[Talisian]

I originally posted this in the general forum but it's getting buried under all the other posts. Here is the post:

Hiya

I'm in the last stages of my odyssey to install 36 mm Mikuni CV's on my 86 750 Gixxer. I'm not a moron when it comes to mechanics but I have some gaps in my knowledge base so here is where my questions come in.

1.) I used new flanges from the 88 Gixxer to mount the carbs. The mounting flanges between the engine and the carbs are slightly off center leaving a 2 mm lip of metal showing on one side of the intake. The O-ring on the flange makes good contact all the way around though. My concern is will this cause some sort of turbulance to the incoming mixture to the combustion chamber?

2.) Now that my stock air box is gone and I have individual filters, the hose that came from the crank case breather and went to the air box has no where to go- is it safe to leave the hose unattached or should I connect some sort of inline filter to it?

3.) Lastly, and most importantly I cannot find where to attach the vacuum hose that comes from the gas tank and then went to my old 29 mm carbs. My fuel lines were different too- I ended up running new fuel line from each of the fuel line fittings into a Y connector, then running that hose into a inline fuel filter before it attaches to the tank. But my main problem is where do I attach the vacuum hose?

Once this is all done and the bike runs I'll be syncronizing the carbs with my new carbtune II tool. I already have a stage three dynojet kit installed but I'll be heading to the nearest dyno for more precise main jet adjustments soon.

Thanks in advance for your help and may I say even though I am new to this forum I have found everyone to be extremely friendly and helpful. Be safe and good riding.

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Youth and talent are no match for age and treachery!

 

[somejeffguy]

(in case you didn't catch my response in general discussion)

unfortunately, there's not much you can do about that lip - the 86 cylinder head was meant for the 29 and 31mm carbs, not 36's. it will affect the mixture flow somewhat, but probably not very noticeably. ideally, if you can get your hands on an 87 cylinder head and bolt it on, you'll find the larger intake ports will match nearly perfectly with the 36mm slingshots.
k&n sells a crankcase breather filter that goes right on the end of the crankcase breather hose, but it's not strictly necessary. in fact, what i used to do on my oil cooled gixxers was to run a longer crankcase breather hose, wrap a bit of air filter material or foam around the exposed end of it, and run the entire end of the hose down into a small plastic evian water bottle that was ziptied to the inside of one of the frame rails. these bikes like to pump oil out of the crankcase breather when running hot, so rigging up a catch bottle will make things less messy.

the 36mm carbs should have a vacuum fitting somewhere for the petcock vacuum line. if you can't find it, you can always hook up the vacuum line to one of the carb sync fittings (there's one on each carb top), and that should work, although i think the vacuum hose from the tank is of a larger diameter. you could always use a clamp to tighten it down, though.

alternatively, you can replace the stock petcock with one that isn't vacuum operated.



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[Talisian]

Thanks a lot Jeff, I appreciate the help. As long as that lip of metal doesn't affect performance too much I'll leave it until I overhaul the engine in the next year or two, then I'll have the intakes ported and polished. Now to find that illusive vacuum port!

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Youth and talent are no match for age and treachery!

 

[somejeffguy]

i'm trying to remember where that vacuum fitting was on those 36 slings - i think there's one sticking out the side of the number 4 carb.

btw, when you get the head ported, don't polish the intake ports. you'll lose power - the fuel will pool up on the polished surfaces and will be harder to combust. especially critical on these older bikes because of the sidedraft port configuration - the fuel will pool up where the port takes its turn downwards. a little bit of roughness is beneficial to fuel atomization and thus combustion efficiency.


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[This message has been edited by jeff (edited 03-14-2001).]

 

[MDill]

My CA-model 92 has 36mm carbs. There is a vacuum takeoff from the intake rubber on the right hand cyl which I assume is for the petcock. My bike for whatever reason has the petcock vacuum line running from the takeoff on the CV-slide cover on the top of the carb(the other ones have caps). Not sure if this is ideal but it's how the bike was when I got it and it seems to work well.

Matt

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