Is there a vacuum I can pull from a 1984 YT125 to run a pulse fuel pump. Dont ask why- I have aquried a Suzuki 185 quad with a Yamaha 125 in it. It actuall looks and runs good just need to get a functional fuel tank. The fuel from a stock 125 is gravity fed. The suzuki had a pump that pulled it to carb. There is no decent way to put a tank on top like the yamaha. So tank has to go elsewhere like a stock suzuki. I wanted to know if anyone knew if there was a place to pull vacuum from the 125 to run a pump. Thanks alot - everyone on here has been great help in the past.

 

All the two strokes I have worked with pull a vac from the crankcase below the piston. Your only other choice would be to pull it from the intake boot between the carb and reeds. You could drill a small hole in the boot and thread/epoxy a fitting in for a vac line. A problem you might run into is the fact that you need a pumping action to run the fuel pump and not just a solid vac. The intake/pumping in the crankcase is perfect for this but I have a feeling the vac from the intake boot might become too flat at higher revs. I could be wrong on this, I have never tried it. Also, the motor only makes 6V DC so running an electric pump is out of the question.

 

Thanks for th info. I was looking at that very same place. However this 125 had oil injection (which is plugged off) I hooked a pulse pump to the oil injection line that is right infront of the boot and seemed to work. Did notice a little fuel going int the line. Also- I think I would need a primer when you first start it like an outboard or my jetski. What do you think?

 

I have had her running great all weeknd on jack stands. I attached a outboard motor pulse pump to the line where the stock oil pump dumps into the carb right before the intake- it draws great vacuum. Now i just have to mount a tank.

PROBLEM NOW_ no forward gears- it workd fine last week. I need to learn more about the Yam. 125 I think maybe i put too much oil in it? Dont know where the level is supposed to be? shifts fine just wont go now? I am trying to find a book at the library. Can anyone advise? thanks again....

 

If the motor seems to rev freely in gear I would first try playing with the automatic clutch adjustment.

I have not worked on a YT125 before.. I'm going to be telling you what I think is the correct way to adjust the clutch based off the part images on yamaha's website. If you can find a shop manual I would use it.

I have an image below off the Yamaha parts website. I will use the part numbers on it to explain what to do.

The clutch setup on the YT is kind of weird looking at first. The image below shows your shifter (#25, #24) on the left side of the motor (right side of the image). When you shift the foot lever it turns shaft #5. Shaft #5 turns the crane looking part #1 near the top right of the image. That locks into your shft drum and changes your gears (not on on the picture) Lever #21 near the top left is also turned when you shift. #21 moving causes part #16 and #18 to twist on eachother and it will disenguage the clutch when shifting. Parts #20 (top left) are the adustment/lock nuts for the clutch. This is all on the clutch side of the motor. When the shifter is idle, shaft #19 should letting the springs do their job of forcing the plates together. You should be able to adjust #19 once the nuts are lose. The adjustment should be on outside of the clutch cover.

 

Thanks for the heads up. I found the problem - 2 actually - I had put way too much oil in so plates were covered. Also when I took all apart to clean noticed he had the circlip on wrong. All working great jumps into gear and shifts fine. Question: since I am premixing and the oil pump is gone do I really need to put oil in it? with case off noticed that nothing is in oil? Also what is the little area for antifreeze for it does not go anywhere to cool? Am i supposed to fill it? The Fuel pump I have added to get gas to carb. is working ok- finding that wide open may be starving a little- I need to look into the specific outputs on different pumps. Thanks again- Have a Great Holiday Weekend- Be SAFE

 

Thanks for the heads up. I found the problem - 2 actually - I had put way too much oil in so plates were covered. Also when I took all apart to clean noticed he had the circlip on wrong. All working great jumps into gear and shifts fine. Question: since I am premixing and the oil pump is gone do I really need to put oil in it? with case off noticed that nothing is in oil? Also what is the little area for antifreeze for it does not go anywhere to cool? Am i supposed to fill it? The Fuel pump I have added to get gas to carb. is working ok- finding that wide open may be starving a little- I need to look into the specific outputs on different pumps. Thanks again- Have a Great Holiday Weekend- Be SAFE

 

Yes, you still need to put oil in motor itself. The oil is needed for the transmission gears. The oil pump cover will not have oil behind it and most of the time the stator cover won't either. Some motors run oil with the stator and others don't. Also, i'm not sure what tank you are talking about. It might be the old 2 stroke oil tank or some tank the last owner(s) rigged up for something else.


By the way.. I totally overlooked the fact that you said you put oil in. I kind of went overboard with the clutch adjustment post. The motor most have almost been filled to the top with oil.. beats none at all. As for checking the oil there are a few ways they use to do it on them old 2 strokes.. Some had a little glass window on the lower side of the motor. Others used a dipstick that came in the bike's toolkit or attached to the cap. Some had a oil check screw or bolt that you would unscrew when fill the motor until oil started to come out.