Topic: Cam chain tensioner ajustment with electronic ignition

[AlekStooge]

Okay couple questions that came up up during a cam chain and valve adjustment.

I will have to redo the valve adjustment because I did that before adjusting the tensioner?

I have a Megacycle 126-00. Electronic ignition.

The manual calls for adjusting the tensioner 15° advance on cylinder 1 compression? Would I have to reattach the degree wheel and turn the engine clockwise (alternator side) from TDC?

About the valves; my Megacycle card increased the values up for both intake and exhaust. I had a discussion about this a while back on here and we concluded to use the stock specs because .005 mm and .006 mm were extreme for this cam so I decided to go with stock specs .002 mm and .003 mm.

My exhaust tappets sit very high and are backed up. They are on the tight side of .003 mm a little tight for my prefrence but by no means very tight. If I back them up any more they won't be on. This doesn't seem normal to me at all.

[bryanj]

No you wont have to redo the clearances except that i cant believe everthing is correct with that much adjuster showing, something is veryvwrong somewhere, as to the chain adjustment would help to know what bike

[AlekStooge]

1978 CB550K, I got too much into the other details I forgot the basics.

Yeah it's bizzare. Makes me really want to recheck my cam timing. I checked it a bunch of times but that's the only thing I could think of that would cause the exhause valves to be sitting so high. All four are like that.

[flatlander]

read the cam card again. lash value is not in mm, it's in inches.
but more importantly, bryan's right: this is not assembled correctly, something's very very off.

[AlekStooge]

My mistake .002 and .003 in.

I am going to check the cam. I started looking through old info.


Flatlander: The cam card was off with the different revisions Megacycle did. I ended up with numbers off the old revision. See this thread below. Yeah I think this needs to revisited. Somethings off. I'm not going to loosen the cam just yet but check what I am getting with the numbers.

http://forums.sohc4.net/index.php?topic=166819.0

[bryanj]

As for cam chain tension
With engine NOT running
1st loosen adjuster nut
2nd put weight on kickstart until engine is about to turn
3rd Whilst holding weight on kickstart nip up locknut.

This works by pulling the front run of camchain tight thus putting all slack on the adjuster side.

You may need to do this a couple of times until you get the " feel " of holding the kickstart at just the right point, you can do this by removing the generator cover and using the bolt on end of crank to turn crank forwards, NOT a good idea to use the big nut on advancer.

This method was shown me way back in the 70's by a Honda field rep and works on all Hondas as long as the adjuster is free

[AlekStooge]

As for cam chain tension
With engine NOT running
1st loosen adjuster nut
2nd put weight on kickstart until engine is about to turn
3rd Whilst holding weight on kickstart nip up locknut.

This works by pulling the front run of camchain tight thus putting all slack on the adjuster side.

You may need to do this a couple of times until you get the " feel " of holding the kickstart at just the right point, you can do this by removing the generator cover and using the bolt on end of crank to turn crank forwards, NOT a good idea to use the big nut on advancer.

This method was shown me way back in the 70's by a Honda field rep and works on all Hondas as long as the adjuster is free

Interesting, good knowledge.

[dave500]

rotate the engine with the spark plugs removed and watch as any of the intake valves begins to close,now what ever cylinder it is keep rotating while observing the timing marks come to the T mark for that cylinder and stop,now check that cylinders tappets,are they tight or loose?have a look at the others with the motor in this position,are they sloppy?

[AlekStooge]

These aren't stock timing marking or stock ignition. The correct tappets are loose at TDC as they should be. Please re-read first post.

[rotortiller]

I wonder if the adjuster screws are the correct item? #1 rockers are on the backside of the cam at TDC right?

[AlekStooge]

I wonder if the adjuster screws are the correct item? #1 rockers are on the backside of the cam at TDC right?

uhh I am a not sure. I would imagine the cam lobe is facing downward. The tappets are both loose on cylinder 1.

[Keith]

He cannot be a tdc when checking clearances. The valve spring was under tension from the cam opening the valve.

[dave500]

QUOTE.
These aren't stock timing marking or stock ignition. The correct tappets are loose at TDC as they should be. Please re-read first post.
REPLY.
it doesent matter what ignition it has,check your tappets at tdc compression for each cylinder,youve gotta be setting them on the cam lobe base circle,if thats not happening at tdc youve installed the cam out of phase/time.

[AlekStooge]

I took the cover off and am going to check TDC and my cam.

I'm thinking about what you said. I don't know where compression is for all four cylinders just 1/4. I don't see how that would help me either. I set the valves in the sequence illustrated in the manual.

[dave500]

forget the manual man!always check and set em individually in sequence,especially with a non standard cam,the ignition timing marks have 1/4 and 2/3 marked,follow that mark,pistons 1 and 4 rise and fall together,pistons 2 and 3 rise and fall together but 180 degrees apart from 1/4.,once on the tdc mark for either pair,one of the pistons will be on compression both valves closed(thats where you set the tappets)the other will be on exhaust stroke with exhaust valve open and inlet close to opening(thats where you do not set the tappets)

[AlekStooge]

Ok makes sense. However I don't think the stock timing marks help me here. I'm not too familar with using them I'll take a look tomorrow. The only method I know of find 180° apart would be via a degree wheel in this situation.

Anyways I verified TDC today I got (37.5°+10°)÷2=23.75° from TDC. I verified it with a paint brush handle and checked my ignition light. I was a few degrees advance.

This is probably a good time to address my previous question how do I find 15° ATDC? The tensioner is adjusted at that point. The valve cover is off. I am turning the crank counterclockwise from the alternator side where the degree wheel is to TDC and go another 15° from 0? Adjust the tensioner and make a marking? I think I just answered my question.

[dave500]

if you have a degree wheel 15 degrees after tdc would be a piece of cake,forget setting the chain that way,use the applied tension on the forward part of the chain method as bryanj posted,keep the ignition out of anything to do with setting the tappets and chain,first,find tdc with a positive stop,then verify the factory tdc mark,if it lines up good to go,check your camshaft is timed correctly,youll be chasing your tail over and again if its wrong.
also depending on how much slack is on your advancer pin when its locked by that centre nut it may be off slightly,dont sweat it,its minimal,heres an example,this motor is at tdc,i can lock the advancer plus or minus,this will also affect your ignition to the same degree,lock it at the tdc mark if the motor is at tdc.

[AlekStooge]

Right forgot about Bryan's method.

I already find TDC as I mentioned in my previous post and checked if it matched up with my ignition. I don't see what the mechanical advance has anything to do here.

My next step will be to check if my cam is dialed in. I looked through my build thread on this engine and saw that I noticed the exhaust tappets sitting high and rechecked everything. I accepted it and moved on but now I would like to dig into this a little more.

[Deltarider]

Bryanj's method is best. It was also practised by professional mechanics in workshops here in Holland. It's easier done with a helper however: one for applying tension, the other for fastening that lock nut.
@Alekstooge Can you post a photo where you have the feeler gauge when you measure the gap? So we can check whether it is done right.

[dave500]

QUOTE.
Anyways I verified TDC today I got (37.5°+10°)÷2=23.75° from TDC. I verified it with a paint brush handle and checked my ignition light. I was a few degrees advance.

I already find TDC as I mentioned in my previous post and checked if it matched up with my ignition. I don't see what the mechanical advance has anything to do here.

REPLY.
you #$%*ting me?how the hell did you time the camshaft?umm?the mechanical advance unit provides the timing index marks chum,it shows you where the crankshaft is.

ok im done here.

[Tracksnblades1]

Looks like you’re not setting the valve lash (clearance) on the camshaft’s base circle.
It looks like your setting the lash on an opening or closing ramp. 
I would verify your camshaft to crankshaft timing (cam chain) is correct after verifying Piston TDC to prevent bending a valve once you’re at full lift.
You can check and verify this by following Dave’s post or turning the crank a little bit checking  for increased or excessive lash, turning the crank a little bit and checking for increased or excessive lash, etc, etc, until you see that valve completely open and close with out the lash clearance changing while it’s on the base circle. Checking max valve lift against the cam card would be the quick way to determine if you’re lashing on the base circle. If you inadvertently set the lash on a ramp or any place other than the base circle the lash will change “increase” as the follower is lowered from the ramp back onto the base circle.

Your spark advancer is the trigger for your ignition timing. Has everything to do with ignition timing. Has nothing to do with camshaft/crankshaft timing other than it provides the factory TDC mark..You can verify the OEM  T mark by the positive stop method or the indicator method with a degree wheel too. Find 1 or 4 TDC. The crankshaft is forged steel so you can’t change 2&3 if it isn’t exactly 180 degree apart anyway..The ignition timing for 2&3 is another story though.

But let’s assume you’ve done everything correctly and you’re “not” settling your lash on the ramp or the nose of the camshaft. The only thing left is the position of the camshaft in relation to the followers’ (rocker arms) fulcrum or the base circle od of the new camshaft is bigger than OEM. Both of which is unlikely, but I’ve seen CompCams that won’t even fit in the block…

Mechanical Timing is everything….just like Ignition timing….

[bryanj]

Most "performance" cams are made by grinding down the base circle giving more lift, to have the adjuster like yours the base circle must be bigger(which means its made wrong)  OR you have not timed it right

[AlekStooge]

Looks like you’re not setting the valve lash (clearance) on the camshaft’s base circle.
It looks like your setting the lash on an opening or closing ramp. 
I would verify your camshaft to crankshaft timing (cam chain) is correct after verifying Piston TDC to prevent bending a valve once you’re at full lift.
You can check and verify this by following Dave’s post or turning the crank a little bit checking  for increased or excessive lash, turning the crank a little bit and checking for increased or excessive lash, etc, etc, until you see that valve completely open and close with out the lash clearance changing while it’s on the base circle. Checking max valve lift against the cam card would be the quick way to determine if you’re lashing on the base circle. If you inadvertently set the lash on a ramp or any place other than the base circle the lash will change “increase” as the follower is lowered from the ramp back onto the base circle.

Thank you for that. I however can't check valve lash at this moment because the cover is off. I'm going to walk through the process of degreeing the cam and take photos. I appreciate the help and hopefully we could catch what is wrong here.

I have the degree wheel attached and got 24° in both directions with the piston stop. I removed the piston stop and moved the crank so I get 0° on the pointer. I verified 1/4 are at TDC with a paint brush.

I checked the manual on where the notch is whilst the cam is installed. This at 1/4 TDC correct? The notch is facing the direction of travel on the right side of the bike. I remember after the degree process everything ended up close to stock.

If everything is correct then I will install my modded cover with rubber bands holding the rockers then adjust the cam chain tensioner using Bryan's method.

Thanks guys appreciate the support.

[AlekStooge]

Here is the notch photo.

[Tracksnblades1]

So, does your Ignition TDC “T” advancer match your degree wheel TDC paint brush mark..?

I’ll look at all your pictures to make sure I didn’t miss anything..