Topic: cracked carb boot

[gregwaits]

I discovered that cylinder one's carb boot is cracked a little bit (carbs are installed and the bike is running). When I was riding around, the bike was stuttering and backfiring a little bit due to the crack.

Is there an easy fix that I can use on this - short of removing the carbs again. It was suggested that I slide the clamp out of the way, apply silicone to the crack and let it dry, then retighten the clamp.

Has anyone else had to deal with this?

[Cvillechopper]

Which bike?  500 or 750?

I've got a set of boots for sale from a 550 that would probably work on the 500 (not completely sure though).

If you REALLY don't want to pull the carbs (only way to truly fix the probelm) you could do as suggested.  Get the clamp out of the way and seal the crack.  Personally, I like the brush-on electrical tape for that.  It's black so not as noticable and dries a little harder than the silicone so there's less worry of the suction from the intake pulling the goop into your carbs. 

Good luck.

[gregwaits]

Hi

The bike in question is a '78 750K8. I have some extra boots lying around, but they are off a '69, and they are a different shape.

Thanks

[bryanj]

If you mean the rubbers between the carbs and head the only real solution is a SET of new ones; if its the ones between the carbs and airbox tape will do

[TwoTired]

If you mean the rubbers between the carbs and head the only real solution is a SET of new ones; if its the ones between the carbs and airbox tape will do

You got something against band aids Bryan?

[BobbyR]

I may have the boot you need laying around. They are old, but in one piece. Maybe you can sneak the old one out and the new/old one in. I used some some black ATV on an old Kawi I had. It worked ok and looked ok.

[bryanj]

Sorry TT we dont got band aids we have elastoplast!

[MRieck]

If you mean the rubbers between the carbs and head the only real solution is a SET of new ones; if its the ones between the carbs and airbox tape will do

I have to agree. If one of the boots is that bad you can bet the 3 others are not far behind. I've seen people spend more time trying to tune around leaking boots, gunked up carbs, crappy ignitions etc.

[sbc1320]

It would be a bandaid at best using silicone. Silicone and gas don't mix. True the silicone mihgt not get much fuel as the intake is sucking the fuel through there. Could use a two part flexible glue/

[BobbyR]

If you mean the rubbers between the carbs and head the only real solution is a SET of new ones; if its the ones between the carbs and airbox tape will do

I have to agree. If one of the boots is that bad you can bet the 3 others are not far behind. I've seen people spend more time trying to tune around leaking boots, gunked up carbs, crappy ignitions etc.

I must raise my hand is tesssssssssssssssst timmmmmmm mony . Brother Reick show me the errors of my ATF, Wintergreen, boiling water, and oven baking ways. He got me a set of brand new rubbers at a good price. They pulse like little hearts at idle, which means they are sealing. Then I could go diddle with other stuff to make the bike run better.

[joeb]

Get new ones save yourself some headaches .

[gregwaits]

Get new ones save yourself some headaches .

Where are new ones available for the K8?

[TwoTired]

Try the Honda dealer.  I just bought some a couple months ago.

[brandon]

I JUST bought four NOS ones on ebay for my 400 as I have the same problem. I paid $40.00 shipped.

David Silver Spares has them listed at $16.00 each BEFORE shipping from the U.K.

I am eager to get these on and retune my bike. Good luck with yours!

[Terry in Australia]

Yeah, get some new ones Greg, but in the meantime, with the carbs on the bike, just rub a little superglue into the cracks, that's what I used to do, it sounds like it shouldn't work, but somehow, it does. Cheers, Terry.

[joeb]

Honda should have them.

[MRieck]

Honda should have them.

They're available. We should all be happy to have a Honda.....nobody has a better supply of parts for old bikes.

[Terry in Australia]

BMW and Harley have a much better parts back up in Oz for older bikes than Honda, that's why I buy most of my Honda parts in the US. Cheers, Terry.

[Buber]

And here's teh cheapo way - worked for me, and worked very well. You go to 1st car shop and look for teh rubber tubes from the cooling system. The ones for HOT water, they usually are reinforced with a sting web. Buy those, as only they are strong enough - I bought once non-reinforced, and blow a hole in them, by engine-braking - suction was THAT strong. Anyway - you find a pipe like that, just make sure the diameter is somewhere close, cut it up to pieces, and trick is to slide it on the engine - but it's easy, once you heat them up a bit with hairdryer, and lube them a bit with oil for slickiness. And hey, presto - you have super-strong, good looking, long lasting, costing close-to-nothing carb boots.

I tried it once, and I'm sold. And don't worry about rubber quality - if it can whitstand coolant and boiling temperatures, a bit of fuel mixture passing throuhg is nothing for it 

Try it - you can't do it cheaper than that!

[TwoTired]

There is a difference between cheap and inexpensive.

Radiator hoses need to withstand water and glycol.  Rubber that does this is not necessarily impervious the gasoline fuel (though it can be) and can slowly dissolve over time.    Rubber that DOES withstand the more aggressive solvent gasoline is usually made with a more expensive compound than that which only needs to withstand water and Glycol.

Also, Honda went to extra trouble the mold the carb boots so that the air way is more or less smooth with no changes in runner diameter.  Steps in the runner walls create turbulence and drag that can upset airflow into the cylinder chambers.  This can hurt performance in specific RPM ranges, and could vary well create some tuning challenges for the carburetors.

Cheers,