DT 40 1995 Fresh rebuild questions...

[Rum Runner]

I just rebuilt my DT40 , new pistons, rings, bored/honed cylinders, planed flat surfaces, all new seals/gskts. Is there any thing I should do with the Oil Inj system before running. what is the proper way of setting the timing. and what would be the best way to break in the eng. And the big question oil inj. or premix . The eng was rebuilt as it had a scuffed piston, I was told the thermostat had stuck and was the reason for eng failure....... many thanks for your input...

[Solarman]

Timing is controlled by the gear counting coil, pulse coil(s), and computer module. Each of the coils have to be mounted in their proper position, per the manual, otherwise they do not read correctly.
The manual should tell you how to bleed the oil system.
For proper break-in, or anytime i work on the oil injection system, I usually run 25-1 premix, until I am certain the oil level is dropping normally (I have twin motors, and can measure if level drops the same). After a rebuild, I would run easy (max of 3500 rpms) for 12 hours, on the premix, to allow the rings to seat properly. After the 12 hours, I go to 50-1 premix (max of 4500 rpms) for at least 4 more hours, and if level of oil in tank is dropping normally (oil system seems to work normally), then go to straight gas. After that, pay attention to the tach, most 2 stroke motors should not exceed 5500 - 5600 rpms. If rpms are going over that, you should re-prop properly to bring rpms down.

Good luck, post back if need to. Happy boating.

[Rum Runner]

Thanks Solarman for sticking with me, I want to do this right and start the boating season on an up beat..
When I rebuilt the eng. I removed the oil pump left all the lines on. laid it on the bench , a fair bit of oil ran out. I think I would like to empty all the oil out of the tank, and flush everything out with diesel fuel or what ever you'd recommend,is there an oil filter inline or just the sensor. Refill the lines , reinstall all components , get the eng. running on 25:1 mix and do a oil inj. pump flow test.
Is there any thing else you would recommend I do or change. Once I get out on the water I can do the break in as you have suggested. I have the manual but I value opinions from ppl like your self that have years of experience ...... Thanks again Solarman..This eng failed with a scuffed piston,( thermostat stuck) it may have set for 1 yr before I bought it, to rebuild.

[Solarman]

I believe the sensor/ flow-switch, is also the oil filter. If you're flushing with diesel then might be good to replace the filter/flow sensor. Once new oil is in, bleed the air out per manual.

Good luck.