Carb Rebuild. New air hose size and replacement?

[Widowmaker]

I was just doing some routine stuff like cleaning my air filter when I noticed that the carb drain hoses were disconnected.

Makes so much sense now.

I haven't tackled a carb project this big before, but I would like to do a full rebuild. I went ahead and ordered a jet kit for the mains and pilots, and I will order all new rubber.

The previous owner had already bypassed the auto vaccum cut off system, I'm thinking about just forgoing the PAIR valve system altogether as well.

With all that being said I want new fuel and breather tubes all around. I'll just cut them all myself. Does anybody know the sizes? I ant find anything on any OEM parts site about the breather/air tube sizes. 5/16"? 3/8"?

Also I got everything disconnected save for one carb boot band, the screw was stripped, going to try and force it out tomorrow but I do not have a pry bar.

 

[Oldbikefixr]

Not much help here, but I just rebuilt my carbs. Before disassembly, I removed one of each size hose, marked it's position with sharpies and went off to various bike shops and auto parts houses. No shop had all the sizes. There are four diameters and...I didn't keep record of the sizes. Some are molded shapes and will be difficult to bend yourself without causing a crimp. Most of these are no longer available from the on line part services.

 

[ST1100Y]

Found a supplier for Nitrile hoses (various diameter) in UK:

Nitrile Rubber Smooth Fuel Tube Petrol Diesel Oil Line Hose Pipe Tubing NBR 1MTR | eBay

Nitrile Rubber Smooth Fuel Tube Petrol Diesel Oil Line Hose Pipe Tubing NBR 1MTR | Business, Office & Industrial, Hydraulics, Pneumatics, Pumps & Plumbing, Other Hydraulics & Pneumatics | eBay!

www.ebay.at

They appear of decent quality (just upgraded my Carbtune with smaller hoses better suited for the ST carb setup), but can't tell if they withstand engine heat over long periods...

 

[Widowmaker]

Found a supplier for Nitrile hoses (various diameter) in UK:

Nitrile Rubber Smooth Fuel Tube Petrol Diesel Oil Line Hose Pipe Tubing NBR 1MTR | eBay

Nitrile Rubber Smooth Fuel Tube Petrol Diesel Oil Line Hose Pipe Tubing NBR 1MTR | Business, Office & Industrial, Hydraulics, Pneumatics, Pumps & Plumbing, Other Hydraulics & Pneumatics | eBay!

www.ebay.at

They appear of decent quality (just upgraded my Carbtune with smaller hoses better suited for the ST carb setup), but can't tell if they withstand engine heat over long periods...

Did you replace all of the hoses on the carbs?

 

[ST1100Y]

Did you replace all of the hoses on the carbs?

Nope, only the drain and vac lines...

 

[Widowmaker]

5/16", 3/16" 1/4", 3/8" and 1/2" ID. For the carb hoses, including breather tubes and stuff. Can't find any vendor that makes heat resistant red colored lines . Might as well just go to O'Reilly's and get around 3 feet of each.

 

[beemerphile]

Hoses are most likely metric. 6mm, 7mm, etc. If you are buying new jets, you might consider the Canadian jetting vs the US spec. The Halls of Wisdom claim that it runs better. I installed the Canada spec jetting in mine when I rebuilt it, but I haven't gotten around to reassembling the bike yet, so I don't know if it is steak or dog food.

Pair valves stripped...

Carbs rebuilt, re-jetted, and waiting to go...

Rebuild project languishing in queue behind a Volvo 240, a BMW K1200RS, and a Yamaha TMax...

 

[fnmag]

Hoses are most likely metric. 6mm, 7mm, etc. If you are buying new jets, you might consider the Canadian jetting vs the US spec. The Halls of Wisdom claim that it runs better. I installed the Canada spec jetting in mine when I rebuilt it, but I haven't gotten around to reassembling the bike yet, so I don't know if it is steak or dog food.

Pair valves stripped...

Carbs rebuilt, re-jetted, and waiting to go...

Rebuild project languishing in queue behind a Volvo 240, a BMW K1200RS, and a Yamaha TMax...

What's that rear tire on the ST?

 

[beemerphile]

What's that rear tire on the ST?

It is an Avon Azaro AV45-ST. Plenty of tread but many years out-of-date as the bike had been sitting since 2013 before I rescued it.

 

[Stylo Steve]

Since you've got the bike pretty much torn down I would highly recommend replacing the steering head bearings and replacing the fork seals. This is if you already haven't done so.

 

[beemerphile]

Since you've got the bike pretty much torn down I would highly recommend replacing the steering head bearings and replacing the fork seals. This is if you already haven't done so.

Yes, every seal and sealed bearing will be renewed. All the parts are in about 10 boxes waiting their turn in the queue.

 

[Widowmaker]

Since you've got the bike pretty much torn down I would highly recommend replacing the steering head bearings and replacing the fork seals. This is if you already haven't done so.

Yes, every seal and bearing will be renewed. All the parts are in about 10 boxes waiting their turn in the queue.

I switched to CBR tapered steering and ball bearings definitely worth it. Carbs are out, I ordered a set of taygon lines, with every size I will need except for the sub cleaner hoses.

 

[beemerphile]

@Widowmaker, are you going to renew the air cut diaphrams?

 

[Widowmaker]

@Widowmaker, are you going to renew the air cut diaphrams?

I'm unable to get the plenum off the carbs. I used a #3 screwdriver and managed to loosen three screws, but the rest got stripped on the first try. I have 3 weeks before my parts arrive to figure something out.

Being unable to use a drill because of the clearance issues with the angle and the velocity stacks, I've tried everything to remove them. I've kinda just given up

 

[beemerphile]

I'm unable to get the plenum off the carbs. I used a #3 screwdriver and managed to loosen three screws, but the rest got stripped on the first try.

Do you have the proper JIS Screwdrivers ?

 

[Widowmaker]

Do you have the proper JIS Screwdrivers ?

Nope

 

[aSTerix]

I'm unable to get the plenum off the carbs. I used a #3 screwdriver and managed to loosen three screws, but the rest got stripped on the first try. I have 3 weeks before my parts arrive to figure something out.

Being unable to use a drill because of the clearance issues with the angle and the velocity stacks, I've tried everything to remove them. I've kinda just given up

These are the best things since sliced bread !

Vessel Impacta JIS screwdrivers. You hit them and they rotate with the impact just like an impact driver but it actually a screwdriver. Being JIS , assuming you pick the correct size screwdriver, the tip stays firmly inside the screwhead when you whack it.

This is how I removed my extremely stubborn Air Cut Valve covers and the intake plenum bolts

 

[Widowmaker]

These are the best things since sliced bread !

Vessel Impacta JIS screwdrivers. You hit them and they rotate with the impact just like an impact driver but it actually a screwdriver. Being JIS , assuming you pick the correct size screwdriver, the tip stays firmly inside the screwhead when you whack it.

This is how I removed my extremely stubborn Air Cut Valve covers and the intake plenum bolts

I wish I used this instead of a #3. Now what if I stripped the screw heads beyond recognition?

 

[Widowmaker]

I wish I used this instead of a #3. Now what if I stripped the screw heads beyond recognition?

I should also add that I've tried the ez outs, but my drill doesnt have enough clearance due to the velocity stacks, since they are angled I also stripped one the the screws that holds the bracket for the stacks in place, since it its next to the supporting bracket a drill doesnt fit. The only I can think of is using a super long bit. But the tooling required for this build is breaking my bank

 

[Stylo Steve]

I wish I used this instead of a #3. Now what if I stripped the screw heads beyond recognition?

The Snap-on carb screwdriver set is a godsend for these types of screws. Make sure they have at least 12" of shaft length to ensuring adequate pressure on the screw head. I learned this from a WW2 Army Air Core aircraft mechanic. If it's helpful.