Evening All,

I have been plumbing up the blade engine this weekend and I believed I had everything covered. Tonight though I noticed a pipe hanging down the induction side of the engine, about 5mm diameter only and comes actually from the block rather than the carbs. It exits the block just below and between number 3 and 4, clutch side. It is about 8 to 9 inches long.

Any ideas what it is?

Thanks,
Steve

Are you sure it doesnt exit the head rather than the block, and links into one of the inlet tracts of the head? If so, its a vacuum hose that attached to an automatic fuel tap, with vacuum it allows fuel to flow, but when the engine shut off it would automatically turn off the fuel feed to the carbs.

If it is this hose, just block it up otherwise that cylinder wil run weak and you'll probably get a lumpy idle

chris

[Edited on 5/2/06 by ChrisGamlin]

Sounds like a breather pipe. (I'm sure there's a more technical name, but I don't have my haynes to hand).
This can be used to allow a little more air into the mixture. Commonly used with aquarium valves, for fine adjustment, to pass the sva emmisions. Leaving it open or partially open encourages the engine to run leaner I believe.
Until then you can just block it off.
Each cylinder has a place for fitting one (if you look closely - they're hard to get at) but normally they are blocked off with a little brass screw.
Mind you all this is from my notoriously poor memory!
Maybe post a picture, I may be talking baloney!

All the best

Ali

quote:

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Originally posted by ChrisGamlin
Are you sure it doesnt exit the head rather than the block, and links into one of the inlet tracts of the head? If so, its a vacuum hose that attached to an automatic fuel tap, with vacuum it allows fuel to flow, but when the engine shut off it would automatically turn off the fuel feed to the carbs.

If it is this hose, just block it up otherwise that cylinder wil run weak and you'll probably get a lumpy idle

chris

[Edited on 5/2/06 by ChrisGamlin]

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Is this it?
Tantilisingly I mention not knowing where it goes to, but don't mention what the solution was!!

Thats the little sod! So where do I poke it, or do I just bung it up?

Thanks,
Steve

Block it off for the time being.
If I'm right - I have no way of checking since the car is 50 miles away and I won't get near it for a week
- you can use it for adjustment if you're doing any emmisions testing.
Have a look for a post by snoopy on his use of fish tank / aquarium valves.
Till then she'll run fine with it blocked off. I think.
Chris any thoughts? Am I talking rubbish here??

Yep thats the one, Im pretty sure Honda intend it for the vacuum fuel shut-off valve (because later carbed engines are gravity fed so no pump in the middle to forcefully stop the fuel flowing), but I guess you could use it as an air bleed to help with emissions too as Snoopy seems to have done at MK before.

Just block it up for now though, its only a small hole into the inlet tract which isnt there on the other three cylinders and would have effectively been blocked off on the bike itself

Chris

If you go to PartsFish, register and select 97 fireblade then select Fuel Tank, you'll see an item they call a "petcock", dunno where the hell that name comes from but this is the vacuum valve which shuts off the fuel.

Chris

[Edited on 6/2/06 by ChrisGamlin]