Topic: Stock air box instal advice needed..

[Toxic]

What is the trick to getting this thing on?

I wrestled with it for more than a hour and no luck.

The connecting rubbers are brand new and as soft as possible.

I can get the bottoms started just fine but it seems when I try to rotate the airbox foreword to slide on the rest of the rubber it won't go.

I've tried with and without the clamps on, so I know they are not binding.

The top portion of each rubber intake is not binding or pinching.

I seems like when I try to rotate the air box foreword there is no room before the back of the box makes contact with the frame tube.

I can't image you guys doing this several times in order to tune your carbs.

I used a slave tank like this to test my float height to make sure it wouldn't leak once installed on the bike.   I had to pop the bowls off 3 times to get it right.
I couldn't image having to pull them off the bike each time.





I've tried to use a tie down strap in order to get more force applied and that didn't work.

I have my main wiring harness passing over the top of the air box as well as the cyl head vent tube and they don't appear to be interfering.

I don't want PODS but I sure can see why people use them.

Any brillant tips cuz I think I've pulled just about every muscle in my back and shoulder.

Any and all advice would be greatly appreciated.

Gary

[Toxic]

So I had a thought

With the airbox secured on it's two mounting screws this is how everything lines up.

What is causing this?

I have the carb to head intake rubbers aligned with the number pointing up.

It looks like these rubbers should be angling the carbs downwards so they will line up with the rubber boots.





Carbs are sitting too tall or too high.

I got to search for a pic of a stock setup.

Frame is a 72 engine is a 76 airbox and carbs are of the correct type.

[mcuozzo]

I'm no expert but I think the rubbers from the engine to the carbs are oriented incorrectly.  Someone will chime in I'm sure, but your carbs are way too high.

And you can't tease us with those pics and not show us the whole bike.  Looks pretty cool from those pics, custom valve cover, frame mod, etc.

Here's a pic of the way the carbs sit on my 74 POS parts bike.

[xenoscr]

Your carbs look like they are at the wrong angle to me. This is how mine line-up with the stock airbox.

XeNoSCR

[Frostyboy]

I can't take credit for the pic, it's from http://forums.sohc4.net/index.php?topic=74014.msg822731#msg822731, but it sure does look different to yours.

[xenoscr]

Are the intake rubbers upside down and in the reverse order maybe? I've never taken mine off but I have notice that they are numbered on the top. 1-4.

XeNoSCR

[Toxic]

Thanks guys.

When I mounted the airbox to the frame like in the last pic it became obvious that the carbs were sitting too high.

I have the rubber intakes mounted with the raised numbers on top.

And the # 1 cyl on the left side as you sit on the bike.

From the phots you guys posted it looks like mine are angled upwords way too much.

I'll pull them off and try rotating them and see if at some  point as I rotate them the inlet for the carb points more downward.

[andy750]

Ah classic mistake...been there done that  ....carb-engine rubber boots shouldnt have the numbers all on top - this is not important...what is important is to angle the boots so all the intakes are vertical - you should be able to look along the row and it should be flat....and remember to use boots 2/3 and 1/4 for the correct cylinders. This is the only way to get a good seal on the carbs and...makes it much easier to get carbs on - should be press and fit...no ratchet straps required (assuming you have new rubber that is).

Kind of hard to see in this pic with the blue tissue there but notice the flat plane as you look along the cabs...



Also I am not sure of the 76 airbox will fit to the K2 frame - maybe someone can confirm this for sure. I tried recently to fit a later model (not sure of year) airbox to my K2 and it was too wide. Anyway it makes it easier to fit the airbox if its just the top half first...get it on the carbs and tightened up and then add the bottom half. Much easier.

good luck
Andy

[Toxic]

from the top




from the side



Are they not lined up correctly?

My carbs end up being 1/2" too high with this set up.

i have them numbered 1 to 4 from the left side.  Number 4 being on the points side.

I see what you are saying about the ends being vertical.

Mine are perhaps in need of some tweaking but the carbs fit on Ok and seal fine.
Why am I at least a 1/2 off as indicated in the above pic.



Honest this has been the most frustrating part of the whole build so far.

I know my k7 airbox won't fit but this one seems to be correct.

Does anyone have a pic showing the clearance between the tops of the carb and the top frame tube?  I think it will show just how high mine are out of whack.

Thanks for the ideas.

[andy750]

In the "from the side pic" you can see that #2 carb rubber is way off...needs to be adjusted...

Sorry dont have the pic you are looking for..

Andy
 

[mycb750k6]

OK so when you put the rubbers on the head, the plane of the face of the rubbers that attach to the carbs should be vertical. Put a 2X4 across the carb end of the rubbers to check. It should fit flat across all four and be vertical. You don't have the rubbers on backwards do you?

BTW, I like your gas can / carb float level check setup

[Toxic]

Thanks Andy

I tweaked it.

A straight edge is now flush against the openings.



Still something fundamentally wrong here.  I'm still way off.

[Johnie]

Keep in mind the air box rubbers have an angle to them too. You can see it in the last picture. Try spinning those air box rubbers a bit. The seam on the air box rubber goes on top. Note the angle of mine below...

[Toxic]

You don't have the rubbers on backwards do you?

This is the end that is going onto the head



This is the end the carbs are fittin on with the double groove in them.



This how my airbox is set up

[mycb750k6]

yes, yes and no.
First your strait edge appears to have them aligned correctly but once the carbs are tightened down, they still point up in the back too much.

The air box rubbers have an orientation. If you look closely, there is about a 15 degree bend that should be on the top on all four. Yours are all over the place.

BTW, what did you do to the finish of that air box. It looks great.

[Toxic]

Keep in mind the air box rubbers have an angle to them too. You can see it in the last picture. Try spinning those air box rubbers a bit. The seam on the air box rubber goes on top. Note the angle of mine below...

Thanks Johnie, you might be onto something. I didn't know this.

Can you elaborat abit on:  "The seam on the air box rubber goes on top"
I'm not sure I understand this.  What seam?

Thanks for all your help.  I didn't expect this to be such a big deal.

Once this is done, I'm into final assembly and posting a build thread.

[mycb750k6]

Can you put the carbs on without the straps and rotate the rubbers until the carbs become vertical and take a picture?

[Toxic]

yes, yes and no.
First your strait edge appears to have them aligned correctly but once the carbs are tightened down, they still point up in the back too much.

The air box rubbers have an orientation. If you look closely, there is about a 15 degree bend that should be on the top on all four. Yours are all over the place.

BTW, what did you do to the finish of that air box. It looks great.

Thanks, in comparing pics of my carbs VS everyone elses, I agree mine seam to be higher at the back but the straight edge shows they are on the same plane.

I'm going to rotate the air box rubbers and refit.  

The airbox was in really bad shape when I got it so I sandblasted it to get an even texture.
Primed it with plastic adhesion promoter and shot it with Duplicor trim paint.
It has a satin finish to it that I like.

[Toxic]

Can you put the carbs on without the straps and rotate the rubbers until the carbs become vertical and take a picture?

I'll give it a try but when I rotate the rubbers with the carbs off this seems to be the only orientation where they all end up on a vertical plane.

I will try that and the air box rubber rotation.

I think I will take apart the airbox and try just fitting the top of it as this will give me more room to adjust.

[Johnie]

Keep in mind the air box rubbers have an angle to them too. You can see it in the last picture. Try spinning those air box rubbers a bit. The seam on the air box rubber goes on top. Note the angle of mine below...

Thanks Johnie, you might be onto something. I didn't know this.

Can you elaborat abit on:  "The seam on the air box rubber goes on top"
I'm not sure I understand this.  What seam?

Thanks for all your help.  I didn't expect this to be such a big deal.

Once this is done, I'm into final assembly and posting a build thread.

On my OEM new air box rubbers there was a seam. I can not recall if there was 1 seam or 2, but a seam goes up. Take a look at the pic I sent earlier...the seam on all my 750's is up. Now take a good look at the picture I sent...you can see the angle on the side of the rubber to orientate yours. Of course, the orientation depends that the motor intake rubbers are properly orientated too. Numbers up...

[mycb750k6]

Yes the seams in the air box rubbers are on the top and the rubbers face down 15 degrees towards the carbs but it won't matter until the carb orientation to the head is corrected. Do you have any pre-build reference pictures of your bike you can look at?

[mycb750k6]

You know the carb rubbers have a number on top and on the bottom and they're different - right?. Don't remember why now but maybe try a different orientation of rubbers.

[Toxic]

No pre-build pics as this is a rescue opperation.

-72 frame
-76 motor
-carbs year unknown

I will go monkey with the angles.

Ya know I've been on this board for a year and a half and never heard of anyone having such a difficult time with this.  A search didn't turn up much either.

Assembly is easier if you are the one that took it apart. lol

thanks guys

[Toxic]

You know the carb rubbers have a number on top and on the bottom and they're different - right?. Don't remember why now but maybe try a different orientation of rubbers.

Got my rubbers on with the numbers on top 1 through 4. With number 4 being on the points side of the engine.

[mycb750k6]

I meant to say the number on the top and bottom of the same rubber is different!!