A little help with some wording so i can do some research - please

[rynosaurus]

Hi guys

Im still a little fresh to fishing/boating as i never grew up with it so im asking for a little help with terminology so i can understand where i need to point my questions/searching on the forums as the terms im trying arent helping very much.

basically i have a brand new quiny dory420 that i bought off a guy who won it at a lucky door prize thingo that has a 30hp yamaha (cv i think) on the back. now as its brand new im following the yamaha book for runin procedure and i realise that going flat out isnt an option to really test it out (waiting on the first service). what i have been noticing is that it planes quickly (so it seems to me and my mate said so who has more experiance than i do imo) but then when i try and give it a little bit the motor seems to shudder and be sluggish. from what i have read and researched people try and raise or lower the motor and put extra plane thingos on to help get better speed and performance (oh and trim/tilt as well)

what im trying to work out is the shuddering caused by not having it high enough and creating ventilation and cavitation (not that i fully understand this but somehow it relates to the amount of bubbles in the water) or is there something else causing shuddering ie slipping propellor or something.

is there some checks i can do or tell the service people at yamaha?

hope i havent lost anyone - though im feeling lost now sorry

regards
ryan

[Aussie123]

You probably have a higher oil ratio for the run in process and a plug may be fouling a bit from the extra oil.
Nothing to worry about at all if that is the problem

[Axl]

I would get the motor run in as per the manual, get a service done once you have done this (if it is required) depending on the hours you have put on the motor to run it in of course.

You will have more room to move with the rev range and be on the sandard fuel/oil mix, then you can start doing some serious testing.

[Moonlighter]

If you are saying that you are cruising along OK on the plane and then when you give it a bit more, the motor shudders and is slugglish to accelerate or wont accelerate, then, in my opinion, that's not normal.

Nor would it be likely to be due to extra oil in mixture fouling plugs, especially if you have been cruising along for a while and it cruises smoothly. It sounds like it might be misfiring at higher revs to me. Check the plug leads to make sure they are firmly on and havent been dislodged a bit when someone has taken the engine cowl off. Could also be a crook plug - it does happen sometimes.

Check that the breather valve on the tank is open too! That's a trap for new players. Tank needs to be able to draw air in to enable the motor to suck fuel thru, and this is more apparent when you increase the revs and it needs more fuel, if its not fully open you can starve the engine and it would produce symptoms such as you have inferred.

If that doesnt fix it, ring your dealer and explain what's happening, tell them you are not satisfied and would like it fixed. Its under warranty. They should fix it.

Cheers

ML

[thelump]

As above is all good info but dont be afraid to give it a squirt of WOT. As long as you dont hold it there on same revs for too long. Dealers do this with larger motors when water testing to make sure prop size is correct so cant be too bad for the motor?