79cc Sportsman Flyer build

Discussion in 'DIY Home Built Motorized Bicycle (non kit)' started by Tom from Rubicon, Jun 23, 2016.

  1. Tom from Rubicon

    Joined:
    Apr 4, 2016
    Messages:
    121
    Likes Received:
    6
    Exhaust is completed, instead of using Pat's well engineered exhaust system. I made my own exhaust system,1" ID flex stainless steel tubing, two exhaust clamps of 6061 T6 aluminum the finned one at the engine and one to clamp the exhaust pipe to the B&S 3/4NPT muffler intake side. Also two strap clamps, one to hold the exhaust pipe to the frame and a larger one to clamp the muffler.. The strap clamps are of HRPO steel1mm steel thick] that I formed and drilled for mounting screws. The strap clamps got a black oxide finish, then hot waxed for corrosion resistance. Photo captures it all.
     

    Attached Files:

    #61 Tom from Rubicon, Jul 20, 2018
    Last edited: Aug 3, 2018
  2. Tom from Rubicon

    Joined:
    Apr 4, 2016
    Messages:
    121
    Likes Received:
    6
    Today was supposed to be the day, turned out it was not. Engine compression is unacceptably low. I had the right side case off to remove the governor assembly and the camshaft comes out to remove it, The tappet rods drop when doing so. That is no biggie, reassembly requires getting the tappet rods back into the rocker arms and resting on their cams under tension. Really simple stuff, but something is not right. I have all sorts of patience but 2018 does not. So I ordered another engine from HF and will install it with out mods. Then with time and beer will sort out that which I chose not to do at this time.
     
  3. Tom from Rubicon

    Joined:
    Apr 4, 2016
    Messages:
    121
    Likes Received:
    6
    Current engine to be pulled, hopefully with Sportsman Flyer engine mount, and diagnose WT# is not right. Surely my fault. Until it is out of the frame. To be continued.
     
  4. Venice Motor Bikes

    Venice Motor Bikes Custom Builder / Dealer/Los Angeles

    Joined:
    Mar 20, 2008
    Messages:
    6,265
    Likes Received:
    42

    Hi Tom,
    I know this is a couple of weeks late, but what makes you think the engines compression is way too low???
    FYI, there is a compression release on the cam (for easier pull starting)!!! The compression will dramatically increase after the engine fires up!!
     
    Tom from Rubicon likes this.
  5. Tom from Rubicon

    Joined:
    Apr 4, 2016
    Messages:
    121
    Likes Received:
    6
    Hi Tom,
    I know compression is way too low???this is a couple of weeks late, but what makes you think the engines


    FYI, there is a compression release on the cam (for easier pull starting)!!! The compression will dramatically increase after the engine fires up

    Hi Norm, you are not late. I am late.. As earlier posted, compression seemed to me not the stated 8.5-1. My Huasheng has more compression. Any way I’m yanking away and the recoil takes a s**t. Great!

    Order new engine from Harbor Freight. That arrived last Saturday. Pull it out of the box and give it a yank…. It is a wimp too! So it gets wrapped up and back in the box.

    And then today, I get a post from VMB (Norm) about compression release in the highlighted above. On a little bitty 3hp? The 8hp Tecumseh doesn’t on my snow thrower. If that baby doesn’t start on the first pull it is aerobic exercise time.

    Back to be beginning. Engine came out of the frame on it’s mount. The frame mount remains with the frame. Genius!

    I put the engine back into the frame mount easy as pie.

    So I’m thinking, instead of screwing around repairing the recoil start just going with rope pull. That option is there to use, and the bike has the cute little tool storage box to store the rope.
     
  6. Tom from Rubicon

    Joined:
    Apr 4, 2016
    Messages:
    121
    Likes Received:
    6
    Well today I gave the recoil start a fair chance at reassembly. Did not go well. After a great day as a Tool and Die Maker, I come home have a few beers and head to the shop with another beer to keep me hydrated. (There were more).(^) I would like to see how it is done at the factory as it was like no spring recoil I have repaired before. Taking up valuable time in my shop. So knowing Pat has done builds (not SF80) but similar with open fly wheel. I did it. Plastic fan had to come off, so I did it the easy way. Copper chisel around cutting right around the pull start hub fan so as not to damage the cast iron fly wheel took two passes around with that copper chisel. I like it.
     

    Attached Files:

  7. Tom from Rubicon

    Joined:
    Apr 4, 2016
    Messages:
    121
    Likes Received:
    6
    Long day Friday ,Saturday, and Sunday . After my brain fart about compression, I went into high gear to reassemble the drive train, complete. Re-attach fuel system. Finally make a reliable throttle system. PZ19 Mikuni on middle needle notch Put a BF Goodrich inner tube in front wheel, Rear went flat first and got a Goodrich too. Schwinn inner tube had a weak spot Read Chinese junk. No offence to my Chinese friends. Went through the whole bike, making sure all fasteners were torqued. Sturmey Archer front brake adjusted, and rear Shimano 110 bearings running free when axel nuts drawn up.

    (Mind you there is no operating manual for any motorized bicycle. I may over time develop one.)

    That said, it was time. Rolled the Flyer 80 over to the machine shed and pumped in a ½ gallon of 90 proof no ethanol, opened the cock, turned on the ignition switch, set the choke, and gave the engine a spin. Then I had to figure out which position is on the ignition switch.

    Now I know. Carb needle is in middle notch, used the longer Champion plug gaped at .030.

    The first 10 minutes and more I wrestled with attaining an idle that did not engage the Bully clutch, and during run in it was still not right. But over the next hour, as the engine started to break in, an engine idle RPM that did not engage the Bully clutch or die is starting to be reliable. Over all performance is with an hour on the machine already exceeding my expectations

    Dry pedaling the drive system was noisy. Under engine load the only sound is engine exhaust.

    So far my only trouble is the Brooks model 190. Their newest biggest model.Stock finish is slippery, the ride suspension superb.

    The Felt springer fork function exceeded my expectations.

    Pat Dolan’s Sportsman Flyer80 Rocks
     

    Attached Files:

    fasteddy likes this.
  8. Tom from Rubicon

    Joined:
    Apr 4, 2016
    Messages:
    121
    Likes Received:
    6
    Primo Pat!
     
    fasteddy likes this.
  9. Venice Motor Bikes

    Venice Motor Bikes Custom Builder / Dealer/Los Angeles

    Joined:
    Mar 20, 2008
    Messages:
    6,265
    Likes Received:
    42
    That's a damn good looking bike that you've built!! (Pat makes the best stuff) (^)

    If you're still having problems with the clutch engaging at idle (or too soon in the RPMs)?, you can simply install lighter bolts into the six fly weights . ;)
     
    Tom from Rubicon likes this.
  10. Tom from Rubicon

    Joined:
    Apr 4, 2016
    Messages:
    121
    Likes Received:
    6
    Does this forum have a PZ19 setup guide? Lower idle would be good too. Lighter bolts? I do like that the clutch stays locked up engine braking into a curve. I am open to all ideas and suggestions as I have never been here before. And thanks VMB a compliment from you means much. Tom
     
    #70 Tom from Rubicon, Aug 7, 2018
    Last edited: Aug 8, 2018
  11. sportscarpat

    sportscarpat Bonneville Bomber the Salt Flat record breaker

    Joined:
    Jun 25, 2009
    Messages:
    1,756
    Likes Received:
    71
    Hi Tom,
    Well look at that, another Sportsman 80 on the road! Nicely done and that definitely puts a smile on my face. It's rare that I build an 80 myself although there are plenty out there being built. Almost all are home builds.
    The clutch is a beautiful piece of engineering and is set to my specs of 2800 rpm, give or take. I do a final set on the clutch based on idle and choke setting. With the choke on there should just barely be no clutch engagement. You raise or lower this point of engagement by adjusting the clutch springs. Also, as you mentioned, you want good trailing throttle so keep the idle setting well under the clutch setting. There is good info on the Bully site. You may not see your exact clutch there as my version, the ones they build for me, are slightly different and have very low engagement. Still the adjustment is the same. Anyway, a lot of people think there is no trailing throttle on a centrifugal clutch but the opposite is true. These clutches when set up correctly have nice trailing throttle and compression braking.
    Once your well accustomed to your bike you will want more power. I find head work is where the power is. Decking it helps, as does stiffer valve springs, and a bit of porting. I have tried fatter cams in the 80's but with poor results. Seems I have advanced the timing with a degree key on the flywheel, too. I believe AGK has performance parts.
    Enjoy,
    Pat
     
    Tom from Rubicon likes this.
  12. Tom from Rubicon

    Joined:
    Apr 4, 2016
    Messages:
    121
    Likes Received:
    6
    Dear Pat your reply adds more questions. I am working on it in Word. But as I said, with this proven machine I am at the point of being an ambassador for Sportsman Flyer. The little riding I have done so far has drawn positive attention. God knows here in Wisconsin wages are held low.
     

Share This Page