Not quite right.

(RIP) trickytree · Apr 10, 2017

2004 twin spark Rockster. 65,000 miles.

Posted before about increased fuel
Consumption over this winter but now there's more problems
Along with the 10% increase in fuel consumption there has also been increased vibration, more of a buzz felt through the pegs and seat. Suspecting throttle body balance I bought some Davida gauges and set to..... no difference. Had another go and again no difference. Riding along on Saturday I had a thought, pulled over and did a motronic reset. This made the bike run a lot smoother.
So thinking things were back to normal went to Prescott with Mrs.tree yesterday and things were not right. The buzzing returned and there was also a loss of performance..... most noticeable when nipping past a car, the zap of acceleration had gone. Then, on the way home, rolled the throttle open to pass a car and there was about a second of heavy pinking and loss of power, then things picked up and completed the overtake. Pulled over and checked what I could, nothing obvious. Stick coils ok (new last year). Started up and ran fine, no
ominous noises. Plugs look good.
Still at work at the moment but I'm stumped where to start with this. I've got a compression testing gauge so I imagine that's a good idea , owt else?

gog · Apr 10, 2017

I had a similar issue paul but not exactly. My left cylinder would occasionally stop firing or fire intermittently, causing the expected loss of oomph and very buzzy running. It only happened from time to time but i managed to stop while it was happening and wiggling the electrical connector to the left injector brought it back to life. Turns out there was water in it and the connectors were a bit corroded. I cleaned it up, packed it with dielectric and its been fine since.

Start the bike on the centre stand and have a good wiggle of the wires to the injectors and see if you hear any changes.

Long shot maybe but easy to check and easy to fix, before you start checking other bits like the HES.

west coast traveller · Apr 10, 2017

Although you have done a throttle body balance, have a check that your cables are operating properly and not sticking. You can tell by making sure the cable quadrants are seating back on the adjuster screws when the throttle is closed. I had a very similar problem a few years ago and the cables were shot.

MikeO · Apr 10, 2017

I had similar symptoms when I had dirty injectors...

(RIP) trickytree · Apr 10, 2017

Started going through a few things....injector connectors are nice and shiny.....cam is seating on the throttle stops fine.
Injectors....got a new set from the states that Gordon sorted out for us but was wanting to get the bike running as it was before fitting them, but that got me thinking. I think the extra vibration started after its last service, which included a fuel filter change....after 65k and 13 years could the fuel hoses be past there best? Perhaps when I changed the filter it dislodged a bit of rubber and has partially blocked a injector?
Another thing is I reduced the idle speed with the BBS, I set the idle to 1000rpm but to do that I had to screw the BBS all the way in....do they have to be screwed slightly out to work? They were very gummed up when I removed them but I gave the screws and the hole a good clean.

dave perry · Apr 10, 2017

I am sure that I read that " two turns out" is a good starting point for the BBS and a yearly clean is oft recommeneded. Mine are set thus, and all is fine and dandy

Many would recommend that you replace the hoses internal to the fuel tank when you go in to renew the filters

(RIP) trickytree · Apr 10, 2017

The intake tube from the air box to the rh throttle body was a tad loose, not sure if it's loose enough to let in air....tightened up now.

I'll re do the throttle body ballance with the BBS turned out a touch....2 turns out has the tickover at around 1200

Given all the wiring connectors the wiggle test...nothing. But then the bike doesn't misfire (apart from the one pinking occurrence).

Think I'm going to order a new fuel filter and fit new hoses inside the tank...then I'll fit the new injectors and take it from there.

ross. · Apr 10, 2017

trickytree said:
The intake tube from the air box to the rh throttle body was a tad loose, not sure if it's loose enough to let in air....tightened up now.

I'll re do the throttle body ballance with the BBS turned out a touch....2 turns out has the tickover at around 1200

Given all the wiring connectors the wiggle test...nothing. But then the bike doesn't misfire (apart from the one pinking occurrence).

Think I'm going to order a new fuel filter and fit new hoses inside the tank...then I'll fit the new injectors and take it from there.

i found suitable 7.5mm R10 hose for inside the tank, but ive not been able to find the 5mm for the vent and drain? anyone have a supplier?

Ian J Hartley · Apr 10, 2017

ross. said:
i found suitable 7.5mm R10 hose for inside the tank, but ive not been able to find the 5mm for the vent and drain? anyone have a supplier?

Motorworks sell the stuff, but it's not cheap, and considering it carries a BMW part number stamped on it, it's probably easier to get it from BMW direct.

Internal fuel tank grade pipe is expensive, and the unusual size like E5 X 10 (I/d 5mm O/d 10mm) is rare.

Motorworks part no FUA25737.

Good luck with your search.

(RIP) trickytree · Apr 11, 2017

The short u shaped hose is a bit eye watering at around 26 squids

Going to order the stuff from Motorworks today, I really don't want to spend the whole Easter hols sorting out problems

(RIP) trickytree · Apr 14, 2017

Getting nowhere with this. Vibration gave me numb hands today and performance is defiantly down. Uphill dual carriageway, 65mph, pull out and roll the throttle back and nothing, had to change down. That's not right for my bike (Rockster gearbox, not a high 6th gear) it should have pulled like a train until I back off.
One new thing I noticed today, had 2-3 half hearted backfires. Not unusual ordinarily, but there usually bloody loud.....these were far more muted, not heard these before.

So, checked the stick coils again, all normal. Took all the plugs out, all dry and normal colour.
Ive balanced the throttle body's 3 times now.....it hasn't really made any difference. I've put the new injectors in but they havnt made any difference to the vibration or performance. Doesn't seem to be running abnormally hot or cool. Took the alternator belt cover off, looks normal although I havnt had the bottom pulley off yet.

Would plugging in a GS911 tell me anything? I've got a compression tester so I'll check that tomorrow.

I don't think the vibrations anything mechanical....it's not chassis related, pull the clutch and coast its smooth as silk. The motronic reset I did the other day helped with the vibration but it didn't last long.
Header pipes are solid, found a couple of very slightly loose clips on one of the intake tubes, tightend all clamps up anyway. I'll pick up a can of carb cleaner and check for intake leaks tomorrow. Bike ticks over smoothly, vibration starts building about 3500.
Need to check as much as I can myself, can't afford to swap stuff out in the hope I hit the jackpot.

(RIP) trickytree · Apr 15, 2017

Did a comp check this morning with a cold engine and got bang on 200psi on both sides. I'll do a hot test when I return, of to buy a can of carb cleaner to check for intake leaks.

west coast traveller · Apr 15, 2017

One thing worth trying is checking the rate of fuel flow back to the tank via the pressure valve. I had problems with this which caused all sorts of problems- intermittent rough running, backfires, loss of power but tick over fine. In the end a new pressure valve solved the problem. Roger 04RT did a thread on checking fuel flow. I diagnosed mine by compressing the fuel return pipe to the tank and this immediately caused the bike to run as normal as it increased the fuel pressure to the injectors back to normal pressure. I think it took about 30 seconds to carry out the check (though much longer to replace the valve!). If I recall correctly it was Roger who didn't think this was best way of testing fuel return pressure as it could cause too much back pressure, but it worked for me. If you decide to check this and use Rogers method I've got a hose with female quick release connector I could lend to you for the price of the postage.

DrFarkoff · Apr 15, 2017

Twin Spark??

Coil failure under load!

Common problem

Either:- stick two spare old plugs into the spark leads and ground them out with jump leads for the bottom plugs

OR Disconnect the old standard coil main loom connector up under the tank

Does it run on that side after you have removed the secondary spark?

If exhaust doesn;t get hot you have your answer

(RIP) trickytree · Apr 16, 2017

Cheers Dr. I'll check it out, although the sticks are less than a year old and the problem I'm having now is not the same as I had when a stick went down. No misfiring at all apart from the occasional backfire.....however, I did notice yesterday that the connector for the left stick coil had a broken cover...all the wires rare still attached and seemed to be making good contact. I reassembled it and glued it back into one piece.

This smacks of throttle body ballance to me......took the bike out yesterday and things were a lot better than the previous day, still a bit vibey but bearable. Got talking to a chap while I was out that's had Beemers all his life, air and oilheads, and the first thing he suggested was throttle cables. Cant afford £140+ for a new set this month though.

ross. · Apr 16, 2017

trickytree said:
Cheers Dr. I'll check it out, although the sticks are less than a year old and the problem I'm having now is not the same as I had when a stick went down. No misfiring at all apart from the occasional backfire.....however, I did notice yesterday that the connector for the left stick coil had a broken cover...all the wires rare still attached and seemed to be making good contact. I reassembled it and glued it back into one piece.

This smacks of throttle body ballance to me......took the bike out yesterday and things were a lot better than the previous day, still a bit vibey but bearable. Got talking to a chap while I was out that's had Beemers all his life, air and oilheads, and the first thing he suggested was throttle cables. Cant afford £140+ for a new set this month though.

£140 for cables

bloody hell really

DrFarkoff · Apr 16, 2017

Tricky Pop the tank off and remove the wire to the old style ignition coil just behind the headstock

That way you cannot damage that coil (a lot of folks just unplug them from the spark plugs and thats a lot of energy going nowhere!)

How does it run? Do you know anyone with an infra red/ laser thermometer ? that you can borrow for half an hour

Start and idle for 30 seconds Do a quick measurement on each header

go for a run and get up to temp and measure quickly again

Is there a Significant difference? 50 degrees or thereabouts?

Quite honestly if the throttle action is smooth and not terribly heavy? Your cables are fine! I know of bikes with 100,000miles with original cables still going strong

"but " worth checking that the fast idle is definitely going off

Making sure your vacuum caps are fitted and doing a check / setting on the TPS (Better with a GS911 reading live data)

IN fact a Live data read would give you info to work from Including your lamda probe!

(RIP) trickytree · Apr 16, 2017

.....worth checking that the fast idle is definitely going off .....

Wouldn't bet my house on it but probably all my furniture......I reckon the problem started when the fast idle lever broke. Stuck in the on possition and I had to 'persuade' it to close. Not been using it since, just one of those 'unimportant' jobs I've added to the to do list.

I'll sort it first thing and do another throttle body sync.

DrFarkoff · Apr 16, 2017

Ah ha okay so make sure it's going complete off and do a tune up

If the fast idle is stuck partially on it screws the base fueling as the throttle never goes back to the rest position
Just free the cable off so that both throttle arms are able to go right off

For cold starts twist the throttle drip about a Centimeter

Check the tps value

(RIP) trickytree · Apr 26, 2017

Still not getting anywhere with this. Checked the idle cable and there's plenty of slack in it (I'd already checked the screws were resting on the throttle stops anyway)

Remembered that I'd bought a brand new genuine stick coil last year as a spare so popped that on the right pot and went for a spin....no difference. Swapped it over to the other pot and again, no differance. Got back home and did yet another throttle body sync, again no differance at all......running exactly the same.

Got the tank off at the momment, can't see anything obviously wrong. Ive pulled the lead to the secondary coil and will give that a try first.

Not quite right.

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