Rubber intake manifold position?
 

Hi, can someone confirm to me how to position the intake manifold as depending on how you install them the boot will angle either up or down and in or out.
Is it as shown in the attached photo with the thing on the left boot pointing up and the right side mirroring that? Also, what is that thing on the left boot?

Thanks :thumbup1:

You have the left one right , that little nozzle goes up. The right then goes on so it lines up with the left. That nozzle is for vacuum lines getting run to parts on other models, just not used on the XT's.

That "thing" is an intake silencer fitting.

In some markets and on most later bikes here in the U.S. it is connected to a simple, long piece of tubing which is simply capped off and terminates up under the fuel tank.

The tube serves another purpose in that it acts as a vacuum storage "tank", storing a miniscule amount of vacuum between intake cycles. It's generally used with CV-type carbs and assists in minimizing "CV lag" relative to good ol' slide carbs.

Probably more than you wanted to know but I suspect all future replacement boots will be made with the option.

Thanks, i thought that was the correct way alright but wasn't 100% on it. Had always wondered what that nozzle was for too!

To harp on the subject a bit further I see a lot of them capped off in the misguided belief that they serve no purpose.

If you have a CV carb consider re-installing the tube, or even retrofitting one to bike not so equipped. The fitting presents the same potential for vacuum leaks whether capped off or with the silencer tube installed. At least the tube does something positive for ya.

It also offers up to a foot and a half of fairly pristine stored tubing which could be utilized for a future bodge elsewhere on the bike, if needed. That little vacuum cap will fail from the heat long before a section of capped reinforced fuel line will.

I got a set of new intake rubbers a year ago.

Now a few months back I was installing a Raptor 660 carb to my XT, and I noticed that this little tube had a tiny hole in the rubber surrounding it. After a closer inspection I found out that the alloy (in which the bronze tube is fitted) has a little crack and is sucking air.

I ended up cutting off the bronze pipe, drilling a 5mm hole (removing the bronze tube completely) and threading it for a 6mm screw. To seal the crack I applied quite a bit of Loctite to the screw's threads and also some heat resistant silicone to the top of the screw (covered the screw head completely), to make sure it doesn't suck air once cured.

So... Should I throw away my 1-year old rubbers with a makeshift sealed crack, and get a set of new ones? :confused1: this vacuum storage sounds weird... It stores the vacuum, but it also will lag to make vacuum for the carb when you quickly twist the throttle: it will have to "increase" the vacuum in the tube before "increasing" it in the carb, thus delaying the lift of the vacuum slide.
Also, in my Raptor 660 carb there is a vacuum slide in the left carb, but there's no vacuum slide on the original YDIS carb.

We're going pretty far afield from the OP's question, but I'll play.

Naturally you can do whatever you'd like. We can argue theory all day and we're still stuck with replacement boots with a fitting which must be capped in some manner. Vacuum caps have don't have ego issues. They don't care if they're an inch long, or 20 :).

Since this is a forum for TRAVELLERS I'm suggesting a way to make lemonade of the fitting. With a CV carb the tube has a known benefit. With a slide carb it is almost no value, but in either case it does no harm. Replace it with a length of fuel line and it can serve double duty as a source of spare tubing. That will be more useful and durable down the road than a standard vacuum cap.

BTT.

They both angle out (as viewed from the head).

Do not neglect to cap the vacuum tube in the left one somehow. The pair I bought didn't have a cap supplied and the cap on the old one was so perished it fell apart when I took it off.

I found some hose the right size, folded it back on itself and cable tied it up tight. It's a bodge, but it works.

Thread a bolt into the open end, then zip it. No leaks.

You'll have a spare bolt, PLUS spare tubing.

Can you tell that the weather's gone crappy here today?:bored::biggrin:

No you dont have to throw them, you wont feel the difference with or witout this..

It's used for many different things, worldwide. Here in the U.S. it's more often used by Yamaha to plumb intake silencers/vaccum storage tubes. Over here the signal for vacuum fuel shutoffs and the like more often comes from an additional fitting on the side of our carbs.

Here's a parts fiche showing the fitting used for a silencer/vacuum storage (Item 22). In this case a U.S. market TW200. This is what I'm suggesting be done if you want to make lemonade. Nothing more than a couple of feet of tubing with a plug in the end:

Yamaha Motorcycle Parts 2011 TW200 - TW200A1 INTAKE Diagram

At any rate the days of straight, fitting-less replacements are over and that's how I've been using the ports to at least serve some useful function aside from being an obvious failure point. We have to buy the identical items to yours and this keeps a couple of feet of clean, uncontaminated spare fuel/vacuum/vent line out of my luggage and attached to the bike at all times. Saw off as much as you need, then re-install the plug.

But then again I sometimes strap a pair of roller skates to my handlebars as added insurance. Walking is for commoners.

I installed an '01 Raptor 660 carb on my 86 600 XT as well. Have you had any issues with intake boots cracking? My first set only lasted a year due to having to 'stretch' them to fit the larger distance between intakes on the raptor carb. Very difficult for me to get the carb intalled w/ out a leak. I was going to machine an adaptor plate but was curious if I am over looking something. I would have PM'ed but this is my first post:)


Thanks!

You notice the Raptor carb bells are bigger diameter than the originals? Turn the od's down a bit but offset closer together. Then they get closer plus the boots don't have to stretch as big to fit over them. It isn't much but helps.

Hey arek600xt,

no, I don't have any cracking issues whatsoever. The carb bells fit there perfectly well, I just trimmed the intake rubber boots in some places to accommodate carb's shape (some places touch the boot and you can't get it any further in the boot, I hope I'm explaining it clearly enough).

Cheers,
Tadas.

I appreciate the replies. I'm having an older set of intake manifold bolts modified and am just going to run 'hose' between intake flange and carb bells. You all are lucky....my raptor carb does not want to play nice w/ OE intake manifold boots. I'll snap some pics once I get this all sorted out:mchappy: