1968 55 hp Johnny - carb question

NES

Cadet
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Jul 13, 2004
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10
My '68 tr-10r will start and idle fine. It will also go into gear (forward and reverse) fine. When I throttle up it will cough and sputter. I've checked the compression, all 3 cylinders are over 115 and less than 5 apart between them. I have fresh gas, a vented gas tank, a hard primer bulb, and the fuel filter is clean. In adition, I've recently replaced most of the ignition parts and the wiring harness. I'm convinced it is a carburator problem. I am not that good with carburators. I checked my manuals (I have two)and they both give detailed instructions on carburator rebuilds. Is there a way to "clean" the carburators without doing a complete rebuild? Any help would be greatly appreciated.
 

dolluper

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Jul 19, 2004
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3,900
Re: 1968 55 hp Johnny - carb question

check your plugs after a run they should be tan colour if not the hole you took it out of has a problem.If you find one gray white colour that is a sign of air leak simple test for air leak is to take a propane torch the lighting end unscrew off install an old straight ign boot over the end so it is a tight fit then insert a hose tightly in the boot you now have a tester .with the motor running take the torch open the just a bit and run the hose slowly around gaskets especially where carb mounts ,if the motor idles up you have found the air leak if the plug is wet it means fuel, spark , ign or compression If all fails rebuild the carbs they are very easy especially with a manual have confidence
 

WillyBWright

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Dec 29, 2003
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Re: 1968 55 hp Johnny - carb question

Welcome to iboats.<br /><br />The carbs are quite simple in design. Go for it! The hardest part is synchronizing them, but it's far from Rocket Science. You can get complete rebuild kits, but all you'll need is bowl gaskets, center nozzle gaskets, mounting gaskets, and float valves. Good luck.
 

NES

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Jul 13, 2004
Messages
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Re: 1968 55 hp Johnny - carb question

Thanks for the encouragement on the carb rebuild. Yesterday after posting I pulled the cover off and ran some sea foam through with the muffs on. I let it sit and ran it again. Lots of smoke but afterward she was purring. Of course there was no load on the prop. So now I have two questions. Will it run poorly in water (increased prop load) and if it does will making an adjustment to the low speed idle (going a little richer - if richer means more gas or less air) help? I'd like to put off carb rebuilding til the water freezes over. Any insight would be greatly appreciated.
 

Walker

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Jun 15, 2002
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3,085
Re: 1968 55 hp Johnny - carb question

Proper color for 2 stroke plugs is black and slightly oily.
 

dolluper

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Jul 19, 2004
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3,900
Re: 1968 55 hp Johnny - carb question

hey walker you just discribed a running rich motor inside should be tan coloured for a sweet running anything
 

NES

Cadet
Joined
Jul 13, 2004
Messages
10
Re: 1968 55 hp Johnny - carb question

I discovered the problem was caused by a faulty primer bulb. When I would pump the bulb by hand no problem but when I throttled up the motor would draw fuel faster and a loose part in the bulb would clog the end. Causing the bulb to flatten out and the motor to run lean (no fuel). I removed the primer bulb, after further breaking one of the ends in an attempt to fix it, and ran a line directly to the tank. After siphoning gas up the fuel line I was running wide open and smooth. I'll put a new bulb on (it was a new one that was faulty) and rebuild the carbs over the winter. The gas didn't taste bad but no amount of beer could get the 2 cycle oil taste out of my mouth.
 

alcan

Commander
Joined
Dec 14, 2001
Messages
2,505
Re: 1968 55 hp Johnny - carb question

Lesson learned, don't buy cheep after market fuel lines,connectors or bulbs. And yes you can remove and clean carbs with out having to add new parts. This business of rebuilding carbs all the time is hog wash. There is nothing to rebuild. They do need cleaned and inspected from time to time. And if you need a part, replace it. The thing is, it is just faster and easier to buy the kit,install it, and be done. I will guess that 99% of all carb failure is due to crud, not parts failure. Most of this crud is due to extended periods of non use.
 
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