02 Yammy 50 hp 4 stroker no power under throttle

[andrew j cox]

got a 50 Yammy 4 stroke 02 , suffering badly with power loss, just won’t perform under throttle, likely places to look before I yank the head off it was rumored to have low compression in two cyl, likely it is a head gasket, 8m throwing this one to the experts

 

[99yam40]

what do you mean it was rumored low compression?
have you not tested anything yourself?

 

[andrew j cox]

The engine is off the boat, I have pulled the head off two cylinders are wet I guess not firing real well, could be plugs, the gasket has delaminated I think that is the prob, the main water feed to block was crusted up totally, bores look good no glaze the hone lines are new as, where do I get a gasket can’t find one on ebay, lots of 3 cyl stuff, I got lumbered with the motor to fix it no battery leads, he just said u der load it’s struggling, Im going through all the usual issues that can happen, the fuel filter looks grubby, I’ll replace that, the plugs, gaskets, decarbon the head and pistons , have alook at the carbys, can’t think of much else it can be, it’s my first four stroke yammy I’ve looked at, it ain’t no chrysler lol

 

[andrew j cox]

When I say rumoured the owner bought it sight unseen the previous owner said it had two cylinders low in comp, current owner bought it cheap hoping it’d be fixable, it came with a paper from a mechanic that charged him 200 bux and said struggling under load, didn’t say he did comp test, the plugs I think haven’t been out in a while, who doesn’t have a good look at there plugs or recognise when plugs are fuelly or oily, I have little faith in a lot of mechs,

 

[99yam40]

The engine is off the boat, I have pulled the head off two cylinders are wet I guess not firing real well, could be plugs, the gasket has delaminated I think that is the prob, the main water feed to block was crusted up totally, bores look good no glaze the hone lines are new as, where do I get a gasket can’t find one on ebay, lots of 3 cyl stuff, I got lumbered with the motor to fix it no battery leads, he just said u der load it’s struggling, Im going through all the usual issues that can happen, the fuel filter looks grubby, I’ll replace that, the plugs, gaskets, decarbon the head and pistons , have alook at the carbys, can’t think of much else it can be, it’s my first four stroke yammy I’ve looked at, it ain’t no chrysler lol

dang that hurts just trying to read that

 

[andrew j cox]

It hurts me having to work on a bloody jap motor, to make things worse I got 4 more yammy to work on oddly enough all 25 s all 2 strokes, 2 I think just need a good tune up, other two have been run hot potentially going to be rebuilds, I found a head gasket for the 50 only available from Yammyha themselves, hopefully I have it sorted