Powerband very different after minor mechanical work

[Constant Mesh]

"Gonna be tough to adjust cam timing without removing the CCT."

Obviously not right. When you remove/move a camshaft to change shims you don't have to remove the tensioner.

If the chain did jump one crankshaft sprocket position you know which way it went without removing the head cover. The chain was already tight on the front side of the sprocket so it couldn't have gotten tighter on that side. So obviously the chain shifted one spot to the front and it got one spot looser on the front side.

 

[olsonm3915]

I guess you're right, it just seemed when I was fixing my screwup I first tried to do it by removing the CCT and slipping the chain around the crank sprocket, I ended up taking out the intake cam to get even more slack. I probably could have just screwed the tensioner all the way back rather than take it off. Live and learn.

 

[Constant Mesh]

There are 19 teeth on the crankshaft sprocket.

360 degrees / 19 = 19 degrees of rotation between teeth.

You can pull out your handy protractor and measure the angle between where the crankshaft timing mark should be and where it actually is and see if it's approximately 19 degrees.

 

[olsonm3915]

Yes, I figured the 19 teeth ~19 degrees thing, which is why the picture I originally posted in this thread had marks added to it- I used a photo editing program to measure the angle, and counted the number of teeth on the line drawings of the camshaft sprockets in the service manual. Since the cam sprockets had 38 teeth, I knew from looking at my photo that it was one tooth off. Not until I removed the intake cam could I manage to manipulate the chain around the crank sprocket enough to get it where I wanted it.

 

[Pepperell]

Be careful not to let the crank move much with the cams still bolted down. While I am sure you can move it more than a tooth before you hit the valves, I don't think it would be a lot more than a tooth. I learned this the hard way when I was younger on an XS1100 Special. Had to replace four valves and I did not feel a lot of resistance. I am not trying to scare you. I am just advising caution.

Ditto xs750...

!

Ditto xs750...

Now there's a coincidence....I did the same exact thing with an XS750, two valves if I remember correctly and no, I didn't feel much resistence either, was actually surprised to find the valves were bent.

Thanks for the reminder, a little caution is a good thing.

 

[dannymax]

I guess you're right, it just seemed when I was fixing my screwup I first tried to do it by removing the CCT and slipping the chain around the crank sprocket, I ended up taking out the intake cam to get even more slack. I probably could have just screwed the tensioner all the way back rather than take it off. Live and learn.

Yes that works....screw the CCT in till it stops and move the intake cam over next to the exhaust cam....this will give you enough slack to back the crank sprocket up one tooth. It's a good idea to cable tie the chain to the cam sprockets too, just for a little insurance.

I called the guy at PCW and he is in total amazement that this bike could be a tooth off on the crank and still pull 120 hp on the dyno. He said to figure up what I feel he owes me and he will send me a check...I'm not going to do that however, it should be back together tomorrow and if it runs like it did prior to the wrenching I'll take it in, let him drive it and put it on the dyno and see what it pulls with the cams timed.

The amount of the refund will be dependant on the outcome of the dyno run....that seems like a fair way to handle it.

 

[dannymax]

I can see the rear mark on the rear (intake) cam sprocket, it's perfectly aligned with the top of the head. It's hard to see anything on the front cam, there looks to be marks there also but it's pretty tight.
I'm thinking if the intake cam timing marks line up perfectly, the crank sprocket should line up too....even if the exhaust cam is off (which I don't think it is)

Is that correct?

It's likely that the two cams are still in time with each other, you can put a dental mirror up next to the exhaust cam to check, but if the intake is lined up and the crank isn't, you know you have to fix it no matter what, and when you do that you will have to verify the position of both cams to be SURE it's right.

Unlike the guy at the shop who charged you for screwing up your bike.

And yes, by all means, check the valve clearances yourself before putting it back together. Now that you've gotten as far as you have, you can see why there really wasn't any reason to have someone else do this job. Taking the cams out isn't a big deal once you've gotten this far, either so if you find any clearances that aren't right, figure out what shims you need and go back to the dealership and ask for your money back and the right shims to fix the clearances. They screwed up and should not charge you for their mistake.

Well, this isn't quite 'dental' quality but it works well for seeing on the blind side of the cam sprockets.

Oh, the valve lash checked out ok, leaning towards tight, but still all within spec.

 

[carlson_mn]

10 of the 16 that I adjusted were all tight. My Yamaha dealer told me it's best to set the exhaust valves on the tight side of the clearance because the valves tend to tighten over time on them, if anything.

You may not see much more hp on the dyno if it only gives peak numbers.... I'd say they give you half of what they charged for valve adjust back considering what you had to do. It's nice to see the dyno runs though, let us know the 'after' numbers. I'm guessing 125.

 

[dannymax]

10 of the 16 that I adjusted were all tight. My Yamaha dealer told me it's best to set the exhaust valves on the tight side of the clearance because the valves tend to tighten over time on them, if anything.

You may not see much more hp on the dyno if it only gives peak numbers.... I'd say they give you half of what they charged for valve adjust back considering what you had to do. It's nice to see the dyno runs though, let us know the 'after' numbers. I'm guessing 125.

I always thought just the opposite on the valve tolerance, setting the spec on the small side just makes them go tight sooner???

125 would be good, there were a couple small flat spots in the curve around 3500 - 4500 and i'd like to see them gone too....I'd like to prove to him beyond any doubt that cam timing was the issue.

 

[carlson_mn]

I guess what I meant to say is that the clearances themselves tend to go to loose side from what he told me.... in that the valves themselves go from looser to tighter. I believe a tighter measured clearance results in a looser valve. He was just speaking of the exhaust valves as I was considering getting another shim to fix an exhaust valve that was measuring right around the .18 clearance.

 

[dannymax]

I guess what I meant to say is that the clearances themselves tend to go to loose side from what he told me.... in that the valves themselves go from looser to tighter. I believe a tighter measured clearance results in a looser valve. He was just speaking of the exhaust valves as I was considering getting another shim to fix an exhaust valve that was measuring right around the .18 clearance.

Ah, I got it now....and it does make sense. :lol:

 

[Constant Mesh]

You don't really need to see the cam sprockets to verify timing. You can easily look straight down on the intake camshaft pip to check alignment with the vertical line on the adjacent cap. While you can't look straight down on the exhaust camshaft pip you can easily use a small right angle two sided straight edge to verify timing. Place one straight edge against the right side of the cap. Slide the right angle corner up against the vertical line on the cap and then note where the other straight edge appears on the camshaft lobe. If it's timed properly the camshaft pip should appear in perfect alignment with the 2nd straight edge. A small right triangle from a drawing set works very nicely. With the straight edge laying down on the camshaft you can easily see the relative position of the pip.

 

[dannymax]

You don't really need to see the cam sprockets to verify timing. You can easily look straight down on the intake camshaft pip to check alignment with the vertical line on the adjacent cap. While you can't look straight down on the exhaust camshaft pip you can easily use a small right angle two sided straight edge to verify timing. Place one straight edge against the right side of the cap. Slide the right angle corner up against the vertical line on the cap and then note where the other straight edge appears on the camshaft lobe. If it's timed properly the camshaft pip should appear in perfect alignment with the 2nd straight edge. A small right triangle from a drawing set works very nicely. With the straight edge laying down on the camshaft you can easily see the relative position of the pip.

Sorry man, I'm just not getting this at all....what's a pip? do you have any pics or drawings?

 

[Constant Mesh]

The pip is a "round punch mark" on the camshaft lobe nearest the chain.

 

[dannymax]

The pip is a "round punch mark" on the camshaft lobe nearest the chain.

These little guys that I refer to as holes?

 

[Constant Mesh]

Yes. Though I thought they are just punch marks, indentations, etc. Don't believe that's an oil delivery port from the camshaft.

 

[dannymax]

Yes. Though I thought they are just punch marks, indentations, etc. Don't believe that's an oil delivery port from the camshaft.

I don't believe they are related to oil delivery either...this sure seems like a good time to check them out.

 

[Constant Mesh]

The oil delivery ports in the camshafts are located at the midpoint between each pair of valves. The oil enters the bearing areas of the camshafts and then flows left and right to the lifters and cam lobes. The oil enters the camshafts at the right end near the sprockets.

 

[dannymax]

Got it back together and fired it up...it started quickly and jumped to 2K, fast idle, and ran nice and smooth. Then I saw the steam rising from underneath....both coolant delivery pipes are leaking around the o-rings where they go in the head.

The o-rings were good, pipes went in smoothly....Oh well, musta screwed them up, I'll deal with it tomorrow.

 

[FJRay]

Got it back together and fired it up...it started quickly and jumped to 2K, fast idle, and ran nice and smooth. Then I saw the steam rising from underneath....both coolant delivery pipes are leaking around the o-rings where they go in the head.

The o-rings were good, pipes went in smoothly....Oh well, musta screwed them up, I'll deal with it tomorrow.

Every time on mine and others when I tried to reuse o-rings they leak. I keep a bunch on hand now. Glad you got it sorted out.