Need help with a gremlin…

[Moo Meister]

Howdy folks! I need your help...

I have two bricks - a 95 low seat model and a 95RT. I bought the latter because the ergos of the former kill my fat old man knees! Anyhow, I have been chasing a possible fueling issue on the RT for three months and I am utterly stumped.

I purchased the bike in Oklahoma from the 3rd owner with 45k on the clock. The bike was running rough-ish when I picked her up, though I attributed that to the fact that the air cleaner had been replaced with an EXTREMELY oily and filthy K&N.

When I got her home, I ordered both the standard and supplemental service kits from Bob's BMW and got stuck in. All in all, nothing concerning emerged from the service aside from the too-tight exhaust valves (not catastrophically so), which I also took care of. Following the service, I warmed her up, balanced the throttle bodies, and set the idle.

Right away she ran ROUGH at idle and would bog down and stumble under any acceleration. Again, I got stuck in. I:
-   confirmed good flow from the fuel pump and new fuel filter
-   replaced all of the rubbers around the airbox and throttle body
-   cleaned the throttle body
-   replaced the injectors (the old ones were quite bad) and fuel lines
-   replaced the vacuum lines and vacuum caps
-   cleaned up the inside of the airbox and ensured the barn door on the air sensor moved freely
-   replaced the spark plug wires

After reassembly she ran much better… above 4k rpm. Currently, she starts fine most of the time with the throttle advance on, and she idles fine once she is warm, though the idle is inconsistent when cold. Also, I can’t get the TBs perfectly balanced at either idle or 4k. They are close, but not perfect.

Also... between 2 + 3500 rpm she will either stumble if we are on the road until we hit 3500 and then run fine OR plateau and then fall back to 2k if she is on the center stand. Also, the idle will increase if I tilt the bike to the left (not the right) with the bars straight! I have never seen anything like on my previous beemers or Japanese bikes.

In addition to the new service parts, the bike is mostly stock. The only real modification is one of the Eu police tanks, which was installed by the original owner.

That is where we are as of today. I have combed the forums (including yours!!!) and have done darn near everything aside from adjusting the air sensor, which most folks say not to do. 

I will graciously accept any and all thoughts y’all might have. Thank you!

[The Mighty Gryphon]

Welcome!  You mention the idle is better when the bike leans to the left.  Have you considered that the fuel pump is on the left side of the tank?

[Laitch]

Does the fuel pump have a sock-style pre-filter or a screen? What is the condition of the pre-filter? Is the pump firmly held within its vibration damper?

[Chaos]

wild guess, water in the bottom of the tank?  Mine did all sorts of weird stuff until I ran a bottle of HEET through it.

[Moo Meister]

Howdy all! Thanks for the speedy feedback.

I actually pulled the pump out of its mount last night before posting and gave things a quick look. This is what I found:

- The rubber damper was in good nick - no apparent signs of damage or degradation.

- The pump itself did not have a pre-filter at the base. Did all the bricks have those? I thought I read somewhere that they did away with them at one point in the production.

- There was no ethanol crust on the body of the pump.

- The pump came out REALLY easy so I wonder if it was fully seated...

As a next step, I'm going to pump out as much of the fuel as I can, pour in some water eliminating cleaner and fill her back up. We'll see if that helps. In the meantime, please feel free to keep the thoughts coming!!! My plan is, with your help, to make this the weekend of troubleshooting! lol.

[Scott_]

I'm pretty sure all fuel pumps have some type of a screen or a sock on the inlet of the pump.
The older pumps had a screen assembly that allowed for the return fuel line to connect to it, the newer pumps only have a sock(fine mesh screen) connected on the bottom.

[Moo Meister]

Looks like you are right, Scott! Thank you. I've ordered a new screen. I'll install her when she arrives, refill the tank, and treat the fuel. I'll let y'all know what happens!

Feel free to keep dropping thoughts in the meantime. 

[Laitch]

The pump itself did not have a pre-filter at the base. Did all the bricks have those? I thought I read somewhere that they did away with them at one point in the production.

What was eliminated was the need for the hose attachment to which Scott refers.

You've got a 52mm diameter pump with a fuel screen.


There is also a 43mm diameter pump with a filter sock.

Although the two styles were developed in different years, they are swapped among models for convenience or in desperation. Their holders and vibration dampers are sized accordingly.  The purpose of the filter screen hose attachment was to evacuate agitated air before it could enter the pump and cause damage by cavitation. If you don't try to run on fumes instead of fuel it's unlikely cavitation would be a problem. When I looked at my Brick's pump it had the fitting but no hose was attached. I had no problem when running on fumes, except, of course, making headway.    The fuel sock model came later.


The ridges pressed into the pump case locate the pump at the correct height relative to the tank floor. If your pump is loose in the damper, it's possible it could be bottoming out enough to periodically slow fuel intake. I encountered that once.
Siphon or drain all the fuel from the tank and rid it of varnish and deposits, if necessary. White vinegar works well as a cleaner. 1995 was a good year; it came with a higher capacity alternator and an uncomplicated fuel return in the tank. Fuel spills like a waterfall over the vapor chamber and back into the tank.

I've got a '95 and it has given me little trouble except for keeping me from doing my chores. Plan on cleaning the ignition switch and maybe replacing the drive cushions of the alternator someday. The cushions—known as monkey nutz among the intelligentsia here—are wear items. This site has downloadable manuals, both shop manual and rider's handbook.

[Moo Meister]

Hey Laitch -

I already have the nutz in hand! (Wait…) Plan is to replace those in the fall.

I once had to push a fully laden r1100GS for 2 miles because I ran her empty. That was the first and last time I EVER strayed into fume territory...

[Moo Meister]

Howdy everyone! I have updates.

I couldn't shake what y'all said about the mesh filter, so I went out, pulled the tank, drained it, and pulled the pump. This is what I found:

- There was sand-like material hiding in the corners of the tank. The bike came from Oklahoma, so this was both surprising and, well, not.

- Inside the baffle where the pump sits were chunks of what I can only describe as epoxy. Under deeper examination, it looks like the material came from the outboard corners of the baffle where it attaches to the inside of the tank. I removed what I could without impacting the strength of the baffle.

- Deep under the baffle was – are you ready? – the bloody filter. I pulled it, cleaned it with some gas, and reinstalled it.

When I was done, I refilled the tank with fresh fuel and dumped in some ISO-HEET. When I started her up, she ran far better.

On the road there is still a smidge of hesitation around 2500 rpm - just enough for my butt-dyno to know that something isn't right. That said, when given a handful, the hesitation disappears.

Thank you all for the help! Now, if you happen to have any pointers on making the damned panels line up, let me know 😉

Also - and I am sorry for being shameless - if you happen to know anyone looking for an extremely nice 95 K75 low seat, let me know. I'd love to keep her, but the seating position kills my *bad* knees after 45 minutes.

Thanks again!!

[Laitch]

Also - and I am sorry for being shameless

Quit being shameless and you won't need to be sorry. 

We could sure use some photos of your baffle problem. Regardless, you can make that Brick into a standard seat model, once you get a standard seat and some parts. Look here.

[Chaos]

Another tune up in a bottle product I've had good experience with is Techron, run a tank or two of it nothing to lose except ten bucks.

[Laitch]

Here's a pump holder mounting plate. It's tig-welded into position. Using it as a reference, where's your concern?

[Moo Meister]

Darn it, I already put her back together... Sorry.

The issue was inside of the baffle (not sure if that is the right word) where the box walls met the tank. Everything looked normal from the outside, e.g., the top tig welds. Could it have anything to do with the fact that it is an old Eu police tank? 

Also, thanks for the conversion link! I will see what I can find locally for parts. I hate to get rid of her as she is a VERY nice bike. Even at nearly 75k, she looks and runs darn near like new. All the bike needs is a taller seat and a new shaft! (The original is getting on…)

[daveson]

I guess installing the pump from your other brick will solve the hesitation issue. Or a lazier way, swap the tanks.

If the panels that don't line up are near the tank, it might be the police tank.

[Moo Meister]

Daveson -

The side panels most certainly don't line up at the tank, though you're right about the tank being the issue. The bike actually came with the standard tank but I love the look and functionality of the police unit. The tank-top cubby has changed my life... lol 

The primary panel issue is where the side fairing inserts into the radiator cover. I have pushed and pulled on the thing every which way but can’t get them to line up. I know the original owner had some of the fairing resprayed when he installed the tank (that Oklahoma sun is intense…) so I tried sanding down the matting surface just in case but it didn’t help overly much.

[Laitch]

In this case, misalignment is style.

[daveson]

I'm thinking were the screws on the top tightened before the ones on the side, or something is in contact with the panels before the panels are tightened.

[Moo Meister]

Ah! I'll pull out the knee bashers - uh, I mean pads... - this week and loosen everything. Hopefully that will allow me to shift stuff around a bit. Thank you!

[Moo Meister]

And Laitch - If panel misalignment is style, my wife's Can-AM Spyder is remarkably stylish...