Smoking and Dripping
Benelli Motorcycle Forum - Benelli Bike Discussions - Powered by vBulletin
Results 1 to 6 of 6

Thread: Smoking and Dripping

  1. #1
    Junior Member
    Member #
    19899
    Join Date
    Dec 2019
    Posts
    4

    Smoking and Dripping

    I was super-fortunate to have this 1968 Wards RiversideBenelli Cobra 125 two-stroke with less than 500 miles fall into my lap after itsat dormant in a garage for almost 50 years. To get it running, I cleaned the carb and tank and changed the gearbox oil.


    Initially is smoked excessively (I mean excessively in thatI heard later some neighbors commented on it) and also leaked a puddle of oilfrom the exhaust. It settled down nicely after a bit of running (normal expected amount of smoke and dripping oil) then I began the restoration. Iíve completed it now after a hard starting issue which turned out to be the new coil and/or wire. I replaced them with the originals and it fixed that problem and seemed like all was well when a couple of miles into my test ride it started the excessive smoke and oil dripping.

    Iím positive my oil/fuel mix is good. The spark plug (whichwas new) is black but smooth. I replaced it with a new one which didnít solve the problem.

    Where to go from here?

    Thanks in advance.
    1968 Benelli Wards Riverside 125
    1980 Honda CX500 Custom
    2007 Honda Shadow Spirit 1100
    2017 Triumph Tiger Explorer XRT

  2. #2
    GBo
    GBo is offline
    Senior Member
    Member #
    18749
    Join Date
    Oct 2018
    Location
    Cumbria
    Posts
    284
    Iím not familiar with that model but two strokes can sometimes suck gearbox oil into the crank cases and then burn it. Did you put new seals in when you rebuilt it or could they have worn or got damaged?

  3. #3
    Senior Member
    Name
    Mark Hollingsworth
    Member #
    8276
    Join Date
    Nov 2008
    Location
    Port Angeles, WA USA
    Posts
    104
    Almost all my vintage 2-strokes have had failed crank seals (allowing gearbox oil and air into engine).

    Did you replace those? If not, there is a special leak-down tester, but Iíd just replace them.
    1978 Benelli sei, 1973 Benelli 250 SuperSport, 1968 Benelli Dynamo Trail, various OSSAs, Betas

  4. Remove Advertisements
    BenelliForum.com
    Advertisements

  5. #4
    Junior Member
    Member #
    19899
    Join Date
    Dec 2019
    Posts
    4
    Quote Originally Posted by Lotus54 View Post
    Almost all my vintage 2-strokes have had failed crank seals (allowing gearbox oil and air into engine).

    Did you replace those? If not, there is a special leak-down tester, but Iíd just replace them.
    I didn't crack the gearbox open since itseemed to be fine. It makes sense to me now that when I initially changed thegearbox oil, it smoked and dripped...until the oil level went down enough tokeep it out of the crankcase. Same thing happened (smoking and dripping) when Itopped the oil off to the max line recently so I drained enough out where thelevel is on the lower side but still adequate and it stopped the smoking anddripping (an Alfa Romeo mechanic taught me that trick when I had a leaking rearseal).

    I ordered a new seal and will replace it atsome point.

    Thanks for the diagnosis.

    Ken

    1968 Benelli Wards Riverside 125
    1980 Honda CX500 Custom
    2007 Honda Shadow Spirit 1100
    2017 Triumph Tiger Explorer XRT

  6. #5
    Senior Member
    Name
    Mark Hollingsworth
    Member #
    8276
    Join Date
    Nov 2008
    Location
    Port Angeles, WA USA
    Posts
    104
    If the crank seal is leaking- you do NOT want to ride it. Even if it is not using gearbox oil, it will bring in extra air- making the mixture lean. That is very bad for a two-stroke.
    I would recommend replacing the seals right away (I generally do both sides when they fail due to age)

    Mark
    1978 Benelli sei, 1973 Benelli 250 SuperSport, 1968 Benelli Dynamo Trail, various OSSAs, Betas

  7. #6
    Junior Member
    Member #
    19899
    Join Date
    Dec 2019
    Posts
    4
    Quote Originally Posted by Lotus54 View Post
    If the crank seal is leaking- you do NOT want to ride it. Even if it is not using gearbox oil, it will bring in extra air- making the mixture lean. That is very bad for a two-stroke.
    I would recommend replacing the seals right away (I generally do both sides when they fail due to age)

    Mark
    Thanks Mark. You make a good point. Iíll keep an eye on the spark plug color in the meantime.
    1968 Benelli Wards Riverside 125
    1980 Honda CX500 Custom
    2007 Honda Shadow Spirit 1100
    2017 Triumph Tiger Explorer XRT

Sponsors

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
Google+