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Thread: Have you Decked the cylinder

  1. #21
    Join Date
    Dec 2001
    Location
    Visalia, CA
    Posts
    193
    Everything you spec'd out looks correct except the intake lift is listed at .345. Purdy durn close...

    I talked to Web today, all 3 of their cams have a LCA of 107.

    All of the cams I have specs for have LCA's of about 107. The lowest is 105 for Megacycles 196-1 (intake side), and the highest is 108 for the stock exhaust.

  2. #22
    Guest
    Just a question as you guys seem to have some good input on this subject.

    I have a 11:1 piston in my 440 with the std honda gaskets and currently no other internal motor mods.

    The engine does run strong but just doesnt seem 100%. I know that it could use a cam and I am looking into one (this post has been a great help thanx) but after talking with the orig owner and checking out some of the posts on the net I am a little confused.

    To get the compression up (which by everyones thoughts seems to be the main problem) would it be better to use the thinner cometic or xr400 base and head gaskets or have it decked or both.

    I will add that since I will be doing a comp and leak down test this weekend I am only assuming that there are no major ring to cyl wall wear problems based on the way it runs now.

    Thanx

  3. #23
    Join Date
    Dec 2001
    Location
    Visalia, CA
    Posts
    193
    Whoa. Stock head gasket? Isn't it hanging off into the cylinder? This could be a problem...

    You will need to check your chamber volume to find out your actual CR. Vary gasket sizes to achieve the correct CR.

    Cometec makes head gaskets as thin as .025. Assuming your cylinder and cases are perfectly straight, you could seal them up with Honda Bond, or Cometec can get you a base gasket as thin as .010.

    If you spend the time to get a real 11:1, and follow it up with a good cam (not an XR cam on a 440), I'll bet you get a bigger power gain than when you originally did the 440.

  4. #24
    Guest
    Matt,

    thanks fr they reply.

    I did not do the 440 so I can only hope that the gasket is not into the bore. I do believe that the previous owner did mean stock honda thickness on the gasket.

    Are there any concerns with the thinner gaskets????

    I am intending on obtaining the cyl volume when finished to help with fuel or octane requirements. Any ideas on octane if i do get it around 11:1 ?

    Also do you guys have any preference on the cometec .010 gasket v/s honda bond ??

    Any recomondation on a cam for this set up? I do like the bottom end stump pullin torque but would like more on th emid and maybe even a bit more on top.

    Also where is a good place to get cometec.

    Thanx

  5. #25
    Join Date
    Feb 2002
    Posts
    39
    440exforme, I am not quite as good as Matt seems to be but here is my thought on the subject. Gaskets are probably easier than decking however you are limited to what you can change because can only get so many different gasket thicknesses. I also do not much care for steel shim gaskets....They work I just don't like em. With decking you would not have this problem, but the big draw back with decking is that most of us do not have access to one of those plasma things Mike400ex talked about so once you cut it it's cut, but so what, you will always be able to get a piston to fit. If your measurments allow I would try to use honda bond or yamabond on the base gasket. I only decked mine I did not do the gaskets so I am not an expert on that but it should work. Now... if the gasket thing does not get you a nice .040" quench area, decking is the only way to go, and put the regular gaskets in. You can get cometics at pretty much every shop, but call cometic and ask them about compressed thickness for the head gasket....very important... As far as cam goes I used the TC GNCC cam and I like it I had a Rocky Ridge cross country cam on a 400 and it was good too but I think the TC is better. TC makes power everywhere. I had trouble getting a cam from tc though it took forever. As far as gas goes I fired up the 440 I'm talking about, this last weekend. It has a comp ratio of 10.8:1. We put cam2 in for the start up because we wanted to be on the safe side of detonation. In car motors 10.6:1 is pretty much ragged edge for pump gas, I know motorcycles can handle more because of the aluminum motors allow heat to be dissapated better. We are going to start weening it off of cam 2 while keeping a close eye to see if there are any problems. If you do all that we are all talking about here you will be pulling stumps and beating up your rev limiter in no time at all....it won't even seem like the same bike.
    440exforme, I hope that is at least a little bit useful. Sorry, once I get going...... Any how good luck and do not forget to post DETAILED results for all of us to see.
    1998 Banshee .060" over, Delta 2 reeds, Stage2 porting, 28mm Mikunis, Toomey T5's, Pro design cool head.

  6. #26
    Guest
    Thanks for the info.

    I have found that both the gaskets and decking are not too expensive so I will need to make up my mind which way to go.

    I have a call in to cometic and will see what they have to say.

    I think the cam will be the more diffilcult deccision now.

    Also should I be worried about the timing? or degreeing the cam?? I hope not. have enough to worry about already

    Also has anyone found any big advantage to valve work at this stage? I know there is an increase just not sure if its worth it on one.

    Thanx

  7. #27
    Guest
    I'm going to take the motor back apart this weekend and take the stock base gasket out and install the xr head gasket.
    I'll post the measurements between that and stock gaskets for everyone to look at when I get done. Maybe that will help clarify some peoples' confusion.

  8. #28
    Join Date
    Dec 2001
    Location
    Visalia, CA
    Posts
    193
    The steel shim gasket is 3 piece, good stuff. The base gasket is far less important, not being in the combustion chamber and all.

    For cams, here's a list of cams that might fit your needs, in increasing size:

    1: White Bros all around- a bit more lift than the XR, but similar duration. 345 .335 240 248 @ .050
    2: Megacycle 196-X1- increased lift and duration over the WB all around. .346 .346 246 246 @ .040
    3: Web 450/451- still a great all-around cam. .350 .345 256 256 @ .050 This one increases the duration over the 196-X1, without increasing the lift much. This is a very popular drop-in cam, as it is also marketed by GT Thunder, and White Bros as their Track cam.

    #1 will certainly have more mid and top than the stocker, but would still have tremendous bottom-end torque.

    I have #3, albiet with a 12.5:1 stock bore. Still has good low-end, but the midrange hit is excellent. Very nice top-end.

    Although there's nothing inherintly wrong with the cams from any of the tuners, I sure as he1l won't buy something without knowing what I'm actually getting...

    You could certainly do some cleanup port work, couldn't hurt.

  9. #29
    Join Date
    Jun 2001
    Location
    BOONVILLE, NC USA
    Posts
    139
    how much clearance should there be between the piston and valves on the 400ex?
    2000 400ex with a mikuni tm38 carb, tc racing pipe, rebuilding motor

  10. #30
    Join Date
    Aug 2001
    Location
    mich
    Posts
    272

    valve clearence

    I like to see around .100, you could go a little less (.080) but I wouldn't risk less than that. Let's see what the other guys think on this.

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