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  1. #1

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    Mikuni Carb rebuild on an SLT 750 (and Reed inspection - advise needed)

    I am rebuilding my SBN 38's. The kit I ordered didn't come with the "O"-ring or Valve Body Gasket (as pictured). I suspect and currently plan to replace these (once I get them from somewhere...).

    I also inspected the reeds and one corner looks a little chipped. These are expensive to replace. I'm thinking I may able to get by for now and defer this cost until I do the next carb service/rebuild (every 2 years or so...). they do seat and fit down against the cage well (although I haven't got a feeler guage between there yet). Thoughts on I should definitely replace these now???

    The carb components are currently all soaking in diesel fuel. I saw one rebuild on these where it was stated that the diesel will provide both the detergent/solvent (?) and lubrication. So far, this hasn't removed all the paint (which I like...). I could jack up to acetone or the local small engine repair shop (for mowers) has a water-based Hydro-Machine that i could hire. So, am I good with the diesel soak for a couple of days? Or, should i get going with a more aggressive solvent? If so, what solvent is recommended? And if the paint gets stripped, then what is a good paint for these, if repainting is recommended?

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  2. #2
    Click avatar for tech links/info K447's Avatar
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    Quote Originally Posted by dbrink View Post
    I am rebuilding my SBN 38's. The kit I ordered didn't come with the "O"-ring or Valve Body Gasket (as pictured). I suspect and currently plan to replace these (once I get them from somewhere...).

    I also inspected the reeds and one corner looks a little chipped. These are expensive to replace. I'm thinking I may able to get by for now and defer this cost until I do the next carb service/rebuild (every 2 years or so...). they do seat and fit down against the cage well (although I haven't got a feeler guage between there yet). Thoughts on I should definitely replace these now???

    ...
    What source are you looking at for replacement Fuji engine reeds?

    Is the carb rebuild kit genuine Mikuni OEM or aftermarket?

  3. #3

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    Mikuni Carb rebuild on an SLT 750 (and Reed inspection - advise needed)

    I got the carb rebuild kits from WatCon (long time ago). Hoping they're good quality. I didn't know to ask if they're Mikuni kits. also didn't get the o-ring and valve body gasket at that time. But maybe they were updated since then....

    They did come with 3 springs. I'll need to figure out which one to use (probably one similar in length to the one I already have. But I'll need to get into how to adjust (and all that). Any guidance is appreciated. Thanks.
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    Last edited by dbrink; 08-02-2015 at 10:28 PM.

  4. #4
    Click avatar for tech links/info K447's Avatar
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    Quote Originally Posted by dbrink View Post
    I got the carb rebuild kits from WatCon (long time ago)...
    How long ago?

  5. #5

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    4 years ago (July 2011). When I also purchased and installed the triple outlet fuel pump.
    Last edited by dbrink; 08-02-2015 at 11:28 PM.

  6. #6
    BlueFishCrisis's Avatar
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    The springs are the replacements for 750s. Swap those out. Watcon still doesn't include the rubber gaskets you are looking for. I have not pulled apart a set of carbs that needed these replaced to date.

    I have good used reed petals for decent price. PM me if interested.

    Let me know if you need anything else for the carbs while you are at it....

  7. #7

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    Thanks!

    I'll stop searching for the O-ring and valve body gasket since mine look ok and can be re-used.

    Now to do the cleaning right...
    What's the best approach for the cleaning before the rebuild?

    I've had the carbs soaking in diesel fuel for the past couple of days since I had seen this provides both solvent and lubrication. However, I'm not sure it'll do the job. So, I'm looking for some additional guidance on carb cleaning. After soaking for a few days, I started to "rinse" them with carb cleaner and got some paint peel. Since I want them to look good when I'm done, I'll likely repaint them when I'm done (any suggestions?).

    That said, I have some acetone, but I'm concerned this may be too aggressive for any non-metal components. The bloke at my local small engine repair shop (for lawn mowers...) uses a jewelry ultrasonic machine for cleaning carbs. He uses an blend of water, oil, & ammonia and the he jacks-up the frequency I didn't offer to try it on my watch... Anyhow, he offered that i could get my own from Northern Tools. He asserted that in his experience, the chemical approach doesn't cut-through the deposits that are left behind by ethanol but the "mechanical action" from the high frequency does a great job. I'm not seeing any deposits on my carbs, but I thought it was an interesting approach. Enough novice speak...

    Should I get one of those gallon cans of "stuff" from the auto parts store to clean the carbs? Go with the acetone? Or, what do you recommend?

    I'll shoot you a PM about the reeds. I also would like to get a newer version of the gas tank dip-lines (i.e the aluminum housing style...)

  8. #8

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    I got a gallon of the Gunk Parts Cleaner. It calls for 20 minutes of soak time. After 20 minutes, I don't see that much has happened... Paint is still there (for the most part). I suppose I don't need to see the paint peel to confirm the internal deposits if any are getting what they need. I'm still not sure if it's aggressive enough. Any suggestions on carb cleaning?

  9. #9

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    any insights on cleaning these mikuni's?

  10. #10
    Sooo...how much for the 780? stimpsonjcat's Avatar
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    It never occurred to me to repaint the carbs. So I have no advice on that.

    Honestly it seems like a risk of getting new paint somewhere it ought not be.

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