Scandal Posted January 29, 2011 Share Posted January 29, 2011 Hi all i purchased a dt175 last saturday 3/4 of the way home it gradually died , i got it to my fathers house were we replaced the spark plug all fine with that , the next thing was the carb as the spark plug wasnt getting wet , so this weekend we stripped the carb which seemed clean we proceded to put back the carb and try starting as normal , at which point we noticed once the carb was full it was constantly overflowing ( had done this before) but writed it self . This time we noticed the spark plug was get fuel as it was wet a good sign, the problem is the fuel overflowing . I shall point out the electrics tyres and everything elese on the bike has been rebuilt the engine has a 1mm overbore and not fully run in yet. The floats were put in exactly how they were taken out just of note . We will take the carb off again and have another look not sure if we are on the right track , we tryed bumping the bike and also noticed it wants to go and there is a puff of blue smoke out the back ??? along with backfireing . any help would be helpful thanks in advance Link to comment Share on other sites More sharing options...
blackhat250 Posted January 29, 2011 Share Posted January 29, 2011 Hi scandeleous " The valve [ float valve] sounds like its sticking, it may be worn , or just shit in it , screw it out & inspect, the misfire could just be its flooded, Oh & when it died ? Was it because it ran out of fuel [ overfowing,] check the correct spark plug is fitted Link to comment Share on other sites More sharing options...
Alan m Posted January 29, 2011 Share Posted January 29, 2011 if the carb is overflowing it is prob the float needle is either worn or there is dirt stopping it from closing ,make sure its clear and check for signs of wear on the rubber tip of the needle when puttin it back make sure the float is closing properly A good trick is to leave the bowl off the carb connect it to a fuel source[ hold it level as it would be in the bike] hold the float closed and turn on the fuel for a second just enough to let juice through, if it flows through with the float closed you have a needle problem if not let you float free and close it again with fuel running through and see if it stops again if it still stops well you have another problem be careful no sparks etc the only way in to a carb is through the float chamber so this has to be were to start looking from probs hope this helps Hi all i purchased a dt175 last saturday 3/4 of the way home it gradually died , i got it to my fathers house were we replaced the spark plug all fine with that , the next thing was the carb as the spark plug wasnt getting wet , so this weekend we stripped the carb which seemed clean we proceded to put back the carb and try starting as normal , at which point we noticed once the carb was full it was constantly overflowing ( had done this before) but writed it self . This time we noticed the spark plug was get fuel as it was wet a good sign, the problem is the fuel overflowing . I shall point out the electrics tyres and everything elese on the bike has been rebuilt the engine has a 1mm overbore and not fully run in yet. The floats were put in exactly how they were taken out just of note . We will take the carb off again and have another look not sure if we are on the right track , we tryed bumping the bike and also noticed it wants to go and there is a puff of blue smoke out the back ??? along with backfireing . any help would be helpful thanks in advance Link to comment Share on other sites More sharing options...
Scandal Posted January 29, 2011 Author Share Posted January 29, 2011 Hi thanks chaps we thought we might be on the right track with the floats tomorrow we are takeing the carb apart again see whats occuring. thanks again Link to comment Share on other sites More sharing options...
Moderator Cynic Posted January 29, 2011 Moderator Share Posted January 29, 2011 Hi thanks chaps we thought we might be on the right track with the floats tomorrow we are takeing the carb apart again see whats occuring. thanks again Erm, going to point you in a completely different direction here. Does the carb leak only when the bike is on the stand firstly. This is a VERY common occurance due to the floats sliding slightly in the float bowl and jamming on the side of the carb. Happens when the jack up kit is fitted even more. With a DTMX it is very worthwhile learning to turn off the fuel every time you stop. Second, gradually dieing and its been rebuilt. How far did the rebuild go?, as bad starting with the odd puff and pop could be just a bad plug (Far more common than you might imagine)or possibly timing being out. Its one of the few things these engines require to be absoloutly spot on. Link to comment Share on other sites More sharing options...
Scandal Posted January 29, 2011 Author Share Posted January 29, 2011 Hi the fuel comes out when the fuel tap is put on and the bike being preped for starting e.g choke then procedes to carry on untill i switch the tap off , the engine has had an 1mm overbore and wasnt run in fully so was being easy with it the gearing on the front of the bike is 1 tooth less for more acceloration and less top end . Link to comment Share on other sites More sharing options...
Moderator Airhead Posted January 29, 2011 Moderator Share Posted January 29, 2011 could be a leaking float, take it out and shake it...can you hear anything? could be a worn float needle can you see a ring worn around the point, and is the float needle free? could be just set wrong should be 21mm float height with gasket removed...you will see a notched out area to measure from Link to comment Share on other sites More sharing options...
Scandal Posted January 29, 2011 Author Share Posted January 29, 2011 We will cheack out the floats and needle we had them out today and never cheaked thinking it was a dirt problem . Link to comment Share on other sites More sharing options...
oak framer Posted January 30, 2011 Share Posted January 30, 2011 I have the same problem with my carb, been through it and can't find the problem. I wonder if it is the jack up kit causing overflowing like Cynic says. Adam Link to comment Share on other sites More sharing options...
Scandal Posted January 30, 2011 Author Share Posted January 30, 2011 Hi all the carb is clean and no longer overflowing bike still wont start, we think its the head gasget gone as it feels like compression is not what it should be , the head could well be warped , as there is oil leaking around the gasget not to the point of leaking on the floor , the bloke i bought the bike off tighterned up the nuts but said they need torqeing up , i get 13 miles down the road and the gradual power loss . Its the only thing that is left as all other problems have been eliminated. Link to comment Share on other sites More sharing options...
Moderator Airhead Posted January 30, 2011 Moderator Share Posted January 30, 2011 Hi all the carb is clean and no longer overflowing bike still wont start, we think its the head gasget gone as it feels like compression is not what it should be , the head could well be warped , as there is oil leaking around the gasget not to the point of leaking on the floor , the bloke i bought the bike off tighterned up the nuts but said they need torqeing up , i get 13 miles down the road and the gradual power loss . Its the only thing that is left as all other problems have been eliminated. could well need torqueing, however!! dont be surprised if the studs start to pull right out of the barrel because the 30 year old threads have finally given up. Link to comment Share on other sites More sharing options...
Scandal Posted January 30, 2011 Author Share Posted January 30, 2011 The bike has had new barrel and head the bolts have been replaced as i have a margarine tub full of bolts and cogs and carb replacment parts gasgets replacement barrel that was the original one . Link to comment Share on other sites More sharing options...
Moderator Airhead Posted January 30, 2011 Moderator Share Posted January 30, 2011 Aahh so it has had a new barrel fitted, well that should be good...must have cost a fortune. Link to comment Share on other sites More sharing options...
Alan m Posted January 30, 2011 Share Posted January 30, 2011 if the head was blowing you would hear a slight whistling sound as you try to kick it over , if you lift the head look at the gasket and the gasket face of the head a leak will show as a darker color on the metal and on the gasket Aahh so it has had a new barrel fitted, well that should be good...must have cost a fortune. Link to comment Share on other sites More sharing options...
Moderator Cynic Posted January 30, 2011 Moderator Share Posted January 30, 2011 Hi all the carb is clean and no longer overflowing bike still wont start, we think its the head gasget gone as it feels like compression is not what it should be , the head could well be warped , as there is oil leaking around the gasget not to the point of leaking on the floor , the bloke i bought the bike off tighterned up the nuts but said they need torqeing up , i get 13 miles down the road and the gradual power loss . Its the only thing that is left as all other problems have been eliminated. Famous last words, you have only had a fiddle with the carb. And speaking from experience if thats a new barrel and piston with new gaskets then it will run fine with a itty bitty leak. Matey tightend the nuts then said they need torquing. Stinks sorry. You do these up once on assembally and thats it. If tightening the heads fixes it buy a lottery ticket for the weekend. Link to comment Share on other sites More sharing options...
Scandal Posted January 31, 2011 Author Share Posted January 31, 2011 hi the bike has had new parts all over have paperwork to prove it the carb was fine and timeing is electronic electrics all fine and there is fuel in the cylinder , the only thing left is the head were the oil is leaking from the gasget the 1mm overbore is not run in yet , and the bolts have been known to come loose as they may need re torqueing at a few hundread miles . Link to comment Share on other sites More sharing options...
CameronMac Posted February 1, 2011 Share Posted February 1, 2011 hi the bike has had new parts all over have paperwork to prove it the carb was fine and timeing is electronic electrics all fine and there is fuel in the cylinder , the only thing left is the head were the oil is leaking from the gasget the 1mm overbore is not run in yet , and the bolts have been known to come loose as they may need re torqueing at a few hundread miles . EDIT: I misunderstood the post! Link to comment Share on other sites More sharing options...
Moderator Cynic Posted February 1, 2011 Moderator Share Posted February 1, 2011 hi the bike has had new parts all over have paperwork to prove it the carb was fine and timeing is electronic electrics all fine and there is fuel in the cylinder , the only thing left is the head were the oil is leaking from the gasget the 1mm overbore is not run in yet , and the bolts have been known to come loose as they may need re torqueing at a few hundread miles . I don't buy it, in 24 years of running a DT175 and any number of other air cooled 2 strokes when the heads on, the heads on. If the head and barrel faces are true with a new gasket that head would seal. Don't missunderstand me, happy to be proved wrong......but Link to comment Share on other sites More sharing options...
Scandal Posted February 4, 2011 Author Share Posted February 4, 2011 hi all took the head off and exhaust polished the head up and barrel piston and exhaust port , while takeing the head off 2 bolts were tight and 4 yes 4 !!!!! were loose above hand tight gasget is in mint condition have got a torque wrench so will tightern up the lot tomorrow will run like a dream i hope lol Link to comment Share on other sites More sharing options...
Scandal Posted February 5, 2011 Author Share Posted February 5, 2011 I forgot to ask is it possable to fit the later dt 175s 1998 onwards tank and seat to my 1980 model as the design did not change much? , cheers . Link to comment Share on other sites More sharing options...
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