Myth versus fact 1250 variable valve trouble

I don't know what this alleged rumor is all about, but it reminds me about schooldays, where the envious kids lived by the rule: "if we can't have what they have, will shit all over it".

Shift cam technology is actually mechanically quite simple, way less complicated than the VVT system that has been used in their cars since late -90's.

What can go wrong? The plungers are two solenoids. Solenoids are known technology, not much to it. A faulty batch may of course happen in the world og mass production, but hardly rocket science.
The camshaft has a shaft sliding back and forth by 2 -3 cm. No more load than the shafts sliding back and forth in the gearbox. Hardly rocket science.

What happens if the system fails to regulate (shift)? You will get less power wide open and when revving above 5K rpm.

Soo...
I'll keep riding and enjoying my 1250. And when I stop, I will park the bike, not worried about parking above a sink hole, and I will walk in to the cafe for a coffee, not worried about the ceiling falling on my head, and enjoy my coffee, not worried about the coffee being poisoned or that the chair that I sit on will collapse. :aidan
 
knutk said:
I don't know what this alleged rumor is all about, but it reminds me about schooldays, where the envious kids lived by the rule: "if we can't have what they have, will shit all over it".

Shift cam technology is actually mechanically quite simple, way less complicated than the VVT system that has been used in their cars since late -90's.

What can go wrong? The plungers are two solenoids. Solenoids are known technology, not much to it. A faulty batch may of course happen in the world og mass production, but hardly rocket science.
The camshaft has a shaft sliding back and forth by 2 -3 cm. No more load than the shafts sliding back and forth in the gearbox. Hardly rocket science.

What happens if the system fails to regulate (shift)? You will get less power wide open and when revving above 5K rpm.

Soo...
I'll keep riding and enjoying my 1250. And when I stop, I will park the bike, not worried about parking above a sink hole, and I will walk in to the cafe for a coffee, not worried about the ceiling falling on my head, and enjoy my coffee, not worried about the coffee being poisoned or that the chair that I sit on will collapse. :aidan
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May I suggest you look for Dual Banks faults, and the standard BMW excuse of we've never come across this problem before.

How many Vtec systems have failed, other than for lack of oil etc ?

Yes, solenoids are a known commodity, and you can always get a bad batch, the purpose of randomised testing ?

But you can also force the price down or the profit level up by using cheap kit too.

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It's another 1st world problem, oh dear, my diamonds have lost some of their shine.
 
Tractors are go said:
May I suggest you look for Dual Banks faults, and the standard BMW excuse of we've never come across this problem before.
Click to expand...

And the relevance to the brilliant shift cam system being?

Tractors are go said:
How many Vtec systems have failed, other than for lack of oil etc ?
Click to expand...

Vtec is a Honda system. If you make a search in a Honda forum, they may be able to help you to find out.
Personally, I fail to se the correlation..

Tractors are go said:
Yes, solenoids are a known commodity, and you can always get a bad batch, the purpose of randomised testing ?

But you can also force the price down or the profit level up by using cheap kit too.

Sent from my SM-G925F using Tapatalk
Click to expand...


That is true. But the solenoids may also work...
 
Tractors are go said:
Dual vanos not dual banks, bloody autocorrect.

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Click to expand...

Vanos was introduced in the early -90. It is a totally different system than the shift-cam. It varied the phase of the came based on rpm and is way more complicated than shift-cam. Vanos bears similarity to the current Ducati system.
The earlier systems had teething problems, and the problems are known amongst the crowd dealing with now old BMWs. Vanos was replaced late -90's.

It bears nothing in common to the shift-cam system except for the badge on the engine cover, and holds no more relevance to the subject than my wife's broken toaster.
 
knutk said:
Vanos was introduced in the early -90. It is a totally different system than the shift-cam. It varied the phase of the came based on rpm and is way more complicated than shift-cam. Vanos bears similarity to the current Ducati system.
The earlier systems had teething problems, and the problems are known amongst the crowd dealing with now old BMWs. Vanos was replaced late -90's.

It bears nothing in common to the shift-cam system except for the badge on the engine cover, and holds no more relevance to the subject than my wife's broken toaster.
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Save for the level of denial that dealers claimed at the time, thankfully independents can fix the now known issues.

The concern will be how any warranty claims are handled.

If your wife's toaster breaks, do you expect it fixed, or get a pile of crap from the seller ?

Sent from my SM-G925F using Tapatalk
 
knutk said:
I don't know what this alleged rumor is all about, but it reminds me about schooldays, where the envious kids lived by the rule: "if we can't have what they have, will shit all over it".

Shift cam technology is actually mechanically quite simple, way less complicated than the VVT system that has been used in their cars since late -90's.

What can go wrong? The plungers are two solenoids. Solenoids are known technology, not much to it. A faulty batch may of course happen in the world og mass production, but hardly rocket science.
The camshaft has a shaft sliding back and forth by 2 -3 cm. No more load than the shafts sliding back and forth in the gearbox. Hardly rocket science.

What happens if the system fails to regulate (shift)? You will get less power wide open and when revving above 5K rpm.

Soo...
I'll keep riding and enjoying my 1250. And when I stop, I will park the bike, not worried about parking above a sink hole, and I will walk in to the cafe for a coffee, not worried about the ceiling falling on my head, and enjoy my coffee, not worried about the coffee being poisoned or that the chair that I sit on will collapse. :aidan
Click to expand...

What about date rape drug in your coffee?
 
As has been said, this is a mechanically simple system and should be reliable, and most failure modes should be fairly harmless, even a mistimed firing of the solenoid would probably be OK as the peg would then probably just fail to drop into its track until the cam was in the right position. The only thing I would be concerned about would be one of the solenoid operated pegs dropping back into its housing before the shift transition is complete in case this could leave the cam mid position, but there may be some design feature which would prevent this.
 
Tractors are go said:
...
The concern will be how any warranty claims are handled.

If your wife's toaster breaks, do you expect it fixed, or get a pile of crap from the seller ?

Sent from my SM-G925F using Tapatalk
Click to expand...

I expect the toaster will be fixed if its less than 5 years old, as will be the case for the bike.
No worries.
As for drugs, Im still waiting ....
 
It does seem a simple bit of engineering and if it stops working surely the engine just chugs along , maybe with to much valve overlap but so what.

I have yet to detect it is or when it works!
 
The cams remain in the 'low opening' mode until you open the throttle for acceleation as well as anytime above 5K.
If the plungers fail the engine will be less spirited at high rpm's, or if the 'High opening' plunger get stuck in the active position, you wiil notice a bit less torque at lower RPM. It then would probably feel.more like a 1200...
 
Think yourselves lucky BMW didn't put Valvetronic gear on the bikes too. Think how much further the heads would have stuck out. :rob
 
knutk said:
The cams remain in the 'low opening' mode until you open the throttle for acceleation as well as anytime above 5K.
If the plungers fail the engine will be less spirited at high rpm's, or if the 'High opening' plunger get stuck in the active position, you wiil notice a bit less torque at lower RPM. It then would probably feel.more like a 1200...
Click to expand...

I suspect there is a ramp in the actuation grooves which will push the plunger back into the parked position once it has done its job. If so, the peg could not get stuck in the active position. If this is how it works, then maybe the solenoid just fires briefly to push the plunger peg out and then turns off.
 
fred_jb said:
I suspect there is a ramp in the actuation grooves which will push the plunger back into the parked position once it has done its job. If so, the peg could not get stuck in the active position. If this is how it works, then maybe the solenoid just fires briefly to push the plunger peg out and then turns off.
Click to expand...

there are no ramps in the groove,cut away engine at the nec on the bm stand was very interesting if you knew a little of what you were looking at .
 
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