facebook1 youtube1 twitter1 instagram linkedin1 pinterest1

NOTICE:  If you are not a free registered member of the site, you will not see the photos in the forum, and you won't be able to access our premium member content. Please consider joining our community! REGISTER AND MAKE THIS BOX DISAPPEAR!

×

Pictures Posting Not Working (12 Jun 2023)

Picture uploads is again unavailable. We are working on the problem. Thanks for your patience.

Makotosun

74 DT250 Starting/Idling Problem

  • Yamalol
  • Yamalol's Avatar Topic Author
  • Offline
  • Site Supporter
  • Site Supporter
  • Posts: 41
  • Likes received: 17

74 DT250 Starting/Idling Problem was created by Yamalol

The bike had been sitting for a couple years before I got it. I cleaned the carb and sanded some corrosion/crap off the points and then it started first kick (with 1/4 turn of throttle). I had to give it maybe 1/8th turn on the throttle to keep it going, but after doing that for a minute or so it would idle fine.

A couple days later, I rode it around my block a couple times. I had to do the same procedure to get it to idle initially, but when I finished riding and rolled off the throttle completely, it died. Yesterday, it started a couple times, but wouldn't idle at all. Today it wouldn't even start. I pulled the spark plug and it looked oil fouled. I cleaned it off, checked for spark (it was good), tried to start, nothing. Tried another B8ES plug, nothing. I did a compression test, 120psi. I went through the carb again, everything was clean and clear. Still won't start.

It seems to me that something is wrong with the air/fuel mixture, but I'm not sure what could cause the bike to run one day, and not even start a couple days later with no changes made during that time. Any help is appreciated!
'74 DT250A, '74 DT250A (another one), ‘72 Honda XL250, ‘69 Honda SS125A, ‘88 KLR 650, '57 Harley Davidson Sportster, '46 Harley Davidson WL, '79 Harley Davidson Shovelhead.
15 Sep 2019 18:25 #1

This message has an attachment image.
Please log in or register to see it.

Please Log in or Create an account to join the conversation.

  • Posts: 9639
  • Likes received: 3915

Replied by RT325 on topic 74 DT250 Starting/Idling Problem

Seeing it was pretty good, then turned to custard plus oil fouled plug i'm wondering about the right side crank seal. If it popped out it could do that or half sitting out top or bottom enough to let oil & air in in big quantities. Might ad just to shoot that theory down, that they're not prone to pooping seals out in that model plus it won't fail overnight if it was ok yesterday--won't fail as a seal but if it got out it'd big fail. Ignore that & try some start fluid or something volatile to see if it'll at least try to run. use a clean plug & if it has spark & fuel then apart from seal i wonder if it's sheared off the flywheel crank key. Have you had the flywheel off or did you just sand the points through the slot. if flywheel's not been off then should still be ok, assuming it was ok two years ago when parked. sorry not very helpful just sending you on a wild goose chase with a few ideas. By the way, choke works best with throttle fully closed but will assist with rich running once going & up above idle, but rev it too high then come down & it might drown it so get ready to flick it off. Good bikes those "74 250's.
15 Sep 2019 20:49 #2

Please Log in or Create an account to join the conversation.

  • Yamalol
  • Yamalol's Avatar Topic Author
  • Offline
  • Site Supporter
  • Site Supporter
  • Posts: 41
  • Likes received: 17

Replied by Yamalol on topic 74 DT250 Starting/Idling Problem

Thanks for your thoughts. I never took the right side cover off, but I do have a new gasket I can put on. I swapped out the old stator cover gasket because it was looking a little crumbly and breaking apart. I did pull the flywheel off, but it's on there solid. I checked when I changed the gasket yesterday.

One detail I forgot to add is that the throttle has been perpetually sticky, and I don't think the issue is with the throttle housing, or anything on the bars. I can spin the throttle around easily with the cable disconnected. I've taken the carb off four or five times to clean it, and sometimes when I put it back on, the throttle won't snap back. A tiny bit of oil seems to help. When I put it back on last night, it was nice and snappy. Didn't try to start it then though. I'm thinking that there might be an air leak either somewhere on the carb, maybe in the choke assembly, or between the carb and the engine. I will try a clean plug today. Confusing issue.
'74 DT250A, '74 DT250A (another one), ‘72 Honda XL250, ‘69 Honda SS125A, ‘88 KLR 650, '57 Harley Davidson Sportster, '46 Harley Davidson WL, '79 Harley Davidson Shovelhead.
16 Sep 2019 06:54 #3

Please Log in or Create an account to join the conversation.

  • Posts: 507
  • Likes received: 210

Replied by run103 on topic 74 DT250 Starting/Idling Problem

Is there rust and debris in the fuel line and it is plugging the fuel intake on the carb
Doug
16 Sep 2019 09:04 #4

Please Log in or Create an account to join the conversation.

  • Yamalol
  • Yamalol's Avatar Topic Author
  • Offline
  • Site Supporter
  • Site Supporter
  • Posts: 41
  • Likes received: 17

Replied by Yamalol on topic 74 DT250 Starting/Idling Problem

Hey, Doug. I'll double check after work today, but I don't think so. I've gone through the whole thing with compressed air and carb cleaner a couple times. I know the fuel coming out of the fuel line is clear, I checked that yesterday too. I tried running the engine with the gas tank cracked to check if the tank vent was blocked, but that didn't make a difference either.
'74 DT250A, '74 DT250A (another one), ‘72 Honda XL250, ‘69 Honda SS125A, ‘88 KLR 650, '57 Harley Davidson Sportster, '46 Harley Davidson WL, '79 Harley Davidson Shovelhead.
16 Sep 2019 09:41 #5

Please Log in or Create an account to join the conversation.

Moderators: yamadminMakotosunDEETVinnieJames Hart