Strange Carb Issues.-

Sea Rider

Supreme Mariner
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Sep 20, 2008
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12,345
Paul,

Is it possible to have issues on the idle carb circuit specially at first starts or cold restarts and no issues once engine is warm. I'm a big fan or running carb bowl and sometimes fuel filter dry. When outing next day or days after, go through the entire process of opening tank vent and priming bulb untill firm, put grip to start position and pull choke all tthe way out. Usually at second pull the engine starts fine but will die seconds later if a combined throtttle/choke movements is not done for some time untill engine stabilizes itself. Once engine is warm presents no issues specially at idle/fast idle while at neutral.

This is a 2 stroke 18 HP with 250 meterd worked hours, tha carb has not beeen pulled once fron new, tank is regularly cleaned along all fuel filters which has been found immaculate clean 99.98 of the times. Was wondering if it's time for a complete carb bath in carb dip and generic carb spray overdose ?

Happy Boating
 
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pvanv

Admiral
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Apr 20, 2008
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Can't hurt. How is compression? How are the shaft seals? 2-strokes might be a little weird (especially cold) if you have a slightly leaky crankshaft seal.
 

Sea Rider

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Everything is exceptionally fine, engine runs good throughout the whole throttle range, just 10 rpm less that its max 5800 wot rpm. Next week will probably tear carb down and check, assume has a microscopic clog somewhere on slow circuit. If carb dip is not available, is it possible to squirt 3 cans of generic carb cleaner into a container and soak carb for some time, will it clean better carb parts than soaking them in acrylic paint thinner ? Alcohol or even acetone won't help much...

Happy Boating
 

pvanv

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Alcohol is too mild to do much in the short term. Most aerosol carb cleaner is primarily acetone. If you have MEK available, it evaporates slower than acetone. You might need to soak for a couple of days to get enough dissolving.
 

Sea Rider

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MEK is not available, it's a forbiden solvent, the Government thinks you can process coca leaves to make cocaine with this stuff, have even banned acetone sold on commercial scale for the same reason. Just fingernail remover in small bottles is available. Don't think its a gummed issue on slow carb circuit, probably some microscopic dirt that has bypasssed all filters as can happen. Will see, thanks.

Happy Boating
 

Sea Rider

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Teared whole carb down, to my surprise was 99.9 clean, anyway squirted 1/2 can of generic carb spray with canula throughout evey hole and jet. Assembled back onto block, guess what, has not improved a bit, it's a bit worse than before. Seems a IC related issue, missing at idle/fast idle but strangely excellent throughout the whole thottle range. Will take advante to retorque cylinder head when pulling IC from block. Wll install a new IC and check if it's the culprit. Fingers crossed.

Happy Boating
 

Sea Rider

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Update, installed a new IC, same problem, changed plugs, same problem, total frustration. While removing IC, took advantage to torque with a torquimeter intake manifold, exhaust lid and cylinder head gasket, to my surprise were a bit loose due to constant long use and controlled abuse. With time internal block heat compresses cardboard gaskets & head gasket which will inevitably cede along. What was factory torqued to, will not remain same.

Cleaning fuel lines, filters, carb, torquing complete block, new plugs and above all fine adjusting mixture and idle screws made all the diffference. Incredible how can an engine performance change so dramatically with use from new. Now purrs happy like siamese cats.-

Happy Boating
 
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