Flat spot fixed 1200 GSA 2012

Pauly S · Jun 30, 2019

I tried The flappy valve bypass tube from Motorworks, and afterwards i seemed to inherit a god awful flat spot from 4 to 4.5k rpm, you had to get the revs above 4.5 for the motor to start pulling again, it kinda hit a plateau.So i refitted the flappy valve and back to the linear power curve we went.Back to normal. TBH all i seem to get with the bypass tube is lots of extra noise.
I fitted the valve prior to a trip to HT and wanted to map the bike with the bypass in place, the story is in another thread.I can only assume my bike was mapped with the valve in place. Anybody else have a similar experience.?

oddshapedballs · Jun 30, 2019

Removed the flappy valve in mine, no issues, a little more noise and some popping on the overrun which I love, but nothing other than that.

Gedspeed · Jun 30, 2019

Just fitted a booster plug to my 1200, solved a few problems at a little cost.

Ged

Mac One · Jun 30, 2019

I fitted the bypass tube and ran it for a couple of years, I've now re-fitted the flappy valve. I didn't notice any difference in performance, just noise.

Howard J · Jun 30, 2019

How much extra noise does the bypass tube make? I have never had a flappy valve on my bike as it had been removed when I purchased the bike due to being gummed up, the thing is I do find the noise a bit too much now.

Pukmeister · Jun 30, 2019

I didn't expect the valve to alter the effective tuned length (back pressure) of the exhaust system a la EXUP ?

Most folk claim its a noise reduction measure.

Pauly S · Jun 30, 2019

I can only assume on part throttle openings it increases the back pressure to aid fuel economy, but on wot the valve is wide open, it has cured the flat spot i had on top gear cruise at about 4k. Its still noisy like the bypass tube, but not all the time, whereas with the bypass fitted its noisy all the time.Performance i found no gain ,aside from a crappy flat spot.

Pukmeister · Jun 30, 2019

Just the problem of maintaining the valve then Paul so it can stay moving and not seize up.

Pauly S · Jun 30, 2019

After much reading Adam, im on the look out for a pair of AF-Xied units.MR HT couldnt do much for me, so i looking down this road now. My boy is off to the States this year and ill get him to pick me up a pair new , saving on carriage, if i cant find a secondhand set.
The valve is a five minute job to remove and clean and service , so not really a chore.

Gedspeed · Jun 30, 2019

The default position of the exup valve is open, when you start the bike it closes, that's why the bike sounds loud first few fires, the valve then opens as power is required to let gases flow free, that's why the engine pops on the over run just before valve shuts, BMW agent says the valve is to reduce noise on the euro drive by test.

The booster plug i fitted to my RS stopped an annoying hesitation when throttle on throttle off situation, caused by lean mixture, the booster plug enriched the fuel injected into the engine slightly while monitoring temperature, what a difference it made. 20 minutes to fit.

Ged

Pukmeister · Jul 1, 2019

I had a booster plug. It worked well at first, but over time the long term fuel trims cancelled it out and I was back to square one.

Gedspeed · Jul 2, 2019

Pukmeister said:
I had a booster plug. It worked well at first, but over time the long term fuel trims cancelled it out and I was back to square one.

I used mine on the r1200rs for 6 months on one and a year on my second one, i removed it a couple of days before i p/x'ed it, it went straight back to its bad ways, maybe you found one that went faulty.

Ged

Pukmeister · Jul 2, 2019

I don't think so Ged, the BMS-K was just doing its job by adapting out via the closed loop feedback signals from the lambda probes.

Gedspeed · Jul 2, 2019

I agree, the booster plug will fool the system into thinking the air temperature is lower than it actually is, thus enriching the mixture, The Lambda will possibly sense the enrichment, although the Lambda is looking for unburnt oxygen, as the fuel will burn all of the oxygen the set up with BMS-K — HEX Code will not change.

I found a considerable improvement when fitted and no going back as it was used over the year, and the bike returned to its bad fueling, after removal of the temp sensor and plug from the airbox.

That was my experience.

Ged

Flat spot fixed 1200 GSA 2012

Pauly S

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oddshapedballs

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Gedspeed

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Mac One

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Howard J

Who?

Pukmeister

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Pauly S

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Pukmeister

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Pauly S

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Gedspeed

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Pukmeister

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Gedspeed

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Pukmeister

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Gedspeed

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