maltatrucker Posted December 27, 2008 Share Posted December 27, 2008 Hi all Lent my DT250(1981) to my brother while I was away came back and found this Cheeky twat says it was ok when he used it,anyway apart from the broken piston and rings the is a grove in the barrel,should be alright if I go a couple of sizes up on the rebore but was thinking could I put the Barrel of the Dt400 on and have 400cc bike instead of 250cc also if putting 400 barrel on is ok would I have to use the 400 head Cheers all Link to comment Share on other sites More sharing options...
Moderator Airhead Posted December 27, 2008 Moderator Share Posted December 27, 2008 Isnt that an engine strip down then to get the bits out of the crank cases? As far as the 400 idea goes, i wouldnt bother, the carbs and exhausts are different between the models i think. i doubt it was your brothers fault though, there must have been something wrong for that to happen, maybe it ran lean or the oil delivery isnt correct Link to comment Share on other sites More sharing options...
maltatrucker Posted December 27, 2008 Author Share Posted December 27, 2008 Right the m8,I was premix the fuel maybe he forgot to put oil in anyway thanks for input on the 400 issue looks like a complete strip down on the books then,relly didn,t want to start on it till I finished my H2 but sods law ain't it bloody great 2 bikes in garage and lovely weather here at the moment never mind Cheers mate Link to comment Share on other sites More sharing options...
blackhat250 Posted December 27, 2008 Share Posted December 27, 2008 Hi all Lent my DT250(1981) to my brother while I was away came back and found this Cheeky twat says it was ok when he used it,anyway apart from the broken piston and rings the is a grove in the barrel,should be alright if I go a couple of sizes up on the rebore but was thinking could I put the Barrel of the Dt400 on and have 400cc bike instead of 250cc also if putting 400 barrel on is ok would I have to use the 400 head Cheers all Not so simple ,, [250] bore/stroke70x64---[400] 85x70... DT400 has longer stroke . so conrod wud need shifted... so its a stripdown if thats the route . also . think DT400 timing is slightly diffirnt. CDI. changing as well . and thier like hens teeth.... Link to comment Share on other sites More sharing options...
JUST ME! Posted December 27, 2008 Share Posted December 27, 2008 Leave her as a 250, For all the rooting about it just isn't worth changing,let alone the balance problems you end up with. Simply wash the bottom end out with petrol, blow it out with compressed air, lube the bottom end bearings with 2 stroke oil, fit the new slug and rings. Fit the bored and honed barrell and your almost done. In my opinion,considering the much greater cubic capacity, the 400s did not go that much better than the 250s. Going by the pics, the piston has grabbed the bore through lack of,or no oil. ALL THE BEST! Link to comment Share on other sites More sharing options...
Moderator Airhead Posted December 27, 2008 Moderator Share Posted December 27, 2008 Simply wash the bottom end out with petrol, blow it out with compressed air, lube the bottom end bearings with 2 stroke oil, Thats a good idea and will save a heck of a lot of work, take the engine to a good compressor and air line. You will have a job lubing the bearings, so just pour two stroke oil into the cavity, about 1/2 pint, then tip engine to each side for a while before tipping it up-side down again to drain off excess oil Link to comment Share on other sites More sharing options...
JUST ME! Posted December 28, 2008 Share Posted December 28, 2008 Thats a good idea and will save a heck of a lot of work, take the engine to a good compressor and air line. You will have a job lubing the bearings, so just pour two stroke oil into the cavity, about 1/2 pint, then tip engine to each side for a while before tipping it up-side down again to drain off excess oil Yeah you are right mate, but you mostly have to worry about the larger particles damaging seals. Any really fine particles of piston alloy will be spat into the atmosphere faster than the space shuttle crew. As you know these jiggers are pretty tolerant machines! ALL THE BEST! Link to comment Share on other sites More sharing options...
maltatrucker Posted December 28, 2008 Author Share Posted December 28, 2008 Cheers guys will take your advice Link to comment Share on other sites More sharing options...
lakin Posted December 28, 2008 Share Posted December 28, 2008 Hi all Lent my DT250(1981) to my brother while I was away came back and found this Cheeky twat says it was ok when he used it,anyway apart from the broken piston and rings the is a grove in the barrel,should be alright if I go a couple of sizes up on the rebore but was thinking could I put the Barrel of the Dt400 on and have 400cc bike instead of 250cc also if putting 400 barrel on is ok would I have to use the 400 head Cheers all hey . all you really need to it get the barrel re-bored if theres enuff left onit ull get the piston to fit it will cost you about 50quid and get a new gasket set as well its not a hard job so dont worrie bout it lol Link to comment Share on other sites More sharing options...
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