In fitting K1100 TB's to my K100, the second hand K1100 TB's I obtained came complete with an attached fuel pressure regulator which is a different type to the one already fitted to my K100. The K1100 FPR doesn't require the vacuum feed from the end throttle body so is it possible to fit it in place of my standard K100 one?? Its purely for cosmetics as the K1100 FPR looks fairly new against the hand painted tar finish (not by me) of my K100 one

I was also curious as to why the K1100 FPR doesn't require a vacuum feed but the K100 one does?

Cheers

Fent

Does it?



and pressure is 35PSI as required.

I think you will find that the Motronic injection runs 3 bar pressure where the L Jetronic runs 2.5 bar so you would run rich because the pressure would be too high.

klompy what can I tell you? my 1984 K100 has a vacuum feed to the FPR, maybe later versions are different??

Rick G, I hadn't considered that there might be a pressure differential between the two types. Oh well it was just a thought and maybe something I can reconsider if the bigger TB's produce lean results.

Thanks both

Fent

Don't forget you're talking about different systems of FI. The L-Jetronic only gets info about the fuel demand from the AMM. The Motronic system gets it from the TPS (or at least has that signal to work with as well). My understanding is that the vacuum line is there to ensure the pressure of fuel injected is constant relative to the pressure in the TB's to allow for correct atomisation (ie have the injectors work optimal).
The bike will run without it, but not as intended. Its a bit like taking the TPS off on the earlier bikes. They can run great, but your missing some of the intended features.