Topic: Cb650, Carbs Blowing out Air, Exhaust sucking in air

[Vinhead1957]

Dave is right you do have a cam timing issue but it shouldn't be addressed remotely get the manual and check double check the procedure in it.

[curemode2002]

Okay here is the info from the manual and a couple of pics from the bike. As you can see from the live pics there are two timing marks on the timing wheel in my pics it is hard to see but they both say T F I || S one is for cylinders 1 & 4 TDC the other is for cylinders 2 & 3 TDC. The marks are very hard to see so you need to identify which is for 1&4 and which is for 2&3 Bailgang suggested to remove the plug for cylinder 1 and use a straw or thin dowl and watch for it to hit the top of its stroke that is the timing mark to use. The if you are not careful with these marks the crankshaft can be out 180 degrees relative to the camshaft see the red note below. You must have the notch on the right hand side (same side as the ATU) and the notch must face forward.

Note: do not use anything on the timing side to rotate the crank use the Stator side to avoid breakage like we see in this post, the instructions below tell you to use the timing side to rotate the engine

Thanks Bailgang and scottly for the extra info!

_____________________________________________________________
51 Engine and gearbox reassembly: refitting the camshaft and setting the
valve timing
_____________________________________________________________

1   Lubricate the cylinder head camshaft bearing surfaces with molybdenum
disulphide grease.
2   Holding the camshaft chain taut to prevent it from bunching around the
crankshaft sprocket, turn the crankshaft by means of the large hexagon
spacer on the ATU until the '1.4T' mark appears in the timing window. Line
the timing mark up against the index pointer in the top aperture (below upper
screw) of the pulser assembly mounting plate.
3   Engage the camshaft sprocket under the looped cam chain. Hold the
camshaft sprocket and cam chain together, and slide the camshaft through
The center of the sprocket from the right-hand side. Note that the camshaft
must be positioned so that the notched index mark on its end is located at
the right-hand end of the cylinder head and is facing forward. Lower the
camshaft onto its bearing surfaces in the cylinder head.
4   Align the camshaft end notch so that its center is horizontal with the
cylinder head mating surface. At this stage, one of the camshaft sprocket
mounting bolt holes should be accessible and in line with the camshaft's
threaded hole. Fit a securing bolt and tighten it gently.
5   Turn the crankshaft through 180 degrees to that the remaining sprocket
mounting hole becomes accessible and then fit the second bolt.
6   It is imperative that the camshaft is fitted in the position described above,
failure to do so will result in incorrect valve timing. Slacken the cam chain
tensioner locknut whilst rotating the ending and then retighten the locknut.
Very carefully recheck the valve timing. It is only too easy to get the timing
one tooth out. Finally tighten the cam sprocket bolts to a torque setting of
1.4-1.8 kgf m (10-13 lbf ft).
7   Install the six rubber sealing plugs above cylinder head retaining bolts
Nos 1, 2, 3, 4, 6 and 8.

[curemode2002]

Here is a larger live pic so you can see the detail

[curemode2002]

Here is a larger live pic so you can see the detail

[strynboen]

i alvays set cyll no 1 in kompresion stroke..vhen mount the cam..just pull the plug..and hold a finger in the hole..and feel komp airkomms aut..and turn to top" t "  marked..then fit the chain and turn it 2 roundt and dobbel thek

but mine are a 550..sooo...

[curemode2002]

+1 strynboen
That is exactly what I did the second time around just to make sure I had it set right.

[Vinhead1957]

Just to be sure take all spark plugs out and rotate the engine by hand to make absolutely certain no valve/ piston contact happens. It will aid by. Making it easy to turn over.

[wdmcdonald]

Ok guys thanks for all the help. I know its not the starter clutch, that can only go in one way.

Curemode, I followed those exact instructions and I'm 100% sure I have the cam lined up in the right position... but I think I figured out the problem... The little pin on the ignition advance unit that registers into the crank somehow got sheared off... maybe I didnt put it in right the first time. So, my theory is that because that part was not in sync with the crank, my 1.4T mark would not have been in the right position and there would be no way for me to correctly set the cam. Thoughts on this?

[curemode2002]

Yes that is very bad. That is what tells you if your crank is lined up so that is most likely the cause of your problems. All it would really have to do is move a few degrees to cause all sorts of havoc.

[curemode2002]

Come to think of it the process of rotating the crank in the manual is a bit scary that pin that is sheared off is what you would be using according to the manual.

[wdmcdonald]

Yep guess it was pretty simple after all. Found some on ebay for cheap. But ya that pin seems like a weak point. Ive never had it happen before though.

[dave500]

that note in red is just the way they like to do it so everyone conforms mate,,you can #$%*ing not for the last #$%*ing time have the cam 180 #$%*ing degrees out!for example lining up a chev or say old windsor v8,,you line the dots together,the crank dot is upwards and the cam dot is downwards facing each other,,but if you set the cam dot upwards aswell is it 180 out?rotate the crank 360 and magicaly the dots are back together,we put the dots together so we all conform to a standard,line your sohc four cam to the rear,now rotate the crank 360,and there it is all proper again,with that pin missing the ignition timing goes haywire aswell.

[pangloss]

So it was the advancer plate...! 
Use the alternator bolt to turn the engine over..you are quite right about the weakness of the advanced plate bolt/system

[Retro Rocket]

With all that sucking and blowing going on i would say it needs a head job.....

[crazypj]

crazypj you can't kickstart the 650's no kick on these which really sucks. Good point on the clutch but I would think they would only go one direction.

Doh, forgot he said 650, I was thinking 550

[wdmcdonald]

So I swapped out the advancer plate. Problem solved! Bike still isn't starting though... Seems like it wants to start igniting but I just get a few back fires and poofs of smoke. Maybe I'm a tooth off on the cam chain?

[goldarrow]

Your advancer is 180 degrees off. 

[wdmcdonald]

Your advancer is 180 degrees off.

180 off now? Or when I had the original problem?

[goldarrow]

Your advancer and advancer springs, stuff down by the points plate

[wdmcdonald]

Ok so how can I tell? Because it shouldn't be off if it registers into the crank, right?

[goldarrow]

The advancer lobe is what controls the points gaps.  So, remove that from advanced springs and turn it 180.  Set point gap again and should start right up

[dave500]

where did you get the new advancer unit from?the points type ones can be dissembled and put back together wrongly 180 out,im not familiar with your 650 electronic type though,id guess and say it hasnt been tampered with?re check your cam timing now with the new advancer,if it has been altered that wont affect the cam timing procedure.

650 gold arrow,,no points,electronic igniton factory on these.

[trueblue]

where did you get the new advancer unit from?the points type ones can be dissembled and put back together wrongly 180 out,im not familiar with your 650 electronic type though,id guess and say it hasnt been tampered with?re check your cam timing now with the new advancer,if it has been altered that wont affect the cam timing procedure.

650 gold arrow,,no points,electronic igniton factory on these.

The advance units on these can be assembled 180 out . 

[dave500]

so if he puts the cam 180 the other way itll be ok then?

[wdmcdonald]

It got it from a salvage yard of a same year 650. I'm pretty sure it hasn't been tampered with though...

Not sure how the advance unit comes apart but I'll try flipping it 180 before I take the head cover back off to test the cam position. If I'm off by one tooth would it not even start?