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Carb/Venturi question

  • Thread starter Thread starter Anonymous
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Anonymous

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I posted earlier ("I admit defeat") about problems I'm having with starting my '82 GS750TZ. It looks like a big part of the problem may be that the backs of the carbs don't fit properly into the boots on the airbox.
Despite some of the suggestions I've been given, I really don't think I'm going to get them fitted any better than they are. So, the carbs are just pushed up tight against the rubber boots on the airbox rather than inserted into them.
What I'm thinking of doing is bridging the 'gap' between the carb throat and the boot on the airbox by inserting a short bit of heave duty rubber hose into the throat of the carb and into the boot. Obviously, this would reduce the diameter of both the carb throat and the airway through the airbox by the thickness of the hose.
Would this have a significant effect on the venturi effect in the carb or might I get away with it?
 
Re: Carb/Venturi question

I think its a strong possibility the bike will barely run at all if "jury rigged" together that way.
I wouldnt even consider doing this. The best thing is to order new boots.

Earl


TEMS said:
Would this have a significant effect on the venturi effect in the carb or might I get away with it?
Click to expand...
 
Re: Carb/Venturi question

TEMS said:
I posted earlier ("I admit defeat") about problems I'm having with starting my '82 GS750TZ. It looks like a big part of the problem may be that the backs of the carbs don't fit properly into the boots on the airbox.
Despite some of the suggestions I've been given, I really don't think I'm going to get them fitted any better than they are. So, the carbs are just pushed up tight against the rubber boots on the airbox rather than inserted into them.
What I'm thinking of doing is bridging the 'gap' between the carb throat and the boot on the airbox by inserting a short bit of heave duty rubber hose into the throat of the carb and into the boot. Obviously, this would reduce the diameter of both the carb throat and the airway through the airbox by the thickness of the hose.
Would this have a significant effect on the venturi effect in the carb or might I get away with it?
Click to expand...

No arguing with that Earl feller, if you do what you suggested it ain't gonna run.

Rather than reading the suggestions given, and then coming up with other ideas of your own, why not try the ones offered? Not just one, but as many as necessary, starting with checking the carbs and getting them set up BEFORE attempting to re-instal them. And don't be afraid to ask questions.

My own suggestion on re-installing was to position the carbs carefully, hold a long piece of 1 x3 or 1x4 tightly across the carb mouths and smack the wood with a hammer.

You don't need to do this hard, but you may need to slap it a couple of times. The carbs WILL go in. Remember, please....they came out of there in the first place.

Since it is winter, (although I don't know where you are) the rubber is probably cold and less flexible, but the silicone spray or liquid will help.

You may want to have someone else help you by holding the carbs so the position is just right...that is important.

The carbs must be fitted in place. There is no other option.

New boots may well be needed, but they will be a very tight fit as well, so you might as well accept that now.

If you already spent a fortnight and got nowhere, remember you had no knowledge or advice during that time, and what you have in front of you now is knowledge based on experience, and at a price you cannot beat.

Take advantage of it.. :D
 
Where I'm coming from

Where I'm coming from

Ron
Thanks again. Don't get me wrong - I'm very grateful for the advice and am working on it. It really p!##*s me off too to be asked for advice and then apparently to be ignored. It's just that I'm up against a sort of deadline. I bought the bike to allow my wife to have the car a couple of days a week. I'm off work for now but, come next week, difficult questions are going to be asked about when the car will be available and mightn't it have been a better idea to buy a second car (no it wouldn't) etc.
Also, I'm in the UK and my model of bike was never imported here. There's about a month's lead time on getting new parts so, whilst I'd love to get the job done properly I'll look for shortcuts too. Finally, I have limited funds - if money was no object I'd be straight out to buy a GSX1400. I went to a bike shop the other day to look at one. I had to be prised off it and left the salesman trying to clean up the drool marks!
Happy new year.
 
One of my 1980 GS850GT's is set up this way except the hose going to the carbs does not go into the carb throats, it slips over the throat just like the original boots. The hose fits tight in the airbox and slips OVER the carbs and are clamped in place. My other 850 which had the original tubes in place did not seal and the bike hesitated, and had a minor backfire and was fouling sparkplugs. I thought the airscrews needed adjusted. I found the bad seal in the tubes and switched airboxes and hoses from one 850 to the other, WOW. Before I replaced the hard original tubes I had hesitation and minor backfire, after I put the airbox with the radiator hoses in place and clamped them on the hesitation and backfire went away and now the bike runs perfectly. If you put the hose into the throat of the carbs as you propose it probably would not run at all as said above, but the way mine is set up you might acheive acceptable results. Let us know what you do and how it works.
 
Arveejay's idea is a good make-up one. You could use radiator hose and cut it to match the length of the original boots.

Please note that many rad hoses come with an inner wire tensioner, to keep it from collapsing , and that is NOT what you want. Both ends of that type would be OK, but once it was cut to size, you would get exposed wire, and then have the problem of air bypass.

Many garages and auto stores have a wide selection of shapes and sizes, so a ready supply should be available, and it will not cost much.

Major point... Whatever you use has to be made of neoprene or similar material that can withstand the fuel/air flow.

Rubber hose must NOT be used, as the fuel will destroy it, and it would make a huge mess of your carbs.
 
Yes I agree with Ron, it has to be able to withstand the gas. When I bought my 850 and seen the hoses installed as described I remember thinking it was a crappy idea, and would have to be replaced. But as I dealt with stiff rubber and the attempt to get a seal on my second 850 I realized this may be a good comprimise. I'm so happy with the way it works I am going to replace the set of boots on my second 850 with the same type of hose. Have not looked for it yet but as Ron mentioned there is all shapes, materials used and availability so I don't think it will be too tough to find. If I wasn't so damn cheap I would replace with originals from bikebandit at about $12.00 each, but as I said I'm pretty cheap, and what the hay, it works great. :lol:
 
I had this problem when I had the original airbox on. To make installation easier, try heating the rubber boots with a hair drier, dunking the airbox in hot water, whatever is easiest. The rubber is more pliable warm. A little silicone grease/spray will also help. The airbox is a bitch to fit..no wonder I put on two oval K&Ns 16 years ago!!!
 
I have had very good luck in first fitting the carbs to the induction rubbers (between the carbs and cylinder head) clamping them down toght and then holding the airbox in alignment with the carb intakes, rotating the rubbers to alignment and then pushing the airbox onto the carb throats. A little silicone spray can sometimes ease thing a bit. :-)

Earl

saaz said:
The airbox is a bitch to fit..no wonder I put on two oval K&Ns 16 years ago!!!
Click to expand...
 
Yeeeeessss!

Yeeeeessss!

You'll all be glad to know that I got my bike working again today.
I bought myselft a 2lb hammer yesterday and used it to try to get the carbs into the airbox boots. Still no luck though. I can get the two end ones in but the two in the middle are the problem. Anyhow, I put the carbs back in yet again. This time I pushed a length of rigid nylon pipe across the back of the airbox. This pushed the bottom of the airbox far enough forward to at least give me the sort of 'fit' between the carbs and the airbox I had before. Don't know if it was the shock of being hit with the hammer, the final spray of carb cleaner or just "one of those things" but the bike started at the second attempt. It now needs the choke again to get started too. I fitted a new fuel line and an inline filter. I took it out for a ride and did 50 miles - a mix of fast straight roads and twisty country roads. Up at 85mph and down to 30, it's like it was before.
I'm sure the carbs still need cleaning but I've bought myself a bit of time so I can plan when to do it rather than trying to beat a deadline. I think the other thing that I'll probably take a look at is the fuel petcock. I think Motorbike Toronto do a petcock kit so I may order one of those.
Very many thanks for everyone's help and suggestions.
Roger
 
It is possible that the pairs of airbox to carb boots have swapped inside to outside and this why they wont reach!
Dink
 
Could be

Could be

Dink said:
It is possible that the pairs of airbox to carb boots have swapped inside to outside and this why they wont reach!
Dink
Click to expand...
Nothing would surprise me. Who knows what four previous owners and twenty odd years might have done to a fine bike. I did wonder if my airbox perhaps comes from a different model. Whatever, there is no way, no how, no siree that I'm going to investigate. Not now anyhow - I'm having too much fun just being back on the bike.
 
Re: Carb/Venturi question

TEMS said:
I posted earlier ("I admit defeat") about problems I'm having with starting my '82 GS750TZ. It looks like a big part of the problem may be that the backs of the carbs don't fit properly into the boots on the airbox.
Despite some of the suggestions I've been given, I really don't think I'm going to get them fitted any better than they are. So, the carbs are just pushed up tight against the rubber boots on the airbox rather than inserted into them.
What I'm thinking of doing is bridging the 'gap' between the carb throat and the boot on the airbox by inserting a short bit of heave duty rubber hose into the throat of the carb and into the boot. Obviously, this would reduce the diameter of both the carb throat and the airway through the airbox by the thickness of the hose.
Would this have a significant effect on the venturi effect in the carb or might I get away with it?
Click to expand...

Hi,

I've the same problem, it was not possible to link "perfectly" the carbs and the boot

the links I found on the boots are not geniune suzuki and not right sized, so at the end, I decide to use a new strong metal link (sorry, I don't know the name), that is right sized to ensure the maximum grip

before the mounting I put the boots in warm tix, just to make them "softer"

it goes now perfectly

you can see here 2 pictures of the carbs after the mounting

http://rackham.camesco.com/files/sml_str_carb1.jpg
http://rackham.camesco.com/files/sml_str_carb2.jpg

hope this help

V++
rackham
 
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