Discussion in '2-Stroke Engines' started by pdxrhett, Jun 25, 2009.

  1. pdxrhett

    pdxrhett Member

    I decided to take of the head of my mitsu 49cc and guess what? It has a lot of carbon deposits on the top of the piston... Normal?

    Also, I can't get the head to go back on - should it be very hard? I'm not using a ring compressor, should i be? (don't have one :p)

    Rings appear to be OK, and the cylinder wall is in pristine condition (looks new, and it has almost 1500 miles on it :O).

    What will make getting the head on easier, and how do I clean up the piston?

  2. Bryan Smith

    Bryan Smith Member

    I recently pulled the jug on mine and was able to squeeze each ring enough with my fingers to get the cylinder to slide over each, one at a time. Make sure you line up the gap in each ring with the alignment pin in the piston groove. A little carbon is probably OK as long as the spark plug is a brownish color. black on the plug would indicate that it is running a bit rich.
  3. Happy Valley

    Happy Valley Active Member

    What oil mix are you using?
  4. pdxrhett

    pdxrhett Member

    30:1, which i will admit is rich in my opinion. my mixture screw is probably set to 50:1
  5. thescooterguy

    thescooterguy Member

    if you removed the rings , make sure you didnt put them back on upside down .
  6. thescooterguy

    thescooterguy Member

    did you get it back together ?
  7. Mountainman

    Mountainman Active Member

    naturally a little oil on them rings helps them to slide back down
    or I should say slide back up

    carbon on that piston thing
    almost every engine that I have ever taken apart has some to a lot of carbon
    and as we know 2-strokes will have the most

    scrape most off forget the rest (carbon)

    ride that thing
  8. pdxrhett

    pdxrhett Member

    yeah, i got the head back on. turns out the rings weren't lined up with the pin on the piston. but, i rode it for maybe 10 miles and then my engine sprocket dies. it literally bent in half. Jerry, I need a VERY hard sprocket please :D
  9. thescooterguy

    thescooterguy Member

    your drive sproket bent in half . something happened to make it do that . any ideas? sounds like something wasnt lined up . you should switch to the 8mm much stronger , but if the original problem isnt fixed it will break something else . can you bring it by my house in gladstone ?
  10. loquin

    loquin Active Member

    Never heard of a mitsubishi 49cc two stroke... Until very recently, the largest one they made was the TLE43 (43cc.) They just came out with the TLE48 (a 48 cc motor.)

    Nor, does the mitsubishi carb even HAVE a mixture screw. There's only an idle adjust screw.

    If it's a genuine mitsubishi, it will have a 'two-barrel' carb. One of the 'barrels' is used to send air (only) to the cylinder for a short time, to reduce emissions.

    If it's a true mitsubishi, you should be running at 50:1 on the premix.
  11. pdxrhett

    pdxrhett Member

    Every single person has told me exactly that. But this is the EXACT motor
    Tell me, if Jerry is wrong, what kind of motor is that?

    My carb has idle adjust, and mixture adjust... the guy i bought it from (not Jerry) said run it at 30:1
  12. thescooterguy

    thescooterguy Member

    the one he has is a knok off . but good motor
  13. loquin

    loquin Active Member

    It doesn't appear to be a Mitsubishi. It looks as if it's one of the Mitsubishi 'clones' from China.
  14. thescooterguy

    thescooterguy Member

    yes . the mitsubishi is from china also isnt it . this was from
  15. pdxrhett

    pdxrhett Member is what jerry meant...

    I got the head back on, but also broke the gasket. the bike is dead to me. I am going to have one of my machinist friends make me a sprocket, then sell this thing. it's too slow for me :D
  16. thescooterguy

    thescooterguy Member

    i will give you an 11t if you bring the bike for me to see
  17. pdxrhett

    pdxrhett Member

    I actually looked at it after i posted that and found the problem.
    Instead of like 12 washers to space the upper part of the aluminum piece (name is leaving me atm), I used a spacer from Ace Hardware. The spacer is hardened steel. I guess I tightened my top bolt a little too tight and the sprocket wasn't lined up correctly. OOPS! At least I didn't get hurt!

    I will probably order a new aluminum piece from you, as well as a sprocket for more speed (the bike it is in climbs any hills with a 10t no problem. even 112th on mt scott)
  18. thescooterguy

    thescooterguy Member

    i have two 8 t left . lots of 11t and some 14 t . that's too tall for your motor . but bring it buy i will hook you up with free sprocket . show you how to keep it running smooth . to line the sprockets up take the chain off and use a straight edge then putt the chain on . with pedals i would say then pedal it without the motor power and see if everything runs quietly over the gear no chatter . then you got it . but with the foot pegs the straight edge will have to do . use the top adjuster bolts to adjust the toe and heal of the sprocket . u should have the bolt configuration looking like this i would like to see the bike . see how it is doing give it a tune up for you . you might be surprised,
  19. loquin

    loquin Active Member

    No. The Mitsubishi is from Japan, and they have very good quality control in their manufacturing. The chinese 'clones' are not of the current design. They're knock-offs of a 20 year old design (at least) of the of the old Mitsubishi TL series engines. Engine quality is unknown (a given motor might be fine, or it might be a lemon. Only the end user knows for sure.)

    The true Mitsubishi's TLE series engines (the new ones) use an interesting design to greatly reduce emissions. They have a 'split' carb, with two 'barrels.' One of the barrels is a straight-through pipe from the air filter; the second one is jetted and supplies the fuel-air mix. At the very beginning of the fuel intake, ONLY air is supplied. A little later in the cycle, fuel-air mix from the second 'barrel' is added. Since it is added later in the cycle, it doesn't have time to go straight-through the cylinder and get exhausted before it's burnt. With the older designs, as much as 25-30% of the fuel gets exhausted, unburnt, out the exhaust pipe.

    Ref the first post in this thread for a link to a Mitsubishi white paper that discusses the TLE design. Also, this thread discusses it in some detail. There's a photo of the genuine Mitsubishi 'two-barrel' carb, for instance.
    Last edited: Jul 1, 2009
  20. thescooterguy

    thescooterguy Member

    like the robyns 35cc very good quality . also made in japan . i will have to change things around on the website . thankyou