of the cam openings.. After redoing those measurements and tripple checking them this is what I have. I even went a size bigger to make sure they were accurate readings but I did not force the feeler gauges in.



I DO have the timimg mark on the intake cam but in the picture I took it's slightly rotated below the flush side of the head. I am going to pull everything off in just minute and head down to the dealer to get the shims. When I put it back together I'll use the service manual and I WILL NOT rotate the crankshaft with the cams off. Any advice here would be great, I'll check the thread when I get back from the dealer.

Agreed on the torque wrench quality. When I did mine, I had everything apart, and then went out looking for a torque wrench. :thumbsup: I drove all over town, went to several different places (Sears, Home Depot, Lowes, a few auto parts stores) and could not find an in/lb torque wrench anywhere. I ended up getting the Harbor Freight one out of need.

It made me sweat a bit, but I tried to at least make sure it was close by using one of my better ft/lb torque wrenches on a light setting, and doing some testing with the cheapie against the better one on a different bolt. It was on close enough for government work (no way to be sure without having it calibrated, of course), so I went with that. Now that I have time before I have to do it again, I'll get a better one. Everything looks good so far.

I also understand both sides on the shim deal. Originally I was going to just measure and bring them down to my dealership, who agreed to swap them out for me. In the end, I ended up buying the $69 kit on eBay with all of the shims. That worked out better, because it was my first time and the shims that I tried the first time weren't right. I ended up having to do it a few times, and the time spent would have ended up being so inconvenient that I'm glad I spent a few $$$ for the shim kits. At least now I have them for next time.

I hear ya on the argument that you will have a bunch that you don't need, but I commute 2 1/2 hours per day and my time is limited for working on my bike. I didn't want to be spending a few weekend days going back and forth to the dealer and hoping they had the ones I needed in stock.

My $.02

I DO have the timimg mark on the intake cam but in the picture I took it's slightly rotated below the flush side of the head.

When faced with that situation, visualize the mark being one tooth either was from where it is, and see if that makes it look better or worse. They will rarely line up perfectly.

Ok I just got back from the dealer Most of my shims measured around 1.79 to 1.74 so they sold me shims that were 1.75 and 1.70 They said they only do incriminets of .05 so I couldnt for example buy a shim that was 1.78 So now I'm going to start putting it all back together.... I called and called and could not find anything better then a craftsman precision series 3/8" torque wrench that does inch pounds it was $80 and they assured me it was ready to be used. Here goes nothing I suppose.. going to put in the new shims, reset the cams and timing and reinstall the tensioner after I check it of course. I'll update accodringly...

Well it's done, the caps are back on and torqued to about 86 inch pounds. I was sweating bullets thinking I was going to strip something but it all went together quite easily and nothing was dropped into the motor!

Now, do I check my clearances now??? The guy at the dealer said the shims will swell a thousanths of an inch once they get hot. I'm getting ready to put it back together completely and put the 45 pilot jet back in the carb.

Now, do I check my clearances now??? The guy at the dealer said the shims will swell a thousanths of an inch once they get hot.

Don't you suppose they will shrink again when they cool off? Check your clearances now.

A thousandth? I seriously doubt it.

Well now i know why you guys buy the kits with a bunch of shims.. I got my intake cams perfect at .008 with just slight drag and .009 wont fit at all.. Second trip to the dealer and now another one in the morning. My exhaust is now too loose, .013 on one and perfect .012 on the other. I just need to get one 1.70 shim and I'm in business. I dont think I should run it with that .013 gap on the exhaust.. so for now I'll leave the bike torn down til the morning. How quickly will the gaps start to close if I just ran it? Not going to but just curious.

Well now i know why you guys buy the kits with a bunch of shims.. I got my intake cams perfect at .008 with just slight drag and .009 wont fit at all.. Second trip to the dealer and now another one in the morning.

Exactly. If you are an old pro, you can probably do it the first time. But, like you, I thought I would have it right on, and it took me a few times. Checking the valves is not like putting a wrench on a bolt, it isn't a perfect fit and there is a bit of variance depending on how tight you think the feeler gauge should fit. Plus, like yours, mine was pretty tight so I didn't know which one to try next.

That's why I was glad that I got the eBay kit. I did spend more than if I only had to buy a few shims, but now I have a kit that will probably last me the rest of my life and maybe even save a buddy or two :thumbsup:

Well I'm happy to report that the bike is done! (for now / crossing fingers)

I forgot that I have my snowmobile guy who lives a few blocks from me (slipped my mind he also repairs dirtbikes) so I gave him a call and he had shims, lots of em. I met up with him and did a swap from 1.65 up to a 1.70 for the exhuast valve. Got home and slapped it in, checked the timing.. Wow there was a big difference in the gap on that one valve.. from a 1.65 to a 1.70 clearance went from 0.013 to 0.010 (a 0.011 wouldn't quite go under and I didn't want to force it but the 0.010 was a little loose) This is as good as it's going to get. Put it all back together, verified my timing marks and finished the rest of the bike assembly. 12-midnight on the dot as I wrap it up, 8 hours from now I'll be heading out for the first ride. I put the stock 45 pilot jet back in (which is brand new) and set my fuel screw to 1.5 turns out for initial tunning. I'll report my results tomorrow, I'm getting good at all of this after having to pull and reinstall the cams 3 times, pulled the carb countless times, and changed the jetting on the fly without completely pulling the carb off the bike. Wish me luck, thanks for all the help. I got pics of the whole process but not sure if I need to post em, if anyone wants em just PM me.

Well.... I'm reluctant to report that adjusting the valves pretty much did absolutely nothing to cure my popping on decel issue. I even had to put the 50 pilot jet back in to get it to run properly. It does run smoother but still same issue that has always been there. I noticed that I had gas coming out of the AP rod hole so I checked the diaphram and sure enough it was split. Went and bought a new one and that's fine, no hesitation or flat spots when throttling down. Still pop pop pop on decel. I'm running the 50 pilot with about 2 1/8 turns out on the fuel screw. The 45 pilot (stock) backfired like crazy and wouldn't hold an idle. I'm not really sure where to go from here.. It also has a new exhaust header pipe and gasket. At any rate I have peace of mind my valves are in spec now. Maybe I have a bad valve, who knows..?

You're absolutely certain you don't have a *slight* exhaust leak?


As sure as I can be I suppose :-P I bought a new header pipe because my old one had a twist in it, new exhaust manifold "crush" type OEM gasket from yamaha. Where the header pipe meets the slip on the gasket tube material there looks kind of melted, it looks burnt and has bubbles in it on the inside of the sleave. I talked to the dealer and he said that shouldn't matter at all if there was any exhaust leak there. It starts easily cold or hot, if I have a stall it can be a bare to get going again. I started using the decomp because I was a little afraid of damaging internal components by kicking through the compression stroke. Now it's second nature to use the decomp, a non-issue. My cousin rode with me today and I lead the entire time so he saw / heard my poppin. He said when he goes to the supercross races all the 4-strokes pop... Not sure if it makes me feel any better but it still seems like something is not quite right because I have such a large pilot jet to make it run better. I have a pretty good idle, good full range throttle response, lots and lots of power, no smoking issues or bogging. just the pop pop pop :thumbsup:

Been riding the crap out of this bike lately, just sticking with the 50 pilot and still getting popping. At this point I give up as I'm not spending any more money trying to make it go away. So I suppose this thread is closed as unsolved.

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