Running lean, getting awful mileage; not sure how to fix. 1994 K75

[breyfogle]

.... How exactly does the choke work?

The "choke" is not really a choke in the traditional sense. It is just a fast idle set. All the handlebar lever does is provide an alternative way to open the TB's a small repeatable amount and hold them open. There is no other computerized enrichment.

 

[toddlamp]

Update....

Tonight I picked up some starter fluid and sprayed it all over the throttle bodies. Sure enough the RPMS picked up.

What is the best way to narrow down the parts that could be leaking?

 

[98lee]

Rubber parts.

Check the two rubber vacuum caps on #1 and #2 cylinder.

Get some carburetor cleaner (like was previously suggested) and use the red spray tube that directs the spray to a small area so you can isolate the problem better.

If it is the rubber manifolds above or below the throttle bodies, replace ALL of them. They are not that expensive compared to the amount of work to get to them.

 

[ted]

That "Falschluft" article walks you through replacing some or all the bits, it really is an excellent tech piece (though the cut and paste to Google Translate can get old...)

 

[toddlamp]

Rubber parts.

Check the two rubber vacuum caps on #1 and #2 cylinder.

Get some carburetor cleaner (like was previously suggested) and use the red spray tube that directs the spray to a small area so you can isolate the problem better.

If it is the rubber manifolds above or below the throttle bodies, replace ALL of them. They are not that expensive compared to the amount of work to get to them.

Sounds good. I'll do that.

That "Falschluft" article walks you through replacing some or all the bits, it really is an excellent tech piece (though the cut and paste to Google Translate can get old...)

What I found out is that you can upload the entire document. When you go to http://translate.google.com, below the text entry box is "translate a document". Only problem is that the translation does not include pictures.

 

[toddlamp]

So I just started to take apart my air box to check the hoses and throttle body tubes and the first thing I saw was the top of the air box. Now I know that there is a bleed valve access hole there but is there supposed to be something plugging the access hole? I don't have anything there. Anyone want to place bets that that was/is my problem?

I'm talking about #5 in the below diagram:

 

[toddlamp]

Actually...the more I think about it that can't be the problem because it is pre-air meter.

I guess I will keep looking.

 

[ted]

It is a frustrating process for sure. Best bet is to replace any of the fault points that look even remotely bad. Remember that the Fi system is very good at compensating for faults and when and if it finally does have problems it could very well be from several things combined rather than one big thing.

Matter of fact, I would be willing to bet that most of the K75 bikes out there have at least one air leak somewhere that isn't enough of a problem to be noticeable, unless someone has gone in and replaced all the rubber and hoses in the last few years.

 

[toddlamp]

It is a frustrating process for sure. Best bet is to replace any of the fault points that look even remotely bad. Remember that the Fi system is very good at compensating for faults and when and if it finally does have problems it could very well be from several things combined rather than one big thing.

Matter of fact, I would be willing to bet that most of the K75 bikes out there have at least one air leak somewhere that isn't enough of a problem to be noticeable, unless someone has gone in and replaced all the rubber and hoses in the last few years.

Thanks Ted.

First off I don't know why BMW discontinued this style layout. I just took about the entire center of my bike with nothing more that a flat head screwdriver. I just want to say that this bike is a joy to work on.

Anyway, I eyeballed the main inlet hose (behind the rad), the crankcase vent host, and the throttle body hoses and have seen nothing obvious. I am going to hit up Bob's on Thursday for the new hoses and work on it this weekend. Thankfully it will be almost 70 here and i'll be riding my EX500.

One thing that I did notice was that there was a large amount (IMO) of oil in the air accumulator. When I removed the crank case hose there was a pretty good stream of oil coming out; enough to soak a paper towel. This may be normal for the K but compared to all the other bike i've ever owed this would be excessive.

 

[toddlamp]

I picked up some throttle body hoses but still need some clamps. I was trying to fine some standard screw clamps but am having trouble locating ones that are thin enough to fit in the recessed areas.

This means that i will most likely replace them with the OEM camps. Problem is I have no idea what tool I need to tighten them down.

Can someone direct me to a place to get the proper crimping tool for the OEM hose clamps?

Thanks.

 

[bmwwrench]

The ideal tool for this job is the plier sold by BMW. It is made by Knipex, so there may be another source than the dealer if they won't get it for you. Since you are so close to Bob's, it would seem easiest to ask them to sell you one. This is a very handy tool anyway, since BMW uses this type of clamp in several locations.

 

[toddlamp]

Thanks for the help. I'll check with them tomorrow

 

[98lee]

Can someone direct me to a place to get the proper crimping tool for the OEM hose clamps?

Thanks.

http://www.summitracing.com/parts/WMR-W83013/ $6.95 I just used it last week. Works PERFECT.

 

[deilenberger]

Ebay or any NAPA dealer. The same sort of clamp (Otieker) are used on CV joints on cars. It is a very common tool, looks like an end-cutting nipper.

http://www.oetiker.com/content.asp?l=4&idNavig=14 - the ones with the red handles - usually can be found on Ebay for $20-30.

http://www.kegkits.com/Merchant2/merchant.mvc?Screen=CTGY&Category_Code=OCLAMP - "clone" ($10) and original ($20)..

http://compare.ebay.com/search/oetiker+clamps?_nkw=oetiker+clamp+tool&_sacat=0&rfn=1 - Ebay, a full page of the tools.

 

[toddlamp]

Thanks guys. I went with the Oetiker Side Jaw Pincers from Amazon. $35 w/overnight shipping.

 

[breyfogle]

Problem is I have no idea what tool I need to tighten them down.

Can someone direct me to a place to get the proper crimping tool for the OEM hose clamps?

Thanks.

The OEM clamps are called "Oediker" clamps. The clamps and the crimpers can be ordered online from McMaster-Carr and many other places.

Your friendly local parts house might carry "CV Boot" pliers, same thing.

 

[deilenberger]

The OEM clamps are called "Oediker" clamps. The clamps and the crimpers can be ordered online from McMaster-Carr and many other places.

Your friendly local parts house might carry "CV Boot" pliers, same thing.

Actually - Oetiker - it's easier to find them if you spell it correctly.. BTDT and learned that lesson..

 

[toddlamp]

I did some more snooping around after replacing the throttle body hoses (since that did not fix the problem)

Turns out it's my injectors not seating properly. I tried over and over again but I just can't get the fuel rail to put enough pressure on the injectors to seal them up.

As for the injectors themselves they are newly reconditioned, clean, stock injectors.

Where do I go from here?

 

[deilenberger]

New O rings on the injectors? Some of the "rebuilding" places do not use BMW's O rings - they use a universal size that doesn't actually fit very well. It's not pressure on the injector that seals it to the head, it's the O ring in a compression fit between the injector body and the walls of the machined recess they fit in.

Willing to bet 1 beer that your O rings are the wrong size. Get three new ones from BMW. That should solve your problem. And this should have turned up with the carb-cleaner test..

 

[toddlamp]

New O rings on the injectors? Some of the "rebuilding" places do not use BMW's O rings - they use a universal size that doesn't actually fit very well. It's not pressure on the injector that seals it to the head, it's the O ring in a compression fit between the injector body and the walls of the machined recess they fit in.

Willing to bet 1 beer that your O rings are the wrong size. Get three new ones from BMW. That should solve your problem. And this should have turned up with the carb-cleaner test..

I will be getting some tomorrow thanks!

This apparently did turn up, I just wasn't looking close enough to see that the carb cleaner was being sucked in. This time around I was looking in the right place.