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Carb & Airbox Questions

Started by Kiwi_XZ, October 30, 2005, 03:48:26 AM

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Kiwi_XZ

Hi all.

I'm new to the forum and purchased my XZ550 a few months back and have just got it roadworthy in the last week.  Usual problems (burnt out stator, rusty fuel tank, front brakes, etc...).

The bike is an 83 but appears to have 82 carbs (with stop screw on the accelerator pump linkage).  Unfortunately I didn't realise carbs were 82 until after both 83 Keyster kits arrived from overseas.  My first question are any of the parts in the 83 kits suitable for the 82 carbs?  Is there a description breakdown of items for the 82 kits similar to the one on the XZ550.com site for the 83 Keyster kit?

My next question, the bike at some stage has had a problem with the inlet flap actuator in the airbox and the actuator and flap have been removed and the vacuum line blanked.  I noticed a slight hestitation when first accelerating around the 3000-4500 rpm range when opening the throttle over the last week of riding the bike.  I had another airbox lid from a wrecked bike, it was fitted with a simple flap which lifts under acceleration and appears to be a Yamaha part.  I've fitted this and it seems to have improved things.  Is the actuatored flap arrangement better and should I look around for the parts to rebuild it or stick with what I have?

Also what does the small grey filter on the carb do and does it require servicing.

Thanks for your help.

Cheers - Shane
I'll fix it, pass me a bigger hammer!

h2olawyer

Hi Shane.  Welcome & congratulations on getting your bike to this point.

Very few parts are interchangeable between the 82 & 83 carbs.  In 1982, when the first bikes were sold, they had some major carb problems.  The airbox with the vacuum actuated flapper door was the main fix.  Yamaha offered it through their dealers to help relieve the 4,000 RPM stumble like you describe.  We call it "The Vision Stumble", and is very common but fixable.  The vacuum flapper does help eliminate the problem.

I recommend trying to get the vacuum actuated flapper parts & installing them.  In the meantime, you can try attaching a couple coins to the flapper door - make sure they are secure so they don't drop into the carbs.  This causes the flapper to open slower & later.  Some people have had success with this but I'd say its just a temporary fix.

These carbs are tricky to get properly adjusted, but with the vacuum flapper door, very clean carbs & proper synchronization, they do work very well.

The small grey filter is an air filter & as far as I know, requires no service.  Lucky will have more info on what it does & the differences between the 82 & 83 carb kits.  (He also is responsible for the xz550.com site.)

H2O
If you have an accident on a motorcycle, it's always your fault. Tough call, but it has to be that way. You're in the right, and dead -on a bike. The principle is not to have any accident. If you're involved in an an accident, it's because you did not anticipate. Then, by default, you failed.

Coil Coyle

Kiwi,
? ? ? ? The coins that have worked best to weight the airbox flap are two US Nickel, $00.05, coins.
? ? ? ? ?I just looked up their weight and two will weigh 10 grams. So you want to attach 10 grams of weight to the flap in a way that won't fail or block the seal of the flapper.

? ? ? ? The vacuum has to reach the flap to open it so the venturi/main jet will be in vacuum before the flap opens.

Have fun ;)

coil

Lucky

the proper way to tell 82 from 83 is with the synq rod. on the 83 it's on the right, 82 is on the left.

the round grey filter disk requires no service.

if your air filter is properly in place the nickles cannot fall into the carbs should they jar loose...

best bet for the flapper is to find a replacement.  I have a spare & an airbox that has been modded to fit 83 carbs if needed, i have no idea what shipping to you would be.

also, did you check the Keyster kit? the bowl gaskets are completely differentbetween 82 & 83. if the gasket you have in the kit matches your carb, you have the right kit, if not i'm sure they'll swap them (you'll be paying shipping)

--Lucky
1982/3 XZ550 Touring Vison, Gold on Black

Kiwi_XZ

Hi Guys.

Thanks for all the replies, from Lucky's post the carbs are definitely 82's the sync rod is on the left.  The different bowl gasket was the first thing that alerted me to the fact that the 83 Keyster Kits might be wrong for my carbs.  I'll contact SCI and try to swap them.

Just fitting the spare airbox lid with the flapper door has removed almost all the stumble so initially I'll try and add a 10oz weight and see how that goes.

From what I can see in the parts book all I'm missing is the airbox actuator, rod and door.  The alloy housing and shaft for the flap are still there.  Thanks for the offer of the airbox Lucky, I'll try and source one here in New Zealand first.  There a quite a few XZ400 still about here (my XZ550 is much rarer) so I should be able to get the parts I need.

Now that I've solved the stumble problem I'm not so urgent on having to overhaul the carbs, they probably need it but I can move it down the priority list.

Cheers - Shane
I'll fix it, pass me a bigger hammer!

Coil Coyle

10 gram Kiwi, not ounce. ;)

10 ounces and it will be way to rich!!!! :-\
coil