Very intense engine vibrations

[fasco]

Hello there.

I've bought a used '07 BMW Xchallenge 650 some months ago with 19k miles on it. The bike needed much care & love to get back to shape (worn bearings on the linkage, dodgy electric jobs, etc.) but now is OK... sort of. I can't get my head around two problems:

Problem #1: the bike vibrate A LOT.

I've heard that this bike is one of the smoothest single cylinder ever build, but not mine. I can usually ride 10 hours on my twin, but after 1 hour on this my butt get numb (and I have an aftermarket seat). Also I'm sure it's engine vibrations, because if I'm at 50mph and pull the clutch, the vibrations are gone. Could be that the clutch is out of balance?

Problem #2: It's down on power.

It should have nearly 55 HP but, but even with a smaller 14 teeth front sprocket I can barely put a wheelie in 1st (sorry, not very scientific test here but you get the idea). The previous owner did not have the valve adjustment done. Could be the lazyness related to this?

That's what I already done:

- new spark plugs
- new oil + filter
- new air filter
- cleaned the throttle body + idle actuator
- leovince X3 exhaust

Thanks for your time guys, I really hope to sort these problems

 

[Losttheplot]

Hello there.

I've bought a used '07 BMW Xchallenge 650 some months ago with 19k miles on it. The bike needed much care & love to get back to shape (worn bearings on the linkage, dodgy electric jobs, etc.) but now is OK... sort of. I can't get my head around two problems:

Problem #1: the bike vibrate A LOT.

I've heard that this bike is one of the smoothest single cylinder ever build, but not mine. I can usually ride 10 hours on my twin, but after 1 hour on this my butt get numb (and I have an aftermarket seat). Also I'm sure it's engine vibrations, because if I'm at 50mph and pull the clutch, the vibrations are gone. Could be that the clutch is out of balance?

Problem #2: It's down on power.

It should have nearly 55 HP but, but even with a smaller 14 teeth front sprocket I can barely put a wheelie in 1st (sorry, not very scientific test here but you get the idea). The previous owner did not have the valve adjustment done. Could be the lazyness related to this?

That's what I already done:

- new spark plugs
- new oil + filter
- new air filter
- cleaned the throttle body + idle actuator
- leovince X3 exhaust

Thanks for your time guys, I really hope to sort these problems

Just a few thoughts:

Problem 1. have you checked the bearings in the sprocket carrier on the back wheel? does the chain have any stiff links in it? Normally the G650 engine is very smooth. Does the bike rattle much if you have the bike stationary, in neutral and give it some revs?

Problem 2. I think the figure of 55hp is a little "optimistic" , I would have thought 40 ish bhp would be a realistic figure, low 40's being a good run. A few guys on here have had their bikes dyno'd and these are the figures that they came back with. Normally the g650 engine, while producing plenty of power, doesn't produce it in an explosive manner as you would require for an off the throttle wheely. You might find the leo vince exhaust actually reduces power unless the bike has been remapped to suit. These bikes run lean anyway, so increasing air flow without balancing the fuel system won't help.

The front end of the xchallenge will come up, you just need to give it a little encouragement.

 

[fasco]

Thanks for the reply!

Just a few thoughts:

Problem 1. have you checked the bearings in the sprocket carrier on the back wheel? does the chain have any stiff links in it? Normally the G650 engine is very smooth. Does the bike rattle much if you have the bike stationary, in neutral and give it some revs?

Good idea, haven't checked those, will have a look at them soon. BUT if they are the culprits, should the bike vibrate also when the clutch is pulled and the bike is moving? When I pull the clutch the vibrations go away.
As for the rattle, yes, there is a metallic noise coming from the engine, maybe I can make a video

Problem 2. I think the figure of 55hp is a little "optimistic" , I would have thought 40 ish bhp would be a realistic figure, low 40's being a good run. A few guys on here have had their bikes dyno'd and these are the figures that they came back with. Normally the g650 engine, while producing plenty of power, doesn't produce it in an explosive manner as you would require for an off the throttle wheely. You might find the leo vince exhaust actually reduces power unless the bike has been remapped to suit. These bikes run lean anyway, so increasing air flow without balancing the fuel system won't help.
The front end of the xchallenge will come up, you just need to give it a little encouragement.

I should have mentioned that I've installed a touratech air filter, which make the mixture even leaner. Maybe I have to buy a booster plug to enrich the mixture?

 

[Timolgra]

As for the rattle, yes, there is a metallic noise coming from the engine, maybe I can make a video

Check your cam chain tensioner hasn't stuck.

 

[fasco]

Update:
- the sprocket carrier bearing seems fine (no play in it)
- the chain seems fine also
- power has increased since installing the booster plug
- valve clearance has been setup by the mechanic, chain tensioner ok
- clutch has been checked, no balancing issue there

The "engine" vibrations are still there, especially on the footpegs. They are unbearable to be fair. Thinking about selling the bike

Any other ideas?

Inviato dal mio SM-T700 utilizzando Tapatalk

 

[fasco]

Sorry to be so pedantic guys

I was checking the forums to have a better understanding of my bike, and found the presence of a "caste nut adjuster" which "It is only used to adjust the play between the engine housing and frame". Could be this somehow related to my problem? Where is it?

Thanks!
Matteo

 

[fasco]

FOUND THE PROBLEM!

It was the secondary spark plug which was not firing due to a corroded coil. In standard conditions, the first plug is always working and the second only works from 3000 rpm up.
The previous owner replaced the secondary spark plug with an Iridium one, with a "thread-like" end, which was not having good electrical contact with the coil. This leaded to corrosion, which prevented the spark plug from working well.

Now the bike does not vibrate and has good power