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at my wits end. rebuilt and cleaned carburetors step by step with larrys book ultrasonic cleaner and all. intake boots were sealed with 60 mm heat shrink tube and had o rings replaced with honda oem o rings. STILL HAVE AIR LEAKS WHEN I CHECK WITH CARB SPRAY. can someone please tell me what Im doing wrong here? what steps have you taken with sealing intake boots that yielded success?
 

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I have good results from a product called "Shoeglue". Available at Home Depot or Lowe's. Use that before the heat shrink tube. It's less than $5.00 if I remember correctly.
 

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Also have had success with Plasti-Dip. You should apply a couple of coats. If you apply it carefully, it even looks pretty good.
Dan
 

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I was about to ask the same. I've had good results with Shoe Goo on cracks. This should be done before applying the heat shrink unless you use self adhesive heat shrink.

Where are the leaks?
  • If they are between the manifolds and heads no amount of crack sealing will help. Either the o-rings you used are too thin or perhaps one or both was displaced during assembly and pinched between the mating surfaces (I've heard of this happening a few times).
  • If they are where the boot attaches to the carb you need to either tighten the clamps better or get better clamps (Norma-Torro 40-60mm diameter 9mm wide clamps can be found at marine suppliers and are much better than the originals)
  • If they are leaking at the balancing port screws either the screws aren't tight enough or the crush washers are hardened or missing.
 

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Discussion Starter #7
I was about to ask the same. I've had good results with Shoe Goo on cracks. This should be done before applying the heat shrink unless you use self adhesive heat shrink.

Where are the leaks?
  • If they are between the manifolds and heads no amount of crack sealing will help. Either the o-rings you used are too thin or perhaps one or both was displaced during assembly and pinched between the mating surfaces (I've heard of this happening a few times).
  • If they are where the boot attaches to the carb you need to either tighten the clamps better or get better clamps (Norma-Torro 40-60mm diameter 9mm wide clamps can be found at marine suppliers and are much better than the originals)
  • If they are leaking at the balancing port screws either the screws aren't tight enough or the crush washers are hardened or missing.
im gonna go through and do all three of these to eliminate the possibilities. do you use oem o rings for the manifold/head connection or do you know of a chunkier alternative for this application? now that you mention it they did seem a bit thin when i put them on.
 

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You don't want to use rings that are too fat because they could cause excess pressure on the ears (a few have broken ears off doing that). The original size should be OK if they are in good condition (= round cross section, not flattened) and the groove is in good shape and the surface on the head is flat. And they don't become dislodged during assembly and get pinched. You can use a couple of dabs of grease to hold them into the grooves during assembly if necessary.
 
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