air bleed pipe on cylinder 1

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trix
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air bleed pipe on cylinder 1

#1 Post by trix » Tue Jan 23, 2018 6:13 pm

There's a small spigot on cylinder head 1 for a pipe that goes to the radiator filler neck. As I understand, this is just for air bleeding from the highest part of the engine? I've fitted an R6 radiator and have nowhere to connect this pipe. WOuld it be ok if this is just blanked off after bleeding the air? Does it need to have coolant flowing through or is there any reason it needs to be connected to the filler neck??

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silverstrom
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Re: air bleed pipe on cylinder 1

#2 Post by silverstrom » Tue Jan 23, 2018 6:21 pm

It has nothing to do with bleeding. That port on the head connects to the port below the radiator cap and in turn that is connected to the coolant expansion/recovery tank. If you plan to have a functioning coolant system you will need a coolant expansion/recovery tank and you will need the coolant port on the head.

See the diagram here https://www.cmsnl.com/yamaha-rd500lc-19 ... ml#results" onclick="window.open(this.href);return false;

Ade SYM
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Re: air bleed pipe on cylinder 1

#3 Post by Ade SYM » Tue Jan 23, 2018 6:58 pm

I have had a similar issue when i used a R6 radiator.

What i did was to use the R6 2co Radiator cap which has 2 exits on it.

One is slightly above the cap itself and will expel any water which is expanded and you can use a hose to go to a bottle or expansion chamber.

The other is below the cap so is a part of the water circuit, this can go directly to the top of the cylinder head to the nozzle you have indicated.

Hope this helps

Thanks

Ade

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Speed Freak
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Re: air bleed pipe on cylinder 1

#4 Post by Speed Freak » Wed Jan 24, 2018 5:10 pm

This is only for air bleeding of the cooling system, no other function.
Therefor it is on the highest point of the engine when the bike is on the side stand.

It need to have a small but constant flow to the highest point of the whole cooling system and should enter the presurized area directly below the pressure cap.

What happens when the System is heating up?
The flow will deliver the air bubbles into the radiator cap neck, due to thermal expansion it will push out the air into the rserve tank until no air is left.
As the reserve tank hose ends below the water level in the tank the cooling system will suck water back in while the system is cooling down.

=> Self bleeding system.

Theoretically you are right, you can bleed the system by hand and close this spigot afterwards.
But in the whole cooling system you have a lot of small pockets and corners where air can be trapped.
If there is no constant flow there is no automatic bleeding. Air bubbles will probably not accumulate at this highest point as the flow takes them with it again as long as they do not get "sucked" into the bleeding hose by the constant flow.

But this should not be a big issue, just bleed the system 3-4 times during heating up and shaking the bike a bit, then no air should be in anymore.
As long as no air can enter from the outside (= empty reserve tank) you should not have any issues.


Edit:
From the pictures I can see that there are 2 spigots ~20mm below the radiator cap.
Which R6 radiator do you use?

Edit2:
The RJ15 doesn`t need this bleeding hose as the engine water outlet is the highest point of the engine.
=> If you want to keep the function you can add a spigot to the cooler or you can add a short piece of aluminum pipe in front of the radiator inlet and add a small spigot to this pipe.
Doesn`t matter if the radiator inlet is below the highest point of the engine, as long as there is a pressure drop from engine to the radiator it will work.
My bikes:
RD500 YPVS 1GE
RD350 YPVS 31K 1985
Honda CBR 1000 RR SC57
Yamaha R1 RN04

trix
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Re: air bleed pipe on cylinder 1

#5 Post by trix » Wed Jan 24, 2018 6:00 pm

Thanks for this guys. Silverstrom; I have an expansion tank connected to the spigot on the filler neck. Problem is; I only have one spigot on the radiator, So i have nowhere to connect the spigot on the cylinder head

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Ade; my radiator is a 2CO R6 but only has 1 spigot on the filler neck; at least I thought it was 2CO!!, when I google images for a 2CO radiator that seems to be correct, i.e. just one spigot. Is yours definitely 2CO?

Speadfreak; if you think its safe enough to bleed it manually several times through the spigot in the cylinder head and then just close it off, I'll just do this rather than trying to put another spigot on the radiator or in a pipe??

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Re: air bleed pipe on cylinder 1

#6 Post by trix » Wed Jan 24, 2018 7:19 pm

Speedfreak; I think I may have a solution. There are threaded bosses on the radiator for mounting the cooling fans. I'm not using the fans so I could drill through the base of the boss and then screw a spigot into the boss and connect this to the spigot on the cylinder head. What do you reckon?

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Ade SYM
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Re: air bleed pipe on cylinder 1

#7 Post by Ade SYM » Thu Jan 25, 2018 1:00 pm

Yes that will work

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Speed Freak
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Re: air bleed pipe on cylinder 1

#8 Post by Speed Freak » Thu Jan 25, 2018 3:51 pm

Should work if the boss is brazed in a way that it will not leak.
As there is no hole in the cooler it`s not necessary to braze it leak tight.

You can check it before you drill a hole in it, just put a spigot in which is not as long as the boss.
Put a hose on it and apply pressure - 3bar absolute pressure should be ok.
Check after 10min if it`s leaking.
My bikes:
RD500 YPVS 1GE
RD350 YPVS 31K 1985
Honda CBR 1000 RR SC57
Yamaha R1 RN04

trix
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Re: air bleed pipe on cylinder 1

#9 Post by trix » Fri Jan 26, 2018 12:50 pm

thanks speadfreak,
the boss goes right through the wall of the cooler, I was trying to show that in the 2nd picture in my last post, when you look down the filler neck you can see the bosses on the inside of the cooler; so they must be leak tight. I've ordered an M6 hose connector with for 6mm ID hose.

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Re: air bleed pipe on cylinder 1

#10 Post by Speed Freak » Fri Jan 26, 2018 3:07 pm

Ok, they are brazed into a hole...
Then it`s the perfect solution.
My bikes:
RD500 YPVS 1GE
RD350 YPVS 31K 1985
Honda CBR 1000 RR SC57
Yamaha R1 RN04

trix
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Re: air bleed pipe on cylinder 1

#11 Post by trix » Mon Jan 29, 2018 7:10 pm

...sorted. This should work ok!

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