HD 25 Carb percolting

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Chacha53
Posts: 16
Joined: Thu Aug 17, 2017 5:14 am

HD 25 Carb percolting

Postby Chacha53 » Wed May 16, 2018 4:07 pm

My Johnson HD 25 carb is percolating up through the gas shut off needle in the float bowl. Carb is too hot to touch after just a minute of running. Obviously overheating. I checked the water pump and it looks OK however, the rubber fitting on the end of the water tube(?) where it meets the pump is rather rough. Can that be replaced?
I don't see water spurting from the two exhaust holes near the top of the leg, but I did see water come out of the bottom of the power head when running after I removed the head drain plug.
Also, I removed the four bolts under the cavitation plate a few inches above the gear case thinking I could drop the drive shaft and water tube with the foot. It wouldn't pull off. A lot of gear oil leaked out at the seam. Is that normal? Should there be a gasket?
I really need a diagram of the lower workings of the HD 25 if anyone has one.
Thanks
Chattanooga, TN

Chacha53
Posts: 16
Joined: Thu Aug 17, 2017 5:14 am

Re: HD 25 Carb percolting

Postby Chacha53 » Wed May 16, 2018 4:10 pm

Ooops! I misspelled percolating!
Chattanooga, TN

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Buccaneer
Posts: 2826
Joined: Mon Mar 09, 2015 9:34 pm

Re: HD 25 Carb percolting

Postby Buccaneer » Wed May 16, 2018 4:35 pm

Not sure if this parts PDF will help.
I can't remember if it was the early HD or TD Johnsons,
but there was something in the manual about gas
percolating in he carb, and the cure was to put
a piece of wire / rod in the carb somewhere to
restrict the flow.
Attachments
JohnsonParts-HS.HA.HD-15.pdf
(1.88 MiB) Downloaded 24 times

FrankR
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Location: Florida

Re: HD 25 Carb percolting

Postby FrankR » Wed May 16, 2018 5:16 pm

I had one of those HD's drive me nuts. Turned out the rubber seal at the bottom end of the water tube was obstructing the flow. It "seemed" to be fine. It is essential that the water flow be 100% or the carb will overheat and vaporize.

Chacha53
Posts: 16
Joined: Thu Aug 17, 2017 5:14 am

Re: HD 25 Carb percolting

Postby Chacha53 » Wed May 16, 2018 7:22 pm

The pdf helps. Thanks Buccaneer!
Frank, I think that may be my problem. I took a pic but now I can't figure out how to attach to this post. Anyway,the rubber part at the bottom end of the water tube looks rough. Does it have to match up perfectly to work or can I clean it up with an exacto knife? What did you do?
Chattanooga, TN

FrankR
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Location: Florida

Re: HD 25 Carb percolting

Postby FrankR » Wed May 16, 2018 8:15 pm

On most of them that I've found, the rubber is mushed over the end of the water tube. I just trim it away. Of course the general condition of the pump is important also. Make sure the rubber rotor isn't swollen and fits the eccentric cam properly.

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Garry in Tampa
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Location: Florida

Re: HD 25 Carb percolting

Postby Garry in Tampa » Thu May 17, 2018 12:03 am

the rubber rotor must be an exact fit to the brass eccentric that drives it. . . :)
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Chacha53
Posts: 16
Joined: Thu Aug 17, 2017 5:14 am

Re: HD 25 Carb percolting

Postby Chacha53 » Fri May 18, 2018 2:42 pm

It looks to me like someone tried to put a little black silicon around the rubber on the end of the tube. The rubber rotor looks ok so i just cleaned everything and tried it again. No change. I think I should put in a new rotor. anyone know of a source?
Chattanooga, TN

FrankR
Posts: 3451
Joined: Tue Mar 10, 2015 6:32 pm
Location: Florida

Re: HD 25 Carb percolting

Postby FrankR » Fri May 18, 2018 4:22 pm

Two club members make them

Brian Wilcox Call 810-794-7685 before 8 pm est please.Or email Baron0418@att.net. please note the b must be a capital.

AND/OR---

http://home.earthlink.net/~flyingscott/


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