Replacing the chain tensioner

[docc]

Well, looks like the tensioners are pretty cheap and they're really not that bad to r&r, so more than a few of us are anxious to see what happens next . . .

 

To a fault I'm always looking for the simplest of solutions . . .

[pete roper]

Thing is pulling the cam chain isn't really any big deal. If you think that things might be improved by swapping the tensioner for a Valtech blade type one then do so! It really ain't any big deal. It can be done with the engine in the frame and will take probably three hours tops.

 

If you look at my engine rebuild blurb you'll get the idea. the Ducati alternatered bikes are a bit different in that the nut that holds the crank sprocket on is a (?) 36mm hex nut rather than a peg nut and needs a thin walled socket to get it off and there is the 'Phonic wheel' behind the cam sprocket but otherwise it's exactly the same once the chest is off.

 

Incidentally the timing chest used to have drain holes in the bottom to allow the oil, delivered by the oil flowing out of the pump, crank and cam bearings, to drain back to the sump. Whether these have been deleted on later models, (I think they have on Hi-Cams.) I can't be sure but you can rest assured that the chain gets plenty of lube! When I was running hellically cut steel gears in my hot-rod I blocked the holes off with epoxy and drilled a couple about the level of the oil pump shaft so the gears were running in an oil bath. Whether this was neccessary I have no idea but it seemed sensibel to me, paratitic drag be damned!

 

Bear in mind Mike Haven doesn't see a problem with the current Guzzi tensioner and Greg, from memory, despises the Valtech type. So this is one of those things where younwill find many and varied opinions! Good news is if it doesn't wor to your satisfaction you can always just stick the original stuff back in.

 

pete

[raz]

The best term I can think of is "erratic". No periodicity to it wotsoever. That is, with engine warm, the mark will be constant for 1 or 2, or as many as 5, 6, or 7 seconds, occasionally longer, then it will jump. Also, no regularity as to how far it will jump when it jumps, could be anything up to ~7 mm. Far less frequently, it will fail to light the strobe 'cause it dropped a signal or even 2 successive signals. <_ again with the engine cold on acceleration or held at rpm for example it constant no jumping dropped signal.>

OK, did my reading now. First a strange note. I bought the lamp, connected it and it did not work. Wiggled and jiggled and tried the other side. No flash at all. So I thought the crap I bought was just that. Back to the store tomorrow. But then I thought I'd tried it on GF Toyota, and it worked fine. WTF? Back to Italian Tractor again, no flash. So now I tried turning the inductive pickup the wrong way, and voila - it works. Wierd. On the Toyota it was hooked up the right way. I don't get it but now you others know what to try. Guzzi sparks go the wrong way?

 

My readings are more or less like you describe, Ratch. As you say, it's pretty hard to find a reference. Now for the main performance, Stay tuned!

[nose2wind]

Well, looks like the tensioners are pretty cheap and they're really not that bad to r&r, so more than a few of us are anxious to see what happens next . . .

 

To a fault I'm always looking for the simplest of solutions . . .

 

Just to preface, I have a 2000 v11s that developed the stumble,chuff,stall symptons we are all discussing.

I decided partly due to a tranny recall to let Mike at MPH give it a go. He felt after some discussion it had nothing to due with the chain tensioner.

 

I picked up the bike yesterday and returned home. Today I took it for a nice hot and humid test ride.

The bike runs great! I don't think it has run this good since I have had it (6years). It is mostly noticed how easy it starts and runs smooth even in the low steady throttle settings. A couple of times I thought it was going to quit when coming to a stop. This is because the idle is set low around 1000 to 900. It just sits there thumping along. Not the slightest indication of a stumble!

 

So what was the problem?

 

Mainly to tight exhaust valves. Some had mentioned early on to check the valves (world spec). I had done this so eliminated it as an issue. Looking back It is hard to believe I might have gotten this wrong (not to difficult a procedure). Also I need to start writing things down as to what milage I have done what procedure. I have been going on memory and could have misjudged what milage I set (or screwed up the valves). They were at 01 I believe. Could they have gotten this tight on there own? Possibly! The intakes were to loose.

 

The TPS was also set to low.

 

The Air temp sensor was bad.

 

MPH completely reset the whole bike from scratch. New plugs,balance etc...

 

Well there you have it.

 

I don't need a new chain tensioner!

 

I need to check my valves every 6000 miles and make sure I do it right!

 

All those having these symptons.

I recommend checking your whole basic set up or let someone like MPH do it for you.

 

It should go without saying I would recommend MPH to anyone within driving range. I could have taken my bike to a dallas shop, but chose to trailer the bike 5 hrs away. MPH also went the extra mile when it came to some little items I had not even mentioned. Since I have looked over the bike I have noticed some vent lines re-routed and nicely zip tied in place. New cap nuts on the exhaust etc... Lots of little stuff done that shows there skill and interest in the bikes they work on.

 

Ride Safe!

[raz]

First pass complete. I have to replace the oil pump sprocket nut. Some idiot PO (or shop) had forced a wrong thread nut on, together with glue(!). I'll have to wait until tomorrow getting one and putting it all together. It's a M8x1, not the regular M8x1.25.

 

Some notes:

• On the Sporti, loosening the oil cooler mounts and pushing it down is enough. All pipes left intact and oil left in sump.
  
• Removed front wheel and fender. Removed fuel tank. And downpipes. Removed rear upper bolts and engine bolts from subframe, Tilted subframe forward with frontmost bolts just loosened a bit.
  
• Removed alternator stator and rotor. Unbolted timing chest cover. One gentle blow with a rubber hammer and off it went. Gasket was a metal type (not reusable) so I have a new paper one ready.
  
• Removed oil pump sprocket nut (13 mm socket). That was far too easy, because it was just a wrong thread nut glued to the shaft. This alone make the project worth any money and time I put into it... It could have come off anytime, and since the Sporti have its' oil light hidden behind the fairing I wouldn't have noticed until rear wheel locked up.
  
• Removed cam sprocket nut, 27 mm socket. It came off pretty easy, with a screwdriver locking the starter gear. A rattle gun can't be used unless you remove the subframe completely. Unless it's a slick one with 90 degree angle maybe.
  
• Removed crank sprocket nut with a 32 mm wrench. The shaft sticks out 90 mm so no normal socket will fit. I put the ring wrench on, then a 16mm spacer (a roll of electric tape), then the alternator rotor and its' nut. This way the wrench was locked in place and wouldn't slip. I had a curious neighbour lock the starter gear and the nut came off without blood spill.
  
• Wiggled the three sprockets until loose, and removed all three and the chain together. Watch the keys on crank shaft and oil pump shaft! The oil pump one you can remove, it's put back after the sprocket is in.
  
• Removed old tensioner. One of its' bolts have no use after removing, and the resulting hole does no harm. The other bolt is one of the front main flange bolts so it has to be put back. But, warning, the old bolt is too long! I did not realise that at first, and what happened was the crank counterweight, or something, knocked into it (on the other side of that barn wall) when I had it all reassembled and rotated the engine with a wrench. I thought it was valves hitting pistons, and it took me a good part of the evening figuring out I had assembled chain and sprockets correctly, and this bolt was the culprit! Replace the M8 x 35 mm with an M8 x 25 mm. This is ordinary hex M8x1.25 and 8.8 grade.
  
• Installed new tensioner with two of the other front main bolts. See Pete's PDF, the Valtech tensioner looks the same as the Stucchi. At this point, I had the spring and blade removed from it.
  
• Put chain and sprockets back. Watch the marks. Put the oil pump shaft key in (see PDF).
  
• Install blade and spring on tensioner. Some people don't use the spring. I did.
  
• Nuts back, loctited. The cam one is spec'd to 150 Nm. I couldn't use the torque wrench on the crank nut so I just tightened it up to what felt good. The oil pump nut is just M8 so I'll use a standard value plus VAT, summing up to maybe 40 Nm. But if it feels right, I may stop before it clicks.
  

This tensioner is... no let's put it another way. The original one did not tension the chain. This one does. It's a huge difference. But I'll have to wait until tomorrow to find out if that actually fixes my problems.

 

I noticed I could probably fit a feeler gauge between outer and inner links in the chain, if you get what I mean. Does this fact alone say my chain is due to the floatation test? I'll measure tomorrow anyway.

 

Yeah, the phonic wheel clearance was between 0.6 and 0.7 mm. I won't touch it.

[raz]

All those having these symptons.

I recommend checking your whole basic set up or let someone like MPH do it for you.

Yes, keep in mind my primary goal with this is to see if the horrible noise I've got from the chain will disappear. The idle stumble is no problem when I use the My16M, and little problem when the original ECU is in and everything is tuned perfectly. The noise at idle, however, remains. But one fact I've established today is the chain can not touch the housing regardless of how bad the tensioner is.

 

I wonder if the noise could be a bearing in the oil pump, or something like that. Since noone came up with any ideas when I asked here in the forum, I figured this was a cool and fairly cheap project just to try and narrow it down.

 

OTOH, my timing chest cover is still off. Is there some good way to check pump bearings health?

[Guest ratchethack]

Outstanding write-up, Raz.

 

Looking forward to the "after" test with the strobe, which will tell the whole tale.

Just to preface, I have a 2000 v11s that developed the stumble,chuff,stall symptons we are all discussing.

I decided partly due to a tranny recall to let Mike at MPH give it a go. He felt after some discussion it had nothing to due with the chain tensioner.

. . .

Nose, your post above may be helpful to others reading this thread. It might be emphasized at this point that replacing a chain tensioner should NOT be considered a "catch-all cure" for poorly running motors!

 

Speaking only for myself, but I suspect Raz and others would agree, we have eliminated all known alternate sources for the symptoms we're attempting to address here -- including everything on your list that was accomplished by our Pals at MPH. It's an increasingly uncommon thing to be able to depend on quality service of the caliber and reputation of MPH, and I congratulate you on achievement of what appears to be exceptional service value.

 

Others of us (myself included) tend to do everything ourselves (right or wrong!) and thereby own the responsibility for maintaining everything 100%. After doing 12 bikes this way, I don't know any other way myself. I'm here to tell you that developing and relying on one's own expertise has it's trade-offs and drawbacks and is certainly not for everyone! On the other hand, circumstances such as finding an incorrect pitch nut glued onto a oil pump sprocket are (I'm sorry to say but it's true) all too common when dealing with unknown service entities (just to be perfectly clear in my meaning here, I certainly would NOT place MPH in that category!), as I have whinged on about for years. This kind of thing can be a huge motivator for doing all one's own work in itself, but not having a highly reputable service like MPH close by would be another.

 

Finding the barnyard kluged cross-threaded and glued-on oil pump sprocket nut and correcting it himself with the right nut will justify the effort of this excursion for Raz, even if this is all he's able to accomplish here! I would have to agree were the same shoe on me own foot!

 

It might be emphasized (again) that the symptoms I'm chasing here in this thread -- erratically dropped signals and cough back thru the TB's -- are ONLY present under the following conditions:

 

1. Engine warm at idle.

2. Trailing and steady throttle.

3. RPMs lower than 3 or 4K or so.

 

IN ALL OTHER CONDITIONS OF RIDING ON THE ROAD, my own bike runs perfectly! That is -- it has NO such symptoms listed above. It is this rather narrow set of circumstances in itself -- at least by my own analysis -- that I believe tends to incriminate the chain tensioner in my case.

 

As a "capper" to the above, by way of more credibly and conclusively differentiating these symptoms from those that may have completely different root causes, it might also be emphasized (again) that observing the degree of scatter with a timing light that both Raz and myself found (see previous posts in this thread) is more or less an "acid test" indicator of loose timing chain!

 

I would not wish to see anyone go to the time and expense involved here without having conducted a capable, methodical and comprehensive analysis first, followed up with this easy, yet very conclusive test before proceding!

 

BAA, TJM, but I reckon YM ain't none too likely to V

[raz]

As a "capper" to the above, by way of more credibly and conclusively differentiating these symptoms from those occuring from completely different root causes, it might also be emphasized (again) that observing the degree of scatter with a timing light that both Raz and myself found (see previous posts in this thread) is more or less an "acid test" indicator of loose timing chain!

 

I would not wish to see anyone go to the time and expense involved here without first doing this easy, yet very conclusive test first!

Still, the question is, are the scattering due to a far too weak tensioner (and fairly good chain), or just a bad chain?

 

I have nothing to compare to, but actually I think my chain is not in the best condition. All papers I got with the bike (dating a couple of years back) backs up the mileage on the clock, but I still can't be 100% sure it just has 46,000 kms. If it has, the chain should really not be bad. But, again, maybe it's 146,000 kms, or something else.

 

Even so, consensus is that the original tensioner is really weak. It probably won't hurt replacing it, and it's by far the cheapest of the alternatives I had. If it masks the sympthoms of a marginal chain for another 50,000 kms it's worth it. If the ringing noise disappears, I'll be extatic. If it lessens the OEM ECU's problems, that's good too!

[Guest ratchethack]

Still, the question is, are the scattering due to a far too weak tensioner (and fairly good chain), or just a bad chain?

Raz, couple more thoughts.

 

IMHO the scatter we've observed has to be due to a weak tensioner -- NOT to a worn chain. A worn chain would make timing go in the direction of a retarded signal, but a tiny fraction of a degree of spark retard is as much as would ever occur, and it won't make any difference. As Pete has explained, when a chain wears out, the distance between the crank sprocket and cam sprocket being the equivalent of just a few links, there isn't enough chain there to retard timing in any significant way even if the chain has worn very significantly.

 

However, a jumping and whipping chain, allowed to go loose by a weak tensioner, would tend to "bunch up" erratically between the crank and cam sprockets as Pete illustrated, occasionally advancing the spark signal pretty substantially, which is precisely what we've both observed on the strobe. As Carl observed, if it gets too loose, allowing enough spark advance that the ECU doesn't actually reject -- "Nope, that one's a flyer, I'll just ignore it", at idle -- well, it can easily cause the crank to reverse course, and try to go backwards. O' course, that'll snuff the motor PDQ.

[docc]

 

BAA, TJM, but I reckon YM ain't none too likely to V

 

[dlaing]

Try googling ymmv tjm baa

It takes you right to Ratchet

[dlaing]

"BAA, TJM, but I reckon YM ain't none too likely to V wink.gif"

BodgersAgainstAcronyms, ThatsJustMe, but I suppose YourMileage is not likely to Vary and I have something in my eye...

[docc]

Just to preface, I have a 2000 v11s that developed the stumble,chuff,stall symptons we are all discussing.

I decided partly due to a tranny recall to let Mike at MPH give it a go. He felt after some discussion it had nothing to due with the chain tensioner.

 

I picked up the bike yesterday and returned home. Today I took it for a nice hot and humid test ride.

The bike runs great! I don't think it has run this good since I have had it (6years). It is mostly noticed how easy it starts and runs smooth even in the low steady throttle settings. A couple of times I thought it was going to quit when coming to a stop. This is because the idle is set low around 1000 to 900. It just sits there thumping along. Not the slightest indication of a stumble!

 

So what was the problem?

 

Mainly to tight exhaust valves. Some had mentioned early on to check the valves (world spec). I had done this so eliminated it as an issue. Looking back It is hard to believe I might have gotten this wrong (not to difficult a procedure). Also I need to start writing things down as to what milage I have done what procedure. I have been going on memory and could have misjudged what milage I set (or screwed up the valves). They were at 01 I believe. Could they have gotten this tight on there own? Possibly! The intakes were to loose.

 

The TPS was also set to low.

 

The Air temp sensor was bad.

 

MPH completely reset the whole bike from scratch. New plugs,balance etc...

 

Well there you have it.

 

I don't need a new chain tensioner!

 

I need to check my valves every 6000 miles and make sure I do it right!

 

All those having these symptons.

I recommend checking your whole basic set up or let someone like MPH do it for you.

 

It should go without saying I would recommend MPH to anyone within driving range. I could have taken my bike to a dallas shop, but chose to trailer the bike 5 hrs away. MPH also went the extra mile when it came to some little items I had not even mentioned. Since I have looked over the bike I have noticed some vent lines re-routed and nicely zip tied in place. New cap nuts on the exhaust etc... Lots of little stuff done that shows there skill and interest in the bikes they work on.

 

Ride Safe!

 

David,

 

This outstanding news! Really great you have you bike running well and that it was actually nothing major.

 

And they did the tranny work as well? Do you notice any difference in it?

[nose2wind]

David,

 

 

And they did the tranny work as well? Do you notice any difference in it?

 

Yes, The clutch was getting a little grabby. This is gone. I have not had a re-occurance of the skipped gear from 3rd up to 5th. It generally just shifts smoother and doesn't leak either! Ready for another 50,000.

 

P.S. MPH recommends running syn. all the way around.

 

Also on that frame dribble we looked at. MPH recommended pulling the bolt and putting it back with some thread locker. I have done this and will let you know if it works.

 

Also my coil mounts are holding as well. NO GLUE!

 

Later

[raz]

All done now. I found a new M8x1 nut (they are not common even in Europe) and had to freshen up the shaft threads a little after the abuse. Man, I'm glad I found that time bomb!

 

Unfortunately I can't take it for even a short ride cause I'm alone with kids all evening. But I've done some strobing. Engine was not warmed up as thoroghly as yesterday though, just from idling. Anyway, reading is rock stable. No scatter at all. It's like looking at a whole different type of engine. What is strange though is that yesterday I couldn't see any marks at all on the flywheel. Today I saw a crisp and steady "D" for the right cylinder and "S" for the left one. I really looked for it yesterday but saw nothing. I'm not sure why

 

Idling was very stable too. And no ringing noise. It will be a very very interesting ride tomorrow.

 

Thanks all of you!