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Carb question

  • Thread starter Thread starter Nicholaschase29
  • Start date Start date
N

Nicholaschase29

Guest
I got the carbs apart to check what mains, and pilots I have.
I have 132.5 mains, 37.5 pilots, I think it's the air inlet jet (the one on in the back of the carb that sits horizontally) and it looked like 760. It has stock needles and I shimmed them with 3 washers, here are some pictures... The first picture is with the c clip. The second is just the washers under the c clip. Also it is in mm. Oh, and the fuel pickup hole is drilled 2 thousands larger.




IMG_3961.jpg



IMG_3929.jpg



My brother ran it around town a bit today, it's about 40 degress Farinheit here. He said it was pretty boggy, when being agressive. . I pulled the plugs and found that it was running lean. Here is a picture of my exhaust disks, I have 13 in, but one is an end cap, so it is really like having 12 in.

IMG_3933.jpg


IMG_3965.jpg



Let me know if this setup sounds right, If not, let me know what I can improve on.
Thanks,
Nick
 
I got the carbs apart to check what mains, and pilots I have.

and because it was running incorrectly, I was looking for anything obvious.
 
Look for an air leak in your intake boots and/or their O rings. That causes the problem a good bit of the time.
 
How should I check for that? spray carb cleaner around the boots, and see if the engine rpm's change?
 
The taper of the stock needle is going to be hard to overcome by shimming. About all that will do is make the bike come on the main sooner. Either get a jet kit or go with a richer needle or needle jet. You can save alot of time with a jet kit.

The white plugs are common without a jet kit because of the needles. They came jetted lean from the factory. My plugs always looked white without a jet kit.
 
How should I check for that? spray carb cleaner around the boots, and see if the engine rpm's change?
Yes, WD-40 or carb cleaner will work. I doubt you will have leaks where the carbs mount to the manifolds. The weak point on bikes like ours are the o-rings under the manifolds and cracking where the boot meets the mounting flange.
 
Yes, WD-40 or carb cleaner will work. I doubt you will have leaks where the carbs mount to the manifolds. The weak point on bikes like ours are the o-rings under the manifolds and cracking where the boot meets the mounting flange.

I second that. I would replace the O rings either way. They're cheap and if you already have the carbs off, most of the work is done.
 
I must point out that being you are working on an 85 700 you DO NOT have intake o-rings to check or replace. however a good visual inspection of the carb boots will be worthwhile, as rubber obviously perishes, and this may allow extra in, hence adding to your lean condition.

Dink
 
Thats funny because I just replaced the O rings........
the one's between the head and manifolds
 
I must point out that being you are working on an 85 700 you DO NOT have intake o-rings to check or replace. however a good visual inspection of the carb boots will be worthwhile, as rubber obviously perishes, and this may allow extra in, hence adding to your lean condition.

Dink
There are o-rings on the head side of the rubber manifolds.
 
Oops my bad!!:oops: I have as you know a Kat 1100, an 1150, and a Kat 750. I assumed (obviously incorrectly) that the 85 700/750 would be the same as my 85 1150 which does NOT have o-rings; neither do either of the Katana's, they all only have boots between the carbs and the head.
Apologies if I misled anyone.

dink
 
Oops my bad!!:oops: I have as you know a Kat 1100, an 1150, and a Kat 750. I assumed (obviously incorrectly) that the 85 700/750 would be the same as my 85 1150 which does NOT have o-rings; neither do either of the Katana's, they all only have boots between the carbs and the head.
Apologies if I misled anyone.

dink
No apologies needed Dink and I knew why you were confused. The 700's have the bolt on manifolds.
 
I see you are in Wisconsin. Should Be a snowmobile parts house somewhere close by? They always have what ever I'm looking for when it comes to carb parts, and usually 30 cents on the dollar when compared to a motorcycle dealers parts department (and they NEVER have what I need in stock)
 
On my GS550 carbs, which I think are the same design as yours, the needle position relative to the slide is controlled by the plastic washer ON TOP of the clip. You need to REMOVE the thick plastic washer and replace it with THINNER metal washers to raise the needle. This is because the small spring on the needle pushes it up until it contacts the plastic plug inside the slide. Reducing the thickness of the plastic washer allows the needle to push up higher into the slide thus raising it.

Hope this helps.
 
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I had heard that from my uncle, but I thought once about it and figured that It was alright. But now that you brought this up I'm having second thoughts. the spring goes against the bottom of the slid, and the orange washer is ontop of the clip. the orange cone thing sits ontop of the whole works, and pushes against the orange washer, and thus the needle. So, if i remove the washer the spring will push the needle up... I think.. Duh.. well... I'm going to have mess with the carbs a little...
Thanks,
Nick
 
Drawing is not the best but should make a point...

If the thickness of the Orange Washer on top the needle is reduced, the spring will push the needle higher up into the Orange Plug - thus reducing the Needle Height (and increasing the richness). Putting washers under the needle clip does nothing other than increase the preload on the small needle spring.

Needle.jpg
 
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