Premix or oil pump or both?

[dyrberg123]

Hi Guys,

I have had many considerations the last weeks about this subject, and for many reasons.. Firs of all because i am running flatslide pwk keihin carbs on my T350, so it is a bid hard to set the oilpump lever correct, as that normally is done by looking for the dots on the slides and the alignment of the marks on the lever.

Next reason is the if the carbs needs to be rejettet that must also have an effect on the mixture

Then this evening i stumbled over an original SUZUKI bulletin on what to do to a T20 and T250 to prepare it for roadracing, and that includes port changes, chambers with drawings and other carbs etc. Then at the end of the bulletin they suggest for race, that you run premix, and block off the oil lines going to the cylinders, leaving the crank bearings oil lines as they are and fix the oilpump lever in the idle position, only oiling the mainbearings.

Is there any shortcuts to see how much oil my pumps delivers, or do i have to make 2 auxilary tanks one for fuel and one for oil to figure out where i am? Otherwise the Suzuki suggested mod could also be a neat trick.

[dyrberg123]

Anyone with experience in this?

[yeadon_m]

I don't know the answers but would prefer the certainty of throttle linked pump oil injection to upper cylinder than to rely on premix. I'd set the pump arm so that marks match when at half throttle and see what it's like to ride. I think these road bikes were way over oiled in the top end anyway so provided the pump is working it probably isn't so critical how you set the pump.
My worthless opinion anyway
Mike

[old racer]

If this is for road use leave the setup as it is,Pump off the throttle,
If it's for racing, then you can fix the pump at a low setting, with pre-mix in the tank.

[Vintageman]

dyrberg123,

I think there is also a notch on pump arm that shows what pump should be at when the slack is just removed out of the cable thus still at idle. Then at WOT you should pass the mark that was intended for the slide dot aligning. Isn't there three notches on the arm? Idle no slack, Slide Dot, and WOT (I'll check tonight)?

I don't know and easy way to check flow rate.


There are several other articles from other mfg that state to run oil with gas along with injection when running hard/modified... I have seen some as rich as 15:1 and many are 20:1.

What I have learned painfully if you run higher rpms or IF YOU ARE TOO RICH ( you may not know it, runs OK) you will ruin your top end due to lack of oil = oil wash out from fuel very very quickly.

What did you settle on for Ex Height change and intake port change.

I decided to pull my T305 (33.3 mm Ex Height per factory) and shoot for maybe 31.3mm

[GT750Battleship]

Hi,I don't know weather this oil flow meter is still available from Suzuki GB....Part Number 09900-21602 $37:00 US dollars
Cheers,
Roger

[dyrberg123]

Hi Guys - thanks for your reply..

I will search for the nots, and try to look into whats going on.

Ex height is now raised 2,5mm and the intake lowered the same, then i run Kawasaki H1 squish modified heads and DG chambers with new stingers and Cans.

[tz375]

If the pump is OK I would just use it. With a new motor I tend to play safe and add oil to the first tank of gas until I know that the pump is pumping. That's probably a waste of time with the GT750 crank design and I jet rich just to be safe too and work down to the right settings.

To check flow rates, set the pump up on a simple jig and spin it with an electric drill. Check the oil flow from each hose by placing each hose end into a small graduated cylinder or container - use identical containers for all lines and compare output over 60 seconds at low and high settings.

The amount of oil is usually really small.

FYI Kawasaki inject oil into the carb float bowl and Yamaha twins put it into the side of the inlet tract.

[dyrberg123]

Thanks TZ.

The yamaha's i have are running premix now, and even with the pump on these you are right, it is injected into the carbs. How come Suzukis aren't kean to run on premix, main crank bearing wise?

As for the pump, i also need to meassure the fuel consumption to figure a ratio out, i might take the tank off and make two graduated tanks, a one ltr for fuel, and a way smaller for oil. But my guess is that it is on more than 25:1.

I am going to add a Little oil when i fired it up hopefully NeXT week... 50:1 just to be safe..

Cheers

[GT750Battleship]

Hi,don't forget that adding a "little" oil to the petrol,could make the thing run "lean" ?
Cheers,
Roger

[dyrberg123]

Hi,don't forget that adding a "little" oil to the petrol,could make the thing run "lean" ?
Cheers,
Roger

Hi

Yes that was also what i planned to do, 50:1 just to be safe...