Yet more TYZ 250 help needed

[izzywithus]

Hi guys,
How does the oil injection work on these bikes?

I know they are gear driven from the waterpump drive but what does the rest of the gear do? Why is it wired into the loom?

Finally how do I check to see if is working correctly?

Thanks

Iain

[David Lahey]

The (competition model) TY250Zs sold here did not have oil injection so all I am going by is a photo you posted a few months ago that shows the RH side of the bike that shows a small squarish bump above/behind the water pump. If it is an oil injection pump and there is no connection with the throttle cable (ie only electric cables) then the reason for the electric cables is probably to control the output rate of the pump. Yamaha did some pretty tricky things with two strokes during the 1990s such as the electrically positioned power valve on the WR200R and DT200R so it wouldn't surprise me what they did with oil injection pumps. Road rego two-stroke Yamahas usually have an oil injection pump that is rate-controlled by motor RPM and throttle position, but not involving electrical control, both inputs being mechanical.
Are you certain the pump is for motor oil injection and not something else such as to run a pump to lube the chain while riding along? (James Bond feature that allows the rider to cause the baddies following him to crash)
Can you post pictures showing some detail of what the oil injection system looks like?
As far as testing a dosing pump, the old fashioned mechanical/mechanical dosing pumps can be operated by hand to test or prime the system (with the motor stopped).
If there is no way to test the oil injection system without running the motor, you could run the motor on pre-mix and look for a drop in oil tank level with use.

[izzywithus]

Hi David,
Definitely not chain oiler or James Bond gizmo! There is a resevior above the exhaust on the riders left side which feeds a small gear diven pump built into the water pump, this then feeds into a unit mounted below the shock (an oil return pipe comes of here as well) which in turn feeds another unit which is powered from the loom. From this point a pipe feeds into the engine side of the carb.

Pictures to follow in the morning.

Cheers
Iain

[izzywithus]

Oil tank mounted on frame

Water pump and oil pump

I guess that the oil is gravity fed to the engine driven pump then fed to the electric gizmo then metered to the carb and excess oil is pumped back up to the tank.

Is the oil added to the fuel / air mix by the venturi effect via that brass nozzle of the side of the carb?

Cheers
Iain

[David Lahey]

Sounds like you have it sussed out
The little screw on the pump with the red washer under its head looks like a bleed screw.
There must be a tiny venturi effect pulling on the oil because the nozzle ends up as a square edged hole, but the mixing of the oil and fuel mix is caused by turbulence.

[izzywithus]

David, you're right. It is a bleed screw but it into the base of the impeller bowl.
I guess if I run it on pre-mix 50:1 and the oil pump works the only problem will be an oiled plug? The engine has been re-built with a new piston / ring kit plus bottom end, re-conditioned barrel and bearings in the gearbox so I really do not want to mess it up.

From what I have been told and the link David put on his reply last time I think these bikes were designed for the Ihatove Adventure Trial in Japan. For the first time it is being run outside Japan in 2010. So it will be good to try the bike in a trial it was designed for. See link below.

http://www.nonstopadventure.co.nz

Cheers
Iain