kiln Posted October 22, 2012 Share Posted October 22, 2012 I have noticed recently that there is a huge air blow back through the air cleaner when i left a cover screw off. The air becomes much more obvious when revving the engine. I have Booyesens reeds installed and they are sealing properly from what I could observe. Is this normal for a 2-stroke or is there a fix of some kind? Is this detremental to the bikes performance? Any suggestions? Link to comment Share on other sites More sharing options...
Moderator Airhead Posted October 22, 2012 Moderator Share Posted October 22, 2012 Hi kiln, not seen you for ages fella...Greetings of course your boyessens are fooked !, get some nice flat standard ones back in there, or some hy-tec ones from yambits Link to comment Share on other sites More sharing options...
dt502001 Posted October 22, 2012 Share Posted October 22, 2012 +1 on the reeds booysen reeds are great but short lived. Link to comment Share on other sites More sharing options...
kiln Posted October 23, 2012 Author Share Posted October 23, 2012 Hi kiln, not seen you for ages fella...Greetings of course your boyessens are fooked !, get some nice flat standard ones back in there, or some hy-tec ones from yambits Hi Oldgi...ergh Airhead. Thanks. I have been busy riding a KLR650, but now and again I jump back on one of the DT's. I will change to a spare reed set and of course I will get the Hytech ones from Yambits. Yambits served me well in the past and I can also recommend them. I have a 1988, DT50 to rebuild for my son so I will be asking help on the forum in the future. Link to comment Share on other sites More sharing options...
kiln Posted October 23, 2012 Author Share Posted October 23, 2012 In the mean time......Found a spare reed block with original parts. My question then is: If the fibreglass reeds only last a short while is it not worthwile to keep the original steel ones? When would one consider replacing the original steel ones, i.e. after how many km's or would the telltale signs also be "blow back"? Thanks in advance for all the advise. Link to comment Share on other sites More sharing options...
Moderator Airhead Posted October 23, 2012 Moderator Share Posted October 23, 2012 Theres not much wrong with the original ones if they are doing their job, you should be able the blow air through the unit but attempting to suck air through should cause them to seal shut Link to comment Share on other sites More sharing options...
wild foamy Posted October 24, 2012 Share Posted October 24, 2012 I have a 1988, DT50 to rebuild for my son so I will be asking help on the forum in the future. I just bought a 1982 DT50 because i missed my old DT so much... :3 i put about 12,000 miles on my old set of reeds, sold the bike with the same set in there aswell, they were hytec ones aswell i think... Link to comment Share on other sites More sharing options...
kiln Posted October 24, 2012 Author Share Posted October 24, 2012 Thanks for the info "wild foamy". I put back the oem type steel ones and will go ride the weekend to test them.The booyesens ones still looked fine and sealed when sucked closed, no evidence of worn edges either. Link to comment Share on other sites More sharing options...
kiln Posted October 27, 2012 Author Share Posted October 27, 2012 Hi all, Today i have opened up the air cleaner box with a 25mm hole and it made a huge improvement. Then I started tinkering with the timing. I moved the plate with the coils about 4mm clockwise and then checked the flywheel timing with a strobe light.Found the flywheel centre line exactly tdc at 4200rpm and after that, moving anti clockwise as the revs climb. Is this correct? By moving the coil plate clockwise is the timing retarted or advanced? Link to comment Share on other sites More sharing options...
Moderator Cynic Posted October 27, 2012 Moderator Share Posted October 27, 2012 Moving it clockwise will have advanced the timing, ie the spark is earlier in the piston stroke. The spark generally starts at or slightly before TDC, (rmember just how fast shit happens in an engine running at say 6000rpm, 6000 burns per minute or 100 burns a second) as the combustion 'the burn' is just starting as the piston reaches tdc and fully compresses the now expanding mix, this means that the expansion is putting pressure on the piston as soon as possible. When the piston moves faster with the rising revs the point at which the spark is supplies needs to be earlier, this is because the engine parts are moving faster but the burn will take the same amount of time. So without advance the energy is wasted as the burn will be chasing the piston down the bore wasting its power. A side effect, if the advance is a little too high (were not talking much) the fuel will burn with a bigger bang. 'Great i hear you cry', not quite that uncontrolled burn will give more power but you will also be allowing it to burn hotter. This will destroy the piston ultimately. Possibly melting the crown or siezing, maybe both but it will die. The opposite is true at lower rpm as the spark needs to happen later or the piston will come up against resistance as it reaches the top of the stroke, its what causes pinking as the burn slows the piston causing the skirt to hit the bore because it cannot 'float'. Short answer, yes you will get more power but the question of for how long is more important..... Link to comment Share on other sites More sharing options...
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