Par62003 Posted March 9, 2014 Share Posted March 9, 2014 Hi all, last year I holed the piston on my 1979 dt175 mx, the debris made its way down into the crankcase which means I've had to strip it all down, got the crank cases separated eventually and the bearings, the big ones, are these the main ? are hard and lumpy to turn so I guess will need replacing. The thing is how do you get them off the crank ? I've never stripped an engine before and think I'm in a bit above my head. Any help would be much appreciated, cheers. Link to comment Share on other sites More sharing options...
dt502001 Posted March 9, 2014 Share Posted March 9, 2014 By the time you buy the tools needed your just better off to pay someone,then they wont mess up your crank like you might. Link to comment Share on other sites More sharing options...
Par62003 Posted March 9, 2014 Author Share Posted March 9, 2014 Too late now I'm in too deep, people keep telling me how simple these engine are but from where I'm looking right now it looks extremely complicated ! Link to comment Share on other sites More sharing options...
dt502001 Posted March 9, 2014 Share Posted March 9, 2014 HAHA they are simple just you need alot of tools to pull the bearings and install them properly.And if you do it wrong then you wasted your money and time. You need a bearing puller and a press to install them most shops wont charge you much to R&R them then you can do the rest yourself Link to comment Share on other sites More sharing options...
Moderator Airhead Posted March 9, 2014 Moderator Share Posted March 9, 2014 Thats hard luck mate, the bearing is supposed to stay in the casing when the crancase halvess are split Link to comment Share on other sites More sharing options...
Moderator Cynic Posted March 9, 2014 Moderator Share Posted March 9, 2014 Nah you dont need a press but if the bearing didnt stay in the case you need an engineering firm to remove it. Link to comment Share on other sites More sharing options...
dt502001 Posted March 9, 2014 Share Posted March 9, 2014 That the way I read it that the bearing froze to the crank,and beating beating bearings into place with a hammer is just wrong,using a press is the right way. Link to comment Share on other sites More sharing options...
dt502001 Posted March 9, 2014 Share Posted March 9, 2014 This is the type of kit you would need nowhttp://www.princessauto.com/pal/en/Pullers-And-Bearing/Bearing-Separator-and-Puller-Set/8160483.pJust to get the bearings off and some way of heating then no doubt. Link to comment Share on other sites More sharing options...
Moderator Airhead Posted March 9, 2014 Moderator Share Posted March 9, 2014 yep thats the type of equipment needed, as cynic said, find someone who can do it for you. Electric motor rewinders in your area would be a good bet or more likely a good car repair outfit Link to comment Share on other sites More sharing options...
dt502001 Posted March 9, 2014 Share Posted March 9, 2014 Once you have the bearing off the crank may need repair / cleaning up.Possibly re trueing if the bearing got that hot then the center pin of the crank may be dammaged as well.I would guess it did not come appart easy and you may have dammaged the crank in the processA new crank/con rod and bearings might be the cheaper way to go. Link to comment Share on other sites More sharing options...
Moderator Airhead Posted March 9, 2014 Moderator Share Posted March 9, 2014 Once you have the bearing off the crank may need repair / cleaning up.Possibly re trueing if the bearing got that hot then the center pin of the crank may be dammaged as well. I would guess it did not come appart easy and you may have dammaged the crank in the process A new crank/con rod and bearings might be the cheaper way to go. It's not uncommon for them to come apart in this way dt, and usually just a simple job with the right equipment as you said Link to comment Share on other sites More sharing options...
dt502001 Posted March 9, 2014 Share Posted March 9, 2014 Then I would question the condition of the case,not to mention the condition of the con rod bearing.Kinda hard to tell how good the big end bearing and center pin is without pressing the crank appart.Spen the money now and do it right or throw the dice and do it again when the big end bearing seizes. Link to comment Share on other sites More sharing options...
Moderator Cynic Posted March 9, 2014 Moderator Share Posted March 9, 2014 Its not too big a gambe in most instances, the engine costs about 40quid in replacing onetime gaskets and you can tear it down including taking it from the bike in an hour or two. Trouble being holing a piston put a very fine aluminium powder EVERYWHERE. I have not got away with the same gamble. A crank rebuild should at least be considered. dt, all you need to reassemble a 175 is a fridge and a heat gun. Done in the proper order they go together fine, cold crank with warm bearings, after cold bearings into warm cases. Link to comment Share on other sites More sharing options...
dt502001 Posted March 9, 2014 Share Posted March 9, 2014 That takes to long LOL freeze the bearings with propane,and quickly press them in the case or oppsit way works a charm Link to comment Share on other sites More sharing options...
Moderator Cynic Posted March 9, 2014 Moderator Share Posted March 9, 2014 Only on you side of the atlantic, price of propane I can wait an hour.. Link to comment Share on other sites More sharing options...
dt502001 Posted March 9, 2014 Share Posted March 9, 2014 Ya but when trying to get something apart and it under 5 ton of pressure allready it works great Link to comment Share on other sites More sharing options...
dt502001 Posted March 9, 2014 Share Posted March 9, 2014 Total off topic though.Best to rebuild the crank and not just replace the bearings now you have this mess to deal with Link to comment Share on other sites More sharing options...
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