HELP PLEASE - Surging, power loss and more

[Marty]

Hi Guys

Any suggestions on the following at all please? (maybe unrelated)

The Oil pressure light came on intermittently a couple of days back - oil level fine, no change in running temperature or any other signs. It came on then went off again as I stopped at some lights and the bike idled....then....

Today on a ride down to Poole the bike started to develop a surge below about 3.5k but most noticeable around 2-3k revs. It was happy (or appeared to be around 4-5k revs constant throttle, then if I tried to open it up say above 5.5+k revs it felt like it was choking up.

Checked the leads and plugs on arrival - all looked good as far as integrity and colouration was concerned. Gave 'em a quick clean up and squirted some WD40 in the plug caps. Then come to return to Bath and again the intermittent oil warning light symptom reappears and the the surging still present and power lack at higher revs also.

Initial thoughts we're fueling (blocked filters, detonation) until the oil warning light came back on. Now wondering if the Motronic unit is playing up or some moisture, iffy electricals somewhere on the loom? Of course could be a whole raft of other stuff too. Might be worth mentioning that the LH throttle body has the 'ol rattle suggesting worn bushes.

The bike's and 1150 (twin spark) with just shy of 18k on the clock.

Any advice/suggestions very much appreciated.



Mart

 

[buellzebub]

The surging and general poor running you describe sounds very similar to the problems I had with my 2000, 1150 single spark when the TPS went faulty. I'd set the correct voltage, reset the motronic (pull the fuse, wait 5 mins, replace fuse, ignition on, 3 fully closed to fully open on the throttle) then check it again later and the voltage was totally wrong again. Anyway, upshot was I bought a 2nd hand one off ebay, put that on and set it up. I then did the tappets and end float, then synced and balanced the throttle bodies and set the idle speed, then checked and fine tuned the TPS and reset the motronic once more and it's ran fine ever since; the voltage has stayed perfect.
Forgive me if I've not typed the above in the correct order, but I did consult the font first then did the cold engine procedures followed by the hot engine ones in the correct order at the time.
Mick

edit: Basically I'd go through the set-up procedure above one step at a time and see if it helps. I'd start with the rockers first when it's cold, then try it. Then do the next procedure and try. That way, hopefully, if it works you may be able to isolate the cause.

edit 2: My l/h throttle body rattles a bit too but doesn't seem to affect the running. And actually I'd try resetting the motronic first, it's the quickest and easiest.

 

[davegs]

Surging

If it's a twin spark possibly one of the coils going down, do a search as there's lots of this about as it is common.
dave GS

 

[dancata]

If it's a twin spark possibly one of the coils going down, do a search as there's lots of this about as it is common.
dave GS

+1 on that

 

[Marty]

Cheers Guys, as it's just a couple of days outside of the dealer's warranty - I'm gonna check to see if they'll cover it tomorrow. Will get back here if not.

Fantastic step by step instructions on replacing the bushes in the TBodies Dancata - top job.

 

[Wrigsby1]

On low mileage bikes it is unlikely the TB bushes will be worn too much. My RH TB rattles but it is lateral movement which shouldn't make a difference to the running.
The actual bush wear talked about is the shaft wearing into the bush wearing an oval into the round bush so making a possible air gap gap and also possible difficulty in accurate balance.

 

[Steptoe]

If it's a twin spark possibly one of the coils going down, do a search as there's lots of this about as it is common.
dave GS

+1 on that

+2 ....

 

[Marty]

+2 ....

+3

Bath Road Motorcycles replaced 2 new coil leads and now its once again running as you might expect. And they honoured the 3 month warranty that came with the bike, despite it technically having expired a few days prior to my visit.

Well done to all and sundry that diagnosed it straightaway - very good work!

Commendable service once again from BRM thanks Mike(s), Kris and Darren