2800rpm miss, grrrrrrrrr

[dangerous]

Ok now I know they are knowen for that bloody miss, hell even my 1100i sport missed a beat at 2800rpm... but the v11 is now doing it at 2500rpm and constently hissing through the induction in gear changes at that rev. Yeah not an issue on the open road but in town... ahhhhhhhhhhhhhhhhhhh

 

whats the fix people?

[luhbo]

Valves and throttlebody synchronisation I'd guess. Maybe leaking rubber connectors between T/B and heads as well. Or is it just a somewhere loose exhaust system?

 

And of course all the other possible hints as well, means bad relais, missing PCIII and naturally the wrong head temp sensor Not to forget the worn cam chain.

 

Hubert

[Tom M]

Ok now I know they are knowen for that bloody miss, hell even my 1100i sport missed a beat at 2800rpm... but the v11 is now doing it at 2500rpm and constently hissing through the induction in gear changes at that rev. Yeah not an issue on the open road but in town... ahhhhhhhhhhhhhhhhhhh

 

whats the fix people?

 

Downshift? I try to keep the revs above 3K.

[Dan M]

Ok now I know they are knowen for that bloody miss, hell even my 1100i sport missed a beat at 2800rpm... but the v11 is now doing it at 2500rpm and constently hissing through the induction in gear changes at that rev. Yeah not an issue on the open road but in town... ahhhhhhhhhhhhhhhhhhh

 

whats the fix people?

 

Pinpoint the hissing and you'll find the problem. Sounds like a vacuum leak. As Hubert suggested maybe the rubber manifolds are loose or cracked.

[fotoguzzi]

my miss was at 4200 but it went totally away when i put on a Mistral crossover.

[dangerous]

Pinpoint the hissing and you'll find the problem. Sounds like a vacuum leak. As Hubert suggested maybe the rubber manifolds are loose or cracked.

I did not explain that one well... the hiss is the backfire through the injuction same sound as a badly timed carb engine when it back fires through the carb.

The only reason it does this is the miss it has at 2800 if I so happen to up shift then the miss becomes a back fire.

 

Now with my 1100i changing the eprom chip helped but you cant do that with the V11, maybe the TPS has slipped making my issues worse than usual?

[Dan M]

What is the ambient temperature? Does it happen even before the engine is warmed up?

[docc]

A "complete" tune with plugs, valve adjustment, TPS and throttle body synch may do wonders. Also check that the ignition wires plugging into the coils are free of corrosion.

[dangerous]

What is the ambient temperature? Does it happen even before the engine is warmed up?

any temp from riding out the drive to riding back up

 

A "complete" tune with plugs, valve adjustment, TPS and throttle body synch may do wonders. Also check that the ignition wires plugging into the coils are free of corrosion.

Yeah thhats what Im looking at, usually do it my self but figgered if it has to go to the shop for the TPS then any info I could give them would be handy.

 

Now correct me if I am wrong... but ALL V11's have a wee miss at 2800 aye?

I am only asuming so cos my 1100i sport had it and they were knowen for it, again I asume MG did not sort this glitch even with a new ECU... or am I wrong?

[docc]

any temp from riding out the drive to riding back up

 

Yeah thhats what Im looking at, usually do it my self but figgered if it has to go to the shop for the TPS then any info I could give them would be handy.

 

Now correct me if I am wrong... but ALL V11's have a wee miss at 2800 aye?

I am only asuming so cos my 1100i sport had it and they were knowen for it, again I asume MG did not sort this glitch even with a new ECU... or am I wrong?

 

With this high overlap cam and the rather big valves, the V11 motor has a sweet spot at 5000 rpm. It'll "run" lower, but it ain't happy.

 

2800 is closer to "idle" than "sweet."

 

With fresh plugs, "loose" valve adjustment (006/008), and throttle body balance (and with the air screws open a full turn and a fresh air filter with the TPS spot on), she'll tolerate lower revs (below 5000), but she still ain't happy.

 

I don't know of any shop that can take the time a dedicated "enthusiast" will. When I was a kid, a friend of my Mom would bring his Triumph TR6 (car) for me to tune. I would put in new points and condenser and set the points with a dwell meter at the bottom of the range. He would drive it and I'd move the point gap in the dwell range until it ran as one would hope.

 

Either the cap or rotor or a plug wire would always break in the process, but "Ira" had a great spirit about it. We'd head up to the dealer and he'd buy the broken parts. In the end, he knew: no one will take this kind of time outside of an "enthusiast." You can't pay for it.

 

After tuning my Sport every 4000 miles for the first 100,000 km (62,000 miles), I can now go the full 6000 mile interval between tune-ups.

 

But, that doesn't mean she's happy about it.

[guzzi323]

With this high overlap cam and the rather big valves, the V11 motor has a sweet spot at 5000 rpm. It'll "run" lower, but it ain't happy.

 

2800 is closer to "idle" than "sweet."

I was going to stay out of this until this last comment.

I know I'm just one more 'internet crazy guy' to all of you but I'm certain it's not the cam profile that's the problem.

 

I did the unthinkable and put carbs on my Scura (HSR 42 Mikuni's) and the biggest improvement for me has been the low end running.

It's completely clean and useable down low like a big twin should be. I don't beat up the motor by trying to accelerate quickly in 5th or 6th at low RPM's but I can cruise happily at 2800-3000.

 

My guess is the carbs atomise fuel better than the injectors at these slower speeds. Since putting the carbs on I get 39 MPG in my commute when I was lucky to get 33 before. And that's regardless of where I keep the RPM's.

 

I'm not saying all fuel injection is bad, but I think the fuel injection they put on the V11's is barely competent.

If I wanted to keep the injection I would have gotten Cliff's setup and looked into better injectors with more, smaller holes for better atomization.

 

Crazy guy out.

 

johnk

[dangerous]

Now, no other V11 owners here have said they have this problem? is it normal (not my bad miss I am yet to sort but the mild mag drop at 28)

 

When I was a kid, a friend of my Mom would bring his Triumph TR6 (car) for me to tune.

now thats a good tast in cars, if only I could afford a TR5.

[docc]

I was going to stay out of this until this last comment.

I know I'm just one more 'internet crazy guy' to all of you but I'm certain it's not the cam profile that's the problem.

 

I did the unthinkable and put carbs on my Scura (HSR 42 Mikuni's) and the biggest improvement for me has been the low end running.

It's completely clean and useable down low like a big twin should be. I don't beat up the motor by trying to accelerate quickly in 5th or 6th at low RPM's but I can cruise happily at 2800-3000.

 

My guess is the carbs atomise fuel better than the injectors at these slower speeds. Since putting the carbs on I get 39 MPG in my commute when I was lucky to get 33 before. And that's regardless of where I keep the RPM's.

 

I'm not saying all fuel injection is bad, but I think the fuel injection they put on the V11's is barely competent.

If I wanted to keep the injection I would have gotten Cliff's setup and looked into better injectors with more, smaller holes for better atomization.

 

Crazy guy out.

 

johnk

 

Point well taken.

[ScottS]

Now, no other V11 owners here have said they have this problem? is it normal (not my bad miss I am yet to sort but the mild mag drop at 28)

 

now thats a good tast in cars, if only I could afford a TR5.

 

 

Mine(2000 V11) does exactly this- odd random misfires at 2800. Since I bought it used , and it always does this , I have no idea what caused it- but I can see my throttle body rubbers are definitely cracking , I have new ones.

 

Once our riding season is over ( November sometime) I will replace the rubbers, do a valve adjustment and set the TPS's so I know what i am dealing with

 

Although I kinda like cruising through town at 2800 rpm and listening to her burble through the CF cans !

 

3500-7000 RPM she runs awesome

[Guest ratchethack]

Once our riding season is over ( November sometime) I will replace the rubbers,

Scott, FYI - there are many posts on surface cracking of intake rubbers.

 

FWIW, I had the same concern as yourself 6 years ago and bought a set of new ones, with the idea that I wanted a set on hand for what appeared to be impending failure. I still have them in ozone-protective plastic bags in "spares stock", still with no problem with the orignials -- and this is after the stress of working them off and back on for gearbox warantee work 6 years ago.

 

A definitive test for leaking intake rubbers is to open an (unlit! ) propane torch at idle, and direct the flow around the area. If there's a leak, RPMs will rise very noticeably.

 

Hope this helps.