My Yamaha aerox had a street race 70 kit on it last night but i had problems getting it running A* so converted it back to a 50. Last night i was out on it and it was wierd to drive. The first drive was fine and flew round the clock like it used to, then after i stopped would crawl to about 18mph then fly again, Dint think anything of this at the time. so anyway this morning was going to play with some clutch springs to sort it out but it wouldnt start, Checked the plug for a spark and saw this , 19 seconds on to the video and thats the problem. Obv the new base gasket had split and fuel is getting out and obv lowering the compersion ratio. But would this be a reason for why the acceleration was weak? as a sign of the gasket going? Cheers Adam.
I bet that's the problem you had with the 70 kit. When my dad rebuilt my engine with new main bearings and crank it was running okay but not quite as good as before the rebuild, we assumed it was because it was running in a new crank and piston. We later put a 70 kit on it and the problem was obvious the crank case joint was not sealed and was sucking in air and blowing out fuel. The effect would be the same as a base gasket and fucks up the mixture a good un, You probably had the same problem with the 70 kit but didn't realise it until it became obvious when it was disturbed with the cylinder change. My advice is put on a new gasket, new cylinder bolts and the 70kit. Make sure it's torqued properly and retorqued the next day when cold Then light the blue touch paper and watch her fly.
Annoying thing is i think the bores fucked, Ill post some pics inamin! But yeah i think this is the problem, I thought the old gasket had gone but obv not and put the 70 gasket over the top! well new gasket on order and will take the engine out over the weekend and clean it proper!
This one is the bad side, You can slightly feel it with your finger, But not much. This side is nothing. Just looks bad. Bad side of the piston (exhaust side) Goodish side.
Whats the cylinder like above the bores? That's been running lean and the piston has nipped up in the barrel, I've seen worse and provided that the bore is okay above the ports it should be salvageable.
Clean up the piston and check the rings (they look okay in the pic) clean the cylinder and if necessary take it to an engineering shop and have then run a glaze buster down it. It will clean the bore and take off any ridges (I doubt if there are any) refit and don't worry. My 70 kit had some marks from when the joint was leaking but as soon as it was run in it was fine.
Them scores on the exhaust side are bad but only just with your nail, I dont even want it any more, its up for sale if its usable lol
The other side are just marks, cant even feel anything that side, But yeah the scores arnt bad one bit lol Just cba with it now want it gone to fund bar conversion
Bores for sale now, cant obv post a add up in the for sale section so if this isnt aloud just delete it please lol yeah offers for the bore and ill pm more about it ( more pics if required) cheers wedge
My dads works in a onsure company so im sure someone in there can sort it, hes back in tuesday so ill get him to take it in with him then, a new piston will be required for the person if they want to buy it but thats £30 cheep as chips!
Now you know what the problem was , PUT THE KIT BACK ON, it's crazy not too as you've got the rest to go with it. Your set up was so close to mine I know you wont be disapointed, my mates gps was showing 65 and I was pulling away from him with some left, the take off lifts the wheel and leaves all of mates for dead. I've just put the Leo Vince on mine to see what it's like, I've only given it a go up and down the road and it sounds much deeper than the stage 6. Tommorow I'll see if it goes any better, but for now it's winning on looks, quality and sound.
