1972 Kawasaki G5 100cc

Discussion in 'Projects' started by SatansPetFerret, Aug 6, 2011.


  1. SatansPetFerret

    SatansPetFerret
    Expand Collapse
    Evil Genius

    2,523
    1
    591
    Location:
    Olympia
    This thread will be updated very infrequently due to work/school/racing. My goal is to have the final build complete next spring (2012).

    My wife sk8rgrl got this bike last year from a friend for free. She likes it because it's a small bike, and she can touch the ground even when it's stock. I'm rebuilding it for her, and going to modify it a little bit along the way. The G5 is a 2-stroke 100cc enduro that was the predecessor of the KE100. Almost the same bike, actually.

    Mitch F's '72 90cc rebuild threads gave me some great ideas, and are worth checking out -
    http://pnwriders.com/motorcycle-talk/139347-72-kawi-resto.html
    http://pnwriders.com/motorcycle-talk/148729-caution-sh-eating-grin-inducing.html

    Initial condition - several broken bits, missing the key, air box cover, and misc little parts. Pretty much all there otherwise. Everything is pretty dirty/trashed, but no major damage.

    [​IMG]

    [​IMG]

    [​IMG]

    [​IMG]

    [​IMG]

    [​IMG]
     
  2. SatansPetFerret

    SatansPetFerret
    Expand Collapse
    Evil Genius

    2,523
    1
    591
    Location:
    Olympia
    Starting the teardown -

    [​IMG]

    [​IMG]

    [​IMG]

    It's one of the first G5's made -

    [​IMG]

    [​IMG]
     
  3. dartmanx5

    dartmanx5
    Expand Collapse

    Coolness! I had the street version about the same vintage, cool little bike! Lookin' forward to seeing this one progress.
     
  4. SatansPetFerret

    SatansPetFerret
    Expand Collapse
    Evil Genius

    2,523
    1
    591
    Location:
    Olympia
    Engine teardown (photos are part of my teardown notes, that's why they appear rather step by step) -

    Clutch side, carb pulled -

    [​IMG]

    Oil pump and clutch actuator removed -

    [​IMG]

    Clutch cover pulled -

    [​IMG]

    Clutch cover -

    [​IMG]

    Piston is stuck solid to the con rod, otherwise it would have come off earlier -

    [​IMG]

    Clutch off -

    [​IMG]

    Rotary valve -

    [​IMG]

    If that's on the outside...

    [​IMG]

    Split cases -

    [​IMG]

    This is the inside...

    [​IMG]

    Finally got the damn piston off after hammering out the wrist pin. Connecting rod was stuck to the crank. WD40 helped greatly.

    [​IMG]

    Main crankshaft bearing on the left cover was completely stuck. After enough WD40, compressed air, small picks, etc it finally came loose.
     
  5. nemisis714

    nemisis714
    Expand Collapse

    3,358
    0
    666
    Location:
    Kent, WA
    Beautiful, I am restoring a 1972 Yamaha LT2 (100cc) right now too.
    I can't wait to see this finished as well
     
  6. SatansPetFerret

    SatansPetFerret
    Expand Collapse
    Evil Genius

    2,523
    1
    591
    Location:
    Olympia
    Misc notes -

    Couldn't find a 72 connecting rod. Crank rebuilt by Mr Crankshaft (awesome job) with a 74+ G5/KE100 con rod that uses a 14mm wrist pin. This will require a 74+ piston when I get to that point. Upside of that is the 74+ rod has oiling slots cut for the main crank bearing.

    Kawi part #s are wrong for the left side main crank seal (and superseded part #s are wrong too). Actual seal dimensions are Od=40mm Id=20mm and Depth=7mm. Kawi says a 40/23/7 will work, but they're wrong. I suspect this applies to all small 1970's Kawi 2-strokes since the part #s are all the same.

    Paulson's hooked me up with the right seal out of a parts box at no charge. They're awesome.

    While figuring out the seal part # issue, found out that my crankcase is pretty damn near identical to a G3 Centurion. This means I could possibly use a G3 air intake instead of the massive G5 intake. 74+ G5's had a different case that requires use of the G5 intake.

    Bearings and seals all installed in the lower end, going to start putting it back together slowly.
     
  7. When I was 15 I bought my first new bike ever, a leftover '72 G5 100 just like that. The old Jim Boltz Cycle Barn, back when it resided in what appeared to be a surplus WWII quonset hut where Costco is now, had bought out he remaining G5's in '73 and they could be had for $399 OTD instead of the MSRP of about $549.

    My Dad sold it w/o asking me when I was in the Army overseas in '78, and I looked for a salvageable, restorable one for more than 30 years 'til I finally stumbled across one a couple of years ago. I started disassembly but have put off continuing the restoration until my imminent retirement...need to build a shed to store some of the M/Cs so I have room to work in my garage.

    I may not need to do an engine teardown as I found another donor bike free on CL that supposedly had a new top end, but we'll see.

    In any case it sounds like you've run into some issues and any information like what you've posted above would be very helpful...so I will greatly appreciate you sharing as much info as possible. I may have a few extra parts too from the parts I saved from the donor bike if you need 'em, although it sounds like you'll be done long before I am, since it'll be a few months yet before I can resume working on mine.

    I remember the bike as having good power for the size, but then I was a lot lighter then, so it'll be interesting to see how it will feel to me nearly 40 years later.

    Keep posting about your restoration, I'll be eager to follow it!
     
  8. Mitch F

    Mitch F
    Expand Collapse

    3,138
    0
    666
    Location:
    The Ham
    Looking forward to seeing the progress... You'll be surprised at how much fun it is to ride methinks :evil4:
     
  9. SatansPetFerret

    SatansPetFerret
    Expand Collapse
    Evil Genius

    2,523
    1
    591
    Location:
    Olympia
    Here's some shots of the crankcase cleaning in progress -

    [​IMG]

    [​IMG]

    [​IMG]

    [​IMG]

    Air intake/cover from a Kawasaki G3. This cover actually fits 72 and 73 G5's, the crankcase is identical as far as I know. In 1974 the G5 crankcase changed to accommodate the round air filter cover that is now standard on the KE100.

    [​IMG]

    [​IMG]

    Crank and transmission in, ready to be pressed -

    [​IMG]

    Cases pressed together. You'll see that I have replaced all the soft Phillips head case bolts with Allen heads. These are normal alloy bolts that I spraypainted the heads on so they won't rust, and the color is close to that of the crankcase -

    [​IMG]

    [​IMG]

    Shift assembly put together. I am going to go back and replace these screws with Allen heads as well -

    [​IMG]

    I found applicable clutch part numbers on the Barnett website. Note that they recommend the same part #s for a lot of Kawasaki 100's, but be sure to count the plates and discs in your clutch. In the G5 there are 4 friction plates and 4 steel discs, the Barnett website said 4 friction plates and 3 steel plates. I am re-using one original steel plate on the outside instead of ordering a fourth Barnett plate.

    [​IMG]

    New Barnett spring on the left, stock on the right -

    [​IMG]

    Note that these parts must be ordered individually, Barnett does not supply a kit for this bike.

    Barnett part #s for the 1972-75 G-5 Series are:
    Friction Plates (Qty.) = 301-45-10002(4)
    Tempered Steel Metal Plates (Qty.) = 401-45-063013(3) - as I stated, this should be 4 plates for the G5
    Spring Kits = 501-29-06051

    Breakdown for all Kawasaki 100's on the Barnett website -
    http://www.barnettclutches.com/prod...ches_other&clutch_make=Kawasaki&clutch_cc=100
     
  10. Thank you for posting up those parts nos. and details, they will come in handy if my clutch will need work too. Are any of your stock springs in spec? I've heard (and experienced on other bikes) how stiff the clutch pull can be with all Barnett Springs. On the RDs if we use 'em we alternative stock with Barnett...strong but without the total wrist-killing lever pull.

    If you aren't using any of the stock springs, please let me know how it works for you and if the lever pull is adversely effected as described above.

    Can't wait to hear it run, hopefully you'll put a vid on YouTube, it'll be like going back in time nearly 40 years. I can still remember the giddy excitement of the day I brought it home.
     
  11. SatansPetFerret

    SatansPetFerret
    Expand Collapse
    Evil Genius

    2,523
    1
    591
    Location:
    Olympia
    21.6mm standard length with a wear limit of 1.6mm. Mine are 21.3 to 21.4 and have ~2k on them.

    Barnett springs fit my riding style better as I don't ever use much of a friction zone. I like the quick engagement.

    I have a Clymer book on 80-350cc rotary valve Kawi's from 1966 to 1980 that I am using for a lot of good info. it has a note in the performance improvement section that states -

     
  12. SatansPetFerret

    SatansPetFerret
    Expand Collapse
    Evil Genius

    2,523
    1
    591
    Location:
    Olympia
    Like I said, swapping out as many philips heads for allens as I can -

    [​IMG]

    New(er) steel rotary disc is standard on 1979+ KE100's instead of the resin (on the left). The steel disc requires a new valve cover, spacer, O-ring, and the sprocket insert for the disc. As far as I can tell, the crank seal is the same.

    [​IMG]

    Installed -

    [​IMG]

    I need to figure out a way to plug the oil injection hole, as I am going to run pre-mix instead of oil injection. The oil injection pump has been known to fail.

    If the stock clutch springs are weak, the Barnetts are ridiculously strong. I wound up going with 3 of each as a compromise -

    [​IMG]

    The clutch is assembled and installed, as well as the flywheel/magneto on the other side, but I didn't get pictures of that yet.

    Here are the covers, pre-blasting and pre-powdercoating -

    [​IMG]

    Mocking up frame bracing (rear hoop is being bent at a local welding shop) -

    [​IMG]

    Old frame braces cut out, new ones waiting to be installed -

    [​IMG]

    [​IMG]

    The Wiseco piston showed up today. I have concerns about the height. It is just over 6mm taller than stock. However, my research indicates that the same cylinder and head were used from 1972 to at least 1980 (by part #), and this piston (Wiseco part # 369M04950, stock bore of 49.5mm) is supposed to fit a '74 (when Kawi changed to a 14mm wrist pin). I had the cylinder honed and it is off getting coated right now, so I don't have a way to test fitment. Not sure how this is going to work out.

    [​IMG]
     
  13. SatansPetFerret

    SatansPetFerret
    Expand Collapse
    Evil Genius

    2,523
    1
    591
    Location:
    Olympia
    Ok, lots to update on. Got the head and cylinder back from Performance Coating in Auburn. They polished the head and coated the cylinder with a thermal dispersant. Looks badass.

    I had a local powdercoater do the covers, they turned out OK. I should have sanded out a couple scratches beforehand, or asked them to, but oh well.

    So, the piston... what a fun experience.

    The compression height (from center of wrist pin to top edge) is 6mm taller on the Wiseco 369M04950. The skirt & bottom end is identical, so there are no concerns about impacting the crank. I emailed Wiseco and they told me that it would be $2400 to do a minimum run of 12 custom pistons. They also said they did a run for the G3ss/4/5's about 25 years ago that might work, Wiseco #140 in PS, P2, P4, P6, & P8. Some are on Ebay, no PS (standard) left but some overbores are available. However, those all take a 12mm wrist pin, so you'd have to use a 72/73 G5 con rod.

    When I started trying to figure out how to swap the crank or con-rod back to a combination that worked, Don suggested I use a 6mm spacer underneath the cylinder. I mocked it up using washers, and it should work.

    Obviously the washers aren't exactly 6mm but they're within .1mm on each post, and this is all sitting free.

    TDC -

    [​IMG]

    [​IMG]

    BDC -

    [​IMG]

    [​IMG]

    BDC looking up through the exhaust port toward the piston, there is a lip of ~1mm but only in the very center of the port -

    [​IMG]

    [​IMG]

    After putting the head on with the spacers, I still have just enough space to put on the washers, lock washers, and nuts -

    [​IMG]

    Plugged the oil injection port -

    [​IMG]

    Mocking up the right side covers with the G3 intake and cylinder on -

    [​IMG]

    [​IMG]

    The frame is off getting the cross-braces and rear hoop welded on, should have it back next week. Also ordered a G3 front fender and exhaust since this will be a streetbike, not a trail/enduro.
     
  14. Mitch F

    Mitch F
    Expand Collapse

    3,138
    0
    666
    Location:
    The Ham
    I've got a G3 rear fender in damn nice shape if you want it, it's just sitting here.
     
  15. SatansPetFerret

    SatansPetFerret
    Expand Collapse
    Evil Genius

    2,523
    1
    591
    Location:
    Olympia
    I might take you up on that. Let me get the frame back and do some mocking up with the G5 fender pieces I've got. I'll shoot you a PM in a week or two.
     
  16. Mitch F

    Mitch F
    Expand Collapse

    3,138
    0
    666
    Location:
    The Ham
    Sounds good. I think I've even got the bracket!

    And your engine looks great!
     
  17. shelbyguy

    shelbyguy
    Expand Collapse
    Picture Whore

    7,311
    0
    866
    Location:
    lacey
    um, ive got a gt80 + engine kit.....i need to get started
     
  18. Mitch F

    Mitch F
    Expand Collapse

    3,138
    0
    666
    Location:
    The Ham
    If you need parts, let me know. I've got 2 GT80's and 2 TY80's :secret:

    Lots of parts!
     
  19. SatansPetFerret

    SatansPetFerret
    Expand Collapse
    Evil Genius

    2,523
    1
    591
    Location:
    Olympia
    Stripped the carb down. It was pretty bad

    [​IMG]

    Didn't really take pictures, but the carb has been blasted, dipped, and ultra-sonic'd. Still had dirt in it, but it should all be clear now after a good (careful) manual cleaning. It has new bowl screws and washers, gasket, drain, a new pilot jet and a slightly larger main jet (from 102.5 to a 105) since I plan to run pre-mix. I also converted from a cable choke to a plunger style like that found on the '76 or later KE100.

    Got the frame back from the weld shop -

    [​IMG]

    Looks pretty good, now I plan to mock everything back up and see what else can be ground off.

    [​IMG]
     
  20. donthekawguy

    donthekawguy
    Expand Collapse

    935
    0
    566
    Location:
    Rathdrum, ID
    Looking good! The motor looks very nice. I wish I could get started on mine. :rant
     
Loading...
Similar Threads Forum Date
1972 175 Kawasaki New Users Jun 22, 2014
1972 kawasaki 100 g5 New Users Apr 30, 2014
1972 Kawasaki F7 Service Manual Mechanical & Technical Oct 22, 2013
1972 Kawasaki 750 H2 Mach IV Marketplace Oct 13, 2013
1972 kawasaki h2 750 Motorcycles Jan 24, 2013

Share This Page