The one I went for is the MIKUNI DF44-18 Single Outlet 20 Litres per Hour.Mustang505 wrote:Angelix
what vacuum pump have you fitted from Mikuni?
I got it from Allens Performance who are the UK distributors for Dellorto, Mikuni and Keihin and at the time they confirmed that it was more than adequate for the FCR39s
The original Monster SS vaccum operated pump flows at 16-18 Litres per hour.
Theoretically 20L/h for an engine with 75-80bhp is tight (average comsuption is 230grams of petrol per horse power per hour), so I guess this application would be to the limit if you are racing, however for a normal average use with the occasional full open throttle it is more than enough.
I mentioned this issue to Allens performance, they told me it would be sufficient even for a higher power and FCR41s.
I think I understand the principle, never though of that, and I will test & compare both solutions as I like to experiment.ducinthebay wrote:In general, vacuum pumps are pretty low pressure and fairly low flow. Easily enough for a 750-1000cc twin. Most snowmobiles use them. A "T" in the line will just allow for a more constant pressure and delivery of the gasoline, which is always good.
If you are running a vacuum pump and the FCRs, the floats can probably deal with low pressure adequately, but a "T" will even out the pressure and it should run better. Even if you aren't experiencing any overflow, you may be running a higher float bowl level than anticipated, which will make the bike run richer across the range. The stock pump, on the other hand, will probably overwhelm most any carb with out a "T" in the line.
Cheers,
I am working on the tank right now and it was my intention to remove the return and go straight from the Pump to the FCRs.
At this point I will leave the return fitted and simply add an "in-line" tap so that I can chose to run the set up with the return either open , fully closed or partially closed.