robin subaru engine trouble

what is tdc? the plug inside was an ngk cmr6a i replaced it with a ngk cmr7a. how do you have your engines serviced? nobody around me deals with robin engines and they cant even get parts. it was stored outdoors under shelter, it was not used very much before that so it was not serviced. i recently changed the oil, it was on the low side. i put the valves back to their original position. it runs, just not very well. the piston looks very dirty, but i haven't really looked at many pistons so im not too sure.

Top dead center, it's when the piston is at the top of it's stroke and the position the crankshaft must be in to check valve clearance. There is a mark on the flywheel that lines up with a corresponding mark on the engine case that aids in determining that position.
(this has to be done when the engine is dead cold btw)

I'm a bit reluctant to offer any advice at this point. I gave you a link to the service manual, I suggest you read it completely. You have changed the heat range on the spark plug by going to a 7a. The recommended plug is the 6a.

If you are at all interested, a primer on spark plugs and how to read them can be found here:
http://www.ngksparkplugs.com/tech_support/spark_plugs/index.asp?mode=nml

Often with small engines, particularly those that were running well, a bit of a problem might develop and it's rather simple, something we did or didn't do. Bad fuel or storage or it got knocked about, etc. It usually doesn't mean you
have to overhaul the engine or try to fix problems that don't exist. It also doesn't mean you should avoid routine maintenance like checking valve lash.....as long as you know what you're doing otherwise you create more problems looking for a complicated answer when the problem is much more simple.

I maintain my own engines but I've been doing that for many years.
When I need service I go to an authorized dealer which can be found here:
http://www.robinamerica.com/dealerusacan.aspx

If your engine is under warranty you could get it serviced at one of the listed dealers. If it isn't you could try calling one of the repair guys and asking for help.
 
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ok, i know that it had to be in that position so the valves would be at the lowest point, just not familiar with the term used.

it was the only plug they had, so i just bought it while there is an identical one on order. just wanted to see if it would start. the heat range shouldn't be that different.
 
Hey did you try running some good fuel treatment in the gas to clean the carb out !!!!
 
the fuel is new, what kind of treatment do you mean? ive cleaned the carb out several times with clean r carb and have blasted the jets with an air compressor.

maybe i need a whole new carb:confused:

can timing get off tracked on these? it kinda idles like the spark plug is firing at the wrong time.
 
Can You

Run your engine in the dark to see if the spark wire is shorting anywhere?
 
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