3 replies to this topic

[Shooter63]

A nice techie one here
I'm in the early stages of the conversion, ie got the head, block, crank etc
But something has been bugging me for ages, the sc components book etc always states that the original injectors will be ok but when you use an injector size calculator things don't add up. If you are aiming for 120bhp at the crank which seems sensible and using the recommended 80% duty cycle on the injectors you will need about 177cc injectors, the Bmw ones top out at 140 odd cc to get these injectors close to 120bhp you will need to run the Beemer ones at 100% duty cycle really isn't good or safe, so I'm thinking people are leaving a few bhp at the top end on the table or running the injectors way out of the safety area, what are people's thoughts?

Shooter

[Bat]

Hi,

What fuel pressure are you using to work this out?

What pressure does the bmw run at?

Failing that someone who knows may be along shortly!

Cheers 

[Sprocket]

The original injectors can still be used, but I’m sure they will be passed their best. They will for sure require cleaning and flow testing. It might be a safer bet to replace them anyway with a more modern injector anyway.

It all depends what model motorcycle you’ve taken them from as BMW used a 2.5bar pressure regulator on some, I know the k100’s for sure but cannot remember about the k1100’s and I seem to recall the K1200’s were maybe 3.5 bar

[Shooter63]

The calculation was based on 3 bar pressure, less pressure would make the problem worse, I'll just put some 250cc injectors in to play it safe.

Shooter