thick or thin base gasket?

Discussion in 'Motorized Bicycle General Discussion' started by metalliatic, Jun 2, 2010.

  1. metalliatic

    metalliatic New Member

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    some peolpe say to add a second base gasket to make the ports stay open longer and make more power. others say take it out and add compression which means more power. i want more power. what should i do with my base gasket. im not interested in any other way of makeing more power because ive tried everything else. right now all i want to know about is the base gasket. throw it out or add to it?
     
  2. Junster

    Junster New Member

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    Ok I tried no base basket and could not keep a good seal. A good seal at the base is vital. I bought a base gasket but I used it for a pattern. The best I've found is the 1/16" thick charcoal black garlock. Very durable, heat resistant, just the right thickness. It re-times the ports just slightly higher. I have a slant head and my motor has great compression. Along with shift kit, tuned pipe, CNS carb I get about 42mph on a flat road with no wind.
     
  3. metalliatic

    metalliatic New Member

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    so is that thicker then the original gasket? what about no gasket and just use silicone to seal it?
     
  4. Venice Motor Bikes

    Venice Motor Bikes Custom Builder / Dealer/Los Angeles

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    Don't build a engine without the gaskets!! It's just bad business!
    I would suggest that you keep the base gasket & go with a thinner head gasket if you want to raise the compression. (Thats only if you're sure you have the piston/ head clearance!)

    If you really wanna go crazy... do what Baird did & smooth & match all the inside transfer ports & port match the intake & exaust, & also smooth the inside of the carb. (But keep the gaskets!) ;)
     
  5. metalliatic

    metalliatic New Member

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    ive already done all the port matching and smoothing and got a bigger carb, sbp exhaust, billet head, shift kit, and getting a balanced crank. all i want to know now is... should i use 2 base gaskets to make it thicker and change the port timing which would make more power or should i use a thinner gasket or even no gasket and just silicone it to make more compression and more power. which would make more power?
     
  6. Venice Motor Bikes

    Venice Motor Bikes Custom Builder / Dealer/Los Angeles

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    Well, think about this... If you add another base gasket, it will lower the compression. (That's not good for power!) :rolleyes:
    Why don't you try both & tell us how they worked! :D

    If you're looking for more 'top end', try cutting the header pipe shorter! ;)
     
    #6 Venice Motor Bikes, Jun 3, 2010
    Last edited: Jun 3, 2010
  7. Junster

    Junster New Member

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    The thickness of the garlock is about the same as 2 of the kit gaskets would be. I tried no gasket and used loctite 743 sealer for aluminum flanges. (the best) It still failed after about 10 miles. A gasket on the base is a must but the kit gasket is very thin and cheap. The garlock is a far superior material. There is a strong suction then pressure on every turn of the motor. I agree with Venice about pipe tuning cause he's right. You shorten the pipe (1/4" at a time) to get the motor to "come on the pipe" at higher rpm. Longer for more low speed torque. Remember how a pipe works. The motor end taper is twice as long as the rear taper. The sound travels down the front taper expands then hits the rear and is reflected back at the exhaust port. The idea is for the energy from that to get stuffed back into the cylinder just as the port closes. The faster the motor is spinning the shorter the header length to get it there in time. It's isn't a huge deal to change the base gasket. If you blow out a weak stock one along way from home. You will wish you'd had the stronger one. The difference in height is tiny and the reliabilty is huge. Go with getting home everytime. Then go with power. You see big differences in a tuned pipe, good carb, slant head. Not much in 1/32" difference in base gaskets. Remember the gasket gets crushed in service. It will be half the thickness it was after it's used a little.
     
    #7 Junster, Jun 4, 2010
    Last edited: Jun 4, 2010
  8. metalliatic

    metalliatic New Member

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    so you think a thicker base gasket is better. but what do you do to gain the comppression lost at the base? use a thinner head gasket? then you risk blowing the head gasket right?
     
  9. sputterputtBAM

    sputterputtBAM New Member

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    thats the impression I get. I think the thread died though.

    I wanted to IM Bairdco but cant figure out how. Eiher of you technical folks have any idieas on what went wrong/ I took motor off to shim forward and elim. tensioner on coasterbrake wheel. Ran O.K with48cc skyhawk alum. intake and CNS carb KN style free low filter. while eng. off I port matched intake and exh. gaskets snd opened up the manifolds to a less round end. I got no power and holding high idle in neautral the eng dies like starved for gas. Oily plug carb lleaner tested good seal!!

    Changed to nt carb ROCKS like never before- maybe 30mph 41 tooth sprocket. Same plug.
    I want to put CNS back with its larger flow. How might I start to adjust it after I blow out the jets and see if they mightv'e picked up crud somehow?
    I btlieve Iv'e given all current variables.
    I love this forum brothers, I get lost in here way too long reading your genius inputs. you know who you are.
     
  10. camlifter

    camlifter Active Member

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    i made a spacer .100 thick and put it under the jug, then put the jug in a lathe and took .100 off the top. this raised the ports and gave very good over all power with a nice bump in lowerer rpm power. it's one of the best running engines i've built.
    this engine also had an expansion chamber exhaust and porting.
    put as thick a spacer under as you can without exposing the top of the piston to the intake port, then take an equal amount off the top of the jug.
     
  11. rogergendron1

    rogergendron1 New Member

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    this is exactly what you want to do !!!!!!!!!!

    i went to nappa and got 1.6mm gasket paper as my stock base gasket was 1mm .

    ripped off my stock base gasket and added the 1.6 one i made . then decked .6 off the jug via sand paper and glass.
    this raised the ports by .6 and maintaned the compression raio
    just make shure your top piston ring does not go into the intake port at BDC... i did some porting and i took a little off the top of my intake and i can just barley see the top ring in my intake port now !!! close with the raised jug but wow what a diff !!!

    i would do this again if i buy a new gt5 ...
    pull the head and jug rip off the 1mm base gasket and add a 1.6mm base gasket
    deck the jug .6 then port the h3ll out the intake bottom and sides leaving the top of the port just cleaned up, port the h3ll out of the bottom of the exhaust and its sides to just clean the top you already raised it lol.
    then deck the head down to about 6.5 cc for around 10.5:1 comp and done !!!
    grind your transfer port ramps and exhaust ramp

    instant race motor !
     
  12. bezee82d

    bezee82d New Member

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    this is not a reply as much as it is a question my engine came with a thick
    base gasket had to rebuild top end any way bought new gaskets and set came with a very thin one not sure which one to use any advice? thanx
     
  13. crassius

    crassius Well-Known Member

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    changing the gasket will change your port timing, which may be good or bad depending on whether you liked it as it was

    the thin gasket *could* let the piston smack the head

    the thin gasket will give a smaller combustion chamber, which may mean higher compression if the new port timing will completely load it
     
  14. turnofftheradio

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    I picked up a thick base gasket last time. I'd use it again. I did not shave or use a thinner head gasket to compensate, my compression is probably lower than most due to that but I can still push 35, possibly with less wear. Experiment, gasket paper is inexpensive and everyone's engine is a little different.
     
  15. BonusParts

    BonusParts Member

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    I have used the JuiceMotoParts Copper head and base gaskets for a while now and will say this...

    On a stock angle fire grubee, using a thinner .016" base AND head gasket, and shaving the head a touch - it'll do some speed and great power.

    i am also using .025" copper head and base gaskets in my fred engine and it its definitely improved.

    Forgot to mention these are infinitely reusable. I've done several rebuilds on my grubee with the same set of copper gaskets. They SEAL VERY VERY WELL. If you torque the assembly evenly and correctly they do at least several hundred miles without any weeping or leaks.
     

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