Timing
 

Just out of curiosity, for those that have set their timing from scratch, do you align the timing mark on the flywheel with the marl on the case or, as it shows in the manual, do you align so that "RT/FT" is completely in the window?

AV

My factory service manual TELLS you to align the timing mark (not the letters telling you it IS the timing mark) with the mark on the case, center of the window and that is how I have done it ..Yes the picture shows you the entire bit you will see...

Old rule, words over pictures..Words tell you what to do, illustrations are provided to help clarify...In this case the picture was there to help clarify ALL the markings you will see.not the specific position of the flywheel and the index mark aligned.

But according to the pictures below and the words, the manual indicates that the entire mark, words n all, is the reference. Not just the mark. I would imagine that Honda could have circled just the hash tag or used an arrow. Now to be fair, I think that it isn't the biggest of deals. In effect if you use the hash tag as a reference the crank will be advanced (cams retarded) and vice versa for the RT/FT mark. This may account for why some people vary so much in jetting, power #'s, tunability etc. Using the hash tag would make better power up top and using the entire mark would make more power down low. Seems to me that what I need to do is use a TDC tool with my indicator and figure out which witch is which.

AV

https://cimg6.ibsrv.net/gimg/www.sup...5bc83bd447.jpg
https://cimg7.ibsrv.net/gimg/www.sup...5737f282b7.jpg
https://cimg8.ibsrv.net/gimg/www.sup...549b71e90f.jpg
https://cimg9.ibsrv.net/gimg/www.sup...f203c24194.jpg
https://cimg0.ibsrv.net/gimg/www.sup...5cd7c88fa7.jpg
https://cimg1.ibsrv.net/gimg/www.sup...ef36c04cad.jpg

I disagree that the manual can be misinterpreted. It says to align the "mark" not the text. The text is the identifier for the mark. I would put beer on the fact that when the flywheel mark is aligned with the case mark, the piston will be at TDC. The timing relative to the cams however is in the lap of the gods of cam chain wear. When new I would expect the timing would align perfectly, but I know in my bike (80000km) the cams lag a a few degrees behind the crank because of chain wear. Still runs well with stock jetting on gutted stock mufflers.

I suppose we will find out this weekend when I get a spare few minutes. But, if it could not be misinterpreted, we should not be having this discussion...but we are...so...

Also, from vtr.org... "Del...im interested to know what yer manual says about timing marks....when doing the rear it didnt seem to be much different with either the line central or text/line central....but on the front it did seem nearer with the text/line central so i left it at that for now...its only a smidge different but needs to be right...post your finding on here as maybe i need to come back 1 tooth on both cams on the front to get the line central......phew!"

"As I said mate, the manual shows the mark as the text and line on the flywheel and not just the line. If you check it too it will be correct, when you use just the line on the flywheel then line on the cam wheels are slightly out of line with the heads but if you get the text and line in the inspection window then the line on the cam wheels will be exactly in line where they should be."

AV

There's a good desrciption of cam chains and timing here.

https://www.diymotofix.com/blog/cam-...lacement-tips1

Good yes but, the author has not used a tdc tool on the vtr and verified where tdc is. I'll do that sometime Saturday and nail it down for sure.

AV

I couldn't wait so I spent a few minutes messing around. To be fair I only checked the front cylinder but I can confirm that the the hash tag is not TDC. It is most near the gap in between F & T in "FTI." So...as it shows in the manual we should be using the entire mark and not the dash as a timing reference. There is quite a bit of crank dwell so I have to admit that depending on how one chooses to tune, you could set it at almost any point from the "T" to just past the "F."

AV

Update* With the heads off and using a dial indicator, not a tdc tool, I have confirmed that on my engine the hash mark under the letters is TDC well beyond any doubt whatsoever....

AV

And...

On my old block with a set of cams in the head I decided to mess around. Even if you set the piston at tdc with a dial indicator, then indicate in each cam, and use a factory tensioner...the cam marks are still out no matter how you dice it up.


https://cimg2.ibsrv.net/gimg/www.sup...2bd577a176.jpg
Parallel
https://cimg1.ibsrv.net/gimg/www.sup...54efdc3e15.jpg
Not so parallel, enough to drive you mad.

Maybe the motor is sitting at an angle?

One of the many reasons Honda built the RC 51

Time to slot the cam sprockets???

The cams will lag in an aged engine due to chain stretch.

Irrelevant, though yes it is on an angle. A 90 degree one.

AV

I conducted the same test with 2 chains from 2 different bikes and two different sets of sprockets. The point I was trying to illustrate was the massive difference between what the marks show and what is really going on. The difference between the stamped sprockets and the machined ones is dramatic. Essentially the marks are all but useless unless your really lucky or not concerned. I have yet another set getting slotted now. that ought to fix things.

AV

Ok, so here are the results from a degree wheel and a dial indicator with stock cams in a stock head with stock chains and adjuster relying on factory timing marks:

The intake center line which is supposed to be 102.5 advanced 2.5 which should fall in at 100, ends up being 107 which means it is retarded by a total of 7 degrees.

The exhaust which is supposed to be 107.5 advanced 2.5 which should fall in at 105, actually falls in at 116, which means that it is retarded by 11 degrees.

Either way there is no real good way to fix the issue without a set of slotted gears unless you're happy to split the difference. You could advance both by one tooth and end up with the intake advanced 9 degrees and the exhaust advanced 6 degrees. Or you could use the crank tooth to change it in which case the exhaust would still be retarded by a couple and the intake would be advanced by 1. Ish....just some food for thought if you like to get picky about such things.

AV

Aww yeah...look what the machine shop done did!:


https://cimg2.ibsrv.net/gimg/www.sup...959707f28b.jpg
4 slotted gears, let's get timing....!!

Perhaps its my old eyes, or angle of pic..But did they just mil a "straight" slot to either side of the OEM bolt hole??
Or is it curved ?

Erik, My eyes are 65 and the right's lens has been replaced and the left's needs to be, and I too see straight rather than radiused (spelling?) bolt slots...

Lol, nah, its the lens. They are as curved as an Aussie's...well, they are curved.

AV