Help with first BMW...'98 K1200RS throttle issues

[RTandGS]

Hello and thank god you're all here. I've been a lifetime MC owner/rider but I finally became a BMW owner when a 1998 K1200RS (98k miles) came up as a storage locker refugee and I went and got her. Varnish gas had me cleaning the tank and replacing the fuel pump and filter. New plugs and battery and she fired up. What I need immediate help with is a low RPM throttle issue. If I rev the bike to 2000rpm and hold there, the rpms dip to 1500 and then back up to 2000, over and over, while I hold the throttle steady. This translates while I'm riding to not being able to have low throttle action, when I try to feather in some throttle to start rolling, it dies back to idle so I have to rev the bike high to get going.

A friend said this was a faulty TPS, and I have tried the TPS reset (key off, On, twist WOT three times, key off) but no change in my issue. I have also disconnected the battery and tried it.

So I wonder if this TPS replacement sounds right to the collected experience here. I tried a search here for TPS and nothing came back. I'd appreciate a work flow for solving this if anyone has one. I am not afraid to do most of the work on the bike, but if something requires the work of a master I'll take it in.

I have changed the oil, trans,and final drive, front brake fluid. I can't find a source for a rear brake line, seems sets are all the rage, so I'll have that made at a shop here and will flush the rear brake lines with fresh fluid. Also waiting on speedbleeders to do the clutch line flush. And plan on flushing coolant and front forks and steering dampener to make the bike as fresh as I can.

Markus
1998 K1200RS (as yet unnamed because bumblebee is to easy)

 

[20774]

Welcome to the forum and BMW, Markus! Where are you from? Maybe there are some other storage locker "finds" in the area!

 

[RTandGS]

Welcome to the forum and BMW, Markus! Where are you from? Maybe there are some other storage locker "finds" in the area!

I’m in Thousand Oaks, Ca.

 

[52184]

I suspect if you call Spiegler they will be able to supply a rear brake line. And if the rest of your lines haven’t been replaced you might want to consider a set anyway, and have them all replaced.

I wouldn’t jump right into replacing a TPS sensor without first checking output from the sensor with a VOM meter. To me, your issue sounds more like a bad O2 sensor and possibly dirty injectors—you mentioned some varnish elsewhere in the fuel system. Personally, I’d go to NAPA and spend the $$ for a can of BG44, treat the (fresh) fuel according to the dosage on the label, then ride it like you stole through a full tank or two of fuel. Then check output from the TPS and test the O2 sensor.

Good luck,
DG

 

[RTandGS]

Thanks GT rider. So an O2 sensor will affect the throttle that much? And only at low RPMs?

I don't have a VOM meter. I have a multimeter. Can I test the PTS with that?

 

[52184]

Thanks GT rider. So an O2 sensor will affect the throttle that much? And only at low RPMs?

I don't have a VOM meter. I have a multimeter. Can I test the PTS with that?

Yes, same thing. VOM is volts, ohms, milliamperes. You can probably find some how-to docs over on www.i-bmw.com.

Best,
DG

 

[rileous]

my 98K1200RS

Hello and thank god you're all here. I've been a lifetime MC owner/rider but I finally became a BMW owner when a 1998 K1200RS (98k miles) came up as a storage locker refugee and I went and got her. Varnish gas had me cleaning the tank and replacing the fuel pump and filter. New plugs and battery and she fired up. What I need immediate help with is a low RPM throttle issue. If I rev the bike to 2000rpm and hold there, the rpms dip to 1500 and then back up to 2000, over and over, while I hold the throttle steady. This translates while I'm riding to not being able to have low throttle action, when I try to feather in some throttle to start rolling, it dies back to idle so I have to rev the bike high to get going.

A friend said this was a faulty TPS, and I have tried the TPS reset (key off, On, twist WOT three times, key off) but no change in my issue. I have also disconnected the battery and tried it.

So I wonder if this TPS replacement sounds right to the collected experience here. I tried a search here for TPS and nothing came back. I'd appreciate a work flow for solving this if anyone has one. I am not afraid to do most of the work on the bike, but if something requires the work of a master I'll take it in.

I have changed the oil, trans,and final drive, front brake fluid. I can't find a source for a rear brake line, seems sets are all the rage, so I'll have that made at a shop here and will flush the rear brake lines with fresh fluid. Also waiting on speedbleeders to do the clutch line flush. And plan on flushing coolant and front forks and steering dampener to make the bike as fresh as I can.

Markus
1998 K1200RS (as yet unnamed because bumblebee is to easy)

My 98 started out as Brunhilde (also a yellow "taxi")...she had a split personality...Brun when running great and Hilde when she was messing with me...I have concluded previous owner ran the piss out of her bc I've done 2 final drive failures, one rear brake total meltdown ( while riding the Dragon, no less), a transmission failure and a suspension rebuild (Ohlins shocks sent in just b4 they were to blow out, whew!!!) in 32K miles...hopefully I've taken care of all the worn out bs and can enjoy a couple seasons break down free....however her name had to change to reflect all we had been thru...her name now is "Moneypit"...lol

 

[RTandGS]

Dear God Rileous that’s a lot of work for a used bike, one might call you a die hard. Testimony to your love of the bike or your will not to be defeated!

So at any point did you experience anything like I have going?