The easy way to get carbs back on.

[Spyug53]

One of the biggest problems in bike refurbing or restoration is trying to get cleaned carbs back on the head.

With old bikes like ours the intake manifold rubbers are usually rock hard even in warm summer weather. New ones would have been quite pliable but not 35 year old rubber like we have. They are extremely difficult to work with.

Now you can douse them in oil of wintergreen if you can get them off the head and also find the elixir, or you can heat them up with a hairdryer or paint removal gun. Sometimes these methods will work but this method will work regardless of temperature or hardness of the rubber.

Firstly, attach all the cables to the carbs, then move the carbs in to position.
Liberally coat the throat of the rubber manifold with WD40 or silicone lube.
Run a ratchet strap around the front of the engine just above the tops of the headers and around the middle of the carb rack.
Move the carbs into the throats of the rubbers and start cranking down on the strap.
A few strokes of the ratchet and the carbs will pop in to position.
Tighten down the manifold clamps and you are done.

Now in the following you will notice the airbox is not in position and this was done deliberately as I want to get the bike running first. Once I know things are working I will detach the carbs again and insert the airbox.





This method works on all bike types and is the easiest method I have yet found to reinstall carbs.

Give it a try.

[MEHall]

As you say 30 years old rubber, then i wonder if it would be easier with new intake rubber?

[Spyug53]

Well it certainly would be if they were readily available and inexpensive enough. My buddy when he owned the bike last year tried to get them but Honda Canada seemed unable to supply them. In addition, he was told they are close to$40 a piece here, at least that was the last retail price showing.

Unfortunately, with old bikes like these we have to make do. I had thought of replacing them with automotive rad hose but I couldn't find anything stiff enough. If not sufficiently rigid I think the carbs will walk their way off when the bike is running.

This is all part of the charm of "old bikes' ha,ha

[mojoblues]

For the boots:
I have ordered them from the online store in Croatia, and I believe they are part of bigger network of shops. Anyway, I odered them for my friend so I don't know if they are orig from Honda or aftermarket since I just gave him the box. But I've paid around 75$ for four of them. I'll go and see tomorrow at his place.

[MEHall]

Well it's a good tip though. Myself i think i need new ones for my bike as it happens strange things when i start to coast after driving in a good speed!

[cb650]

I have a new set but keep making the old ones work untill I have to use them. SOHC4 has some threads on refurbishing them. A 2x4 as a "push" bar works also.

[Volker_P]

Nice idea!

Once I know things are working I will detach the carbs again and insert the airbox.

Even if things are easier that way, I would anyway avoid annoying the 35year old carb boots as far as possible.

[my79650]

I have put them in boiling water for a few minutes. Softens them up but you have about 10 minutes to get the carb rack back on before they cool down. works good for me; just wanted to throw that out there.

[cb650]

On sohc4 one of the ideas was boiling in wintergreen oil.

[Spyug53]

I have heard of the winter green treatment but never had any luck in finding any of the stuff. Not very common hereabouts.

In the olden days of "typewriters" ( remember them, ha,ha) there was a product called "Rubber Renew" which was used to soften up the rubber rollers. I had a bottle for years and used it to soften up door rubbers on old cars. it used to work quite well and likely would work on the intakes. I don't know the ingredients but one of them could have been wintergreen or perhaps glycerine.

The bottle is long gone now and I've never again seen the stuff so I have to revitalize them with some heat from my paint stripper gun and a good shot of WD40 or silicone spray.

As I mentioned, I have been looking for some semi rigid rubber tubing to try but for the present I haven't located anything workable. A friend has mentioned some type of high pressure hydraulic hose that has internal Kevlar sleeving that might work but he hasn't turned up with it yet.

I'll let you know if that works out.

In the meanwhile, the carbs are off once more and I will clean up and possibly repaint the engine before reinstallation and tuning.

Cheers.

[pabs11]

Great Idea!

wish I would of thought of this. I struggled a lot with putting them on, I even came close to knocking down my bike because of all the force i was putting on to get these things on.

I searched the internet and found a Youtube video of a guy boiling his boots before putting them on. I was going to try that but thought i would damage the rubber so i came to compromise and ended up steaming them in a bamboo steamer. Like a previous post on here said, you have a 10 minute window to get them back on while they are hot. Also make sure they are dry before putting them on. Once they are nice and hot, they slide right one with little force.

Thanks for the tips, and if anyone has more tips, keep them coming.

[hardpattern]

I have had success using a hairdryer. But one has to aim it at the boots for some time, like, really a long time. I did it last time in my garage in January, when it was about 20 degrees F outside. It took about 20 minutes of heat. But they went on DRY. I think the ratchet strap is a great idea; I'm not saying I'm going to remove the carbs just to find out. But it's a great idea.

[johnny340]

Side note: For me it was WAY easier to mount the boots (boiled for 10 minutes first) to the carbs first then wrestle all four of them on to the cylinders as opposed to mounting the boots to the cylinders first and trying to get all four onto the carbs. This method took it from being impossible to only being 'an absolute prick of a job'! At one point, I wanted to simply throw a lit match into the gas tank... Good luck to all!!!

[RideOrDie]

What about the timing on dual/quad carbs? I have been told not to try to clean the carbs because getting the timing correct is very difficult. I am not mechanically inclined, but I can learn. How do you time the carbs once you put them back on? Or have I been misled.

-Chuck

[CB650CPastor]

What about the timing on dual/quad carbs? I have been told not to try to clean the carbs because getting the timing correct is very difficult. I am not mechanically inclined, but I can learn. How do you time the carbs once you put them back on? Or have I been misled.

-Chuck

Hey Chuck, rather than look to get an answer to a question that is not the subject of this thread, you should probably start another one. You'll probably get more participation that way. I assume when you say 'timing' you're referring to synchronizing the carburetors. You may want to use that terminology.