Cam timing

Hello. I am currently re-ringing my 1105 kit. I just noticed that my aftermarket cam sprockets do not have marks on them. Is there any other method to place exhaust cam in the correct position to start the process other than using a degree wheel? Thanks.

Overlay your original factory cam sprockets with the teeth lined up and its mounting holes in the centre of the slots and simply transfer over the position of the marks.
That said, the slots in the aftermarket sprockets should only allow the cam to move within the range of one tooth anyway so placing the cam with the mounting bolt in the centre of the slot will put the timing very close to std.
You will still need to degree the cams to get the timing specs correct.

Thanks for your reply. I do not have stock sprockets anymore. This motor was built in '79. It's been a while since I've rebuilt it so I'm not fresh on the R.C. 388 cams. I've attached pics of where I'm at. Stock cam lobes as you know on the right side face each other when on the 1/4 timing mark. The pics show that I am not. .416 lift, .298 duration, and 108 lobe centers. I have a scratched in mark on the exhaust cam that I'm not sure I should trust and intake sprocket for 28th pin has three punched in dots. Don't remember if they should face the same way as stock regardless of cam specs or whether they would be different. Thanks for any help. NOTE: number 4 intake in pic is open.

Are there any dimples? If you look at the sprockets you should see to holes close together and one across from them. Basically the plane of the head should pass between the two close ones and through the center (ish) of the singular bolt. The single bolt should be on the outside of the head. That said, it doesn't make sense that thereally are not any marks as you need an indicator for the 28th pin to correctly time the cams. My APE sprockets have dimples.

Dimples only on the intake cam. (and I have those as the 28th pin mark) No markings on exhaust cam other than a weak scratch that I put in years ago but it's so weak I don't know if it is the mark I cut in or not.

Kawasakikid wrote: I've attached pics of where I'm at. Stock cam lobes as you know on the right side face each other when on the 1/4 timing mark. The pics show that I am not..416 lift, .298 duration, and 108 lobe centers Don't remember if they should face the same way as stock regardless of cam specs or whether they would be different. Thanks for any help. NOTE: number 4 intake in pic is open.

No! you have got that wrong.
You need to be on the TDC mark NOT 1/4, that is why the lobes don't line up ( 1/4 is for ignition timing )
lining the TDC mark should put everything in the correct position.
Sprocket marks should be on the right side facing the ign housing so that they can all be read from the same side of the bike.
Also it is the exhaust valve open in the pic not inlet.

[b...]so placing the cam with the mounting bolt in the centre of the slot will put the timing very close to std.
You will still need to degree the cams to get the timing specs correct.[/b]

I guess that would only work if the cam grinder had reground the nose of the cam precisely where the factory grind was? also some models have several different cam gear locations and three pairs of cam gear mounting positions.

KK 108 degress lobe centres are symetrical, when I've done this before I usually line them up and make them look about in the right position before carefully dailing-in. You need to dial-in anyway really as if the head has been skimmed this will affect cam timing. I use loctite on the m6 bolts when set right. Be really careful to alter your setting only when the cam isn't under a closed spring tension to avoid damage to the cam. :sick: :blush:

My bad Tyrell. I meant to say TDC not timing mark! Working too many hours. I think you're right about the mark being ground away. There are grind marks on that particular sprocket that don't look like the intake sprocket. I'm going to take a close magnified look at it.

Kawasakikid wrote: My bad Tyrell. I meant to say TDC not timing mark! Working too many hours.
.

In that case your cams look to be one tooth retarded in relation to the crank .
At 108 degrees lobe centres the cams should be near enough pointing directly at each other regardless of the ram profile either side.
with the mounting bolts in the middle of the sprocket slots , lobes pointing each other and the pin count at 28 you should be in the right position to accurately degree them.

Thanks for the replies! Here's a new picture. I took the cams back out and realigned everything. Mark on the "T" 1 &4 . 28 pins from where it looks like there is a mark on the exhaust sprocket. The lobes are closer but still not pointing exactly at each other. Do you suggest taking it another tooth closer and are you certain the lobes should be pointing exactly towards each other? Picture also of the three dots I described on the intake. I am assuming that's to be aligned with the 28th pin. Exhaust sprocket pic. shows bolts level with head and no real markings. Thanks.

Kawasakikid wrote: Thanks for the replies! Here's a new picture. I took the cams back out and realigned everything. Mark on the "T" 1 &4 . 28 pins from where it looks like there is a mark on the exhaust sprocket. The lobes are closer but still not pointing exactly at each other. Do you suggest taking it another tooth closer and are you certain the lobes should be pointing exactly towards each other? Thanks.

Yes! It needs moving another tooth.
As for timing marks...
On the STD exhaust sprocket the single bolt nearest the front of the engine is almost exactly in line with a sprocket tooth.
The timing (arrow) mark is just below this tooth , it's halfway to the next tooth which coincides with the link pin that should be close to being level with the cylinder head surface.
Your second pic (195kb) clearly shows this mark and it is certainly one pin away from where it should be.

P.s. Are you sure they are aftermarket sprockets and not just std ones with the rubber removed.
Looking at the pics I can't see any slots where the bolts are, just holes.
They look suspiciously like stripped off skimmed std sprockets with no provision for degree adjustment.
The little holes near the edge look to be still filled with the remains of the old rubber damping.

Did you count the next tooth up then to 28?
Steve