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1 hour ago, Onibaka said:

And the fact that the valve clearance may increase when the piston leaves the TDC is wrong? Or maybe it's okay and I'm worried for nothing :whistle:

I've never heard of valve lash increasing after TDC. Yet, I have never actually checked the clearance anywhere but TDC.

The only mechanical explanation I can think of is the cam is not perfectly degreed. :huh2:

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Good . Put on some Steppenwolf and go !

The problem is found and resolved. Everything turned out to be very banal: the TPS sensor died. I checked all the relays, sensor resistances, ignition coils and all harness connections, grou

This was my first thought. You said that you had the heads off? I take it you replaced them using new head gaskets? When this is done the engine should be warmed up and then left overnight and wh

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"If" the camshaft were wearing , or any of these components were wearing , the clearance would be opening instead of closing . 

Not necessarily true. You are setting them on base circle of the cam. If the cam is wearing, the next time you check it, the valves will be tight.

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16 minutes ago, docc said:

The only mechanical explanation I can think of is the cam is not perfectly degreed.

Yes ... I consider this as one option. Only, logically, the gaps in the TDC should have changed, but they remained at the level (it seems). Okay, set it up again and watch.

 

32 minutes ago, docc said:

I've never heard of valve lash increasing after TDC. Yet, I have never actually checked the clearance anywhere but TDC.

Maybe the next time you adjust the valves, pay attention to this ;)

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13 minutes ago, Chuck said:

Not necessarily true. You are setting them on base circle of the cam. If the cam is wearing, the next time you check it, the valves will be tight.

This could not be a case of the heads needing to be "retorqued?" (Something I also have never done.)

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This was my first thought.

You said that you had the heads off? I take it you replaced them using new head gaskets? When this is done the engine should be warmed up and then left overnight and when fully cooled the rocker gear removed and the heads re-torqued by cracking the nuts loose and then re-tightening them. The valve need re-gapping after this and then the bike should be heat cycled a few times, (Ride it for say ten trips and allow it to cool completely between each trip.) and then the re-torqueing procedure repeated. After that you should be right pretty much forever!

The thing is the kingerlite gasket will compress during their initial few heat cycles. As that happens the valve gaps will close up. Re-torqueing will exacerbate this compression and the caps will close up more. After a series of heat cycles the gasket's limit of compressibility will be reached and the clearances will stabilise and cease to change very much.

 

 

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Make absolutely sure you are at TDC . Put a screwdriver into the spark plug hole and verify you are reaching TDC while you are rotating the engine . You want to KNOW it is at TDC before you adjust valve clearance .

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I see you have changed your avatar ?  

You will get this sorted out , just don't complicate it . 

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11 hours ago, gstallons said:

Make absolutely sure you are at TDC . Put a screwdriver into the spark plug hole and verify you are reaching TDC while you are rotating the engine . You want to KNOW it is at TDC before you adjust valve clearance .

I apologise in advance for pointing this out and I don't want to be picky, BUT.........................a screwdriver can do a lot of damage if you're not careful, I see where you're coming from and agree.

However I'd use either a small wooden skewer or a chopstick, something of that ilk thats less likely to cause mayhem if it gets jammed in the cylinder.

Realise that if you know what your doing and you've done it a few times it's straightforward, but if you haven't it's better to err on the safe side.

God knows I've done some real stupid shit in my time.

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Onibaka , can you watch a YouTube video in your language on this procedure to keep it simple on your end ?

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1 hour ago, gstallons said:

Onibaka , can you watch a YouTube video in your language on this procedure to keep it simple on your end ?

Guys, I’ve been trying to explain many times that adjusting valves for me is not a problem B). I am sure that the piston is in the DTC position. I see the movement of the piston in the hole of the spark plug, I see the mark D (for the right) and S (for the left) of the cylinders. The piston during DTC is in compression. Both valves have a gap and I can adjust them. All the same, I have my Guzzi for the 8th year and I have done this procedure many times.

13 hours ago, docc said:

I've never heard of valve lash increasing after TDC. Yet, I have never actually checked the clearance anywhere but TDC.

The only mechanical explanation I can think of is the cam is not perfectly degreed. :huh2:

doсc understood correctly. This is my question, I noticed that the valve clearance in the TDC position is not the largest for the entire crankshaft revolution cycle.

That is, if the intake valve clearance in the TDC position is 0.15 mm, then with further rotation of the flywheel, when the piston leaves the TDC and the exhaust valve opens (exhaust stroke from the combustion chamber), the intake valve clearance increases to 0.20 mm.

This is also true for the exhaust valve. That is, on the injection cycle (when the injection valve is open), the clearance of the exhaust valve is greater than in the TDC position

I hope you understand me. I am sure that I am not confusing TDC. I just accidentally decided to measure the gaps in other positions of the piston (not in the TDC) and they turned out to be larger.

Maybe it's me having some problems with the camshaft. Or maybe this is normal? :wacko: I just want to understand this issue.

 

2 hours ago, gstallons said:

I see you have changed your avatar ?  

Yes, I decided that there should be something themed :bier:

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My first thought was TDC on the wrong stroke, you seem confident that's not the problem.

As Pete says the heads should be re-torqued irregardless.

With the timing of maximum lift apparently being off, is it possible that the timing chain is misaligned by a tooth or two on the camshaft or worn and badly stretched?

fwiw

Good luck

Kelly

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The fact that the gap may increase at other phases in the cycle isn't much of a worry unless it is extreme.

My guess is that if other people tried it they'd find that exactly the same thing. All it means is that the base circles aren't ground perfectly which doesn't really matter as long as the clearance doesn't shrink to nothing over the greater part of the base circle.

The whole point of of having a clearance is to a.) ensure the valve is allowed to close fully when it's supposed to be closed and b.) to allow a film of lubricant to enter between the cam and lifter to cool and clean during the unloaded part of its work cycle.

If your engine's top end has become suddenly more rattly I'd suggest checking the rocker bushes and spindles and ensuring they are getting sufficient lubricant.

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17 hours ago, docc said:

This could not be a case of the heads needing to be "retorqued?" (Something I also have never done.)

If the valves are tightening up, yes. The only other thing I know of is the valves are stretching. That isn't common on the big blocks as far as I know.

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My guess is that if other people tried it they'd find that exactly the same thing. All it means is that the base circles aren't ground perfectly which doesn't really matter as long as the clearance doesn't shrink to nothing over the greater part of the base circle.

I just never imagined that the base circle wouldn't be on the money. Grinders are very accurate machines by design. Maybe a case of a little knowledge getting me in trouble? :huh2: Forget everything I said last night.. :D

Set them at TDC and forget them, Onibaka.. don't worry, be happy.:grin:

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I hope everyone knows all the input is given to help a brother get everything dialed in on his bike . 

 This valve adjustment is simple when you realize you are adjusting valves on a single cylinder bike . Then you are doing the same thing on the other side .  

I've never looked for the marks , just bar the engine over to TDC . Set the valves , repeat . 

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