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Discussion Starter · #1 ·
hi all,

still plugging away at (and uncovering issues with!) the 74 cb200. one of the stud bolts connecting the left carb insulator boot to the cylinder is shot and the bolt hole going into the cylinder is stripped out and now somewhat oversized. i got a new stud bolt fitted in as best i could and managed to tighten the insulator boot pretty snug to the engine. but i can see a bit of daylight in the bottom corner of the insulator boot where it meets the engine. i'm afraid of an air leak since it's not as tight (especially on one side of the boot) as it should be. is it a bad idea for any reason to use a thin coat of form-a-gasket/honda-bond on the face of the insulator boot that meets the engine? i figure it'll help hold things in place and seal it up a bit better...just not sure if it's ok to use honda-bond in that way and in that location on the bike. i don't want anything making it's way into the carbs or (worse) the engine...

thanks!
 

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Sensei
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I think you already know this, but, you should fix that stripped hole.....(helicoil or similar)
If you rapidly close the throttle, ALL the intake vacuum will pull at your "chewing-gum" repair, and probably try to suck it inwards.....Right into the cylinder....
 

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Discussion Starter · #3 ·
yeah, i've been going back and forth trying to decide if the way the bolt is seating/threading is "good enough", but you've convinced me that even "good enough" isn't a smart way to go in this case. i have zero experience with fixing stripped holes and this is the first i've heard of heli-coil. is it difficult/tricky to do? and once i use the stuff (or something similar) will i be able to use the regular 6mm stud bolt that should be in that hole?
thanks (as always!).
 

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Discussion Starter · #4 ·
i'm wondering most if this will require any drilling of that hole and, if so, can i do that (and clean out any 'shavings' from drilling) without taking the engine apart? again, i'm afraid of getting pieces of this stuff into the engine itself, since whatever extra pieces or shavings i create will fall into the cylinder....
 

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Sensei
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Yes, you must drill.....It should be a "blind hole" so "through drilling" shouldn't be necessary.... Pack a rag in the inlet, and/or use duct tape over it to prevent any "thrown" chips from entering........Alternatively, you could permanently install a 6mm stud in the existing "loose hole" and "stake" it in place (if you'll have enough room for a nut on the rubber manifold) by "pushing" some existing metal inwards (to hold/pinch it in) using a centerpunch or tiny chisel.......
If you are careful you could try the alternative, and still do the primary repair if it does not work out for you........
Not being able to feel or see how much "grab' the existing hole has prevents me from specificly picking the best method for this situation.....It's your call.......
 

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Discussion Starter · #6 ·
ok--thanks! this is all really helpful. i tried a 6mm tap to see if i could salvage something of the existing thread (i was optimistic that there might be enough in there to work with, so i figured starting with the cheap and easy option was best). it seemed to work to some extent. the 6mm bolt threads in better (in that it's no longer just sliding in and out but is actually grabbing a bit and threading--especially towards the back of the hole where i'm guessing the threading was better to begin with). i set the stud in the hole tight (and used some loctite before i threaded it in). i'll try again to tighten down the boots after the loctite sets up. hopefully i've created enough "grab" to make it work. if not, i'll try to drill it out and use some heli-coil or try your suggestion of making a "permanent" stud.

i'm sure there's enough grab there to keep everything in place. and, you're right, it is a 'blind hole'--only about 3/4 inches deep--so the stud can only come out (in other words, it can't get sucked into the cylinder as far as i can tell). still, i want to make sure the nut grabs down tight and seals up that carb boot so that i don't have to worry about air leaks...

many thanks again.
 
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