steptoe1111 Posted May 29, 2009 Share Posted May 29, 2009 hey guys can i got a 77 dt 175 mx from the tip for a hundred bucs and been working on it for a wile when i got it the piston was seized cause it had been left dry for years how anybody could let that hapen to a great litle bike is beyond me but was wondering can i replace the piston rings without reboreing and replaceing the piston can i just slap em on and away i go basicly can i get away with it ???? and one more thing im finding it hard to maintain an even idle there are no itake or exust leaks garenteed it seems like im for ever playing with the idle scweew i have already filed off the impreshion the scweew leaves on the carbi piston and cleand the tip off the scweew up pluss ive totaly cleand up the carbi aswell if theres something wrong with the idle jet will make it dificult to hold an idle between 500- 1300 i can get an idle at 500 revs after its been riden for a good hour or so but when you back off the gas after a good rev in neutral it will drop to 12-1300 revs run there for 5 secons or so the slowly drop to 500 revs but it wont drop and keep the same idle rev all the time its either to fast or to slow any imfo or knowledge any one has would be very greatly apreciated thanks heaps ps. whats the best mix ratio for the 2 stroke im running pre mix no oil pump Link to comment Share on other sites More sharing options...
TylerP Posted May 29, 2009 Share Posted May 29, 2009 If you know there are no vacuum leaks and the carb is good & clean you need to check the compression. Once under 90-100 lbs the idle can be erratic. If you have the cylinder off you can probably hone it and clean the piston up so you can put the new rings on. It's always a good idea to check the piston to cylinder clearance if you have one apart. If it's to loose the skirt can break off and wedge between the crank and case,knocking a hole in the case. Thats not good. Link to comment Share on other sites More sharing options...
steptoe1111 Posted June 11, 2009 Author Share Posted June 11, 2009 g'day mate how are you the bike sais on the meter that its done 12600kms its been a few years since i fixed the seized piston i know its the original 50mm piston it has a 50 stampted on the top so i asume its stil got the same rings it dose have a bit of a rattle maybe big end? after reading your reply i stuk a compreshion gage in the plug hole just a rubber ended one and kicked it over as hard as i could im getting 800kpa out of it dose this sound average? the bike has a bit of go acualy it goes pretty hard! reading the specs on the dt175 they recon the front will lift bewtween 2nd and 3rd at full poower it wont do that you acualy have to reef the bars up hard in high 1st or verry high second keeping in mind the motors 30 years old but there all similer ive tried difrent sprokets ratios curently i find the best is 14 on the front 44 on the rear i find they give it good high speed 90kmh and still has plenty down low anyway would a hone and anew set of standard rings give me a bit more compreshion than what im getting and if ther is a bit of piston rattle would the new rings help even it out a bit basicly would new rings help make it better than what it is already or am i just wasting my time in therory it make sense to me new rings beter compershion equals more power any knowlegde is greatly apreciated thanks shaun Link to comment Share on other sites More sharing options...
Moderator Airhead Posted June 11, 2009 Moderator Share Posted June 11, 2009 g'day mate how are you the bike sais on the meter that its done 12600kms its been a few years since i fixed the seized piston i know its the original 50mm piston it has a 50 stampted on the top so i asume its stil got the same rings it dose have a bit of a rattle maybe big end? The standard piston for a 175MX is 66mm, the 50 you are seeing will be 0.50 and this means it is now 66.5mm or 0.5 oversize. after reading your reply i stuk a compreshion gage in the plug hole just a rubber ended one and kicked it over as hard as i could im getting 800kpa out of it dose this sound average? the bike has a bit of go acualy it goes pretty hard! reading the specs on the dt175 they recon the front will lift bewtween 2nd and 3rd at full poower it wont do that you acualy have to reef the bars up hard in high 1st or verry high second keeping in mind the motors 30 years old but there all similer ive tried difrent sprokets ratios curently i find the best is 14 on the front 44 on the rear i find they give it good high speed 90kmh and still has plenty down low anyway would a hone and anew set of standard rings give me a bit more compreshion than what im getting and if ther is a bit of piston rattle would the new rings help even it out a bit basicly would new rings help make it better than what it is already or am i just wasting my time in therory it make sense to me new rings beter compershion equals more power any knowlegde is greatly apreciated thanks shaun You should really go through a top end checking routine to datermine the state of your engine, the most likely problem is ring wear, a set of rings should be replaced occasionally, to determine whether this is necessary...do the checks...see this post Here ...Paul Link to comment Share on other sites More sharing options...
steptoe1111 Posted June 12, 2009 Author Share Posted June 12, 2009 hey thanks alot paul all that imfo was just what i needed after reading it all ive decided to go ahead with the new rings pluss a top end cleanup and see how we go thanks again you guys are great and if ya like ill let ya know how it all comes together thankyou so mutch shaun Link to comment Share on other sites More sharing options...
Recommended Posts