needle shim

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tastethefloor
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needle shim

Post by tastethefloor »

hello
does anyone know if this shim is present or necessary?
I don't have it and I got rich mixture...

[img]https://ibb.co/1z6j43q
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freeridenick
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Re: needle shim

Post by freeridenick »

The rear cylinder carb has a shim under the needle in the stock setup but not the front. It makes the needle slightly richer though so if you don't have it I'd suggest you look at the size of the main jets first.

I think that diagram is confusing as it looks like the shim sits on top of the head of the needle but that isn't right and wouldn't make any difference to the mixture anyway.

Have a read through the carb setup guide in the welcome in section.
viewtopic.php?f=31&t=14214
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tastethefloor
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Re: needle shim

Post by tastethefloor »

thank for the reply,
maybe I misunderstood your post.
does it make any mixture difference to have or not this shim?
is the stock sequence spring-shim-needle the correct one?
because my carbs jet are 178 175 (45 middle jet) and still have rich mixture on the front cyl (fouled plug)
pilot screw are 1-1/4 out both
best regards
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Pete.L
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Re: needle shim

Post by Pete.L »

Putting a shim under the needle will richen up the midrange. But if your bike was okay before and now is running rich the first thing I would look at is the choke cables. They have a tendency to stick occasionally and not seat correctly at the carb end.

Pete.l
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tony.mon
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Re: needle shim

Post by tony.mon »

The shim won't make enough if a difference to foul the plug.
There's something else going on.
It's not falling off, it's an upgrade opportunity.
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tastethefloor
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Re: needle shim

Post by tastethefloor »

thank you,
could be the float level too high? anyone have an experience with this?
lele
tony.mon
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Re: needle shim

Post by tony.mon »

Floats are not adjustable, and almost never fail.
Check your fuel tap diaphragm first.
It's not falling off, it's an upgrade opportunity.
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freeridenick
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Re: needle shim

Post by freeridenick »

The engine is standard and the needles too, right? What fouling do the plugs have? Are you sure it's excess fuel and not oil? If the engine is high mileage then worn valve seals would allow oil in and cause fouling. Worn rings too.
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8541Hawk
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Re: needle shim

Post by 8541Hawk »

tony.mon wrote: Wed Jan 06, 2021 6:17 pm Floats are not adjustable, and almost never fail.
Check your fuel tap diaphragm first.
Only seen one set of bad floats in 23yrs, so yeah they are pretty reliable :thumbup:

What altitude are you at?
Loud pipes don't save lives, knowing how to ride your bike will save your life.
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8541Hawk
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Re: needle shim

Post by 8541Hawk »

As for the shim in the first post, that goes in between the spring in the needle holder and the top of the needle.
Nice to have but not critical (though I would not run adjustable needles without it in place) and will not change the mixture :thumbup:
Loud pipes don't save lives, knowing how to ride your bike will save your life.
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tastethefloor
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Re: needle shim

Post by tastethefloor »

freeridenick wrote: Wed Jan 06, 2021 6:52 pm The engine is standard and the needles too, right? What fouling do the plugs have? Are you sure it's excess fuel and not oil? If the engine is high mileage then worn valve seals would allow oil in and cause fouling. Worn rings too.
engine is ok, I think it's fuel...i can clean the carbon deposit on the spark with my finger and it's not "oily"
Last edited by tastethefloor on Thu Jan 07, 2021 7:50 am, edited 3 times in total.
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tastethefloor
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Re: needle shim

Post by tastethefloor »

8541Hawk wrote: Wed Jan 06, 2021 6:52 pm
tony.mon wrote: Wed Jan 06, 2021 6:17 pm Floats are not adjustable, and almost never fail.
Check your fuel tap diaphragm first.
Only seen one set of bad floats in 23yrs, so yeah they are pretty reliable :thumbup:

What altitude are you at?
Italian pianura padana 15mt :lol: :lol: :lol:
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tastethefloor
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Re: needle shim

Post by tastethefloor »

my problem is strange because only the front cyl mixture is rich
is the standard pilot screw setting 1-1/4 out correct? maybe I have to lean it only on the front carb
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tastethefloor
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Re: needle shim

Post by tastethefloor »

tony.mon wrote: Wed Jan 06, 2021 6:17 pm Floats are not adjustable, and almost never fail.
Check your fuel tap diaphragm first.
sorry why the fuel diaphrag ? can be related with a rich mixture?
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Pete.L
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Re: needle shim

Post by Pete.L »

tastethefloor wrote: Thu Jan 07, 2021 7:15 am my problem is strange because only the front cyl mixture is rich
is the standard pilot screw setting 1-1/4 out correct? maybe I have to lean it only on the front carb
If it's not the front choke try blasting the pilot air hole through with some cleaner. You might have got a bit of muck caught in one

Pete.l
My new ride is a bit of a Howler and I love to make her Squeal
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