Engine not going beyond 7000/8000 rpm

[luigi]

Hi,
I have a quite nasty issue with my 1991 GS500E(M).

I found a minimal hole due to rust in the tank and had the tank disassembled and threated internally plus the hole fixed.

Once remounted everything the bike cannot go over 7000/8000 rpms.

I've checked the fuel hoses and I'm pretty sure all is fine.

I've been told that some dirty could have entered carburators but I find strange the timing plus it's very strange that the minimum is perfect and that the defect happens only at an almost precise rpm value...

Any ideas I can try before going for carburators disassembly and cleaning?

Thanks!

Luigi

[gsmattis]

Maybe, there it's only one cylinder running. When the engine in running, unplug one sparkplug. When the engine dies, this cylinder runs. If the engine keeps running, this cylinder is not running.
In this case change the spark plug from left to right and repeat the procedure. When the mistake goes to the other side, the spark plug is broken.

[luigi]

Zitat von gsmattis

Maybe, there it's only one cylinder running. When the engine in running, unplug one sparkplug. When the engine dies, this cylinder runs. If the engine keeps running, this cylinder is not running.
In this case change the spark plug from left to right and repeat the procedure. When the mistake goes to the other side, the spark plug is broken.

Thanks Mattis,
I tried.

If I unplug the right spark plug the engine stop immediately.
If I unplug the left spark plug the engine continue running (even if it seems to feel a bit the difference).

I replaced both spark plugs with some old ones I had available but everything remain the same.

What can be the issue?

Thanks!

Luigi

[Kay73]

Bedeutet, links arbeitet der Zylinder nicht.

Von kaputter Zündspule über Schwimmernadelventil des linken Vergasers bis zur Membrane des Unterdruckanschlusses des Benzinhahnes kann es alles mögliche sein.

Was hat das mit dem Wiki zu tun?

[Campino]

Seppi had the same issue.

We fixed it by changing the spark cables.

But before doing that you should check wether you got sparks on both cylinders.

If thats the case i'd start checking the carburettor.
Maybe you've got some dirt in it.

Also... if both Cylinders are running well... maybe you've got the wrong air filter...
There is a known issue when using the wrong air filter that fits your description.
You'll find quite a few topics in this forum when looking for "Leistungsloch"

[luigi]

Zitat von Campino

Seppi had the same issue.

We fixed it by changing the spark cables.

But before doing that you should check wether you got sparks on both cylinders.

If thats the case i'd start checking the carburettor.
Maybe you've got some dirt in it.

Also... if both Cylinders are running well... maybe you've got the wrong air filter...
There is a known issue when using the wrong air filter that fits your description.
You'll find quite a few topics in this forum when looking for "Leistungsloch"

Thanks Campino.
I will give it a try.

BTW: If I posted into the wrong section of the forum please let me know. Thanks!

[Campino]

You actually did post in the wrong category.
You could contact one of the Admins and ask them to move it to the right category.

[snailie]

Just a Mod here, but I'll move it to the right category anyway...

[luigi]

Zitat von takoda

Just a Mod here, but I'll move it to the right category anyway...

Thanks. I'm sure through this forum I'll improve my German language knowledge

BTW: I think I will go first for a carb cleaning as it seems that power is arriving to both sparks but the left cylinder is not giving full power....

[Campino]

Keep us updated and if you find something extraordinary try to take pics for those who might have the same issue in the future.

Btw off topic: I might be in your area around june this year... maybe you‘d like to join me and some friends of mine for a day or two on our tour through italy and the alps..
It might be quite helpfull to have someone who speaks italian! All we understand is "bibidi babidi"
And i figured out most italians don't speak english. (At least the ones we tried to talk to...)

[luigi]

Hi all.

Problem solved: a good carb cleaning solved everything!

BTW: it's NOW much better then I remember even when it was getting all RPMs: much more consistent at all RPMs

I guess, a carb cleaning in 26 years and 65.000 km is ok

As per trip: happy to meet you for a day especially if you are around the Como lake

And as per language, don't worry many people might struggle but I'm sure all will try to help

[Campino]

Zitat von luigi

And as per language, don't worry many people might struggle but I'm sure all will try to help

Thats actually absolute true!
I've never met as kind and helpful people as in italy!
Seems they have a totaly differend mindset than germans do...

But thats only true as long as they're not behind the wheel...
When you're used to german traffic it seems like ALL italians are maniacs who try to kill you! o.O

We did arrive by ferry in Bari last year and after two minutes on italian streets my colleque said over the intercom:
"Guy from now on we've gotta be extra careful! In the last minute two cars cut me off.... Italian drivers are maniacs! Drive safe!"

And this kind of italian driving lasted until we reached Austria....

[DonArcturus]

Zitat von Campino

But thats only true as long as they're not behind the wheel...
When you're used to german traffic it seems like ALL italians are maniacs who try to kill you! o.O

Depends on the perspective. A biker friend described that the Italians drive very fast, even with a stinky panel truck. For faster Bikers, this is very comfortable since you don't have those slow f**ers. But if you're the slow f**er who gets "in their way", I can imagine that they're not very cautious...

[Campino]

Thats a nice description of me on the road...

The thing is we sticked to the speed limits....
Some SUV did try to overtake me in a tunnel with oncomming traffic.
He was so close to me i would have been able to touch him... and on my right side i would have been able to touch the wall...