Brian Emerson

Looks like I may have fixed this quad, even though I had the carb off numerous times and set the float height to specifications I decided to do the fuel level check with the clear hose up the side of the carb, fuel level was way too high, above the seam where the float bowl screws on, so ended up adjusting the float height until I got the fuel level about 2mm below this seam, tests so far have been good, the only backfire I have had was a really small pop/fluff sound, no huge bang..I will take it for a good run, check deceleration for noise, then check for any back fire after key off. Thanks to all who gave me some suggestions here, very much appreciated...take care...

Hello Mech, connected up my in-line spark plug tester, ran the quad to hot, when I got the bang out of the exhaust when turning the key off there was no evidence of any residual spark or spark plug firing happening so I can rule that out. Will concentrate on the carb, maybe too rich, did notice that when running I only need to open the choke control a little and it causes the engine to bog...

Thank you, I have an inline spark tester, will connect that and then see if I am getting any sign of a spark after turning key off, will let you know..

No this petcock/fuel tap is fine, someone has replaced it previously, I did try the quad with the tap set on 'Prime' and the vacuum line to the intake blocked off but made no difference, still the huge backfire after turning key off..and yes, a leaking diaphragm in the tap allows unmetered fuel to enter the intake manifold via the vacuum line..have checked all of this and it is fine..

Hello, quad belongs to one of my customers so not sure the history, I know he hasn't had it that long. A QuadMaster is very similar I believe to a Quad Runner, they call it an LTA500 (but not to be confused with the late model LTA500) it is year 2000 so 24 years old! It is a carburettor model, Mikuni CV type that I have had off a couple of times and also put a new kit in it, ie jets, needle etc. Have checked the valve timing, adjusted the valves, tried another CDI unit. It does a massive backfire out of the exhaust after you turn the key off so unburnt fuel is being ignited in the exhaust system and not by the spark plug, called 'afterfire' I believe.

Hi Guys, this Quadmaster has an extremely loud bang after turning key off (from idle), scares the stock, dog and missus, any ideas on what to check. Thanks and regards, Brian