Engine "miss firing"

[Uncle-Fester]

Morning all, I was in Wales at the weekend having a blast around the A roads and goat tracks, and despite the clutch cable breaking on the M25 before I even got there (thanks to the nice man from SOS recovery who had a universal cable with him and got me back on the road within the hour ) and the starter motor playing playing up and the ABS stopping working, it was a great weekend.
But I digress, whilst riding I thought the engine had an occasional misfire, but the more i rode the more it felt like the the clutch had the occasional wee slip, but as I took more notice, it only happened between 3750 and 4250 rpm, and happened during both acceleration and deceleration. It felt like the injection system stopped for a split second, it's difficult to explain.

I'll do a search for the ABS issue as I'm sure that has been covered many times

So any ideas that I can explore are welcome.

 

[beemer pimp]

What bike is it ?

 

[Ian J Hartley]

What bike is it ?

I'd put money on it being and R1100, most probably a GS.

The clue is cable clutch.

 

[beemer pimp]

Agree it 1100 and GS , it will take all day to take ferings off to replace cable on rt

 

[Karlread]

May well be the TPS (throttle position sensor) though it may be best to drop "Yoda" aka Steptoe a PM.

 

[Steptoe]

Mmmh, 1100 model you say .. Rather than a misfire could it be the gearbox is "hopping" under acceleration/de acceleration ? Feels very similar to a misfire and the 1100 gearbox is well known for this problem.

 

[Uncle-Fester]

Yes, it is an 1100 GS, yes, it could indeed be the gearbox "hopping" (my first thought was clutch slip) what is the cause of this, and what is the remedy, and if the remedy is too expensive for right now (IE before spanish trip in June) then is it likely to fail at the most inopportune moment?

Oh, and why is the clutch cable I bought 2" too long

Are there different length cables among the 1100 bikes?

 

[flatdog]

Yes, it is an 1100 GS, yes, it could indeed be the gearbox "hopping" (my first thought was clutch slip) what is the cause of this, and what is the remedy, and if the remedy is too expensive for right now (IE before spanish trip in June) then is it likely to fail at the most inopportune moment?

Oh, and why is the clutch cable I bought 2" too long

Are there different length cables among the 1100 bikes?

June trip you say.....your G/B shafts run on bearings that are tapered and if worn the shafts can hop under acceleration.
A well known 1100 issue. There's still time to get that box out to Steptoe and sorted.

Drop the oil and see how much swarf is present

Cable issue. no idea.

 

[Uncle-Fester]

Thanks, I'll change the oil this week and see what I find.

Is it terminal??

 

[Uncle-Fester]

Well is it?

 

[tadhgocuilleain]

When I was researching GSes to decide which one I wanted to buy, I almost bought an 1100. When reading into the gearbox issues, I learnt that the best set-up is an M97 gearbox (which was fitted in bikes manufactured from late '97 onwards) with the input shaft from an M94 gearbox.

If you intend to hold onto the bike for a while I'd see if you can find an M97 gearbox for sale and fit that, along with the input shaft of your own gearbox. You'll have a bullet-proof bike then.

I'm rushing out the door to work now, so I don't have time to trawl through my bookmarks to find the specific information that explains why this is the best set-up, but here are two links with plenty of information on the 1100 gearbox. It might be in there somewhere:

First is from our own local guru:
http://www.ukgser.com/forums/showthread.php/346792-R1100gs-clunky-gearbox?p=3547999&viewfull=1#post3547999

American website, so prices don't apply, but the information is very good:
http://www.largiader.com/tech/oiltrans/

Hope that helps,
Tim.

 

[flatdog]

Well is it?

asking me?
then yes it's fucked IF the gears are jumping then it will eventually destroy itself.
Definately sooner rather than later.
Tadhgocuilleain offers good advice on alternatives.
Probably be a good idea to get the fault diagnosed before ripping into it tho.
Then call Steptoe or mikeyboy to discuss your options.

 

[Uncle-Fester]

Thanks for advice chaps, i'll look at those links, thanks Tim.

 

[Puffin]

Fester drop your gear oil and check for metal debri or discoulering if there is none dont worry a friends 11 has the odd 3rd gear skip for closer to 40k kilometers and mine skips on occasion in 5th

 

[Uncle-Fester]

Ok, so I drained the gear oil, and found it to be quite thick and of many colours, from a creamy colour to almost black (although no metal flakes or swarf that I could see) probably the worst looking oil I've ever seen!

Drained FD oil and found not much of similar quality, this from a bike with FULL BMW service history (last service less than 2000 miles ago)

I'm guessing the GB oil has never been changed, just topped up from time to time with varying grades of oil

So, I flushed with clean oil and refilled to correct level, same with FD, and then did the engine oil and filter (which was pretty black too) changed air filter as this was pretty dark in colour.

I have ordered a full set of brake pads also as these look like they need to be replaced ( definitely before the Spain trip)

So I think I've probably done a better service than the BMW dealerships, and I'm a Plumber!! All I can say is, I'm glad I'm not relying on a dealership to service a new bike if this is the level of service they give.

Test ride showed that the "slip" from the GB (or whatever it is) is still there, but only happens in top gear around 4000 rpm

I will keep an eye on it for now.

Thanks for the info chaps, I'm sure I'll be back again soon

 

[MarkShelley]

When my previous 1100 box expired due to bearing failure the oil was milk chocolate colour. I suspect a big bill is on the way but good luck with it.

 

[Uncle-Fester]

When my previous 1100 box expired due to bearing failure the oil was milk chocolate colour. I suspect a big bill is on the way but good luck with it.

Hmmm, bearing failure you say?

Do you know which bearings, or is it a case of replace all bearings?

 

[flatdog]

Hmmm, bearing failure you say?

Do you know which bearings, or is it a case of replace all bearings?

Bearing failure causes exessive movement which also wears out gears/shafts other bearings and gearbox casings. - take your pick.
But I'd guess the layshaft bearings if it's jumping in top.

 

[Uncle-Fester]

Bearing failure causes exessive movement which also wears out gears/shafts other bearings and gearbox casings. - take your pick.
But I'd guess the layshaft bearings if it's jumping in top.

Ok, thanks, well it'll have to get me to Spain and back or fail in the process, I don't have the money to do both.

Thanks for the advice, if it gets me through Spain then I'll get it rebuilt later in the year.