98 K1200RS poor running

This was the 1st year I stored my 98 K1200RS as the dealer I used for this closed. I put Stabil in the tank at the recommended amount. Battery was maintained with the factory BMW charger, same one used last 5 years while at the dealer. I started the bike a couple times a month and ran until warmed up, according to the gauge. With the carona thing, I did not try to get on the road until about 6 weeks ago. When I would pick the bike up from the shop, it would run crappy for the first tank of gas, getting only 38 mpg. Then it would get back to normal running and 42-45 mpg. It has not run right at all this year, app. 1/2 normal power, LOUD noise from airbox area (loud enough to drown out the Staintune exhaust) and I'm getting 15-20 mpg. I put in the recommended amount of Sea Foam in tank, bike ran a little better but still not right. Bit the bullet, removed the tupperwear, and tank (after buying $45 worth of hose clamps) and inspected the air filter which was fine. Now, it has been mentioned by a member of our local club to change the fuel filter. Is it better to ride the fuel out or to drain the tank in order to get at the fuel filter w/o creating a huge mess and/or fire hazard?....I am not planning on removing the fuel pump as the manual says but going in thru the filler hole after removing the filler cap. Any advise will be greatly appreciated. TIA, John rileous@hotmail.com or 765-577-1409

In addition to the air filter, check the intake nozzle and it’s pre-chamber for nests from rodents or insects, like wasps. That would account for restrictions but not the noise you mention. If you wish to change the fuel filter you will want to drain the tank—completely, if you are going to change it on-bike, or near completely if doing it with tank off and on its side.

Best,
DeVern

rileous said:

This was the 1st year I stored my 98 K1200RS as the dealer I used for this closed. I put Stabil in the tank at the recommended amount. Battery was maintained with the factory BMW charger, same one used last 5 years while at the dealer. I started the bike a couple times a month and ran until warmed up, according to the gauge. With the carona thing, I did not try to get on the road until about 6 weeks ago. When I would pick the bike up from the shop, it would run crappy for the first tank of gas, getting only 38 mpg. Then it would get back to normal running and 42-45 mpg. It has not run right at all this year, app. 1/2 normal power, LOUD noise from airbox area (loud enough to drown out the Staintune exhaust) and I'm getting 15-20 mpg. I put in the recommended amount of Sea Foam in tank, bike ran a little better but still not right. Bit the bullet, removed the tupperwear, and tank (after buying $45 worth of hose clamps) and inspected the air filter which was fine. Now, it has been mentioned by a member of our local club to change the fuel filter. Is it better to ride the fuel out or to drain the tank in order to get at the fuel filter w/o creating a huge mess and/or fire hazard?....I am not planning on removing the fuel pump as the manual says but going in thru the filler hole after removing the filler cap. Any advise will be greatly appreciated. TIA, John rileous@hotmail.com or 765-577-1409

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John,
I store my 2003 K1200RS similarly to what you describe: fuel stabilizer & battery charger, but I'm not one to start stored bikes unless I can ride them for 15 or 20 miles to do a through heat soak. However, many do start them periodically like you do and seem to have good results.

As to your problem, the poor performance, low mileage, and backfiring all sound to me to indicate a fuel system problem: fuel pump, fuel filter, or injectors most likely. The backfiring on a K12 is not normal and would indicate an overly rich condition. The odd thing is the noise you mentioned - I'm not sure where that fits into this puzzle.

It is possible that the fuel filter is plugged, but in my experience with many different K-bikes all using that same filter it can last for tens of thousands of miles under normal circumstances, but can and *will* plug up from water in the fuel as it's designed to not pass water. Was your tank full during storage? Could there have been a lot of condensation?

So, while possible that your fuel filter is plugged, I think that is not as likely as dirty fuel injectors which are not fully closing. That could explain the backfiring and the very bad fuel mileage. If it were my bike, I would pull the spark plugs to check the mixture. Under normal conditions they should look on the light side of a perfect mixture - light colored tan but very, very clean. If they look bleached white you are running lean, if dark and/or sooty, then rich.

If they look rich, then I would drain the gas and refill with fresh fuel with an ounce and a half of Chevron Techron per gallon. Accept no substitute fuel cleaners. I have had numerous experiences with the Techron additive doing wonders cleaning a fuel system and injectors. The "Techron Complete Fuel System Cleaner" cleans the entire fuel system including removing carbon deposits. They also have a "Fuel Injector Cleaner" blend specific to injectors and I think I would use that if you can find it, but if not, then the "Complete" should still do as great a job as any additive cleaner can do. As bad as your problem sounds, if it is the injectors, even Techron may not solve your problem, but you should see enough improvement in that first tank to indicate you do have dirty injectors. If one tank gets it running as it should or close, then I would do a second and maybe a third tank, and then change the oil and filter.

However, if that doesn't work, then changing the fuel filter will require an empty tank, and if you do the Techron treatment, you can run the tank all but dry doing that. I am not aware of any way to change the fuel filter on a K12RS/GT without removing the fuel pump assemble from the right side of the tank. If you do know of such a way I would love to know it! If you have not removed the fuel filter assembly before, it is a bit of a process and you will need a proper tool to loosen and tighten the big retaining ring. There is a pretty good thread elsewhere on this Forum about that process.

I hope this helps.