80 cb650c valve clearance? ...I'm NOT 180 degrees off

[petev123456789]

Hi all i am setting my valve clearance after my first ever top end rebuild. I have gotten tons of help from the many topics and threads on this site but have ran into a problem.

When setting valve clearances I can set them for cylinder #1 at TDC but not for the #2 exhaust or #3 intake as per manual suggests... no clearance even with screw all the way out.

I am positive of correct cam timing the end 1.4 T mark lined up and cam end mark parallel to head both front and back, cog marks perfect, 1/4lobe Vs the same for both. unless I jumped it somehow while messing with ignition timing the little nut inside the large one to turn the crank came loose but i dont see how that could have done it.

My question is do i adjust clearance with the lobe v pointing up or down? is the lobe v up or down at TDC for that cylinder?

This may be a stupid question but the manual is unclear and I have dug for hrs to no avail. Can I just set the clearances at the 2.3 T mark?

Thanks for any help or advice you can give

[usbear]

Which stroke are you on?
TDC compression stroke on #1
Four stroke engine. Two Full turns of the crank. Twice on timing mark.
Get on correct stroke first.
remove #1 plug and put finger over plug hole to get to TDC on compression stroke. Then set #1 and follow procedure in book.

[Volker_P]

Yes, in a four stroke e.g. the "V" for #1 could either point up or down at the 1.4.T mark. One turn of the crankshaft will toggle between positions.
The position for valve adjustment is both lobes to downside so the rocker arms are free of load.

[petev123456789]

So both lobes of the "V" are up on 1 and Im able to set clearance, but not for 2-ex or 3-intake.. no clearance really at all even with the screw and lock nut completely removed from rocker arm.

Did I lap the valves too much or what could be causing this? a twisted cam?

I might have to verify the cam timing for my own peace of mind again I will post pics or report success or both.

[petev123456789]

thanks a ton guys!

just went and checked things again and the tdc for compression stroke on cylinder 1 was set AS 2.3T which means.... i'm an idiot.

Oh well at least i didn't break anything. Cylinder 1 is on the right when your sitting on the bike correct?

Maybe ill make a video or some kinda tutorial for people to critique as I set this timing for literally the forth time in as many weeks.

[Nevernoluck2]

Cylinder 1 is on the left sitting on the bike

[Volker_P]

Did you disassemble/swap the advancer?
Because one may reassemble the advancer 180° off. Time to verify piston position with a straw then.
Cylinder 1 is on left side.

[petev123456789]

I didn't mess with the advancer but previous owner could have it set that way. I thought the plugs were in the wrong holes but now that makes more sense.

So I verify that 2.3T is actual tdc for 1/4 by finding where their heights coincide when one is on in compression stroke. If 2.3 is my actual tdc for 1/4 just proceed as if it is for all aspects of cam and ignition timing and valve clearance and this will work fine?

lol i actually thought 1 was on the right because of the numbers hand written on the coils in comparision to the wiring diagram.

[Volker_P]

So when the pistons of 1+4 are at TDC position, your reading at the advancer mark is 2.3T, right?

On the other hand this means you probably did set the proper cam position at 1.4T which unfortunately in your case would correspond to pistons 2+3 being in TDC position which is definitely wrong cam timing!

For the advancer, the tip has to point to the left / rear pickup coil (with the blue cables) at the F1.4 mark (with 1+4 pistons being close to TDC position).

Hope that helps to figure out what is actually wrong.

[petev123456789]

So when the pistons of 1+4 are at TDC position, your reading at the advancer mark is 2.3T, right?

This is correct and definitely the reason my cam timing was off and causing my whole clearance issue.

My plan now is to reset cam timing using 2.3T and reset ignition timing again using 2.3T there is a mark that was made where the ignition timing was set initially I will return to that if it seems off.

Can ignition timing being off cause serious damage or only performance issues?

[petev123456789]

no i guess i was wrong again. I may need to practice more patience while considering this.

T 1.4 is tdc for 1 and 4

While they do hit T2.3 at the same time that is due to bottom dead center 2 and 3 were at the top.

Now I think the last thing I need to figure out is how to tell the difference between #1 compression stroke and #4 compression stroke. They seemed nearly identical if not identical. I will do a little digging my guess is that the one on the compression stroke will be a few mm lower during the stroke but I will look into it.
I may have put the cam notch forward for the number 4 instead as I didn't take compression stroke into account.

Thanks for all your help guys im learning a ton. This timing stuff is by far the most difficult I have tried yet.

[Volker_P]

The key fact (for every four-stroke) is:
For one turn of the camshaft, the crankshaft does two turns.

[petev123456789]

so i guess my question is on pg. 6-16 and 6-17 of the manual where it says T1.4 align cam notch to the front, is there any way to determine T1.4 from T-1.4 at this point or is this only determined by cam position? Which should be or IS on compression with notch front?

If the crank turns twice then the exhaust stroke and compression stroke are identical except for the spark. My issue is how do I ensure that I am not going to have spark on the exhaust stroke etc.

The static timing method on 3-4 where it says either 1 or 4 must be at tdc makes me think it is a mute point though and the cam will figure it out somehow

[entropy]

You have spark on both the compression stroke *and* the exhaust stroke. This motorcycle uses a "wasted spark" system, where it fires 1 & 4 at the same time, 2 & 3 at the same time. That means either 1 *or* 4 will be on the compression stroke, but both will spark; 180 degrees of crank later, 2 & 3 will both spark (again, only one of them will be on the compression stroke); 180 degrees later 1 & 4 will spark again (so if #1 was on compression at the first part of this, now #4 will be).

So while you care during valve adjustment whether #1 is on compression or exhaust, for timing you don't care a whit since it sparks on both.

[MiGhost]

When setting valve clearances, You can take the compression, and exhaust strokes out of the picture. The only concern is to get the #1 piston (Far left as sitting on the bike) to the top of its stroke, and the T1.4 mark on the pulser lined up at the same time. You can verify that the #1 piston is at the top of the stroke by using a straw as Volker suggested. The straw will go into the spark plug hole only a little way when compared to the #2 cylinder.

If you have this lined up, and the cam lobes for #1 are not touching (The rockers should be loose) the rocker arms, but the #4 exhaust lobe is touching (The rocker should not be loose). Then you are set to begin the valve adjustment procedure. You will set the #1 in/ex. along with the #2 ex, and #3 in at this time

If the #1 exhaust rocker is tight. Then you need to turn the engine 1 complete revolution (360*) to get on the correct alignment.

Once completed with the first half of the clearance adjustment. Turn the engine 1 complete revolution (360*) to get on the correct alignment for the second half of the clearance adjustment. At this time you will set the #4 in/ex along with the #2 in, and #3 ex valves.

If your timing mark is showing T2.3 while the #1 piston is at the top of the stroke. Your pulser timing is 180* off, and needs to be corrected or the bike will not run period!

One final tip. It will be much easier to turn the engine over will all 4 spark plugs out. You will not fight against the compression stroke when turning the engine this way. Disconeccting the battery is not a bad idea either.

Ghost