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O & R Carb Repair Tutorial

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48 minutes ago, Freak said:

A very helpful tutorial. I have  a chainsaw with an O&R engine, and the tutorial was exactly the issue. Forgive me in I cross a line here, Where do I go to find replacement parts?  

Thanks in advance.

:)

 

:WMOM:

Webhead and Wallfish on here have spare parts for these engines as well as the new diaphragms for the carb.

 

David

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Send a PM (private message) to either Webhead or Wallfish to ask about parts, if you need help with anything else other than carb problems with your chainsaw it would be best to start a new thread about it.

 

David

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Zak    0

Hey guys, i'm attempting to do this on my own ohlsson & rice engine i got around 10 years ago ago from a relative back when i when studying automotive in highschool haha, sparks great, compression's good, took off the air intake and had the same disintegrated foam air filter issue - cleaned it the best i could, but its the type that doesn't come apart :(

anyway i'm a bit 50/50 on this - even if the foam is disintegrating, how would it get back into this part of the carburetor?? is it worth taking apart and having a look?? more importantly, if i undo the 3 top screws, will all the springs pop out and the mechanism come apart???

 

All that being said, i finally was able to start it for the first time ever after spraying some fuel down the air intake - though didn't run long since i'm sure its not getting any fuel which is due to either the carburetor, and/or blocked fuel lines (got new ones so hopefully all good) - anyway would you recommend this to a dude who's been out of the automotive game for almost 8 years??? 

 

Also - on the left hand side of the re assembled carburetor/air intake system - what is the purpose of the screw with the spring on it?? - and the 2 holes underneath - for a throttle cable i'm guessing?? - after your engines started in the choke open position, would you only use the small choke to run faster/slower???

 

Many thanks, Zak

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Hi Zak,

 

:WMOM:

Both the single and double air filter have one housing that doesn't come apart.

I usually use the little pick tool (shown in the linked post) or a small screwdriver to poke as much of the old filter foam out using all the holes in the housing. Compressed air can help with the remaining bits, I usually give it a wash with petrol/gas after.

The new foam is then squeezed in through the opening at the back and again poked through the holes at the front to spread it out to fill the housing.

Your carb will probably need to be stripped and cleaned following the procedure at the start of this thread, Old fuel/oil mix tends to gum up all the parts. Take your time, nothing should fly out, but have a tray underneath to catch any small parts if you want.

A new primer diaphragm gasket is usually required for the engine to run at it's best, the old ones usually dry out & crack (Wallfish or Webhead on here have new diaphragms, as well as the check valve gasket if you need them).

 

The screw with the spring of the left of the carb is the idle stop adjustment screw, the holes underneath are used on some tools for the throttle cable.

The small quadrant control on the other side of the carb is used to adjust the governed speed. There are two types of this control, one can be set to any position and the other is moved by lifting the spring loaded washer & has five positions. Early production carbs don't have this control.

 

5980e4afadb83_OhlssonRiceLabela.jpg.9c0bd6e6170f8fd21542562ea57c8d7f.jpg

 

5980e4b65bf94_OhlssonRiceLabelb.jpg.7fd767aefd0f85ab09894475ab990069.jpg

 

David

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Zak    0

Ahhhh sweeet! will give that a try for sure with the air filter :D

 

And ahhh damn....now that i think about it, yeah....should probably do it.... fuel line from fuel tank to carburettor was in pretty bad shape, seemed to be blocked at both ends, also iv'e got  another fuel line that just runs across the fuel tank? (with the one i have the fuel tank is sort of built into the engine you could say - its under the engine/crankcase so gravity will do me no favors it seems.....though as long as iv'e got a clean carb, clean fuel lines,and cylinder compression, that *Should* suck the fuel from the tank into the carb right???

Could i test to see if the carb fuel line hole is clear by poking a small needle through it? or would that penetrate some sort of filter in there....would opening it up and pouring some petrol to see if it leaks out out the port work?? or is it a one way valve? Thanks for the advice on the diaphragms as well!!! will see how they are, rubber air intake gaskets were in surprisingly good shape so hopefully all good :D

 

and ahhhh nope no governor/quadrant control for me, though i have some sort of metal strip/ air vane connected to the cylinder that apparently acts as a governor....think i put it back on the wrong way though after reinstalling the air intake/carb....if i'm right it should be placed on the bottom left of the butterfly valve/throttle- making it closed partially??? 

 

Thanks heaps for the advice:) - this forum is a godsend!!! Haven't worked on Engines for about 8 years now, so a lot to lean/re-learn, but its coming along well....last ones i worked on back in highschool were the small single cylinder 4 stroke's, and then the big 4 cylinder holden engines (though we had A LOT of instructor guidance for them haha!)

anyway hopefully i can work on the carb one of these mornings before doing afternoon shift, would love to give it an entire weekend to work on, but never easy when have the girlfriend to deal with!!! haha 

 

 

btw not carb related, but could i theoretically clean/flush out the crankcase/ cylinder by overloading it with the gas/oil mix while the air intake and cylinder are removed, and then turning the crank?? good or bad idea??? need to see more vids/pics, but cylinder/exhaust assembly seems to just be able to be unscrewed after taking off the starter??? just a bit cautious of having to disassemble/reassemble the entire crankcase/piston assembly....plus theres the coil and electrical system which i don't even want to mess with since it still works haha 

 

 

Many thanks again!!! :D  

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See the linked post for checking the carb inlet, there is a one-way ball valve inside the diaphragm chamber.

It's best to disassemble and clean all the parts of the carb using either clean fuel or carb cleaner.

 

The air vane fits inside the shaft of the butterfly valve (left side of carb), here is a picture I took earlier. The butterfly valve will be open normally, it closes when the blade part above the flywheel moves up with increasing air flow.

 

SAM_19451a.jpg.adf052c36333a122570f5022aa13f299.jpg

 

There shouldn't be any need to clean the crankcase with the cylinder removed unless there are bits of the old air filter inside (these would be visible inside the carb & induction housing), I would follow the engine rebuild thread if you have this problem, which is caused by running the engine without removing the old disintegrating foam.

There is a special tool that fits the slot in the top of the cylinder for unscrewing it, you will need to replace the exhaust collector gaskets if you need to remove the cylinder for de-carbonising, they tend to leak if you don't replace them.

See the last post in the engine rebuild thread for a details of the cylinder removal tool.

 

Taking pictures as you dissemble things will help when you put it back together, I always take more than I need to and not just with engines (vintage electronics is my other hobby).

 

David

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Zak    0

Ahhh i see.....carb cleaner and fuel it will be then :) - safe for all the metals in the carb/engine right??? heard that stuff can damage/eat away at plastics or gaskets???

 

and hmmmm yeah i think i saw a few small pieces of the old foam air filter inside past the air intake when took the carburetor off, so probably best to just give it a check out,  might be a pain with my limited knowledge lol, but better than running with it and possibly causing damage :(  only other thing i'm worried about for disassembling/reassembling (cause i have no idea) is the electrical/spark system - will that need to be timed to the piston cycle? or nothing to worry about???

 

Thanks again for all the help!!! :D

 

 

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You may be best using clean fuel then, as I've never tried carb cleaner I don't know what it can damage (certainly some electronic & switch cleaner sprays can damage plastics or cause other problems with vintage electronics).

 

Be careful the power output shaft doesn't slide out & let the tiny bearing rollers fall out, if you take the induction housing apart and nothing is attached to it.

 

The only adjustment for the timing is the contact breaker gap (should be listed on the starter decal along with the spark plug gap). The flywheel position is fixed with a key.

 

David

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Zak    0

Ahhhhh i see i see....hmmmm maybe just carb cleaner for some definitely metal parts lol, and the air intake + exhaust since theyr'e especially rusted out with my one....

 

and ahhhh alright then sounds awesome!!! if the flywheel is fixed with a key and then contact breaker gap is the only timing adjustment then should be a lot easier :D seen it opened up/how it works in one of the youtube vids so makes it a lot easier for me haha

 

Very much appreciated for helping me out here!! :) i know iv'e said it a lot, but its been literally 10 years iv'e had this engine and in that time all i knew was that it was a model engine, had compression and spark, and thats it, lol,  never worked up the courage to disassemble it properly or do any serious trouble shooting on it :P  

 

I could ask like a million other unrelated to carb questions on here, but should i put them on another thread??

 

Thanks heaps David!!! :D 

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Hi Zak

 

You could start a new thread, or add to a relevant existing one and we can help with any other questions you may have.

The Compact engines were of course designed as a small industrial engine to be used for powering all sorts of portable tools, but were also used for powering (and still are) models.

 

David

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Zak    0

Awesome as! :) hmmmm i might as well start a new one not as to go too off topic from this carb repair thread :) i'm sure il'l have tonns more carb questions when i actually get the time to take it apart haha :P

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Hi guys, Thanks so much for this thread. An old gent asked me if I would get his tiny Tiger 300 running for him, and when I opened the carb, those little bits were rolling around in there. I'm lucky I didn't lose any of them. There's no way I could have figured this out on my own.

Best,

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