Saft eats carbs aluminum body as time goes byĪfter few sessions theres lot of mixture residue to clean from right hand case, carb underside, frame etc. On tillotson HB15 the throttle lever/cable fixture assembly cause side pressure to throttle saft bore. Took a screwdriver - turned air screw/needles while driving until throttling was good
It hesitated a bit each time and just wasnt right.
I have opened air screw about one revolution more than in manual - I couldnt adjust needles enough to make engine run clear between sifts. So it runs way way too rich, pukes and splutters if I even try to run on factory settings. Throttle shaft has developed excessive play - bad news as on this tillotson model theres extra fuel feed channel via throttle shaft. Its equipped with tillotson carb (HB 15 A) that has seen at least 3 seasons of racing. I might have same issue with my iame 175 super sifter. Since air temp affects air pressure along a few other factors, most people use an Air Density Gauge to Tune by rather than temp alone. Atmospheric pressure (aka Air Density) affects amount of fuel charge going into the engine as well. Ideally you want to find a plug temp that burns as much of the fuel load as possible, without creating a pre-detonation situation and power falling off or fuel load not combusting completely and power falling off with the added result of excess fuel/oil in the exhaust. The higher the ambient temp, the higher the combustion temp and so you can regulate combustion temps in this manner. The different plug temps somehow change the rate of ignition of the fuel load inside the combustion chamber creating either a faster/hotter burn or a slower/cooler burn relative to one another. I may have this backwards, but as I understand it in warmer weather you use a colder plug and in cooler weather you use a warmer plug. As I understand it, most top ends are rebuilt before this typically begins, but as you say, the kart/engine is new to you.ĭepending on the ambient air temp and atmospheric pressure, you may have to alter the spark plug temp. There may also be a slight drop in compression from a stuck ring or worn friction surfaces. Mind you that is a four stroke engine and not a two stroke, but the principle is the same. Very common in the Automotive world these days is carbon building up around the rings and causing it to stick.
You can pull the exhaust header and rotate the crank for half a view of the piston and sleeve or pull the cylinder and for a full view of both. Any irregular surfaces could allow over oiling. The piston ring should swipe excess oil from the cylinder walls with each pass. As the fuel/air mix travels through the engine, it leaves a thin film of oil behind. To what extent did you rebuild the carb? Did you replace the metering needle and seat or just the gaskets and diaphramgs? A bad seat, worn needle tip or debris could be dumping too much fuel at idle.Ĭheck the piston, ring and cylinder if you have not already. Low speed needle could be to rich as well. The Setting in the Manual caused excessive oil spitting from the exhaust side for me too. Start with this as a guide for Tuning the Needles: Is the fuel ethanol free? Ethanol can play havoc on the seals, diaphragms and soft metering needle tip of the Carburetor. At the factory settings, the carburetor was still dripping from the carburetor and the exhaust oil was flying everywhere.
On my settings, during the warm-up on the stand it is quite ok.
I know the revs on the track are different, but it’s a nightmare. In YouTube videos or photos, I haven’t seen anyone who has the same engine had everything so dirty. After each session, I have to wipe everything, everything is black oil. The spark plug temperature is according to the service manual. At lower values, the engine starts to revolve poorly, it chokes. The factory settings are very rich, currently I have the L45 ‘and H45’ setup. Iame Leopard engine, Tillotson HL 334a carb, after rebuild. So far, I drive to around 6.000-8500, max 10,000 rpm, on a large asphalt square. After riding, the helmet, seat, exhaust axle and engine are dirty. I have a big problem because I have everything dirty on the back od kart.