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Makotosun

1974 Yamaha DT175a with vm24ss carb

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1974 Yamaha DT175a with vm24ss carb was created by Yamaha2strokes

 So I’ve decided to put my pride to the side on this one I have spent 3 weeks day and night on the ol girl and she doesn’t want to run properly ..
so what happened was it ran pretty good the air skrew wasn’t with the bike when I got it (I know usually pain in the ass lean conditions) but the needle was moved down one notch than recommended to make up for it. I’ve rode the bike like this for about 8 months or so. One day I had a really bad exhaust leak and then the bike wouldn’t run right I figure this was the problem so  (I was getting max  2 mph just enough to stay balanced couldn’t give any more throttle was so ever or she’d bog down and die out) I replaced the exhaust manifold seal. De-carbon’d  the exhaust and rebuilt/ cleaned the carb throughly.. completely cleaned the air box new oem filter. In the meantime I replaced rear wheel bearings axel re-greased and replaced grease fitting on swing arm sanded painted( waiting on powder coat ) just to clean up rust and give her the attention she desperately deserves  went thru all ground and connections wiring harness rebuilt both switches (oem) from the ground up and she looks sexy just doesn’t run… 1st kick turn over sometimes 2nd (compression good) checked piston rings (fairly new ..less than 75 miles on em)  I have checked the main needle settings jet sizes air filter box exhaust crank seals oil drain plug seal . I have been thru the loop with this bike the only thing I can think of is bad reed valves I mic’d the carb and its exact 

signs and symptoms : runs extremely rich (I have all air ports currently blocked off per oil tank Reservoir needs to be completely gone thru from the inside (haven’t that far want her to run first) it was like this when I got it . I have a skrew with the same size threads in the airport but the moment I take it out I have run away RPMS and kill it quickly (idle adjuster skrew doesn’t seem to make a difference ) with the makeshift air skrew in there (still alows some air in) it will partially idle only it seems every other stroke kinda and any throttle given completely bogs down and dies almost like no throttle response only dies from being to Rich. I’ve checked the gas tank vent the petcock gas tank was cleaned throughly 3 times before I put back on .carb flushed air box flushed (while off same with carb ) and air filter properly oiled … I am getting close to my wits end with it but I can’t give up ANY HELP WHAT-SO-EVER WILL BE APPRECIATED !!  
thanks ..and sorry for the long post
Last edit: 22 Sep 2024 15:49 by Yamaha2strokes. Reason: Mis-spelled some stuff
22 Sep 2024 13:39 #1

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Replied by Yamaha2strokes on topic 1974 Yamaha DT175a with vm24ss carb

Rich conditions firing every other stroke with any kind of adjustment to idle skrew(out)(I believe) take out air skrew super lean runaway RPMS COULD IT BEED BAD REEDS!?
22 Sep 2024 15:51 #2

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Replied by Swoop56 on topic 1974 Yamaha DT175a with vm24ss carb

Bad reeds typically either won't run at all at low revs , or run extremely poorly .
Once you get up in the revs , their effect is minimal to none .
You have another problem entirely .
The following user(s) Liked this Post: MarkT, RT325
22 Sep 2024 22:56 #3

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