compression

  1. 661_Minis

    10.5 to 1 compression on 212 predator

    Hello, I’m building a predator 212 non hemi and need advice on achieving a 10.5 to 1 compression ratio, how much should I shave the head? I haven’t measured how deep the piston is in the hole yet because I already took the whole engine apart and I’m waiting on my ring compressor and other parts...
  2. gwoods27

    HS50-62023 - Compression question

    Any one know the proper compression reading for a HS50-67023. Just rebuilt one with new rings(measured proper gaps and gaps spaced properly), cyclinder honed, valves lapped, valve guides w/in specs, valve gap w/in spec. Im only getting about 60 psi. Shouldnt it be more than that?
  3. S

    Bullfrog Hemi Predator High Compression Piston

    Has anyone ever used one of these high compression pistons from bullfrog motorsports in a Hemi predator? According to their website with no other mods it gets you to 11:1 compression. I was thinking it'd be a lot wiser to do this than mill my head to get 11:1. Ole4 reccomended this to me but I...
  4. DeadPixel

    Are my calculations on compression for my 196 clone correct?

    Just checking to make sure I am not making a mistake on my compression. I am wondering if some one else can verify my calculation of my compression is correct. I am using a compression calculator for the math here. I am going to be building a 196 clone motor for a mini bike. I calculated the...
  5. Phil1958

    Snap On Compression Gauge

    $75 + shipping. pm me if interested. :thumbsup:
  6. BWL

    Vibration issues solved but lost compression!

    https://www.youtube.com/watch?v=IzJtlmvfRYM
  7. D

    Compression release working?

    I have a bigblock that rope started fine with the head cut .050 and 35# valve springs. It still has the same cam (.246 duration, .260 lift) with a compression release. I have a new head that I got cut .080 with the same thickness head gasket as before (.020) but has 55# valve springs, and...
  8. 7

    What's good compression numbers??

    My HS40 started out as a worn out big time smoker. I rehoned and used .010 over rings file fitted. I get 70psi on the first hard pull, 95psi on the second and 105 on the third. This is a hot engine with the throttle wide open and air filter off. Im guessing this is good??
  9. D

    Predator 212 valvetrain question.

    Hey guys, I'm building a Predator 212 for a minibike. I'm going to be running 14cc heads, flat top piston with .020" lower compression height, and a billet rod that's .020" longer to account for the lowered compression height. I plan on running 1.3:1 ratio rocker arms and I was wondering what...
  10. C

    Just double checking 10.5:1 compression recipe for Predator 212

    I am trying to decide if I should get my head milled. I already have +.20 Rod which brings piston flat with stock head gasket. Is having the head milled worth it? I want to run 87 octane with 10.5:1 compression.... How much should I take off .30-.50? I am new to all this so please excuse my...
  11. raypennachio

    Tecumseh 3.5 compression issues

    Hello all, We have recently acquired a manco thunderbird that had been sitting for several years. I started it and it ran for three minutes before it wouldnt start again. It had about 40psi of compression. We took the head off, cleaned the valves piston and head, tried to start it again and...
  12. B

    Old Briggs No Spark, 100 PSI Compression

    Hello, I have an old B&S vertical shaft engine (3.5 horsepower) with no spark and a hundred PSI for compression. The model # appears to be 92902 1140 01 7606 1704 but I'm not certain this is the original pull starter. What usually knocks out the spark on these engines? I believe this...
  13. B

    Hemi 212cc Predator Increased Compression Clearances

    Brand new to the forum. Thanks for having me. Been working on first engine and first project. Anybody have experience with increasing compression on these 212 Hemi engines? It is all brand new to me. I don't want to do any Milling. I have a Black Mamba Jr Cam (0.275 lift) and want...
  14. C

    Build Predator Hemi 212cc Higher Compression On Pump Gas

    I am building a another Hemi engine and this time would like to add a little more compression. I want to still run pump gas (91 octane). Its for my Original Doodlebug. Here is my setup..... ARC flywheel Black mamba Jr cam 26lb springs gx140 emulsion tube w/Jets Intake Under Seat...
  15. M

    Compression Ratio for 196cc Clone

    I know that the tolerances are all over the place for these motors so I am measuring piston deck height(amount piston in hole) as well as gasket thickness and head volume to determine compression ratio. My question is what is the average cutoff point where 93 octane can no longer be used and...
  16. S

    clone lots of compression after head and cam swap

    Ok i got a brand new box stock project engine just put in a black mamba cam a 22cc head milled .65 26lb springs and 26/25 valves this is my first engine I did I can't seem to get the valve lash set right when I tighten down on the 10mm head screw holding back the 14mm one the gap closes to...
  17. doodlebug6.5

    Loss in compression

    Shaved the heads and installed different valve springs, turn the motor by hand the first time and could barely spin it it. Then it felt fine. Then it fired right up. Running higher tension valve springs not sure what size stole them off another motor, with 1.3 ratio rocker arms. Did I bend a...
  18. CJdoodlebug90

    HELP Preadator with dyno cam AND NOW HAS CRAZY COMPRESSION!!!

    I installed a dyno cam inst my preadator and it has crazy compression. Almost pulled shoulder out trying to start it. I tried lashing valve and didnt work. I have ordered 18lbs springs. Only mod I have is header. WHAT IS THE PROBLEM? HOW CAN I LOWER COMPRESSION SO THAT I CAN START IT?
  19. dajsnipe

    need advice on a pushmower

    This mower is going on its third season but it's only been used for triming so she's seen light duty. Yesterday it was running fine and then just stopped, we didn't hit anything, the blades are good, had fule.... I had a chancen to look at it today, hears what I know: -good spark -getting...
  20. R

    Nice powerful tecumseh 5hp oh-195-ea

    Newer generation Tecumseh OHH50-68110 AKA OH195EA-71237 5 HP Great compression & Spark Runs Great ! $125 Plus Shipping or Local Pickup
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