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  1. #1
    Seat Tester
    My Bike(s)
    1976 Suzuki RM 250
    Location
    Slave Lake Alberta
    Posts
    60

    Question Rebuilding 1976 RM250

    I am trying to rebuild an 1976 RM250 that was given to me in a box. I am having trouble getting it to start. It has spark, but seems week. I have a new plug. The carb looks ok on the bench, but after I crank about 5 or 6 times gas runs out the exhaust. Where do I begin? Supposedly the motor was overhauled but I am beginning to wonder..

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  3. #2
    Sprocket Pilot
    My Bike(s)
    Which one of the 9?
    Location
    USA
    Posts
    878
    Gravity fed carbs require a float with a needle valve. Once the float reaches the correct height the needle valve closes on the seat stopping the gas from flowing into the carb. You need to strip the carb and clean it out, then check your float and make sure it does not have a hole in it causing it to sink and not be able to float. Once you have the float sorted you need to adjust the height of the float so that it will shut off the fuel flow with the needle and seat properly. to do this you need to hold the carb upside down and measure from the carb body up to the top edge of the float. To adjust the height you bend the small tab gently that is attaced to the needle valve until you get the proper height. You should invest in a Clymer or OEM Suzuki manual if you can get it.

  4. #3
    Sprocket Pilot
    My Bike(s)
    Which one of the 9?
    Location
    USA
    Posts
    878
    Also check that your ignition is putting out the required spark by testing with a volt meter.


    Also wanted to congratulate you on the bike. They are fast becoming a collectors item and you own a piece of MX history. Take good care of it and enjoy it. I restored a 1977 RM-370 that I purchased for 200 dollars 5 years ago. I sold it for 3,600 dollars, just to give you an idea of what they can be worth to a collector!
    Last edited by Dave2122; 08-08-2005 at 03:42 PM.

  5. #4
    Seat Tester
    My Bike(s)
    1976 Suzuki RM 250
    Location
    Slave Lake Alberta
    Posts
    60
    Thank you Dave. I will re look at the float. I had done all of that except look for a leak. It has two floats, one on each side, and I was wondering if they were not working correctly. The valve seems to work fine on the bench, easy moving and am not able to blow air through when closed.

    Also, how do I check the voltage? What voltage should it be putting out at the plug? I am currently trying to find an owners manual, but no luck so far. We do have a great recycle place for bikes about three hours from here and I will be visiting them on Saturday.

    I am excited about getting the bike going. So far I only have $150 into it.. not too bad.. but knows I will have about $500 when done, sprockets, chain, levers etc..

    thank you again..

  6. #5
    Newbie
    Posts
    1

    Thumbs up 1976 rm 250

    happy to someone else interested in old rm's i have some old rm's and,
    if i can help you let me know!

  7. #6
    Seat Tester
    My Bike(s)
    1976 Suzuki RM 250
    Location
    Slave Lake Alberta
    Posts
    60
    Thank you, It has been fun. I got it running last night, put new sprockets and chain on it and took it for a short spin.. wouldn't you know that the bolt holding the arm to the rear brake drum broke and then went the brake shaft and all.. Laughs, so now I have to find a new rear break assembly.. but that shouldnt be too hard.

    The main thing I am having trouble with is getting it to idle and run well. I have adjusted, cleaned, recleaned, readjusted, the carb so many times. I have tried to find air leaks, etc.. new plug.. only thing I havn't done is tore into the reads.. The motor was supposedly rebuilt then promptly totaled.. like within a half a mile of starting..

    Any suggestions would be awsome.. thank you and have an awsome weekend.
    Have a great day and be safe.

  8. #7
    oldtimerwrenchturner
    Guest
    first check the compression
    if it is goog check the reeds

  9. #8
    Seat Tester
    My Bike(s)
    1976 Suzuki RM 250
    Location
    Slave Lake Alberta
    Posts
    60
    Ya I think I will tear into the reeds next thing.. have been waiting for the owners manual I ordered, to make sure I am doing it right.. thanks oldtimer..
    Have a great day and be safe.


 

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