Topic: K7 750 - where to buy Carburetor to Cylinder Head Insulator

[Erny]

I decided to buy new ones, but hesitating, if I should buy genuine ones, knowing they are not easy to find and they are manufactured quite some time ago - rubber can be "hard", no?

If aftermarket, do you have tip where to buy to get high quality and perfect fit?

[MikeSimon]

There are a couple of posts in different forums about renewing the carb boots with "Wintergreen".
It is a stinky, messy process, but supposedly works A1.

[Davez134]

I would buy genuine Honda ones if you can. I have tried aftermarket ones, and the rubber is different, hardens very quickly. I have genuine ones on my 750 K2 right now that are still soft like new after about 3 years.

[Erny]

Thanks for advice, I also prefer genuine ones.

Issue is that I did not find genuine #2 and #4 yet. #1 & #3 are available.
Found also complete kits, but not sure if it is really genuine one.

I keep searching...

[Bankerdanny]

Have you checked David Silver Spares? He carries a lot of genuine Honda and has operations in both the US and UK so shipping to European locations isn't generally a problem.

[Paintedseat]

What year is your bike? If a 77 or 78 they don't make 2 and 4 just 1 and 3. Supposedly they are just mirrors of each other and can be used for 2 and 4. I don't know for sure I bought 4 new ones aftermarket from a reputable seller that has good reviews

[Bodi]

I don't think Honda would have four different parts listed with four different part numbers if they were identical and could be used interchangeably.
Currently there seem to be the #1 and #3 oem ones listed at the usual places but #2 & #4 are NLA.
Maybe the aftermarket ones are your best/only choice?

[Paintedseat]

Many people have used them with success. Does not really matter what you "think"  if they work.

[dusterdude]

Vintagecb750.com,very nice boots

Sent from my R1 HD using Tapatalk

[Paintedseat]

That's why I bought mine. 100 bucks. Only been on about 300 miles so can't really say how they hold up but they do seem good quality.

[750K]

Oem 1&3 are able to be flipped and used as 2&4, but aren’t a perfect fit. I found a couple hard but uncracked sets and did the wintergreen oil soak, that works like a hot damn and is what I would try over the 1&3 flip.

[AwesomeCB]

There are a couple of posts in different forums about renewing the carb boots with "Wintergreen".
It is a stinky, messy process, but supposedly works A1.

I read those and other posts, so I tried this recently with carb boots and it was pretty much a waste of time. I let them soak for 10 days and I could barely tell the difference in pliability. After a few days, they went back to being rock hard. You'd figure I'd learn by now, but I don't know how many of these hacks I've tried that seem to work old only for old wives and mythical garage gurus.

[Paintedseat]

You did something wrong.

[750K]

I

You did something wrong.

Agreed, it really works. I let them simmer in a water and wintergreen oil bath for 30-60 min iirc and they are still soft, this was 3-4 yrs ago.

[PeWe]

I bought K1-K6 boots from Cruzinimage. Not cheap since 2 of them got deep cracks within a few months.
Only Honda to my bike. Aftermarket rubber parts that must withstand oil, heat and fuel seems to be crap too often.

Mikuni VM29 carb boots for CB750 produced in the 80's even worse! Rubber too soft and flapped when engine sucked in the mix. They must have caused loss of flow collapsing the rubber instead of air-fuel mix.

[Erny]

Vintagecb750.com,very nice boots

Sent from my R1 HD using Tapatalk

yes, seems they have these : http://www.vintagecb750.com/products/6/fuel-system/54/carb-holders-air-box-rubber-boots-clamps, item Part #: 48-0757, but they do not say origin (japan?)

I found also these : declared as made in Japan (Keyster) : https://www.mvh-shop.de/Carburetor-Repair-Kit-4-pieces-KH-1156NFR

what do you advice?

[enwri]

I decided to buy new ones, but hesitating, if I should buy genuine ones, knowing they are not easy to find and they are manufactured quite some time ago - rubber can be "hard", no?

If aftermarket, do you have tip where to buy to get high quality and perfect fit?

The carburetor to cylinder Head Insulators need to be a "bit" hard, so as not to collapse and flex too much when there is vacuum inside. I can see mine flexing at idle.
The carburettor to airbox side are much softer.

[AwesomeCB]

You did something wrong.

How do you figure? Is soaking them in a solution of wintergreen oil and 91% isopropyl alcohol for 10 days incorrect? It must been your elevation that makes a difference in success.

[Paintedseat]

What was your source of wintergreen oil?

[Phinn]

You did something wrong.

How do you figure? Is soaking them in a solution of wintergreen oil and 91% isopropyl alcohol for 10 days incorrect? It must been your elevation that makes a difference in success.

I found xylene to be a better solvent for this application than isopropyl alcohol. I mix xylene at a 2:1 ratio with synthetic wintergreen, and pre-warm the boot (with a paint-stripping heat gun) before dropping it in. Leave in 6-8 hours, longer if it's still too stiff.

The xylene causes the boot to swell, but evaporates a few hours after being removed.

[750K]

Wintergreen oil and water in a pot, heat the solution on a Coleman stove or single burner till it’s rolling boil. Then put your carb boots in the solution till they are soft again, don’t do it inside unless you like the smell of wintergreen on everything lol.