Yamaha 3HP Malta

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Honda Z50M

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HI, noob recently purchased a Yamaha 3HP Malta (6L5), use it for the first time last weekend but found it a little sluggish (pushing 3.2M dinghy 2daults 2 children).

Also revs don't drop as quickly as I would have expected and sometimes revs float around a little (in neutral).

Today replaced spark plug and checked water impeller as tell tail was never much above river water temperature if at all.

Ran it in a bucket of water, starts fine but again revs don't drop as quickly as I would expect also if I hold throttle say in start position the revs sometimes run away (in neutral) and doesn't always idle (possible air leak is ringing a bell for some reason)

Air/fuel mix screw is currently 1 1/8th turn out (fresh fuel currently mixed to 50:1, I know it should be 100:1)

When engaging prop engine doesn't seem to want to rev out (hence feels sluggish) or am I expecting too much?
 
Check for stale fuel and blockages within the carb jets. Also check if its drawing air at the carb mounting gasket/flange
 
The tell tale water is exiting before it has been round the engine and only shows that the water pump is working. Does sound like a carb issue and may need a good clean. There are a few threads on pbo page about the Malta. I would put a link in, but find I can't when using a tablet.

Edit bit. Managed to copy one link but there are a few other earlier threads as well.
I'm beginning to despair of ever getting my Malta O/B to run properly
 
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If it does turn out to be stale fuel in the carb dont do what i did and spend time cleaning out only to refill with the same stale fuel from the tank.
 
Double checked spark gap ok (0.95mm)
Removed and cleaned fuel mix needle (it was clean anyway)
Gradually adjusted fuel mix out a further 1.5 turns so now total turns out 2 & 5/8ths
Idle slowed a little, still runs away a bit when throttle opened slightly but not as bad as before and revs drop off a bit faster
Idle is also smoother and more consistant (doesn't float around).
Time limited so didn't strip carb but gave i a blast through with some cleaner.
One thing I forgot to mention previously was I couldn't start it without choke even when warm but now starts first pull without chocke (when warm)

Does anyone know where I can find the carb gasket part number as I would like to replace it being as I removed the carb (looked like it was made up of two gaskets) this will also help me rule that out.

Thanks
Tom
 
Old carb adjust methodsis to adjust the speed the idle up slightly, then using the mixture screw turn it in or out until you get the fastest idle possible, then readjust the idle acrew.
That is it idle mixture set.
 
I managed to find a gasket, found a sold one on ebay and contacted seller asking if they had any more and they just so happen to have 1 left.
 
So dug my malta out today, test run reveals powerhead is bloody cracked and peeing water!
Ebay two maltas being broken, no powerheads, general google revelas much the same, so might be something to watch out for ?
 
lynallbel said:
So dug my malta out today, test run reveals powerhead is bloody cracked and peeing water!
Ebay two maltas being broken, no powerheads, general google revelas much the same, so might be something to watch out for ?
Click to expand...
IS it just a water channel that's cracked? if it's low pressure could you get it welded or use jb weld? JB weld is good enough to repair a hole in a cylinder head.
 
Honda Z50M said:
IS it just a water channel that's cracked? if it's low pressure could you get it welded or use jb weld? JB weld is good enough to repair a hole in a cylinder head.
Click to expand...

Pretty certain just water jacket, CT1 has been suggested, and I am leaning that way, it is only a toy so if it dies!
Think I will pull head off for a better look.
 
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