Posted November 24, 200915 yr Hi I have a 2001 dt230 which only has about 6000km on the clock, I bought it two months ago. It has had a strange vibration/rattle when you accelerate under load from low revs. As soon as the Revs build up it goes away but while its there it is very pronounced, almost like the plastic ducts leading to the radiator are shaking and slapping in the wind. Any thoughts?
November 24, 200915 yr Moderator check the chain for wear, lube it and check the free play (slack) is correct.
November 24, 200915 yr Author The chain and sprockets are all good. This vibration has no relation to road speed, only engine speed. It is when the engine is labouring... could it be piston slap? Maybe I have been out of two strokes for too long and this is how they sound under load at low revs?
November 24, 200915 yr Moderator The chain and sprockets are all good. This vibration has no relation to road speed, only engine speed. It is when the engine is labouring... could it be piston slap? Maybe I have been out of two strokes for too long and this is how they sound under load at low revs? First off you say you have been off smokers for quite a while, you are letting it get some revs on. If you are plodding around at 2or 3 thou then it will protest. You ideally want to be keeping the motor at around 5 tho for general knobing round town (under the powervalve but running clean) less than that and it will get messy.
November 25, 200915 yr Author Nah, I rev the tits off it all the time. It seemed to get worse after I went up 2 sizes on the main jet. I leaned it out on the needle at the same time but now I am thinking that maybe I need to fool with the air screw it get it running right at idle.
November 25, 200915 yr Moderator Nah, I rev the tits off it all the time. It seemed to get worse after I went up 2 sizes on the main jet. I leaned it out on the needle at the same time but now I am thinking that maybe I need to fool with the air screw it get it running right at idle. Right so you are riding it properly then . Why the jet change? Going up on the mains and down on the needle will just confuse things. Especially 2 sizes , whats that 10 points? The jet is shaped to supply the right fuel ratio at different throttle openings, the main jet will make it richer across the board. Dropping the needle will weaken the high end slightly but you may have made the low rpm range too weak to run properly causing it to pre ignite (pink).
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