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  1. #1

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    Riva Head Questions

    Just won some heads on ebay. Couple questions about them though. In the riva installation, a part # RY10028-H , Non-girdled Hardware Kit, It lists:
    14 - Bolts/washers
    2 - Straight Fitting
    1 - Block Off fitting

    The kit is $70 from riva. I can get the bolts/washers without a problem, but what are the straight fittings and block-off fitting?

    What is the difference in the girdled and non-girdled? I have only seen one thread on here for a girdled GP head. Not really sure which i have without seeing pics.

    Also, should a colder plug be used with higher compression? The install recommends a 3/4" reach plug i.e. BR8ES. Is it good practice to have colder plugs on hand if detonation starts? Or is that not a problem with 150 psi?





  2. #2
    Napkins........ I Fly a Starship seajm's Avatar
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    You have a non girdled head shown. If you have a pipe(s) and high comp. a girdled head would be recomended to avoid damage to your cylinders.

    The more mods you add the colder the plug you want. The only engine mods I have on my GP1200 are F/A's with the Yamaha carb update(1.2 n/s to 1.5 n/s) primer kit and a Pro Design Cool Head 42cc domes 150psi. I run the BR8ES. You have to check sometimes when you purchase your plugs. if you get a lazy parts guy he might give you a BR8ES-11 which has a .44 gap instead of a .32 gap which is fine if your running a 1200 p/v. The higher the # on the plug the colder it is. Hope that helps

  3. #3
    Napkins........ I Fly a Starship seajm's Avatar
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    Here is a good read on plugs

    The term spark plug heat range refers to the speed with which the plug can transfer heat from the combustion chamber to the engine head. Whether the plug is to be installed in a boat, lawnmower or racecar, it has been found the optimum combustion chamber temperature for gasoline engines is between 500°C–850°C. When it is within that range it is cool enough to avoid pre-ignition and plug tip overheating (which can cause engine damage), while still hot enough to burn off combustion deposits which cause fouling.

    The spark plug can help maintain the optimum combustion chamber temperature. The primary method used to do this is by altering the internal length of the core nose, in addition, the alloy compositions in the electrodes can be changed. This means you may not be able to visually tell a difference between heat ranges. When a spark plug is referred to as a “cold plug”, it is one that transfers heat rapidly from the firing tip into the engine head, which keeps the firing tip cooler. A “hot plug” has a much slower rate of heat transfer, which keeps the firing tip hotter.

    An unaltered engine will run within the optimum operating range straight from the manufacturer, but if you make modifications such as a turbo, supercharger, increase compression, timing changes, use of alternate racing fuels, or sustained use of nitrous oxide, these can alter the plug tip temperature and may necessitate a colder plug. A rule of thumb is, one heat range colder per modification or one heat range colder for every 75–100hp you increase. In identical spark plug types, the difference from one full heat range to the next is the ability to remove 70°C to 100°C from the combustion chamber.

    The heat range numbers used by spark plug manufacturers are not universal, by that we mean, a 10 heat range in Champion is not the same as a 10 heat range in NGK nor the same in Autolite. Some manufacturers numbering systems are opposite the other, for domestic manufacturers (Champion, Autolite, Splitfire), the higher the number, the hotter the plug. For Japanese manufacturers (NGK, Denso), the higher the number, the colder the plug.

    Do not make spark plug changes at the same time as another engine modification such as injection, carburetion or timing changes as in the event of poor results, it can lead to misleading and inaccurate conclusions (an exception would be when the alternate plugs came as part of a single precalibrated upgrade kit). When making spark plug heat range changes, it is better to err on the side of too cold a plug. The worst thing that can happen from too cold a plug is a fouled spark plug, too hot a spark plug can cause severe engine damage

  4. #4

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    Maybe i should rephrase that question..Per personal experience, would you all recommend goin with a colder plug if changin from stock compression to 150psi?

    I think the straight and block off fittings are for the water. Which i already have those from the looks of the pics (haven't got them yet). so i can just buy the bolt/washers and o-rings and be all set.

    What is best to clean carbon from the heads to prep for install? Carb/choke cleaner strong enough? Also what is the best tool to scrap off the old gasket without scoring the block?

  5. #5
    Napkins........ I Fly a Starship seajm's Avatar
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    Quote Originally Posted by akjose View Post
    Maybe i should rephrase that question..Per personal experience, would you all recommend goin with a colder plug if changin from stock compression to 150psi?
    If you are running a BR7HS, yes with that head you will need to run the BR8ES.

  6. #6

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    I am running BR8HS. That is why i was wondering if i should go colder. The install suggests BR8ES. I understand that is 1/4" more reach than the 'HS'. Thanks.

  7. #7
    old school big raider's Avatar
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    Quote Originally Posted by akjose View Post
    I am running BR8HS. That is why i was wondering if i should go colder. The install suggests BR8ES. I understand that is 1/4" more reach than the 'HS'. Thanks.
    BR8ES PERIOD unless you run a motor like mine i run BR9ES

  8. #8
    jdog800's Avatar
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    the domes on that head are different sizes. Doesnt look like a matching set....

  9. #9
    o0 RASTA 0o's Avatar
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    I used a razor blade....works very well, especially if you use the tool box razor blade with only one end that is sharpened. With this you will be able to get it really clean and ready to be sealed again.

  10. #10

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    Quote Originally Posted by jdog800 View Post
    the domes on that head are different sizes. Doesnt look like a matching set....

    You're right, one head is all 41cc and the other is a mixture of 86mm and 81mm...selling the odd domes when i get it.

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