Zuma 50 2T oil injection woes

[silver03zuma]

Hi, my 03 50 2T has just an expansion pipe and rollers. Trying to keep oil injection. It leaks oil and is hard to start and smokes a lot. After riding and it sits for a few hours, the oil pooling starts again underneath onto the ground. Hard to pinpoint where it’s coming from. I go to start and the bike sounds and feels flooded. When it starts It smokes a lot and for a long while. Cranking it over and over again causes the carb to overflow to the ground and it looks like heavy oil presence in the fuel. When i drain the carb bowl i can see oil in the fuel. After draining it starts amazing. And it’s good riding until it sits again for a few hours.

I found a thread that the check valve in the carb could be stuck allowing oil through the carb when it sits. I took the carb off and removed the press fitting and saw the ball bearing and spring. Didn’t look stuck. To test it, I used a new Amazon replacement carb, thinking the OE relief spring or BB could be suspect , and it improved starting very slightly but it still experiences the same symptoms. I am not sold on the aftermarket inline relief valve another user recommended. I am wondering if I crossed cables to carb - throttle and oil injection - and I am activating the oil pump that way. Anyone have pictures of the cables so that i can verify? Also i am wondering if I can adjust the oil injection cable at the throttle and add / remove slack? Any one have experience with that? Finally there are China aftermarket oil pumps on eBay but most people say the stock ones are crazy reliable so I am hoping it’s just another simple solution and I can keep OE. I tried premix as a test leaving all stock oil injection parts in and the problem went away. I am trying to save the oil injection system though. Any help is appreciated!

[silver03zuma]

Doing more research I am adding another possibility. The seals in the oil pump may have gone bad. It sat for months. And somehow that oil is getting past the pump into the crank case and flooding or interfering with start up. Once I get it running and the oil burns away, it runs fine.
I found this video. It’s may be on point. I probably need to take out the oil pump and have a look at it and the seals.

youtu.be/ix25IRby7os

In the video he replaced the whole pump but one of the commenters says there is an O ring behind the gear that can be changed out. Then another commenter says it’s an oil cap seal and he used size 9.5-16-4 but I don’t see that seal in any pictures or diagrams. Just the O ring. Any ideas?

[geoffh]

The oil feed pipe from the pump to carb should only be about 4mm od and will only fit on the small brass spigot on the carb,if its bigger than that it could be your problem.

Geoff

[silver03zuma]

The hose from pump to the carb is OE.
I ordered an aftermarket oil pump and I’m going to swap it out. I’ll keep the original oil pump. Whenever I have time, I will replacing the seals on the original one and maybe replace the aftermarket oil pump back to original with new seals. I also will probably go back to original carb after I’m done cleaning it and reassembling the oil inlet spigot with oil relief check valve .

[ThaiGyro]

Hey silver03...is there a reason you wish to keep the original oil injection? In my world, that is the first and likely most important performance killer to eliminate. They simply suck even on a new scoot. Best test is to block it off and go directly to a "pre-mix" of gas and oil...this will ensure that your mixture has a better consistency.

Many articles here and on other sites. Total tune-ability.

[bigmatthew86]

I would never remove it for a daily driver as the ease of not mixing gas isn’t worth it to me. On my old Zuma the seal had gone bad where the oil level sensor went into the oil tank. When full it would run out there & make its way down to the ground. Might not be your issue but worth looking at if you haven’t.

[Zino]

I bought aweedwacker repair kit at lowes it is the proper size tubing for whne I had to replace the oil hose on the zuma carb

[sinfull]

My opinion has always been to bin the oil injection and go to premix.

Opened way too many 2t that sat and case is almost always full of oil from the pump leaking.

Easier to carry small oil bottle with a squeeze measure than fuss with the oil injection