What’s this gunk in my right carb?

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75R60
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Joined: Mon Jul 25, 2016 11:24 pm
Location: Boston

What’s this gunk in my right carb?

Post by 75R60 »

Anyone know why the oil coming from the crank case breather tube into my right carb looks like this? The oil in the pan looks correct and the level is good. This gunk has coated the whole inside of my right carb

1975 R90/6
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Dang
‘75 R60/6
‘75 R90/6

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schrader7032
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Location: San Antonio, TX

Re: What’s this gunk in my right carb?

Post by schrader7032 »

Looks like antifreeze! Anyway, we know that the engine breather valve dumps oil into the right carb. On your bike, the original breather might still be in there...it's a circular phenolic disk held down by a spring. The newer version is a reed valve...the reed tends to lie flat covering the outlet, but bends under internal pressure with piston movement.

Usually the residue is oily. Yours looks gritty, maybe even dirty? Any chance that the clamps holding the carb inlet tube are loose, letting outside air in?
Kurt in S.A.
'78 R100/7 '69 R69S '52 R25/2

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srankin
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Location: Spencerport, NY USA

Re: What’s this gunk in my right carb?

Post by srankin »

I saw a pile of gunk like that only once in my boat's gas tank after I tried to seal something with the wrong kind of sealer and it dissolved in the gas into the tank.

Sorry, that probably doesn't help you much.

Are you the only owner of the bike or I should say are you the original owner? If not, the previous owner could have used some kind of goo to seal something in the air intake system? Have you washed the bike with some kind of new cleaner something may have gotten into the air cleaner and made its way into the intake.

It is a mystery, Kurt makes a good point about checking for loose stuff. Sorry I can't put a finger on it, good luck, St.
Owner of a 84, R80RT and 78, R100RS

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75R60
Posts: 29
Joined: Mon Jul 25, 2016 11:24 pm
Location: Boston

Re: What’s this gunk in my right carb?

Post by 75R60 »

I bought this bike a couple years ago in Muscle Shoals AL and drove it back here to Boston. When I got it home I noticed an emblem glued to the rear light
448C9618-55F8-4E4E-BF51-27893BCBBD8D.png
that indicated the bike was from New Hampshire. Regardless I’ve gone through pretty much everything with this bike so unfortunately I can’t blame anything on the original owner anymore :-)
D9486B9C-930C-4726-8F7A-1FC285D5B6D6.jpeg
The substance inside the intake tube I agree does look textured, but I ran my finger through it and it’s simply oily and slimy. Reminded me of what the inside of my valve covers looked like on my 66 Chevy II wagon. Moisture of some kind.

I cleaned it all up, put it back together and we’ll see if it returns. The PCV valve is indeed the original style. What do you guys think of the non-tube kind the EME sells? Just replacing the tube all together with the drip back check valve.
Dang
‘75 R60/6
‘75 R90/6

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schrader7032
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Re: What’s this gunk in my right carb?

Post by schrader7032 »

Generally the OEM setup works well, so I'd be inclined to just get the new reed valve type and use that. I kinda feel like the EME thing is trying to solve a problem that really doesn't exist. If the bike is puking a lot of oil into the right carb, rather than a bandaid, the basic problem should be found and fixed.
Kurt in S.A.
'78 R100/7 '69 R69S '52 R25/2

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75R60
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Re: What’s this gunk in my right carb?

Post by 75R60 »

Thanks again guys. as a follow up I believe the problem was one I created. The bike came with an oversized oil pan which hung down an extra 2” lower than the stock one. Since I’m riding mostly dirt roads and trails over the next month, the clearance was needed. I installed the new pan and snugged it up but forgot to torque it. That night I got caught in a serious downpour for about a half hour which was a great test of the bags and jacket I’d purchased for this trip. The bags passed, the jacket failed, and I believe water seeped into the oil pan on the ride. I torqued it up the next am and I was low on all of them.
Dang
‘75 R60/6
‘75 R90/6

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srankin
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Re: What’s this gunk in my right carb?

Post by srankin »

A tiny amount of water in engine oil, and I can imagine this happening. Makes sense. Thank goodness, it wasn't a lot of water.

I saw a bike someone overdid things with a pressure washer once and a bad gasket then went for a ride with a bad ending. He didn't have mystery gunk in his intake, he had an engine rebuild.

Nice catch and thanks for letting us know the solution. St.
Owner of a 84, R80RT and 78, R100RS

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