Distribution chain and sprockets

[dan cata]

Hi all,

 

A friend of mine had a seal leak around one cyl. He got home and changed the seal with a new one but unfortunatelly, he did not use a zip tie to hold the sprocket to the chain and put it wrong back in, one tooth apart that it was initially.

 

So now the bike will not pass 160 km/h.

 

To get everything back in as it was, I was thinking of putting the engine on TDC on the compression stroke on and observe the 2 arrows on the sprocket "<--( )-->" and check if they are horizontal(as if it were to performe a valve adjustment job). If not, re adjust the sprocket so that the arrows would be horizontal while the engine is in TDC on compression stroke.

 

How does my assumption sound?

If that works, I was thinking of a valve re-adjust and a TB sync would cure the issue. Is that it or are there more to it?

 

Thanks,

Dan.

[dan cata]

Bike is an r1100RT, dunno the year as he did not give me that detail, but I don't think it matters.

[dirtrider]

Morning Dan

 

You didn’t say what side but all the assembly, as far as chain timing, is based on the R/H side at TDC.

 

So start by getting the R/H side to TDC on compression-- then pin the engine.

 

You have to move the cam sprocket anyway so loosen then remove the bolt that holds the cam sprocket on. At that time you can use the pin and alignment marks on the cam sprocket.

 

 

[dan cata]

Hi,

 

The isuue is on the L/H side.

@DR, what you are saying is to get the engine at TDC on the R/H side, lock it on the flywheel, observe the arrows on the L/H side (most probably they will not be horizontal).

 

Then unscrew the bolt that holds the sprocket while the engine is still locked(btw, won't that tension the timing chain by alot??).

 

Also, to fix this, does the whole valve assembly need to come off again or only the valve head cover is enough?

 

Dan.

[dirtrider]

Morning Dan

 

Remove the valve cover, then loosen the cam gear bolt (very carefully), then remove the chain tensioner to slack the chain. Then remove the cam gear bolt. Then pull the gear off & move it on the chain. Sometimes the pin comes out with the gear & sometimes it stays in the cam.

 

You need the cam gear pin to be at the very top and the alignment marks correct between the gear & cam carrier (see picture above-circled area).

 

[dan cata]

So removing the tensioner (PITA on the L/H side) would give me enough room to move the sprocket on the chain.

 

My other concern would be the unbolting of the screw that holds the sprocket... You said carefully What would that mean? Won't the chain break or get slightly longer when foing that?

 

Dan.

[dirtrider]

So removing the tensioner (PITA on the L/H side) would give me enough room to move the sprocket on the chain.--- No it won’t. You just need to do it to slack the chain enough to get the sprocket off the cam pin & back on.

 

My other concern would be the unbolting of the screw that holds the sprocket... You said carefully What would that mean? Won't the chain break or get slightly longer when foing that?--- You need to be careful, sometimes when the bolt snaps loose it can cause the cam chain to jump and possibly damage the end of the chain guide. There have been a few reports of damaged chain guides from being over aggressive on loosening the cam gear bolt.

[dan cata]

Something else came in my mind.

Can't I just take the spark plugs off so there would be no compression as I turn the engine, put the engine in TDC on the left side where I work, then take the black plasic cover on the back of the sprocket off, remove the tensioner, mark the sprocket and chain in position as they are now (which is bad) then using a sharp screwdriver or something re-arrange the chain onto the sprocket correctly and then turn the engine so that the chain goes all the way on the sprocket now, like I used to do on my bike when the chain went off?

 

This way there is no need to undo the sprocket off the cam, no risk of dropping anything in the engine.

 

Does that sound reasonable? What I am not sure about is if just taking off the tensioner will give me enaugh slack in the chain to move it one tooth further.

 

Dan.

[dirtrider]

Morning Dan

 

I haven’t actually tried it but there is so much chain wrap on that cam sprocket that I can’t see any way that would work. You would need so much chain slack to do that there is just no way to get that kind of chain slack by just removing the short stroke tensioner (remember the chain guide is still in position holding the chain).

 

I will almost guarantee that you will need to unbolt that sprocket to move the chain on the sprocket.

 

[dan cata]

Got it.

 

It would have been nice though to do it as I imagined it.

What I am most afraid of is unbolting the sprocket so that it would not break the screw. But since this has been recently done (when changing the seal) I hope it won't break tomorrow.

 

I have a spare bad engine and will practice on that one tonight.

 

Dan.

[dirtrider]

Dan

 

You won’t break the screw (at least I haven’t ever broken one or heard of anybody else breaking one).

It’s the screw (actually a bolt) snapping loose that allows the chain to jump possibly catching the end of the chain guide rail breaking the end off the guide rail.

 

I have had good luck using a long breaker bar & using SMOOTH constant force to loosen that can sprocket bolt. Avoid jerking the wrench or using an impact wrench.

 

While I have no proof I’m guessing a lot of damaged chain guides are from using an impact wrench to remove the cam sprocket bolt.

 

[dan cata]

Remove the valve cover, then loosen the cam gear bolt (very carefully), then remove the chain tensioner to slack the chain.

@DR, are you sure that is the correct order? I mean, should I not first remove the tensioner then slack the bolt? Won't the rails break because of the tension in the chain when undoing the bolt?

 

I was thinking of putting the engine on TDC on compression on L/H side, then undo the bolt, back off the sprocket so that the pin does not touch the cam, rotate the rear wheel while in 5th gear then re-adjust the chain then put everything back.

[dirtrider]

Evening Dan

 

It probably doesn’t matter that much. I always beak the bolt loose with the tensioner still in place to keep the loose chain from jumping & catching on the guide end. In any case if working on the left side be sure to remove the tensioner BEFORE actually removing the sprocket from the cam or you chance the tensioner parts dropping down into the crankcase when the chain comes real loose when the sprocket is removed.

 

 

--was thinking of putting the engine on TDC on compression on L/H side, then undo the bolt, back off the sprocket so that the pin does not touch the cam, rotate the rear wheel while in 5th gear then re-adjust the chain then put everything back.

 

Might work, just be real careful to not rotate the engine even a little with a loose cam chain or you run a high risk of damaging the end of a chain guide. What worries me a bit about what you want to do is the fact that the chain will be over on the edge of the chain guide with that sprocket pulled out when you turn the engine. You are going to have a difficult time moving the chain on the cam gear anyhow as that chain has a lot of wrap on that darn sprocket.

 

Personally I would leave the engine pinned, then move the sprocket within the chain, then rotate the cam a bit so the pin lines back up (cam should move easily if on TDC left side as the spring tension should be loose).

 

[dan cata]

Ok, I did the job. It took some time but in the end, the chain was in the correct position on the sprocket. Thanks DR for the advice!

 

However, it did not cure the problem... The engine is vibrating a lot and the top speed is still 160 km/h...

 

This only leads me to one thing. Maybe one cylinder is not running... As the fairing was off, I did not check for spark or spray from the injectors.

Can an one cyl running bike get to 160 km/hr max?

So if one cyl is not running:

 

- it cannot be the coil as it is double and the bike would not start at all;

- it cannot be the HES (from what I remember, but sensors feed info to the motronic. If 1 sensor would be bad, it would not run at all. Another thought would be that 1 sensor manages fuel and the other one spark - but that is wrong, right? )

- since the bike has been ridden for some time, I think it's an injector that does not work. The oil level is OK, if the injector would be ok and the spark plug wire would be bad, I think gas would flow dirrectly in the engine and the oil level would increase.

 

Any thoughts on the above?

 

Dan.

[dirtrider]

Afternoon Dan

 

I’m not sure it could get to 160km but it might especially if that off cylinder is operating at higher throttle openings.

 

First thing is check for seated throttle cables—Maybe one is mis-seated or maybe it was balanced with mis-seated cables then the cable went where it belonged. You really should do a TB balance check here.

 

Otherwise look for a malfunctioning fuel injector (are both exhaust pipes the same temperature?) Can you remove both fuel injectors & point them into bottles then crank the engine to verify they both spray the same?

 

Or a tight valve.

 

Or a bad plug wire.

 

If nothing easily found then run a compression test, if possible a leak-down test.

 

Again a mis-seated throttle cable will make them vibrate like crazy.

 

[dan cata]

Afternoon Dan

 

I’m not sure it could get to 160km but it might especially if that off cylinder is operating at higher throttle openings.

 

Right, that's something easy to check

 

First thing is check for seated throttle cables—Maybe one is mis-seated or maybe it was balanced with mis-seated cables then the cable went where it belonged. You really should do a TB balance check here.

 

Not the case. After the chain and sprocket job, did a valve adjustment and a sync.

 

Otherwise look for a malfunctioning fuel injector (are both exhaust pipes the same temperature?) Can you remove both fuel injectors & point them into bottles then crank the engine to verify they both spray the same?

 

Again, if the cyl temp test shows difference in temperature, the injectors are to be tested. Doesn't the electrical resistance indicate the same, in case of a bad injector. As I remember, it shiuld be ~ 16.5 ohms each

 

Or a tight valve. No, I have adjusted them.

Or a bad plug wire. Might be, but then, the gas from the injector on that side would get into the engine, maybe a lot of backfiring? It does not...

If nothing easily found then run a compression test, if possible a leak-down test. That would be the final thing to do...

 

Again a mis-seated throttle cable will make them vibrate like crazy.. Cables seated, valve and TB's adjusted/in sync.

 

Just as an reminder, the bike ran just fine before the L/H cyl was taken off and the seal replaced. Can the timing missed by 1 tooth hurt that much the internals of the valve train?

[dan cata]

It all turned out OK No bent valves.

When the pistons were at TDC, all 4 rocker arms were free to move, as if it were to adjust the valves.

 

The owner took off the chain on the R/H side, rotated the engine untill the piston was at TDC again and put everything back and it was all OK

 

Dan.