Okay my aerox is getting the sledgehammer treatment soon. The setup: s6 streetrace s6 pro rep 17.5mm carb manual gravity fed fuel manual choke 100 jet Ok the bike has been dyno run and the main jet is bang on (look at the dyno sheet) but the bike dies at about 50mph or slower if throttle is open. The garage said this was the vaccum fuel system not creating a big enough vaccum. that got changed and problems still here. The plug looks a healthy colour so im pretty certain its not the jetting. Also when i decelerate it 'backfires' and bike bogs down. what could be causing this? thanks
Hi I'd try raising the needle by a clip or two - and possibly upping the idle jet. But first - rich up that middle section with the needle. The backfiring is because it's too poor. Unless it's because the float bowl is not filling up fast enough (as your garage suggests). How long does it keep going at full blat ? If it dies with the throttle wide open after 45 seconds then it could be the float bowl. f not, it's the needle. What kind of carb is it ? If it's a DO - odds are it isn't the floats.
dellorto carb and my float bowl is non adjustable -.-. ive just bought a new spark plug cap as the old one was toast and noticed half the screw end of the spark plug was gone so possiblity it wasnt sparking properly?
Maybe I misread the post. If it dies at full throttle - it's either too poor or the bowl is running dry (for whatever reason - floats ? Fuel line?). I thought it was OK at full blat (dyno mentioned) but was having trouble in the middle - hence the needle. Like most carb posts - it's impossible to really know without sitting on the machine & trying it. So it's at full throttle that it dies. Does it do it instantly or does it take time ? Hence the 45 second question.
takes about 45 seconds yeh, i run a gravity fed fuel system (straight on/ off no vaccum) like the dyno people said but still nothing, my float looks like its leaning to one side, hard to explain but its not flat. When it 'backfires' it bogs and shoots a tiny flame out the exhaust. Im going to try to clean the carbon out of the exhaust see if this helps anything but im stuck on ideas now.
New floats and fatter fuel pipes ! I don't know of a 50 cc scoot that uses an actual pump. It's all gravity. I use the same system as you. Straight through - with a tap. I'd call delorto UK. They're very helpful & they have everything. http://www.dellorto.co.uk/contact.asp Good luck
While tuning it at the dyno, did they made changes to the ignition? Becouse, you can play a little with the timing of the stock ignition, But that only helps with the old type ignition, the newer type has issues with it several times.... So did you placed a differend rod or something? or drilled up the holes from the groundplate from the ignition? Shooting flames out of the exhaust means normally that the ignition timing isn't right, The fuel inside the engine explodes when the exhaust port is open, so the ignition timing is to late. To much fuel can also expode in an heat exhaust, but mostly won't, becouse the exhaust does get pretty heat, but not that heat when the fuel is to much, ( fresh fuel is cold and cooles the cilinder and also the exhaust when its not burned and comes into the exhaust. and with less fuel, ur engines gets pretty warm ( fresh fuel cooles the cilinder ofcourse ) If its not enough, the cilinder gets to warm, and then also your exhaust, but becouse their isn't enough fuel, it won't get rid becouse of the exhaust. last option is that your fuel is good or some to much, but your 2stroke oil isn't enough? do you still use a oilpump? or do you mix it yourself? Without oil or enough oil you get friction ( couses a heat cilinder and heat exhaust ) and when you get then to much gas getting lose in the exhaust it can explode. For me, i gues its something with the ignition becouse the engine is setup wel on the dyno, in most cases what won't be a problem. But before trying anything of those options, try to change the hight of the needle, way easier to try than all the other stuff i mentiont. What sparkplug do you use?
NGK BR9HS (long reach) spark plug for the 70cc kit. And personally i think the timing is off as everything else has be checked and replaced, im tempting to change the needle height but what way shall i go up or down? (its currently at stock 17.5mm dellorto setting). Also how can i adjust my timing? thanks
hmm, not sure with the streetrace if it should be a long or short reach sparkplug, Can't remember it anymore from my own or the people i mounted this cilinder for, ( to long while ago ) Changing the height, well, i just would write down what the stock is or take pictures. and start testing. But maybe you should start with placing the clip on the lowest place ( means that it is richer on fuel ) Adjust your timing is something you can't do. Or there are some options, but that depens on what type aerox you have, one with old type ignition or a new one. What is the building year from yours? But probably its not something you want to mess with! especially not when ur engine isn't working well like it should be. Those changes can be made when the engine is already funning fine/perfect, It has a stock timing, and normally can't be or has to be changed, If the timing isn't right its not something you can adjust to right, it means something is broken.
2011 aerox Geussing thats new style I upped the needle height and lower the main jet to a 98 and it runs good, couldnt get it to die but only time will tell... Also cleaned the carb, airbox, put new carbon fibre reeds in and put a new coil and HT lead on. Exhaust has be decoked and repacked so hopefully it will be good as new but who knows!
2011 does have the new type ignition, all ignitions after 2006 have problems when you try change the ignition timing. The older ignitions can have a better gasresponse and give some extra power, the older versions ignition was standard a littlebit timed to late. When you buy a Top Performance due + cilinder, on one of the papers is writen some information about changing the ignition timing to a little earlier, but that only works for the older types. When you do this with a new type ignition, there is a big change you will get trouble. Buddy of me had the same... so we stepped over to a racing ignition to have some more performance. but if you don't know what you do, i don't recoment it to play with the ignition time. And about turboovetto, this is true, keep an eye on the sparkplug's collor, Its a great indicatio to see if the fuel/air mix is good.
2011 does have the new type ignition, all ignitions after 2006 have problems when you try change the ignition timing. The older ignitions can have a better gasresponse and give some extra power, the older versions ignition was standard a littlebit timed to late. When you buy a Top Performance due + cilinder, on one of the papers is writen some information about changing the ignition timing to a little earlier, but that only works for the older types. When you do this with a new type ignition, there is a big change you will get trouble. Buddy of me had the same... so we stepped over to a racing ignition to have some more performance. but if you don't know what you do, i don't recoment it to play with the ignition time. And about turboovetto, this is true, keep an eye on the sparkplug's collor, Its a great indicatio to see if the fuel/air mix is good.
