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  1. #1
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    Default I need rebuild advice.

    So I am rebuilding my motor just a small bore and new pistons but from what I gather the biggest performance gains come from head work and new cams I'm wondering what one would suggest to get better performance and better reliability out of my machine...it runs good but I am having valve problems with the front cylinder and its burning too much oil and I suppose a freshen up after 34 years wouldn't hurt it....I just want to know what to do to make it as best as it can be...thanks!!

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    Clean everything before assembly. EVERYTHING! Performance is tricky bc without changing everything to match you will never see full potential. Maybe a light cam and some hand porting would do the trick and be fairly cheap.

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    What exactly do you mean by "hand" porting?? Would it be easier to buy new heads??

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    You never said make, model, or year?

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    If your looking to be on the cheap in would say find some p cams and a good carb. Maybe upgrade to better valves when you get the heads re done.
    You have q cams now which are crappy emissions cams. Our bikes are pretty similar, we are outcast with 79-81 frames and such.
    I have p cams and XLR exhaust valves along with a super B and my bike hauls pretty good.

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    Sorry it's a 1979 Harley Davidson sportster 1000cc ironhead

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    I already have a super b the valves in the front are shot man just want to beef it up a little

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    Like opening up the ports and polishing with a hand dremel. Just dont polish the intake Ports.

  9. #9
    xllance
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    For sure get the heads up to snuff. Be careful "porting" your heads. This needs to be done by someone who knows what they're doing with a flow bench. You can however use a dremel or whatever to clean any burrs or casting marks in the ports and in the manifold. A good carb, ignition and a sensible exhaust will do wonders for an Ironhead. Oh yeah p-cams work great !

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    Thank you guys a lot I have a lot of looking at parts to do lol thanks for your Input!!!

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    You already got very good info here, but there is one thing I want to add. My experience is, that crankshafts tend to fail after top end rebuilds. New valves, new pistons and hot cams produce more horsepowers, which a 34 years old crank can not take up for long. Don`t know what knowledge you have about the mileage of the engine, but Im sure you are not the first owner as the bike is older than you are.
    Building a good performing engine should always start at the bottom, you would not build your new house on a foundation you can not trust.

    Heads: I use cast iron valve guides, because they last long. I shorten them on the spring side by 2mm = 0,08" and machine a 0,5mm = 0,02" deep groove about 6mm = 0,24" from the top. This makes room for a valve guide seal and the seal hooks into the groove firmly. This will make your engine stop burning oil and avoid carbon build up on the valve stem, what often causes sticking valves. Have the best experience with Rowe melonite valves and hardened valve seats. The best improvement to the valve train of my 79 engine was a set of baisley roller rockers. One can not think how quiet an ironhead valve train can be. These roller rockers will extend life time of valves and guides, puting less side force on the valve; rolling over the tip instead of pushing on it.
    If you have the chance to get your heads grinded on a surface grinding machine go for it. I do not do that to raise compression, but to just clean the gasket surface. Grind rocker side first and than cylinder side carefully and watch out, exhaust flange is sticking out. Copper head gasket and James silicon rockerbox gasket will make your cylinder head oil tight.
    Now that I have been boring everybody to death, I will get my a beer and go to bed.
    Good night!

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    Thanks man I was actually looking at roller rockers today lol I will keep all this in mind as I start my project...this is the reason I love this site man nowhere else am I going to get this kind of input! Love this shit! Thanks again!!

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    If you have the chance to get your heads grinded on a surface grinding machine go for it. I do not do that to raise compression, but to just clean the gasket surface.
    Also note that the "belt grinder" at many automotive machine shops is not an actual precision "surface grinder".

    Cast iron heads, all kinds, clean up nicely using Roloc wheels and similar if you don't get the heads ground on a surface grinder.

    Spraying Coppercoat on copper gaskets works very well by the way. I hang gaskets from coat hangers, spray both sides (outdoors) then let dry for a few minutes before installing.

  14. #14
    xllance
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    Quote Originally Posted by farmall View Post
    Also note that the "belt grinder" at many automotive machine shops is not an actual precision "surface grinder".

    Cast iron heads, all kinds, clean up nicely using Roloc wheels and similar if you don't get the heads ground on a surface grinder.

    Spraying Coppercoat on copper gaskets works very well by the way. I hang gaskets from coat hangers, spray both sides (outdoors) then let dry for a few minutes before installing.
    Not hi-jack but I guess it'll all be usefull info for the OP. Farmall how many times do you re-use copper head gaskets ? Everytime I order new gaskets, they send the thin ones which I don't want so I end up heating the old ones up in the oven to expand them and slap them back on. Yes I use the Permatex copper spray. I think I've re-used this set about three times. So far so good.

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    Quote Originally Posted by xllance View Post
    Not hi-jack but I guess it'll all be usefull info for the OP. Farmall how many times do you re-use copper head gaskets ? Everytime I order new gaskets, they send the thin ones which I don't want so I end up heating the old ones up in the oven to expand them and slap them back on. Yes I use the Permatex copper spray. I think I've re-used this set about three times. So far so good.
    I reuse them as well, but did not dare three times. People already call me tight-fisted.
    OEM - number is 16769-82 for the thick copper gasket,
    James has .045 thick
    Cometic has .043 and .032" thick

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    I anneal them too. If sheet copper doesn't look fucked up after it cools off and I wipe off any oxide, I don't have a limit on reuse.

    I never mic'ed them since I don't run high compression ratios.

    I've reused a set at least three times over the years. Some others a couple times. Never gave it much thought, and have done it on various Britbikes too.

    I also copper-coated a used Fel-Pro "blue" Shovelhead fiber head gasket on a weekend to get a bud going. It worked perfectly for years until the engine was rebuilt for unrelated reasons.

  17. #17
    xllance
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    Thanks farmall and GermanG. You two seem to always know your stuff.

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