cutting on my engine- did I go too far? (pics)

Discussion in 'Performance Mods' started by Fletch, Jan 3, 2011.

  1. Fletch

    Fletch Member

    After reading about porting I got the "want more power" bug and started going to town on my engine with the dremmel!

    First I trimmed the piston skirt. I know this is a substitute for lowering the intake port, but my compulsiveness, love for power tools, and "more is better" mentality possessed me to also lower and widen the intake. :devilish:

    I had already opened up the exhaust port quite a bit for the expansion chamber, but I decided to make it even higher! It is now well less than 1 inch from the top. (I keep reading that 1.1" is the magic number). I also opened up the manifolds and gaskets.

    It is all very crude and imprecise because it is by eye with a hand held rotary tool with no measuring, but I'm hoping I will get lucky and have it have a good wide power band without losing too much torque.:confused: I cut the header on the expansion, so I can always make it longer if I need more bottom torque back.

    I'm going to test it out today so I'll let you guys know how it goes. It's wet and rainy though. If you check out the pics...please let me know what you think as far as possibly messing the engine up or sending it to an early death with these mods, because I have another cylinder I can replace it with if need be.

    The carb intake is jb welded, hence the inside view of the port. The second cylinder is stock and there for comparison.

    Thanks!

    P.S> I know the exhaust is ridiculously misshaped but I was worried I had taken too much off already and that if I kept going I wouldn't get it even and go too far. I could of used more select dremmel tools but that requires patience and a trip to the store ;)
     

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    Last edited: Jan 3, 2011

  2. ken murphy

    ken murphy Member

    Ok Now You can see why i don't start the motors before I do the cylinder work,The transition between the chrome and the aluminum has much to be disired it chips and drags into the bore,thus causing the lines in the cylinder(drag marks) very crude.
    one thing you can do on your exhaust port is take the piston and put it in the bore n look at the top of the piston on the up stroke n try to make it even.I would stay away from carv'n the piston if your guna work the cylinder.(ya gota know where to take stock with the dremmel tool).its opposite on the intake.
    Happy trails
     
  3. ken murphy

    ken murphy Member

    cylinder work

    a 2" ball hone works good two
     

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  4. Fletch

    Fletch Member

    I was wondering about those marks. What exactly do you do you do to the cylinder before starting? I have a new engine.

    Sorry about my ignorance...but is that for polishing the cylinder?

    *I ran the bike and I lost all bottom end torque. I did too many things at once in order to tell why though. I cut an inch off the expansion chamber header, switched to a 41t sprocket from a 44t, and all this "cutting".

    The bike isn't broken in yet (only about 30 miles). I can always add that header length back, or switch back to the 44t I suppose. ****! It revs like mad though!
     
    Last edited: Jan 3, 2011
  5. ken murphy

    ken murphy Member

    the transition(the edge)between the crome and aluminum needs to be hit wth a cratex wheel and smoothed over Champer so the chrome dont peel the ball hone is for the final procedure it puts crosshex's in the bore so that the rings seat well The bore measures 1.851+ or minus .0005.its all about clearance and friction. good luck
     
  6. ken murphy

    ken murphy Member

    Do you have an expansion chamber? I wouldn't suggest any jb weld on the intake or exhuast and the motors leak when you seal them up they work way better I make my own gasketts,I fab my own intake manifolds to to match the carbs the stock gaskett for the intake is way restricted I hope you can see where the chrome failed in these pictures.
     

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  7. Fletch

    Fletch Member

    I agree about the JB weld. I stripped one of the intake holes and I'm using a ported billet intake from pirate cycles, so I just decided to jb weld the one hex bolt in place but I did leave the gasket on. I make my own gaskets and match them too. I tripled up on it actually because I knew it probably won't ever be coming off. If it was a stock intake I would have just tapped a new hole + one size and found a matching bolt.

    I definitely see what you're talking about- the jagged edges around the ports right? Looking at the photo I took of my first cylinder, I can see how bad it looks stock! I can't believe anyone just throws them on like that.

    Yes, I have an expansion chamber. I planned on breaking the engine in more before all of these mods, but the way things turned out I didn't. I'm hoping it will be fine with just 25 miles before this, and the compression will continue to get better.

    I want to make sure I do this next engine really well because it's going on a new bike with my first shift kit and I definitely want it to last. I appreciate the advice and I'm going to look into the ball hone, cratex wheel (any specific shape or part # for a dremmel?), and Google "crosshex's" ;) ...Lot's of googling because I'm learning about all this stuff, but it's fun.

    Yeah, I know the skirting and the intake were redundant but I'm a dremmel addict I think, and I just go into a cutting/sanding/grinding trance. When I "come to" I regret the aftermath sometimes..

    Thanks Ken

    BTW... If I just leave the cylinder the way it is- what is the end result or the reality of the situation... ie. how much life am I taking off the engine/how bad is it? I used Indian Shellac in place of a base gasket (messy stuff) and it is more or less glued on for now. So in a perfect world I would leave it be. I just need the risk vs reward brake down :thinking:
     
    Last edited: Jan 4, 2011
  8. ken murphy

    ken murphy Member

    I would saty away from those shift kits and make a reliable everyday rider the 36 tooth sprocket will get ya all the speed you need on a bike.
     

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    Last edited: Jan 4, 2011
  9. Fletch

    Fletch Member

    Wow... nice bikes, and black bottom pool ;)

    I got the shift kit to keep the speed up at lower rpm, climbing hills, and extending the engine life maybe.... not for top speed really. Have you ever used one? I have a feeling that comment is going to spark a debate lol. I know some people are very addiment about their shift kits!

    Do you have a closer/clearer pic of the mountain bike? I'm trying to figure out what your exhaust/intake/boost? setup is. From the pic it looks like the exhaust comes out of the intake, but I'm guessing that wouldn't work too well. I can't even see a carb. What do you got goin there?

    I live in hilly San Diego, so the 36t probably wouldn't cut it for me. Arizona is perfect though. What's your top speed on those?
     
  10. thine82

    thine82 Member

    considering the shift kits cost just as much as the motors do .. yeah they should be fond of them.. i dont have one but i would only want it for its top speed to get to work quicker .. but would use it to keep the rpms down mostly.. how fast does those things help you actually go? anyone ever test them next to a car ? or a car following behind them and then reported the speeed back to them.. ?
     
  11. Fletch

    Fletch Member

    True, they are expensive compared to the price of the engine, although they will last much longer and you can just get a new engine which you'd have to pay for anyway.

    They have them for the 4 strokes now, so they aren't as expensive as the engine if you're running one of those. They also very in price by dealer.

    I'm the wrong person to ask about the details. The closest I've been to one is a youtube video, but I'll let you know. I'm sure someone else could answer that for you though.
     
  12. ken murphy

    ken murphy Member

    I've never seen one----all I know is I do not want to go any faster on a bicycle, my bikes do 35-40 mph n thats plenty for me
     
  13. ken murphy

    ken murphy Member

    china girls

    I dont know what a black bottom pool is but that is my neighbors back yard w/the the pool my yard is w/the dogs and that house across the street I built is the one w/the pool.
    Anyway a two sroke engine has a power band finding it w/these lilchinagirl motors(thats what I call em)is a challenge---when you do then you have vibration thats why you balance the crank------and fab insulator motor mounts,then you dont feel the vibration that is where its at for me.the crank bearings are a 6202.there is a big diferance once you take the vibration out.
    Reliability is the key
    heres the trike I built
    N that thing is to fast it has three chains
     

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  14. motorpsycho

    motorpsycho Active Member

    Wow!
    I have some punctuation for sale, really cheap!
     
  15. ken murphy

    ken murphy Member

    NEXT?
     

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  16. motorpsycho

    motorpsycho Active Member

    Sorry, but I hate reading posts that are one long sentence. It's hard to make sense of what is being written.
     
  17. ken murphy

    ken murphy Member

    Grammer

    Accepted,I wasn't addressing your comment.tho I'm not a scholar by any means,nor do I claim to be.
    I Do know some good teacher's though. The point I was trying to make is relibility and being able to ride twenty miles at any time w/out tools in your pockett.And comfort,sorry that I made you Uncomfortable.
    That is the second of dozen I built, that bike took third place in the death race.
    cYa @ the RACE
     

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  18. motorpsycho

    motorpsycho Active Member

    No thanks, i'll pass on the deathrace.
    I'd rather race on a real motorcycle at real racing speeds, rather than on a bicycle at sub100 mph speeds.
    You didn't make me uncomfortable at all, but I am a teacher, and it pains me to see how many kids can't read, write or puncuate sentences correctly.
     
  19. ken murphy

    ken murphy Member

    Clueless

    Why ? are you on here--------------Read the title of the web site and get a cl__,I wasn't even communicating with you from the get go so,In otherwords keep your illfated comments to yourself.
    O buy the way I have trophy's in all kinds of races.
    Again none of this is any of your intrest then.
     

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  20. motorpsycho

    motorpsycho Active Member

    why am i on here?
    I'm no here because i do this as a hobby and to try and help others with mechanical problems.
    I don't race my bikes because neither one of them are fast enough.
    My bikes aren't for racing anyway, mine are just for messing around.
    besides that, my bikes are far more unique than the typical mountain bikes that you see on here every day.
     
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