Best Big Bore Kit

Discussion in 'Modifications' started by SeaBeagle, May 23, 2021.

  1. SeaBeagle

    SeaBeagle New Member

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    Got my 1971 CT70 3 speed running. A few things need attention still. The carb bowl drain is pitted badly and leaks a little. The spark plug threads have about one more removal before the last threads come out with it. So, I was thinking of a big bore kit. The most common seems to be an 88cc. But , I'm not against going bigger which would probably need a new carb with it. How about a performance cam? I'm ok for a complete upper end and carb if I could still maintain the look of the bike. I want to keep the stock exhaust, skid plate, and 6 volt (because I ordered a 6 volt CDI from Ohtokc). And I don't want to bore the crank case up for a super sized piston. The eBay kits look like something I made in high school metal shop. What can you recommend?

    [/ATTACH] IMG_2140 (2).jpg IMG_2141 (2).jpg
     
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  3. kirrbby

    kirrbby Well-Known Member

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    Great lookin bike.

    Check out tbparts.com they make very nice and affordable kits.
    May be even better yet to order a t parts kit from northeast vintage cycle. Or from tbolt. Or dratv.com is a awesome, and trusted vendor. You can buy a complete kit that will come with a "race head" with a good cam installed...carburetor and intake...piston/cylinder kit, or course.
    It will still look... pretty stock.
    No major modifications needed.

    Welcome to lilHonda!
     
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  4. SeaBeagle

    SeaBeagle New Member

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  5. OLD CT

    OLD CT Well-Known Member

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    I would fix the sparkplug threads, straighten out the carb do the CDI conversion and call it a day. That would maintain the look and keep the value of the bike as high as possible. That kit has a turnout intake and free flow filter and not the ''best choice of carb'' that you will need because 88cc engines can't benefit from any true gains with the stock carb and airbox. Especially a noticeably non stock race head. No way that airbox can handle that mod. If that cylinder is healthy, why mess around, ''yet''.
    That bike looks great, all stock to me.

    You will possibly get the ''little boost of power'' you are looking for doing the cdi conversion...
     
    #4 OLD CT, May 23, 2021
    Last edited: May 23, 2021
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  6. lukelaw1

    lukelaw1 Active Member

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    You can get that kit, but you may not get that carb to fit without a different intake that has a turn out, also stock throttle cable pry wouldn't work with that carb and to use that cable you may have to change out the throttle tube to an aftermarket.

    i need someone with more knowledge on installing that kit.

    I have done the below:
    i know you can get just as 88cc big bore kit (119.95), buy a mini monster cam (46.95), add hd valve springs (12.99), uni filter 45 degree if you want (9.99) main jets (4.89ea). repair the head this will let you, keep a very stock appearance, run stock exhaust (baffle removed), stock carb(re-jetted) typically 1 step up from your current main jet will do. source a new carb bowl from ebay, chp, or member.
     
    #5 lukelaw1, May 23, 2021
    Last edited: May 23, 2021
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  7. OLD CT

    OLD CT Well-Known Member

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    Yep, you will lose the fuel reserve feature also, if you use that tb/tbolt carb and need to hang a remote petcock somewhere. The mini monster cam/new rockers is a good choice. You won't usually need the ''wide space'' springs unless you go bigger than the mini monster.
     
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  8. Clayton

    Clayton Active Member

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    Iv never used it but CHP offers a big bore kit that will use the original air box/filter. On there website it looks pretty nice of you are trying to keep the original look of the bike. Iv been wanting to try it out.
     
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  9. Deoodles

    Deoodles Well-Known Member

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    I built an 88 using the chp privateer head. I’ve always liked it but it doesn’t play well with future engine upgrades. I tried to take it to a 108 and it didn’t work. The piston hit the head. It’s still an 88 and looks closest to stock IMO. Going on 6 or 7 trouble free years. Stock intake and exhaust
     
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