Fuel Injector Upgrade & Compatibility

[triplek]

I've been searching and reading for quite a few months now and although I find enough hints to keep me certain the info exists, I simply can't find it.

Simple idea: What specific Bosch fuel injector model # is a suitable 4 jet upgrade for an original single jet K Bike?

My end goal is to look up which vehicles cross reference to the part number and then pull, clean, check and rebuild a set. I personally view rebuilt Bosch as both just as good as new and infinitely better than anything not Bosch made.

I can follow some bread crumbs discussing the various flow rates and pressure pressure regulation, butt dyno results and general happiness of general injector upgrades from 2007, 2009, 2011, 2017...etc, but nothing definitive. 

Is there an ideal Bosch part number for a stock K?  There are just too many Bosch possibilities for me to process and work out which one to look for. Over my head, for sure.

[frankenduck]

The stock number is printed on the side: 280150210

I've tried the 280150415 four hole injectors on both 2 and 4 valve Ks with no noticeable difference. I now just stick with the factory FIs and get them serviced at https://www.mrinjector.us/

[Martin]

A mates son who worked for an injector specialist had a look at my mates bike and stated it was a waste of money. The single hole injectors are a narrow angle and designed to spray on the back of the inlet valve. They are designed to cool the inlet valve and atomise when they hit the head of the valve. Some members have reported no performance increase and a higher fuel consumption.
Regards Martin.

Cutaway K Engine Injector angle .jpg.png (59.96 kB . 768x568 - viewed 1106 times)

[The Mighty Gryphon]

Can anyone tell me why the people who are selling four hole injectors have never done an actual dyno run with their injectors to back up their claims of improved performance?   

[frankenduck]

I make no claims that my butt dyno is any better or worse than anybody else's but I've got 100s of thousands of miles on dozens of Ks and the four hole injectors register a big fat zero on my butt dyno. I've tried them on both a K75 and a K1100. Are they any better or worse than stock FIs? I don't think so.

It's been a while but in the past I spent an inordinate amount of time researching this. It seems that the Jeep crowd is very into this but I could never find any REAL dyno results to substantiate the claims about how wonderful four hole injectors are.

And think about it. The FIs are are injecting fuel BEHIND the valves, not into the cylinder, where the fuel will also get atomized anyhow by the heat of the metal engine parts.

In the last 20+ years the only thing I've found that really improves the butt dyno performance of a K75 is Luftmeister high performance cams that really seem to help at lower RPMs.

Reality: The K75 is a heavy old turd designed in the early 80s. (Still great bikes though. Six of my eleven K bikes are K75s.) If you want to go faster then buy a CBR600.

JM02.

[Martin]

I had a significant increase in performance by cleaning my injectors. When riders say that they had an improvement in performance when they fitted 4 hole injectors. They would have probably have gotten a better performance by getting the old 1 hole ones cleaned.
Regards Martin.

[The Mighty Gryphon]

I had a significant increase in performance by cleaning my injectors. When riders say that they had an improvement in performance when they fitted 4 hole injectors. They would have probably have gotten a better performance by getting the old 1 hole ones cleaned.
Regards Martin.

This is the reason Jo so strongly recommends regular doses of Techron and an Italian tune up.

[stokester]

I've had two sets rebuilt by Mr Injector - highly recommended.