Cam Timing

[tmckeen]

So I'm finally getting to reassemble the engine for my R6 and I can't for the life of me get all three of the timing marks to line up, both the marks on the Cam gears are lined up dead perfect with the top of the head, but the ignition mark refuses to line up with the case split, I've taken it apart and put it back together a dozen times, adjusted the cam chain back and forth one tooth on the cam gears and one tooth on the crankshaft gear, and I simply can't get the mark any closer than this. If i shift it one tooth it ends up exactly the same amount off, only slightly before the case split.

 

 

 

 

[Balistic]

So I'm finally getting to reassemble the engine for my R6 and I can't for the life of me get all three of the timing marks to line up, both the marks on the Cam gears are lined up dead perfect with the top of the head, but the ignition mark refuses to line up with the case split, I've taken it apart and put it back together a dozen times, adjusted the cam chain back and forth one tooth on the cam gears and one tooth on the crankshaft gear, and I simply can't get the mark any closer than this. If i shift it one tooth it ends up exactly the same amount off, only slightly before the case split.

 

 

 

 

The first thing I would ask is are you pulling the cams all the way down with the cam towers and looking at it? the cams will retard as you tighten the cap down. I usually set the crank and then worry about the cams, it would appear that the cams will be retarded with crank position. If you have done everything right the question of how much the cam chain has stretched may be an issue. You can get slotted cam sprockets and preposition the cams so you can get the crank at top dead and the cam marks lined up.

Will

[tmckeen]

all the caps on the cam's are snugged down tight, not final torque'd but all snugged down,

 

hopefully a new cam chain fixes it, would you recommend replacing the chain guides along with the chain, or only replace if they are worn or damaged ?

 

thanks

 

Tyler

[Pepsi Drinker]

Set the crank to the case split then install the cams- there are factory "tolerances" and I have seen cam timing vary by more than 3-4* on the same year and model of bikes, So if the marks on your cam sprockets are off by what seems like 1/4 to 1/2 tooth I would not be surprised.

 

Cams down but not torqued, is the tensioner fully tensioned?...minor difference but it is a difference

 

Once you have it all together and think it is correct (as it can be) rotate the engine over by hand a few rotations and make sure.

 

The best choice would be to actually pull out a degree wheel and piston stop and set it up and see what the cam timing is actually at and adjust as necessary- but that is not always necessary or practical, especially if you "just" adjusted valves or some other mundane service work on an engine you know to run good. On the other hand if you just rebuilt the engine or milled the head or did some other performance work that could/would decrease piston to valve clearance I would definately check, set cam timing and piston to valve clearance. FWIW.

[tmckeen]

I lack the degree wheel or top dead center indicator and other various tool bits for playing with the cam timing which is why I'd rather not mess with slotted cam gears just yet.

 

the chain tensioner is fully installed, it doesn't have any oil pressure, but the chain is under plenty of tension,

 

I've rotated the engine by hand many times so I know there isn't a clearance issue with the valves and pistons, If I do end up having to leave the timing mark off a few degrees is it better to have it retarded or advanced ?

[ScrmnDuc]

If I do end up having to leave the timing mark off a few degrees is it better to have it retarded or advanced ?

Basic answer. Retarded = more top end power. Advanced = more midrange power.

 

As I am not familiar with the R6 motor I hope you don't mind me asking what could be a couple of silly questions. These questions are based on my knowledge of working on Alfa Romeo engines from days gone by.

Are the cams in the right slots ( aka IN on the intake and EX on the exhaust ) or are the cams even marked which one goes where?

With the engine at TDC on #1 do the cam lobes should either face each other or point away from each other? That doesn't really matter but what really matters is that the cams don't mirror each other. To explain that statement. If the cam lobes on both cams face the intake or exhaust runner at the same time you have 1 cam 180 degrees out.

[tmckeen]

The cam's are not identical, so in a way they are marked, the Exhaust Cam has a extra spline?? with a notch in it, when the timing marks on the Cam Gears are lined up with the top of the head the lobes for #1 are facing away from each other at ~45°'s, I've checked the service manual many many times to ensure that I didn't have em reversed.

[ScrmnDuc]

OK T, good to know about the cams. I would have expected the lobes to be facing ~80- 90 degrees apart from centerline or almost facing the intake and exhaust runners. If they are facing the spark plug and 45 degrees apart then ok. One should be coming off the valves and the other should be going on the valves. I am assuming that your motor does not have rocker arms. If so what I just said may be a waste of time.

 

I use the degree symbol in word almost every day. What is the key combination to get it here?

[tmckeen]

thats Alt+0176 , but i normally cheat and just use the character map for all my odd characters

 

side note, if you click the advanced view check box at the bottom there is a search function so finding the symbol your looking for is much easier

 

and uh, they are facing apart from centerline, or away from each other like I said, the intake has just closed and the exhaust is about to open

[ScrmnDuc]

Thanks for the posting help.

 

I guess you may have read this thread in the R6 forum

 

http://www.r6-forum.com/forums/showthread.php?t=156538