Pleased with mods........ (Thanks Jag)

Discussion in 'Performance Mods' started by geebt48cc, Nov 29, 2012.

  1. geebt48cc

    geebt48cc Member

    Yes, I just hope that she stays together. Thanks to coaching from JAG, and with my past real street motorcycles I've had, this little fellow is a trip! (CONSIDERING ITS QUESTIONABLE QUALITY) YES, it's a PEDAL bike, but there's not much pedaling here. With reed, drilled piston, ported- grooved intake,better carb, expansion,Jag CDI,high compression head...........We are moving down the road!!...........LOL, and even up too.

    I'm getting ready to elongate baffle in expansion for even more torque. Anyway, if you stick to it, it will start coming together!

    (Engine 66cc has 715 miles all SYNTHETIC/Castor.....Everything is on the up, but did notice a few very small chips of chrome around the exhaust side of cylinder?)........But, runs now like there's more than 3hp there.......

    Glen........(See, I'm 258lbs, and bike is 65 ish?!..........I've got to let off throttle so it wont continue to rev past 33mph on flat with 44T!) SERIOUSLY--crazy rpms.............) 66cc........WHAT? naaaaaaa
     
    Last edited: Nov 29, 2012

  2. jaguar

    jaguar Well-Known Member

    Way to go man! Nothing like getting these crappy engines to start working like a normal 2 stroke engine should.
    I am a bit surprised you are getting it to go so fast though. Did you raise the exhaust port and lower the intake port?
     
  3. geebt48cc

    geebt48cc Member

    Hey Jag,

    I just got in from about a 8 miles run, going over hills that would get the best of this little engine. A hill that's every bit of 200 yards long in a good back roads ride, I would be doing good to top the hill at about 15mph. Well, today, I topped at 19.5mph. (Remember now, I'm 6' 6",258lbs...not including bike)

    Jag, I followed the directions of going up from main intake, inside jug 32.00mm. I didn't go that deep, but then ramped it to a point right at top of side ports. I really didn't know how deep to start ramping with, so the ramp starts about 1/16 of a inch then declines to a total of 32.00mm UPWARDS. I ramped top of piston at each intake window, and also drilled piston 7 times on intake side 7/32.

    Like I said, bike now will keep on reving even way over 31mph-------------, but I'm not going to kill this engine finding out with only a 44t! You know what's wild Jag, is I've not even started the torque pipe we've talked about!~
     

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  4. jaguar

    jaguar Well-Known Member

    so the piston ramps increased your port timing for higher revs. that's ok as long as you don't wipe out the low rpm power in the process. I do hope you mod your pipe for more torque.
    You can make the header pipe longer in order to lower the maximum rpm and gain more down low power.
     
  5. geebt48cc

    geebt48cc Member

    Yes, Well, Jag, I'm not now going to do anymore to a good thing. I didn't make the ramps that great of angle at all.......

    Jag, the only thing I didn't do that most people ask about, is triming the piston skirt.........uno, the half circle that covers intake window at TDC. What do you think about that?

    Off this topic, I noticed there are a few places where the chrome has chipped off...............not big , about size of a pin head?
     
  6. jaguar

    jaguar Well-Known Member

    yeah I get the chrome chipping on most of my cylinders. They still run good. A lot more blowby happens at the ring ends than from lost chrome.
    When the piston is at the top of its stroke is when theres the least pressure difference between the crank area and the intake tract so don't worry about that little bit of overlap. Port width and port timing (when it opens) are much more important. But now that yours is running good I wouldn't touch it.
     
  7. geebt48cc

    geebt48cc Member

    True Jag, I'm not going to touch a thing. I just don't want it to get worse, and then cause other problems? Wish I had taken pictures of the jug when I had it off bike, but yes, I'm just going to keep it AS IS for a good while.Curious, do you think it will continue? See, I' m keeping a very close eye on plug chop, and I'm burning just right, nearing riche,r which I like considering better richer than leaner. Sometime very soon, I'm going to take the SBP's expansion chamber off, and extend the baffle 2", like we talked about for better torque. See, the way it is now is great!~ One just thinks that it can even be that much better. Now, I can take just about any hill as long as I'm not starting from a dead stop.

    Jag, on other site, a few people told me when I mentioned that I drilled wholes in my piston, that doing that would kill my torque possibilities, but I have had to good of luck with other mods for these engines that you have ever studied. There's a part of me that just says to leave good enough alone, but once again I kmow that extending baffle will put that cherry on top of everything else I've done.

    Uno, Jag, I just want you to know, that everything I've done to this little engine for the better has been do to you! Your going to not be so pleased about hearing this, but I did get a RT carb. Jag, it does really help quite a bit in comparison to the Speed and CNS stuff!! I know, I know, but it works well for $$. I never stuffed crank for the Arrow reed I'm using on this Skyhawk 66cc, but now from about 20mph the reeds seem to be helping. Much stronger top rpm's. Either way, I'm not going to do anything else other than baffle, considering.

    Jag, I realize it's not a big amount of money, but I just don't want to be polluting the bottom end with these small chipped off areas?(Uno, eatting bearings up) Do you think that it will continue, or just go with it?

    Glen (I also wanted to tell you I put a new set of rings on piston when I had out)
     
  8. jaguar

    jaguar Well-Known Member

    Reading the plug color is not a good method when you are using synthetic oil. It's best to jet according to how its running.
    If it runs good uphill but sputters downhill then it's too rich.
    If it runs great at top speed but is weak climbing then it's too lean.
    Set the main jet first for correct running at wide open throttle and max speed.
    One way to set the main jet is to start lean and keep increasing the size till top speed starts to slightly decrease. Thats the perfect main jet size. Then if the low speed running is lean on the Dellorto you have to drill an additional fuel column hole. (see my site in the "Dellorto carburetor" section). It should be lean enough that you have to choke the carb for it to easily start.
     
  9. geebt48cc

    geebt48cc Member

    Jag, does the 2" extention piece that I'm going to put on baffle............Does it have to be smooth? Can I use a air tight accordian finish? Would this be ok for the 2" insert?

    Glen
     
  10. jaguar

    jaguar Well-Known Member

    I wouldn't recommend it if the accordian had anything more than the smallest of width. Best to just use flat metal. Go to the junk yard and cut a piece off of a water heater.
     
  11. geebt48cc

    geebt48cc Member

    Well,Well,Well,

    Once again, you did it Jag..... I put extention on expansion, and its now got the best torque of anything I've done with motorbiking. Only thing I dislike, is its just a bit louder, but overall, a very good gain............Anywhere!~ One thing you need to know, is around here, there are very few flats, just HILLS!~ Not good pic, but you can see.....................

    It extended expansion about 3" . That 200yrds long hill that bike would only top at 15mph, can now be topped at 20.1mph. Uno, considering the power to weight ratio.............One would never think a little 66cc china engine would do this?! BUT, it is!~ GRACEFULLY.

    I went about 7 miles, and right when I got off bike, I felt baffle, and it had a very cool temp.
     

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  12. geebt48cc

    geebt48cc Member

    Baffle extension

    Before:










    After:
     

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  13. jaguar

    jaguar Well-Known Member

    With your pipe being wrapped its hard to tell exactly what you did to it. If you'll look at my Torque Pipe page on my site it is the E section that I was proposing you "splice in" to the baffle cone.
    Well, as long as you're getting the results you wanted I guess we can't complain. People don't understand that its the strong compact return wave from the baffle that diminishes the potential of really good mid range power because that positive wave cancels out the negative wave from the diffuser cone at mid range rpm. Only at top rpm does the baffle cone have any benefit. Pipes sold for these bikes were not made for it, they were made for screaming pocketbike racers.
     
  14. geebt48cc

    geebt48cc Member

    ahhhh, I see. I would say that that would even be better than.

    I'm really still seeing positives from cutting mid way in the belly of the expansion. You post the baffle is about a couple of inches back from belly. Well, at this point I guess I can just cut it all I want, but do believe I need to stop before I really mess things up. Where I did cut, It still helped quite a bit. More torque................... Still glad I did.
     
  15. jaguar

    jaguar Well-Known Member

    Some street bikes have a diffuser, belly, and a silencer replacing the baffle cone so that they get maximum low rpm power.
    So obviously you diminished the baffle cone effect which enhanced your low end power, so just stick with it because it worked.
    What you did reminds me of the expansion chamber on my old Husqvarna 125cc which gave good mid range power:
    '77huskyPipe.jpg
     
  16. geebt48cc

    geebt48cc Member

    Stinger

    Jag, wonder if it would help torque even more to make this stinger a bit longer than this? Fabian, was telling me that it really helped his. How long, if any, would you try? Or, do you think it would be better without?
     

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  17. jaguar

    jaguar Well-Known Member

    More exhaust restriction improves torque. On mine I cut a rectangular piece of aluminum (from cheap cookware), rolled it to fit inside the stinger (before the silencer), and glued it in place with JBWeld. I think on a 66cc you can go as small as 12mm inner diameter.
     
  18. geebt48cc

    geebt48cc Member

    So, in hearing that, I believe that I'll put this silencer I have from SBP's on for good. I just wasn't using it because I thought it would inhibit power more?
     
  19. Fabian

    Fabian Well-Known Member

    :ee2k:

    I don't use an expansion chamber on my bike, just a stock standard exhaust system.
     
  20. Fabian

    Fabian Well-Known Member

    The three inch silicon exhaust deflector (attached to the end of the muffler tip) was used primarily to reduce noise, but this has now been changed to a 2 foot length of high temperature silicon tubing to further reduce noise (which it does terrifically) and can be seen in the third photo from the bottom.

    Just do a search for:

    "Twin Spark Plug Cylinder Head for 80cc Happy Time Engine"
     
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