Internal Oil pump leak?

[SkidMark]

Ok so ever since I have had my AR for the first 2-3 km I ride it if I give it a good bit of throttle then it bogs down for a second and then seems to 'pull through' and rev freely. After a few k's it seems to 'clear' and perform as you would expect.

Last night I pulled off the output line from the oil pump, attached a short piece of hose (4in) and put a container under it suspecting that oil was leaking through the pump even when the throttle was closed. Well, the next morning I checked the container and it was dry so I thought, bummer, that isn't the prob. Then when I took the short hose off I blew through it and some oil was inside it:

Although this was a relatively small amount (over one night) it can be a couple of weeks between rides sometimes and so this could be fair amount of oil sitting in the carb inlet.

Oil pump adjustment is set per book.
Carb just recently stripped, new jets, seals etc.
Bike always starts first or second kick.

So,
Do you think this would be my problem?
Any other ideas?
Anyone 'fixed' an oil pump before and know what is likely to have broken/worn inside it? (Parts book does not show individual parts for the pump)
When I remove the oil pump do I need to drain gearbox? (looks like I do)

Thanks in advance for your wisdom!

Regards
SkidMark

[knackeredMk1]

I think maybe you are worrying more than you should. I find my Mk1 tends to 'bog' when you give it some beans after you have been warming the engine through in just the same manner as you. Once it's cleared out it runs fine. I put it down to running a bit rich on the pilot jet and the engine not giving complete combustion until it is warmed through.

You could try leaning it a bit but I would always err on the side of being too rich than too lean.

If the oil pump was leaking as your test would suggest the tank would be empty after a couple of weeks.

[delvey91]

Yep mines exactly the same, even if yopu leave it idleing for 5 mins or so it still takes about a mile before it will rev cleanly. Just keep in under 5k revs for the first few miles then go for it flat out

[Gammakeith]

Other 2 strokes (eg my RG500) have check valves in the carb bodies that can leak and can cause oil build-up in the engine/carb float. It is possible that the check valve in your oil pump is failing but the symptom will be clouds of very thick smoke on startup and for the first few miles (particularly after a long period of non-use). A small amount of oil is not a cause for concern though. My AR seems to rev cleanly from cold so it might be worth another check of the carb and jetting? Try moving your needle a notch to see how things change. 2Ts can be very sensitive to the needle setting.
Keith

[fallenmikethebike]

Other 2 strokes (eg my RG500) have check valves in the carb bodies that can leak and can cause oil build-up in the engine/carb float. It is possible that the check valve in your oil pump is failing but the symptom will be clouds of very thick smoke on startup and for the first few miles (particularly after a long period of non-use). A small amount of oil is not a cause for concern though. My AR seems to rev cleanly from cold so it might be worth another check of the carb and jetting? Try moving your needle a notch to see how things change. 2Ts can be very sensitive to the needle setting.
Keith

A.R. non moveable?
Mike

[fallenmikethebike]

I think maybe you are worrying more than you should. I find my Mk1 tends to 'bog' when you give it some beans after you have been warming the engine through in just the same manner as you. Once it's cleared out it runs fine. I put it down to running a bit rich on the pilot jet and the engine not giving complete combustion until it is warmed through.

You could try leaning it a bit but I would always err on the side of being too rich than too lean.

If the oil pump was leaking as your test would suggest the tank would be empty after a couple of weeks.

+1
Mike

[SkidMark]

Other 2 strokes (eg my RG500) have check valves in the carb bodies that can leak and can cause oil build-up in the engine/carb float. It is possible that the check valve in your oil pump is failing but the symptom will be clouds of very thick smoke on startup and for the first few miles (particularly after a long period of non-use). A small amount of oil is not a cause for concern though. My AR seems to rev cleanly from cold so it might be worth another check of the carb and jetting? Try moving your needle a notch to see how things change. 2Ts can be very sensitive to the needle setting.
Keith

When I removed the carb I remember now that the intake between the filter and reeds was oily. There is no check valve on the AR's - but I guess there is nothing to stop me fitting one inline in the oil pump outlet hose.
I do get a lot of thick smoke on start up and until the bike 'clears' itself. Part of my problem is that as soon as I leave my house I have to go up two pretty steep hills so keeping the bike at low rpms isn't practical.

Re - needle adjustment - the AR's needle is not adjustable.

Thanks for the advice everyone I may pull the oil pump and check it out, and test whether it passes oil when closed (more for the fun of it than anything) - otherwise does anyone have a part number for an inline check valve?

Regards
SkidMark