Posted August 15, 201410 yr I've put new piston kit On as my old 1 shot a hole bang in the middle. I got it to start but it wouldn't go faster than 15mph if that I'm wanting some advice on so may be causes. The bore looked ok to me nothing jumped out a mate says it could need a rebore but I don't know as he hadn't seen the barrel Off the bike. I think I'm asking for a second opinion. Please please help its a nightmare!!!!! Thanks so very much any ideas/advice I'm grateful
August 15, 201410 yr How does it start, ? and 15 mph .is that in 1st gear,,, i think the compression is low,,
August 15, 201410 yr Moderator dunno fook all about a majester? is this a majesty scooter thing, does it have a carb...a choke etc ?
August 16, 201410 yr Author Yeah it's a scooter four stroke. It takes a few attempts on the electric start to get going. Hmm compression low seems like the bore could be a problem???? Thanks guys for taking time to reply always appreciated
August 16, 201410 yr I'm not familiar with the Majesty, but when I had a Piaggio scooter I had a similar problem. There was a simple screw below the seat (just above the carb) which needed adjusting. I know it was a carb setting which affected the mid and high revs. Mine was only a 50cc. If there isn't this screw, have you had the carb apart - could be one of the jets is blocked??
August 16, 201410 yr Moderator burning a hole in the piston can be ignition timing too advanced, I'd suggest checking the timing and stripping/cleaning the carb and it's jets, you can buy aerosol carb cleaner sprays
August 17, 201410 yr Author Im thinking it's the choke. Is there awaybti test it before I purchase a new
August 18, 201410 yr Author Ok I have git it running but wen I put the throttle back it bogs out and cuts out I only have to put it bk a little bit
August 19, 201410 yr Lean mix would be my guess. Would explain the cutting out under throttle input and the holey piston.
August 19, 201410 yr Author I've never messed with suction carbs before so a lean mix to me in 1 if theses means nothing lol. How would I adjust this??
August 19, 201410 yr Look in your manual for the carb settings and turn the fuel mixture up or the air mix down, whichever is set wrong, best bet is to take it back to factory settings and go from there. Usually the factory settings are ok when new but stuff wears out and needs adjustment, usually a quarter turn in or out can be a major benefit but DON'T do big changes from the original setting as that can cause problems as well.
August 19, 201410 yr Take out your spark plug, if its white then you are getting too much air and not enough fuel, this in time will course piston damage. If the plug is sooty blck then you are getting too much fuel and not enough air, again over time will course piston damage. When a engine bogs down under load (throttle) normally points to not enough air (but also not enogh fuel) hence the spark plug check. As you have changed the piston and have had to remove the barrels to do said task you have removed the carb from the barrel?? if your a good lad and done this have you tightened up the inlet rubber that clamps the carb to the barrel? if you haven't then you will be drawing in extra air through this gap and running weak. Make sure that the inlet rubber is done up tight. If that fails or you have done the rubber up tight then dose the bike rev when the choke is still on? if it does then we need to suss out if your choke adds more fuel or more air.
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