Hello everyone! I have finally decided to get my K100 out of storage and start to build it. I am coming from 70s CBs, so this whole EFI thing is a bit foreign to me. I want to go through the drivetrain and make sure that everything is up to snuff, as well as get comfortable with the system itself. What sort of EFI specific checks should I do. Or really just any general items that I should look at with these bikes?

Thanks!

Hi welcome 

It depends on how long your brick has sat, and if it was stored with ethanol blended fuel. 

It can seem intimidating when you switch to fuel injection systems. Actually they're probably more reliable and less maintenance, maybe cause less moving parts. 

You probably don't have to do anything on the fuel injection side of things. As an example one of my bricks sat for five years unused with ethanol free fuel. I changed fluids, replaced a faulty starter relay and it started within seconds. Another one sat for ten years, it needed a new pump, fuel filter, injectors, and EFI computer. With the help of this forum, you can probably fix all your issues without replacement. 

Good luck with it.

daveyson wrote:Hi welcome 

It depends on how long your brick has sat, and if it was stored with ethanol blended fuel. 

It can seem intimidating when you switch to fuel injection systems. Actually they're probably more reliable and less maintenance, maybe cause less moving parts. 

You probably don't have to do anything on the fuel injection side of things. As an example one of my bricks sat for five years unused with ethanol free fuel. I changed fluids, replaced a faulty starter relay and it started within seconds. Another one sat for ten years, it needed a new pump, fuel filter, injectors, and EFI computer. With the help of this forum, you can probably fix all your issues without replacement. 

Good luck with it.

I honestly have no idea how long it has sat. I have personally owned it for 2 years now, but I am not sure what its life was like before me. It is just the drivetrain and computer. I picked up wheels and a frame today. Was planning on taking it apart, giving everything a nice clean. And reassembling. Is it okay to clean injectors in a ultrasonic cleaner?

Thank you for the quick response!

I haven't cleaned them, but there are threads here about it. I went to the junk yard and got injectors from a six cylinder BMW car that worked. I think injectors from a Hyundai worked too, it was a '97 Excel model.

Workshop manuals and coloured wiring diagrams, available on this forum, were a big help for me. 

If you're able to contact the previous owners, I'd ask as much as possible about its history.

daveyson wrote:I haven't cleaned them, but there are threads here about it. I went to the junk yard and got injectors from a six cylinder BMW car that worked. I think injectors from a Hyundai worked too, it was a '97 model, I think it was a Lantra model.

Workshop manuals and coloured wiring diagrams, available on this forum, we're a big help for me. 

If you're able to contact the previous owners, I'd ask as much as possible about its history.

Alright! Thats actually really nice that normal car injectors will fit. I did not know that was the case!

Thank you very much for your help!

If your junk yard has a web site, you probably want to check first, that model BMW probably doesn't pop up often, cause it was a 1983 520i. I'm sure that injector and part number will be on other models too, from that era. On the net I found a chart comparing it to brick injectors and they were virtually identical. The part numbers are;

0 280 150 208: BMW 520i
0 280 150 210: Brick

daveyson wrote:If your junk yard has a web site, you probably want to check first, that model BMW probably doesn't pop up often, cause it was a 1983 520i. I'm sure that injector and part number will be on other models too, from that era. On the net I found a chart comparing it to brick injectors and they were virtually identical. The part numbers are;

0 280 150 208: BMW 520i
0 280 150 210: Brick

Cool! I have been doing a lot of research today. Sounds like I need to find out how many valves the drivetrain I have has!

I really appreciate your help!

You might have an engine number under the oil filler cap. 

On mine it's 104EA 4785 2099. The second set of numbers means it was built on the 47th week of 1985, which also means it's a two valve design.

The Vin number on the frame will reveal its year too. You need two computers, the fuel injection computer which I think you have, and the Ignition Control Unit, on the frame under the tank.

Start your research by going to realoem.com and enter the last 7 digits of your VIN. You will find production dates and all the parts info you need with diagrams, part numbers and most handy is the parts compatibility with other models. Handy if you're sourcing secondhand parts.
If sourcing parts off ebay for example, you can't rely on the vendor's description. You need the oem part numbers to ensure you're geting the right part for your machine.


Finding suitable aftermarket injectors is difficult. Don't believe vendors that tell you theirs are an upgrade.... that's very doubtful. The Bosch #210 injector was specifically made for the K100 2v. They've been unavailable for a long time and they're now as scarce as hens teeth. It bothers me that some guys chuck them in the bin to install so called upgrade injectors. If looked after they have a life of around 400,000 miles and probably even much more. They're real easy to clean with a can of injector/carby cleaner and an attachment like this...
https://www.ebay.com.au/itm/153787862990?hash=item23ce788fce:g:QAMAAOSwQ4ReE9MW&frcectupt=true
Or take them to a professional injector cleaning service.

0 280 150 208: BMW 520i .... This one is very close in specs to the oem #210
0 280 150 210: Brick

Comprehensive info on everything about the K can be found here.
http://www.kforum-tech.com/

I looked into doing a four hole injector upgrade many years ago. A mates son who was an injector specialist at the time looked into it. The single hole injector was designed to spray onto the back of the inlet valve and therefore cool it, four hole injectors will not be as effective. (See picture) If 4 hole injectors are so superior to the single hole injectors why is there no dyno comparisons, and I've looked. Seat of pants dynos are not valid as cleaning your single hole injectors will probably give you a similar boost if the are dirty. A few guys that did report seat of pants boost also reported higher fuel consumption. The chance of blockages in a 4 hole injector is greater than the single hole injector.
Regards Martin.

MartinW wrote:I looked into doing a four hole injector upgrade many years ago. A mates son who was an injector specialist at the time looked into it. The single hole injector was designed to spray onto the back of the inlet valve and therefore cool it, four hole injectors will not be as effective. (See picture) If 4 hole injectors are so superior to the single hole injectors why is there no dyno comparisons, and I've looked. Seat of pants dynos are not valid as cleaning your single hole injectors will probably give you a similar boost if the are dirty. A few guys that did report seat of pants boost also reported higher fuel consumption. The chance of blockages in a 4 hole injector is greater than the single hole injector.
Regards Martin.

+1 A while back I put a set of aftermarket "replacement" injectors in a K100RS I was restoring. They made it hard to start and it ran like crap. A set of used injectors replaced them after I cleaned them with the above fixture and carb cleaner. The bike starts and runs much better wth them.

I'm skeptical of the four hole injectors. The four orifices are 1/2 the size of the standard injectors so in my feeble mind they are at least twice as likely to clog up and have spray pattern issues.