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Old 14 October 2011, 08:23   #1
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Carb Removal & Cleaning

I have a 2 stroke Johnson 60hp (approx 1990).

It has been bogging down quite a bit recently when on higher throttle, but runs fine on lower throttle & idle.

I have been using some older fuel, which may have clogged things up rather. My first course of action is to take off the carbs and clean them.

Is this a job that a reasonably diligent and enthusiastic amateur could undertake himself? What are the pitfalls that I may come across? Am I likely to require new gaskets?

Many thanks
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Old 14 October 2011, 09:56   #2
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You should have the three cylinder looper engine with 3 carb's. Bogging down at high speeds could well be the induction indeed, I would say you are on the right track. I've worked on some Johnson's from that same period, and a two-stroke carb in general is a simple device which you cna isnpect as amateur.
There are some stuff on the market like carb cleaner, but nothing beats a complete tear down to visually inspect everything, in my opinion.

You won't need no special tools, just the right size screw drivers for the carb jet's, and a compressed air tank. If you're careful on the gaskets, you might be able to re-use them.

Some tips you perhaps appreciate:

- Above the carb throat is a flat-head screw with a spring behind it, this is your idle air-set screw. Before removing this, take note of the exact position by counting the turn's clockwise.
- Remove the high-speed jet, is situated in the fuel bowl below the carb's throat, and you can remove it after you've removed the flat-head drain plug. (this jet is MOST LIKELY the cause of your trouble)
- If you suspect old fuel, take a thin copper-wire and rub it through the jet, this will take care from build-up caused by stale fuel.

- Blow compressed air through all holes and passages you see.

-I sometimes use a little flashlight to inspect if all passages are clear.

- When you're finished; hold the carb upside down and visually inspect if the float is laying horizontal in-line with the edge of the carb. If it is not, carefully bend until it does. Incorrect setting could result in carb floading.

- I would do all three carb's one-by-one to limit confusion. Also if the engine ain't already equiped with one; mount a fuel filter between the connector and the fuel pump.

(english isn't my native tongue, but I hope most of it makes sense)

To anyone; feel free to correct me in the above if necessary.

Good luck and feel free to ask.
Chris
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Old 14 October 2011, 10:09   #3
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Turtle,

Welcome to ribnet!

Gaskets - always repalce unless you are really stuck. Same for O-rings and any other sealing materials.

As for the carbs, based on :: iShopMarine.com ::
it looks like your jet is accessible form the front, so you could pul lthat out & clean it as a first try. If not, you now have a pic of what should be in there!

The best thign to do is find a large sheet of cardboard, and as you strip it, lay the parts out in a logical order on the card. If you keep a pencil to hand & write notes beside what's lying there, it can help in the reassembly process.

Likes of Clymer have full dissassembly & rebuild instructions, but as a general rule, whenyou put it back together, there will be a flat surface on the float which should line up with the gasket face. that is how every carb I've ever dismantled has checked the float & valve adjustment, so is a pretty safe bet.

As for cleaning, there are numerous carb cleaning sprays out there, all do much the same thing. Aim for scrupulously clean when you reassemble, then you realistically might actually get the level of cleanliness required. I;m not insulting your abilities here, but just being realisitc as to what "clean" means when you are playing with with orifices measured in tenths of a thou.
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Old 14 October 2011, 10:10   #4
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This is the sort of information I am looking for - thank you.

Is there much of a likelihood of small parts dropping out whilst I take the carb off, or bending, or damaging small parts?

Where is the best place to get hold of the spare parts from? (I am in the UK)
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Old 17 October 2011, 06:57   #5
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The self dissassembling" part is usually the float valve (which is held together by the float - removing the bottom bowl frees that up nicely) Just be careful removing the bowl, then carefully & slowly remove the float, as there is usually a spring in there somewhere It;s not a strong spring, but will go flying if you release it suddenly..... Some carbs have separate jets to the screw you remove to change them, but looks like yours will be relatively well behaved when screws are removed.

If you are worried about loosing bits, another good trick is to take an old cornflkes box, and cut one big side out & dismantle in that - anything dropped is contained. Also cover the thing you are dismantling with an old dishtowel if the diagram shows a spring in the assembly, and that will catch 99% of any components that get thrown out. Only down side is you can't tell what order they came out, so best to study the exploded diagrams first to work out which (if any) screw has a spring behind & undo with due care & caution.

Once you've done the first one it's only a matter of time until you'll be able to do it with your eyes shut.
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Old 17 October 2011, 08:07   #6
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Thank you for the information.

I have found a supplier for the gaskets etc. now, so I will look forward to having a go at this.
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Old 26 October 2011, 08:16   #7
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Just in case anyone is interested, I successfully disassembled, cleaned, and put together the carbs again. I learnt a lot from doing this.

Just out of interest, looking through the "ishopMarine" site, I could not find any details of the fuel pump for my engine (J60TLESM). Any ideas why this is?
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Old 09 June 2012, 18:03   #8
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Just thought I'd resurrect this thread.

Just by way of an update, I stripped down and re-fitted the carbs.

I took the boat out and all was working well for half an hour or so - the engine was providing decent amount of power and doing everything that it should.

After the half hour the engine started bogging down again. It was working fine at lower revs, and in neutral is revving fine, but in gear just bogs down can carries on a low speeds.

I suspect the carbs are blocking again, but what is the cause? It is a new tank and I have used new fuel.

I have a suspicion that the fuels line between the filter and carbs are starting to degrade, allowing rubber from the lines to enter the carbs. Does this sort of thing happen?

Thanks
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Old 09 June 2012, 18:29   #9
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You would think the filter would pick the bits up have you made sure the filter and priming bulb are fitted the correct way
Just a thought
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Old 10 June 2012, 14:51   #10
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Quote:
Originally Posted by mick View Post
You would think the filter would pick the bits up have you made sure the filter and priming bulb are fitted the correct way
Just a thought
Yes - the filter & bulb are the right way around. The only thing I can think of is that the lines between the filter and the carbs are starting to degrade.
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