hey guys, yet another thread! i have see posts saying to get rid of the oil pump, all one has to do is remove the plastic gear, and you will be done. (587 yellow motor btw) however, my question is how MUCH oil pump related stuff can i remove safely? the reason i am asking this is because the brass worm gear on the oil pump shaft had a tooth shear off which went up into the pump itself, and severely mangled the flat half circle disc thingie. so i am wondering if i can remove the shaft with the brass worm gear, and the flat half circle metal plate thingie as well? if my descriptions arent good enough i can attach a parts list and point out which parts i am looking for. thanks in advance for the help!
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oil pump removal (going to pre-mix)
- Thread starter Gnommad
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Linescreamer
New Member
If you are talking about the metal rotary valve that is splined to the shaft in the center be carefull. Putting in back on wrong will change the engine timming. It sounds like you need to get a manual on line and do some reading and looking at the pictures. Do you have the oil pump block off kit with instructions? It's hard to tell what parts you are talking about. Yeah, picks would help. :thumbsup:
ok, the brass gear which had a tooth shear off is this 
and the flat metal half circle thingie is this 
since i am planning on switching to premix, i am almost certan i can remove the brass gear, but what i really need to know is if i can remove the second part (half circle flat metal thingie) because that is severely scraped/damaged
and the flat metal half circle thingie is this since i am planning on switching to premix, i am almost certan i can remove the brass gear, but what i really need to know is if i can remove the second part (half circle flat metal thingie) because that is severely scraped/damaged
ocod
Well-Known Member
Negative.
You need gear to time open and closing of intake ports with the flat half moon RV
ocod
Well-Known Member
Combustion.....
http://www.seadooforum.com/showthread.php?25229-How-a-Two-Stroke-Engine-Works
Oil pump was to inject oil into intake track.
RV gear inside case still needs oil.
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i understand how a 2cycle engine works (altho i did like looking at the moving pictures!) i guess i just dont see where the half moon plate comes into play, when the piston is up, the path for the fuel/air mixture is blocked by the piston itself, when the piston is down, it needs the fuel/air, makes the half moon plate seem kind of redundant, or am i completely missing something obvious.
p.s. please note, i am not arguing with you, i am just trying to understand how this works, i have taken the carbs off my bike, and never saw anything like the half moon plate *shrug*
p.s. please note, i am not arguing with you, i am just trying to understand how this works, i have taken the carbs off my bike, and never saw anything like the half moon plate *shrug*
Strizzo
Well-Known Member
The rotary valve does the job of the reed valve in that animation. You said the ger sheared a tooth and was caught in the plate, it sounds more serious than just the oil pump. If that gear sheared off, the rotary valve (half moon plate) won't turn,and your motor won't start.
:agree: Yes, you will need to replace the rotary valve gear and time the rotary valve. If you get rid of the oil pump you will need to leave the oil tank in the ski and leave about 1/4 tank of oil, leave the oil line from the tank to the rotary valve gear connected and also the return line back to the tank. You can remove the oil pump or remove the nylon gear on the oil pump and block off the injectors under the carb.
Lou
Lou
If you are familiar with how 2 strokes work, then you understand there has to be some type of backflow preventer to keep the intake charge from just being pushed back out the carb as the piston is coming back down in the bore. As the piston decends, it pressurizes the crankcase and as the intake ports are uncovered the intake charge rushes into the cylinder. If there was not a rotary valve or reed valve to block off the carb opening during the pistons decent, it would just push the fuel charge right back out the carb.
Dr Honda
Well-Known Member
Linescreamer
New Member
You maybe getting in over your head on this repair. Is the rotary valve is good condition? Is there any scoring on the block? If you pulled the rotary valve off, cleaned out and removed all the oil pump parts, you will need to follow all oil block off proceedures, and time the engine when reinstalling the valve with a degree wheel.
I just edited this after re-reading your post. You may need a new block and based on the damage to the rotary valve you probably need to replace it. Pictures of the rotary valve and the surface of the block where the splined shaft comes through would help.
I just edited this after re-reading your post. You may need a new block and based on the damage to the rotary valve you probably need to replace it. Pictures of the rotary valve and the surface of the block where the splined shaft comes through would help.
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ok, let me make sure i understand all the terms correctly, the rotary valve = the half moon plate = the flat piece of metal in the rough shape of a half circle which fits onto the end of a shaft with teeth on it? and we are saying that even with blocking off the oil pump (but still leaving lines attached to the oil tank for to lube the bottom of the motor) we still need the rotary valve in place to prevent blowback into the carb. this makes sence to me. the valve itself is fine, however the housing that the valve is in is pretty grooved (dont have pictures with me) so i will work on getting them smooth again. also i marked the gear and valve when i removed the rotary valve, but if i also need to replace the rotary valve gear (brass worm gear) then marking the rotary valve is probably useless as once i remove the shaft the timing will be lost. sound about right?
Linescreamer
New Member
I think you're getting it. :thumbsup:
Linescreamer
New Member
Some parts are better bought new. Try Jetking for used parts.
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