Just for record on third intake w/reed

Discussion in 'Performance Mods' started by geebt48cc, Mar 29, 2013.

  1. geebt48cc

    geebt48cc Member

    Well, I pulled jug, and grooved from main intake to bottom of skirt. I also opened a window on bottom lip of skirt. This has really helped the Arrow reed, and the engines lower case circulation. Bike now has even better torque, and has even made reed produce more power at lower RPM's!! This all is happening even while using the same fixed 44t sprocket. I'm sure that if I stuffed lower case of engine, I would even see better results.

    Also, I trimmed thinner the bottom of the two transfer ports of jug.


    Glen .........
    Last edited: Mar 29, 2013

  2. jaguar

    jaguar Well-Known Member

    So did you make the groove (boost port) the same height as the transfers?
    I got something else you can do to improve low rpm power. Reduce the pipe outlet diameter. That is assuming that it is too big for your application which they almost always are. What is the inner diameter of the outlet? length of outlet tube (stinger)?
  3. geebt48cc

    geebt48cc Member

    Hey there Jag,

    Yeah, just one groove down from center intake to bottom skirt. Remember, I've already drilled piston, and grooved up from main intake 32mm.

    The outlet is just the standred SBP end in mm?????????? I'll get tomorrow.(Also remember I put about a 10" center baffel on that stock SBP chamber)

    PS-- Jag, it seems to be just about as strong as a little 66cc from china can get? After I put wrist bearing on, which was much lighter, it really is very smooth now.

    This has really helped blow some of the remaining dust off the arrow reed valve!!!!!!!!!!!!!~

    Would the diameter on exhaust be about the same exit as a pencil diameter? Tell me from the point of end of expansion chamber, how long that pipe outlet should be? Does it really matter? You can see in picture, at top right of bike the rubber hose that I just put on there to quiet down a bit................(But, I would say it needs to be thinner in diameter?!)

    Any, got to get up early................

    Talk tomorrow big guy!!!!!!!!!~


    Attached Files:

  4. jaguar

    jaguar Well-Known Member

    Tell me the engine size and the peak rpm and the stinger length and I'll tell tell you the maximum and minimum inner diameter you should have. It's easy to reduce the size, just fill it with JBWeld and drill the new smaller hole after 2 hours of glue setting.
    The stinger is the smallest diameter outlet pipe. Yes, the distance matters. I got a noticeable power boost by reducing the diameter. Seems the stock 10mm diameter is set for the 69cc engine although the same pipe is used for the 48cc.
  5. geebt48cc

    geebt48cc Member

    Well, the problem is I don't have tac? Anyway, I've got a pipe 4 1/2" long, and about 14mm diameter that I could put on the end of that rubber hose coming off the end.
  6. jaguar

    jaguar Well-Known Member

    What is "tac"?
    The range for a 4.5" stinger on a 69cc w/top rpm of 6500 is 8mm to 10mm.
    You could fill the last 2" of your 14mm pipe and then drill it with a 11/32" drill bit. (9mm)
    Or cut up a cheap aluminum cooking pan, roll a section that is 14mm O.D., then stick it inside the 14mm pipe and hold it in place with a screw if you don't have any good glue like JBWeld.
  7. geebt48cc

    geebt48cc Member

    Ok, will do!~

    Yes, Tac, my short for Tachometer...... (sorry)

    Jag, I've got great compression with all, but I've been noticing the jug is scuffing up a bit, and some chips of chrome?

    Is this the norm for 800 miles ?

    Ratio 25:1 2.5 Amsoil 2.5 Castor Maxima =5oz a gallon
  8. jaguar

    jaguar Well-Known Member

    on a 26" bike 6500 rpm gets 30mph

    Any amount of ingested abrasives (dirt, etc) will take the weak chrome off these cylinders. I prefer to use foam air filters oiled with engine oil or air filter oil. Motocrossers never use paper air filters.
  9. geebt48cc

    geebt48cc Member

    I see...........Yes, the one that DAX has is nice........... I just got back from a few miles and really, stinger didn't help at 8-9MM. I'm sure it will, just need to keep fulling around with it. Jag, just woulder if those chips will get worse......... Guess I should just chill and enjoy...........huh?
  10. jaguar

    jaguar Well-Known Member

    the whole idea of a small stinger is to have more pipe pressure to prevent loss of intake charge out the exhaust port. But if you have any leaks in the pipe then it won't work because the leaks relieve the pressure. I think you still have a southern engineered pipe that still needs to be all welded up and could very likely have a leak. right?

    ps- what is a "chip" that might get worse?
  11. geebt48cc

    geebt48cc Member

    I was talking about a few areas it seems on the front half of the interior of jug. The chips aren't bad, but do look like they are multiplying? Everything has been running out very smooth with very clean riding conditions. Sense I have put engine on bike (now at 800 miles) it appears to be multipling? Once again, bike has always run on richer side, or just darker brown.

    Uno, it appears that it really started coming on after I replaced ring set. The ring went in well, and travel smoothly with good compression. Bottom line is, I just wonder if I'm trying to find issues, or if this is somewhat typical?
  12. jaguar

    jaguar Well-Known Member

    I wouldnt worry about it till it starts to affect performance.
    I think the stock rings are part of the problem. They have a large contact area and are fairly stiff which means they put more pressure on the cylinder. I tried my 60cc race engine with just the top ring on and it ran the same all thru the rev range. If this is on your 48cc you can use a $30 Honda piston which I link to from my site. Not sure what good motorcycle piston would work on the 66cc.
  13. geebt48cc

    geebt48cc Member

    I was thinking that maybe the reason there are a few places on jug, is because I really didn't do anything (as far as nursing new rings) on the rings I put on. In other words, I continued to just run RPM's as normal use!

    Jag, wonder if that could of maybe helped put even more pressure on the original cylinder? Like I said before, there isn't really any very big chipped places, just surpized to see any at all.

    Anyway, now with work I've done, Puch head & reed are performaning together. Obviously Jag CDI/and the southern torque expansion creation also!~ I'll check again for any leaks, but it's very buttoned up tight. I'm going to get the stinger to work at 4.5" long,11/32 or 9mm diameter....................

    good talking to ya

  14. HeadSmess

    HeadSmess Well-Known Member

    an engine doing 6000rpm is 100Hz.

    the "G" two octaves below mid C is 98Hz.

    so when youre motor is tuned to "G" its doing 5880 rpm :) and tuned to "A", 6600 rpm.

    yes, i use a guitar tuner as a tacho... or i would if i didnt have perfect pitch... :jester:

    as for the chrome plating on the cylinder. ive noticed pinholes in just about every cylinder, even when new. only real permanent cures is to insert a cast iron sleeve but whos gunna make it and install it? or to get it rechromed by a professional, in which case....get fifty done and sell them :)
  15. Fabian

    Fabian Well-Known Member

    So why are you wasting your time with that expensive 2-stroke oil ???