1. Hello Guest. You have limited privileges and you can't "SEARCH" the forums. Please "Log In" or "Sign Up" for additional functionality. Click HERE to proceed.

To Rebuild or Not to Rebuild

Discussion in 'XJ DIY How-To Videos' started by Joshua Olkowski, Aug 2, 2018.

  1. Joshua Olkowski

    Joshua Olkowski Member

    Messages:
    295
    Likes Received:
    12
    Trophy Points:
    18
    Location:
    Los Angeles
    Has anybody out there ever rebuilt an 81 xj550 Seca Engine. I have one that's running...okay, but I also have access to one in a junk yard for 350 bucks. Was thinking of doing a complete Seca teardown and restoration taking the best of both bikes and going to town. However, to really make it worth it I feel I would also have to rebuild the engine otherwise you're just slapping old parts together. I am a novice mechanic and this is my first venture into bikes. The 81 Seca is one of the sexiest bikes I've ever seen and I really want to go for it. Any vids, tutorials, articles would be very helpful. Thanks. Josh
     
  2. XJ550H

    XJ550H Well-Known Member Premium Member

    Messages:
    9,714
    Likes Received:
    2,602
    Trophy Points:
    113
    Location:
    Great North Woods
    first consideration is the amount of money you are going to spend. Complete restoration is a costly project.
    what milage do you have on motor? test the compression. all you should have to do is rings and valve job.
    consider that the valve job is usally just a refurbish of the head

    ground up rebuild of motor would have you spending money you do not need to.
     
    Franz likes this.
  3. Joshua Olkowski

    Joshua Olkowski Member

    Messages:
    295
    Likes Received:
    12
    Trophy Points:
    18
    Location:
    Los Angeles
    Thank you for responding. Money is definitely an issue since I want to do it myself. However, I like your idea of just doing a rings and valve job. Are there any tutorials you could direct me to? Thanks.
     
  4. k-moe

    k-moe Pie, Bacon, Burbon. Moderator Premium Member

    Messages:
    16,598
    Likes Received:
    5,114
    Trophy Points:
    113
    Location:
    Dust in the Wind
    How many miles are on the engines?
    A runner typically won't need to be rebuilt, and there are many things that need to be checked in order to determine if the rebuild is necessary.
    There is also the issue of parts avaliabllity. So few of them have needed rebuilding that Yamaha stopped providing pistons, oversize piston rings, and plain bearings a long time ago. Anything you find now will be from someone's stash of NOS parts, or from an engine that's being parted out.
     
    jayrodoh likes this.
  5. Joshua Olkowski

    Joshua Olkowski Member

    Messages:
    295
    Likes Received:
    12
    Trophy Points:
    18
    Location:
    Los Angeles
    Got it. Unfortunately, I don't know the mileage because the studs on the metal ring that make the speedo wheel turn were bent. Wish I knew that before I bought the bike. Nevertheless, this bike has had a full life, I'm sure. I only got 96 miles on a full tank. Most of that was city driving but I'm guessing I won't get much more then that on the highways. If I do a top end rebuild or any rebuild for that matter will I get better gas mileage or am I just stuck with a beautiful gas guzzling machine from the 80's.
     
  6. Joshua Olkowski

    Joshua Olkowski Member

    Messages:
    295
    Likes Received:
    12
    Trophy Points:
    18
    Location:
    Los Angeles
     
  7. XJ550H

    XJ550H Well-Known Member Premium Member

    Messages:
    9,714
    Likes Received:
    2,602
    Trophy Points:
    113
    Location:
    Great North Woods
    you should get 45 to 50 mpg out of the city
     
  8. Joshua Olkowski

    Joshua Olkowski Member

    Messages:
    295
    Likes Received:
    12
    Trophy Points:
    18
    Location:
    Los Angeles
    I'm not sure if it will. As it stands I'm only getting 25.
     
  9. XJ550H

    XJ550H Well-Known Member Premium Member

    Messages:
    9,714
    Likes Received:
    2,602
    Trophy Points:
    113
    Location:
    Great North Woods
    yes but how much 6th gear time do you get in the city
    and once you get shims in spec and carbs cleaned and tuned your milage should improve

    do the compression test see what you get ( should do this after shims)

    90% of my riding is 55 mph and above
     
  10. Joshua Olkowski

    Joshua Olkowski Member

    Messages:
    295
    Likes Received:
    12
    Trophy Points:
    18
    Location:
    Los Angeles
    Pardon my ignorance but are there any tutorials you could direct me to on a compression test.
     
  11. Rooster53

    Rooster53 Well-Known Member Premium Member

    Messages:
    1,215
    Likes Received:
    389
    Trophy Points:
    83
    Location:
    North, FL
    From the Information Overload Hour:

    https://www.xjbikes.com/forums/threads/the-information-overload-hour.27544/

    - COMPRESSION TESTING:

    Yamaha recommends that you perform a compression test every 5,000 miles or so, and that you should record the readings, per cylinder, for future comparison and evaluation. The acceptable readings (specified at sea level) are as follows:

    To do a compression test properly, you should first make sure all of your engine valves are properly adjusted to their recommended clearances, as valves that are too "tight" (not enough clearance) will allow the intake or exhaust valve to be open more than is necessary, or at the wrong time within the compression stroke cycle, thus bleeding off compression that would otherwise be developed.

    http://www.xjbikes.com/forums/threads/compression-test-xj650.113151

    Do not use thread adapters or the like on your pressure gauge, as the added volume of air space within the adapter will reduce the indicated pressure readings.

    a) make sure the engine is warm (at operating temperature).

    b) remove all spark plugs, and then stick the plugs back into their caps and make sure the plugs are grounded to the cylinder head (or even better, disconnect your TCI unit).

    c) remove the airbox filter lid and the air filter.

    d) make sure the battery is FULLY charged, and remains so throughout the course of these tests! It is actually recommended that for purposes of compression testing that the TCI be un-plugged and jumper cables to a large capacity battery (i.e. car battery) be used to make sure that the cranking speed remains pretty constant between each reading. Slow or sluggish cranking speeds will reduce the indicated compression pressure. Yamaha specifies their compression pressures at 300 rpms (which is why the battery needs to be in good shape).

    e) open the throttle FULLY and keep it open during testing.

    f) crank the engine over until the needle stops advancing.

    g) Let the starter cool down for a minute or so, then do the next cylinder, etc.).

    h) If the readings are below spec, then shoot about a teaspoon amount of motor oil into each cylinder, crank the engine over a few revolutions with the starter (to spread the oil around), and then re-test each cylinder using the above procedure.

    i) compare the two results and analyze.

    j) keep all of your figures, and note the date and mileage from your odometer, so you can compare the next time you take readings (every 5,000 miles or so).
     
  12. David A. Guerrero

    David A. Guerrero New Member

    Messages:
    1
    Likes Received:
    0
    Trophy Points:
    1
    Location:
    Land of Enchantment
    Hey Josh, I just bought the 81 SECA, the first bike I had in college and was wondering what you did to your bike? I might have to redo the seals and gaskets since there was a lot of oil and grease over the outside of the engine.
    Also my engine revs high on start up. Might be a vacuum problem.
     
  13. k-moe

    k-moe Pie, Bacon, Burbon. Moderator Premium Member

    Messages:
    16,598
    Likes Received:
    5,114
    Trophy Points:
    113
    Location:
    Dust in the Wind
    Please start a thread for your bike.
    His bike is not your bike.
    His problems are not your problems.
     
  14. Joshua Olkowski

    Joshua Olkowski Member

    Messages:
    295
    Likes Received:
    12
    Trophy Points:
    18
    Location:
    Los Angeles
    Sorry for the blurry pic. I'm having an oil leak out of this little drain hole. Does anybody have any idea how to fix this?
     

    Attached Files:

  15. k-moe

    k-moe Pie, Bacon, Burbon. Moderator Premium Member

    Messages:
    16,598
    Likes Received:
    5,114
    Trophy Points:
    113
    Location:
    Dust in the Wind
    Remove that cover. Behind it you will find the ignition pickup and reluctor. Behind that is the seal for the crankshaft. That is where the leak is coming from.
    Chacal has replacements that do not require splitting the crankcase to install.
     
    Joshua Olkowski and Chitwood like this.
  16. Chitwood

    Chitwood Well-Known Member

    Messages:
    809
    Likes Received:
    332
    Trophy Points:
    63
    Location:
    Fort Atkinson, Wisconsin
    Just be very careful not to damage the pick ups themselves or the reluctor
     
    k-moe and Joshua Olkowski like this.
  17. Joshua Olkowski

    Joshua Olkowski Member

    Messages:
    295
    Likes Received:
    12
    Trophy Points:
    18
    Location:
    Los Angeles
    Is this the part you are referring to:
    HCP18762 Aftermarket crankshaft flange OIL SEAL, fits on the left end of the crank to the case on all XJ550, 1984-85 FJ600, 1986-87 FZ600, 1986-90 YX600 Radian, 1992-98 XJ600 Seca II, XJ650, XJ700, XJ750, and XJ900RK, RL, N/FN, F, and S/SH engines, and on the right end of the crank on XJ1100 and XS1100 engines. Use 1 per engine. NOTE: Approximately 1/2mm thicker than original seals and is metal-shielded (unlike the original).
    $ 11.95
     
  18. k-moe

    k-moe Pie, Bacon, Burbon. Moderator Premium Member

    Messages:
    16,598
    Likes Received:
    5,114
    Trophy Points:
    113
    Location:
    Dust in the Wind
    I think so, but start a conversation with @chacal to confirm.
     
  19. Joshua Olkowski

    Joshua Olkowski Member

    Messages:
    295
    Likes Received:
    12
    Trophy Points:
    18
    Location:
    Los Angeles
    Would anybody have some ideas on why my bike is having a bit of trouble getting into first gear? At first it was a little sporatic but now my Seca 550 is consistently having trouble getting into first to the point that I have to really stomp on the gear shift lever to move down into first. I use to be able to comfortably push it into first gear now I have to bring the weight of my entire leg down on the petal to get it into first from neutral. When I start to take off it will sometimes have trouble catching and I can't take off as quick as I use to, almost like trying to start in 2nd. it even pops a little bit more. I first noticed something was fishy about two months ago when sometimes I would shift into second gear and it would often get hung up into neutral and then I'd have to shift again to get it into second. All the other gears work fine after that.
    The only thing I've tried so far is adjusting the clutch cable of course and no matter if I make it tighter or looser it's still a bit of a struggle to get down into first gear. Any ideas would be great. Thanks.
     
    Last edited: Jun 5, 2019
  20. Chitwood

    Chitwood Well-Known Member

    Messages:
    809
    Likes Received:
    332
    Trophy Points:
    63
    Location:
    Fort Atkinson, Wisconsin
    Pull the shifter cover. Look for any bent/broken parts/springs etc. Also look for broken bits of plastic. It could be from the alternator chain guide breaking up. With the bike up on the center stand, not running, can you shift through the gears without excessive force? You may have to rotate the rear tire to get it to hit all of them since it's not running. Maybe you need a clutch
     

Share This Page