[ovrrdrive]

It's been a while since I posted anything worthwhile so this was long overdue.

Last weekend the kid’s bike was ticking so I figured it was time to check the valves. Seeing as how there is a lot of mystique surrounding valve adjustment I thought I'd take a few pics and post a guide while I was at it.

This was a very simple job. I'd rate it a 4 on a scale of 1 - 10. Nothing too tricky here, but just be sure to check the adjustments carefully and button everything up snugly when you're done.

And as always, I'm not a mechanic or a trainer. Any adjustments you make to your own bike are done with you and you alone being responsible.

That said, let's get on with it...

The first part comes with no pics as you all should be able to do it. Take off both "radiator" guards, the entire airbox, and pull the plug.

When you do that, you're left with this:

http://www.ovrrdrive.made2own.com/ttr90_valves/ttr90_valves1.jpg

I took the liberty of labeling the air screw while I was labeling stuff. It's commonly looked for and I figured the reference would come in handy.

Now look at the side of the motor where the covers are. You'll see two covers that need to be removed:

http://www.ovrrdrive.made2own.com/ttr90_valves/ttr90_valves2.jpg

After you carefully remove the covers with a large regular screwdriver you'll see the next image. Note I say carefully. I almost stripped out the small one covering the timing marks. I ended up taking a hammer and tapping the screwdriver in the edge a few times to loosen it up. After you remove the covers you'll notice the pointer in the small hole, and after you rotate the crankshaft bolt with a 17mm socket counterclockwise a few times you'll see the two marks come up, and go a little further and you'll see the one single mark. that's the one we want to line up with the pointer like this:

http://www.ovrrdrive.made2own.com/ttr90_valves/ttr90_valves3.jpg

Now, you have to be sure that you're on the compression stroke. The way you do this is you wiggle the rocker arms. If both the intake and exhaust arms wiggle you're on the compression stroke. If one or both are really tight you're on the exhaust stroke.

The two tappet covers are removed with a 21mm socket wrench.

Now, let's focus on the intake valve. It's the one on top of the engine beside the intake runner:

http://www.ovrrdrive.made2own.com/ttr90_valves/ttr90_valves4.jpg

The specs call for it to be between .05 and .09mm (or .002 - .0035 inches). I couldn't get the .05 (.002 inch) gauge to slide through it so my valve was too tight. I backed it off so that the .05 (.002 inch) would slide easily and then I realized that without the SST valve adjustment tool I couldn't hold it here it was when I tightened it back up. The way I compensated for this was I loosened it up a little more until the .07 (.0028 inch) fit snugly and with the .07 (.0028 inch) feeler still in there I tightened the locknut back down. As it snugged up it tightened the valve a little more and it ended up being almost a perfect .06 (.0024) which is right in spec.

Here's a pic of the exhaust valve before I checked it:

http://www.ovrrdrive.made2own.com/ttr90_valves/ttr90_valves5.jpg

and a good pic of the 8mm wrench loosening the locknut:

http://www.ovrrdrive.made2own.com/ttr90_valves/ttr90_valves6.jpg

Specs for the exhaust valve are between .08-.12 ( or .031-.047 inches). When I first checked it the .08 (.031 inch) wouldn't slide through. After I backed the adjuster off a little, I got the .08 (.031 inch) to slide in tightly:

http://www.ovrrdrive.made2own.com/ttr90_valves/ttr90_valves7.jpg

As before, I picked a center gauge to tighten it down on. here’s a pic of tightening the locknut with the .10 (.004 inch) gauge inserted:

http://www.ovrrdrive.made2own.com/ttr90_valves/ttr90_valves8.jpg

And that about sums it up...

Put the tappet covers back on, put the plug back in and hook up the wire, put the airbox back on (might as well clean and oil the filter while you have it out), and put the side covers back on and you're done.

See, I told you it was easy...


As always, if there is any bad info, or anything I could have simplified let me know and I'll edit these posts.

[ovrrdrive]

And I meant to put this up last night but it got too late and my computer was mis-behaving...

Here's a scan of the manual section dealing with the valves.

http://www.ovrrdrive.made2own.com/uploader/files/1/ttr90_valve_manual.jpg

[chgr70]

Nice visual guide only one big problem. You didn't convert mm to inchs.
Intake should be .002-.0035 and exhaust .0031-.0047

[ovrrdrive]

A bigger problem that I just found when I went back to edit was the extra zero's I had in all the metric measurements... :lol:

I had to delete one zero from every number in the post.

And an even bigger :lol:, I just realized that I looked at the wrong numbers on my feeler gauges and adjusted all the valves wrong.

Well, the guide is correct so I'll leave it, but I need to go back out and readjust my valves I guess. Man, these suckers are really tight compared to car engine valves...

[Hathawaydr]

Very Nice Post. Thanks

[ovrrdrive]

I still don't have the right feeler gauges to redo ours... The guide should help take the mystique out of the job though.

[RHOGEO]

I can't get any of the pictures to come up with this guide. Anyone got a copy of it with pics?

thanks!

[ovrrdrive]

It should work now...

I had taken the pics down because I didn't think anyone was using this thread...

I used the wrong feeler gauges in the pics so don't pay attention to the numbers on the ones I used. I did go back and get the right set of gauges and reset mine, but like I said I didn't think this thread was worth the trouble to take new pics.

It's kind of banged up, but there it is. The pics will still help...

[RHOGEO]

Thanks OD. I appreciate it!

[ovrrdrive]

No problem...

[yzman400]

Oh and while that airbox is removed take the 2 screws that hold it onto the frame and the 3 screws that hold the cover on down to the dealer and get some hex head screws/washers to replace them. I find it easier to pull the entire airbox on the 90 when its time to clean the filter. That way you can dunk the entire airbox in cleaner. And the hex head screws help in doing that. Philips head screws suck on motorcycles. Why do they keep puting them on bikes????



Oh and something that is not in your guide. If you havent drained the oil 1st when checking the valves.....When you remove the bottom exhaust valve cover oil will pore out the hole. I ended up raising the front end of the bike up with some tiedown straps hanging from the ceiling joists so all the oil went to the back of the motor. Then I cleaned up the oil that spilled on the floor from my earlier learning experience.

[ovrrdrive]

Hmm, mine didn't leak any oil at all.

I had it on the kick stand and there was a little in the exhaust hole but none poured out at all.

I epoxied the floor anyhow though so I could have just wiped it up. :p

[CaptainJ]

Got a question ...

If you rebuild your top end with new piston included, and you do end up tuning the crankshaft while it's apart (like your not supposed to do :mad: ) can you just line up all the marks and consider it good or what?

I did just that, but I turn the crank and notice that those marks come around everytime the piston reaches TDC. How can you be sure that it's on the power stroke if those marks are supposed to mean it's ready to fire? I assumed those marks would only come around every other stroke.

Thanks,

[ovrrdrive]

The bottom end only has one stroke, so to speak. Its the top end that determines whether or not its compression or exhaust. Just put the bottom at TDC and install the head so that both valves are closed.

I think you'll find that even the spark plug fires every stroke, but every other fire is to nothing but an empty cylinder.

[CaptainJ]

Thanks that helps. I was thinking that it only should fire every other stoke and could not figure out where the **LL to line it up.

Could you please do me one big favor and take a close up photo of your cam gear as it is installed? The one thing I was wondering about that is "where is the small tab on the gear supposed to go? In between the large gap in the cam? or what.

I noticed a small flat spot on the cam where it could go, but I wasn't sure.

I sure appreciate all the pics you have done so far.

Thanks,

[ovrrdrive]

Is the cam gear under the cover with the two phillips head screw on it?

[CaptainJ]

Yes that's the one.

Thanks,

[ovrrdrive]

I'll try to get you a pic tomorrow when I get home from work. It's too dark and cold out right now.

[CaptainJ]

Thanks for your time, and quick reply.

CaptainJ

[ovrrdrive]

Sorry for the delay... It's been a hellish week.

Here are the pics, the high res versions are linked to go easy on bandwidth. I almost stripped the screws when I loosened them. Those guys get a little carried away at times in the factories...

Anyhow, here they are. Hope they help.


http://www.ovrrdrive.made2own.com/uploader/files/1/TTR90_camgear_3_small.jpg
http://www.ovrrdrive.made2own.com/uploader/files/1/TTR90_camgear_4_small.jpg

High res pics are 2048x1536 except for the last which I cropped. I compressed them a little so they average around 650k.

http://www.ovrrdrive.made2own.com/uploader/files/1/TTR90_camgear_1.jpg

[CaptainJ]

Hey Pal,

Thanks for all the effort. It does show me what I need to know. Great pics!

CaptainJ

[ovrrdrive]

When I read your request the first time I didn't really understand what you were asking so I just went out and took a bunch of pics of it and hoped what you were looking for was in the pics. Now after looking at the pics and rereading your request it makes perfect sense. Had I known what I was looking for I would have gotten a better pic of it.

Still, glad the pics helped.

That "old" Canon A70 is still going strong isn't it? It's taken great pics from day 1.

[Slowmotion426]

Good information in this thread- :ride:

[camuchi]

TTT for some great information. Thanks for the help ovrrdrive!

[ovrrdrive]

Glad it can still help even without the pics. I keep deleting them because they clearly show the wrong feeler gauges...

One of these days I'll have to redo them I guess. Like I said though, glad it still helped. ;)