Desmo service. Anything else?

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Desmo cable clearances have me beat. I've had measurements on the exhaust valves ranging from 0.17mm to 0.53mm. I checked by rotating the engine, the closing rockers for all valves are never in contact with the closing lobe. I spoke to a well respected tuner and they said they measure in about 3 locations and then adjust based on the tightest clearance. At this stage I'm either changing a couple of exhaust closing shims or doing nothing. I'd really like to know which!
 
Disco said:
Desmo valve clearances have me beat.

I've had measurements on the exhaust valves ranging from 0.17mm to 0.53mm. I checked by rotating the engine,

the closing rockers for all valves are never in contact with the closing lobe.

I spoke to a well respected tuner and they said they measure in about 3 locations and then adjust based on the tightest clearance.

At this stage I'm either changing a couple of exhaust closing shims or doing nothing. I'd really like to know which!
Click to expand...
Don’t give up

On the same valve?

That’s because there are springs

That sounds right. The tight spot is what needs to be within specs. I wouldn’t worry bout the rest

Why you gonna tighten up ex closing? I bet they are touching at rpm! The springs are light compared to coil springs

Yank head put on stand maybe it will make more sense. Don’t give up tho man...
 
The exhaust closing is at 0.2mm, max is 0.18mm. The lash spring must be doing the work until the engine is up to temperature, otherwise I'm missing something.

I'll press on, but so far 1 exhaust closing clearance is 0.19 so out of spec. If the cams are coming out, then I'll likely adjust any that are at the upper end. The shop said they aim for 0.1mm on exhaust closers.
 
What is the opening clearance for that ex that is extra loose on the closing?

You realize the closing shims ARE the retainers right? I suggest yanking the heads if you are gonna .... with em

Or put air pressure thru the plug I guess. Done 2 valve pro stock motors that way in between rounds. But only cuz I had to
 
Yeah Don, but the lash spring holds the rocker against the shim while there is clearance between the cam and the rocker. The clearance in the opener was good, I just don't have it in front of me.
 
I bet that extra .1mm don’t create hardly any extra overlap

We are talking about the ex valve being open a few thou more than spec (while closing)

It’s on the intake stroke then so I wouldn’t trip. A few degrees prolly won’t make that much difference. It’s not an intake valve

I am more concerned with getting the intake valves closed asap cuz these things have such a short effective compression stroke to begin with

Do you have the stuff to check the cam timing while it’s opened up?
 
Vertical:

Inlet (0.07-0.22 & 0.13-0.23)
Open 0.14 | 0.15
Close 0.18 | 0.18

Exhaust (0.12-0.27 & 0.08-0.18)
Open 0.19 | 0.19
Close 0.17 | 0.16

Horizontal

Inlet (0.07-0.22 & 0.13-0.23)
Open 0.15 | 0.15
Close 0.15 | 0.20

Exhaust (0.12-0.27 & 0.08-0.18)
Open 0.22 | 0.25
Close 0.16 | 0.19

So all good, bar the horizontal right exhaust. These closing measurements were taken by rotating the engine and continually checking until the tightest clearance was found.
 
I don't have a dial indicator anymore, but this is the first time the engine has been opened up so I'm not concerned.

Sorry, the last post took a while to write. I'll change the opening shims to bring them closer to lower end of the spec, but happy most of the closers are good. They look like a PITA to change!
 
I've spent enough on dyno tuning, playing with the cam timing will cost another round. 185rwhp is plenty enough for me and the first step for more midrange would be to play with the throttle mapping, but I don't feel it's lacking at the moment. As a daily rider, reliability is pretty important.
 
Damn. I would love to hear what centerline numbers you got

Did yers have identical shims for all the intakes and then again for all the exhausts? My opening shims were all the same. 2.90 n 2.20 Never seen that before. Crazy good machine work : )
 
Not sure what you mean by centreline. Average? I didn't take them that way. I use the upper limit feeler gauge then work down to the min clearance.

I replaced 2 exhaust opening shims, both 2.95mm and was going to replace one exhaust closer; 3.30mm, but after installing, it closed up too much. I then out the original in and it was at 0.10mm so I left it.


The right engine cover looks like a pain to get off; possibly the ABS unit, the swingarm support bracket and rear brake. I didn't find any debris in the screen, but I've ordered the water pump gears so might as well continue on. The cam covers are back on, plugs checked, and radiators, sump and exhaust will go back in tomorrow. I'll pull the side cover off ready as well.
 
The lobe center in relation to crankshaft tdc

Center line method is most accurate way to measure cam timing. Me thinks

Intake: take ° btdc intake open 1mm + 180° + ° abdc intake 1mm from closing. Add the 3 together (=duration at 1mm lift), divide by 2, subtract out the opening number=intake center line

Ex works same way except you subtract out the closing number

Glad you got it handled : )
 
I didn't take measurements that way, just used the upper limit then kept decreasing until the min clearance was found. It's quick, but not as in-depth as what you've described.

I installed the steel water pump gears today and reassembled most of the bike. The gears were likely a waste of both time and money. My originals are mint with 22000km on them. Absolutely no wear or marking. But they're in anyway. Just some reassurance to those worried about the condition of theirs.
 
So finished up the service and gear install. Final verdict on the service: simpler than expected. Yes there's a lot to remove, but keeping the fasteners separated and following the manual keeps it straight forward. The gears don't appear to be any louder than the plastic ones either.

I might have also cured a persistent exhaust leak too as a bonus.

I did strip the tread in the number 1 bolt of the clutch cover (not the clutch inspection cover). As it's up high and has Loctite, I'll monitor for now. It would have happened as there are supposed to be 2 30mm bolts on the cover, but mine only had 1 (yes I checked all of then 3 times). I'll probably look at the Loctite thread repair solution if it comes loose. I doubt it'll leak as the other bolts are quite close and I got a solid looking bead if Threebond when I installed the cover.
 
Was wondering how anyone could hear metal water pump gears over the noise the cam gears make

I was explaining cam centerline (timing) above cuz you had asked. Has nothing to do with checking clearance.

With yamabond you could prolly leave half of the bolts out and be fine : )

Glad you got it handled

*check out ‘time sert’ to fix thread
 
Yeah, took some serious work to pry the cover off. I'm almost a bit disappointed with the promise of gear noise, I always loved the sound of my VFR400!
 

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