UK_DT Posted September 21, 2012 Share Posted September 21, 2012 I've just fitted a new NOS air filter to my DT400E as the original disintegrated as soon as it was touched! The new filter came sealed in a bag and was pre-oiled. Having been out for a reasonable run with a brand new spark plug fitted, I checked the plug condition on return and it has sooty deposits. This is sometimes attributed to the air filter, but with a new one I wouldn't have thought this would be the cause. However, I wonder if the oil in the filter has perhaps thickened in the time since it was made and is restricting air flow? Should I take the filter out and clean it and do they really need to be oiled for UK conditions? Also, the bike wasn't keen on being run at a constant part throttle opening, is there anything that can be done to improve this? I seem to remember it being mentioned in a road test, so maybe that's just how they are. Link to comment Share on other sites More sharing options...
Moderator Airhead Posted September 21, 2012 Moderator Share Posted September 21, 2012 No thick oil never did them any harm I oil mine with 220 viscosity gear oil is the main jet the standard size for the bike? Perhaps the choke isnt seating, is that a possibility? RH crank seal passing and burning gearbox oil...is that also a possibility? Link to comment Share on other sites More sharing options...
UK_DT Posted September 21, 2012 Author Share Posted September 21, 2012 Thanks Airhead for the quick reply. Haven't dismantled the carb to check on main jet. I'll have a look at the choke to make sure that it's seating correctly, though the lever seems to "click" off ok. Hope it's not the crank seal, though being 34 years old I guess it could have hardened. Is replacement a big job? Link to comment Share on other sites More sharing options...
Moderator Airhead Posted September 21, 2012 Moderator Share Posted September 21, 2012 I think it can be done with the engine in the frame mate but the drive pinion and clutch would have to be removed has the gearbox got a breather pipe in the top on that model? Can you smell petrol if you remove the gearbox dipstick? With extended use does the gearbox oil level change? Link to comment Share on other sites More sharing options...
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