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A4 carbs help
Posted: Sat Mar 29, 2025 3:58 pm
Author: Mally
Rebuilt the carbs on my Z900 A4 , just need to assemble onto the linkage plate.
Any recommendations on how to clean the carb bodies, don't want to go to expense of vapour blasting more so I've now re assembled them.
Been through the ultrasonic cleaner a couple of times and blown through with compressor. will Solvol the float bowls and tops but main bodies are in need of a clean, I did flash them with carb cleaner once they came out the ultrasonic cleaner to stop them getting that white film you always get on alloy parts.
One other thing the black rubber breather link pipe between 1/2 and 3/4 , should they have clips to secure on them ? Cant say I remember them having them.
Listed below parts used and where I got them from for info: New genuine Mikuni jets from Motcarb ,
http://www.motocarb.com/New air mixture screws, springs and viton o rings, float bowl drain screws with viton o rings, new choke plunger viton o rings , choke plunger alloy bobbins and choke plunger caps from Centurion Motorcycle Projects on eBay ,
https://www.ebay.co.uk/sch/i.html?_ssn= ... 61.l161211 New carb linkage grommets and blanks . From Allens performance
https://www.allensperformance.co.uk/Choke plunger refurb with viton seal from Zed1015 ( Rob)
https://www.ebay.co.uk/itm/254873112045Viton float Bowl gasket Aire Valley Classics
https://www.airevalleyclassics.co.uk/ka ... proof.htmlCarb top gaskets from ZPower UK
Re: A4 carbs help
Posted: Sat Mar 29, 2025 5:12 pm
Author: zed1015
Looking good with all the right parts.
I never use any clips on the breather link pipes and apart from maybe polishing the bowls and caps i leave the bodies natural .
Re: A4 carbs help
Posted: Sat Mar 29, 2025 5:32 pm
Author: Mally
Cheers Rob , was thinking maybe some alloy wheel cleaner as they are a bit dirty looking , but yeah agree, don't want them super shiny.
Plungers top job as usual , ta. Work a treat on my RD too. Thanks for pointing me in the direction of the EBay parts from Centurion.
Thanks for confirming the link pipe info, was sure they didn't have clips but memory isn't as good as it used to be.

Re: A4 carbs help
Posted: Sat Mar 29, 2025 5:54 pm
Author: zed1015
I do use these cheap long bristle soft brass wire brushes on the bodies to get in all the nooks and crannies which gives them a light natural sheen without scratching the surface.
https://www.ebay.co.uk/itm/126808760232 ... FJEfos0tSGThis is the recent result on the Racecrafters carbs.
Re: A4 carbs help
Posted: Sat Mar 29, 2025 6:03 pm
Author: warren3200gt
Or you go the other extreme

Re: A4 carbs help
Posted: Sat Mar 29, 2025 9:32 pm
Author: gray
I know this sounds a bit daft ... but brass bristle brush and tomato ketchup - it's apparently mildly acidic but washes off easily
Re: A4 carbs help
Posted: Sun Mar 30, 2025 7:40 am
Author: DeadZedDave
Looks like a thorough rebuild. Can I please just check / confirm pic.4 shows a packet marked 4 x 120....
Are you running 120 Main jets ? and 17.5 pilots ?
With an air box or with individual pod filters ?
This would be useful information to confirm thanks !
Re: A4 carbs help
Posted: Sun Mar 30, 2025 8:55 am
Author: zed1015
DeadZedDave wrote:Looks like a thorough rebuild. Can I please just check / confirm pic.4 shows a packet marked 4 x 120....
Are you running 120 Main jets ? and 17.5 pilots ?
With an air box or with individual pod filters ?
This would be useful information to confirm thanks !
120's would be miles to big in either configuration.
Especially with VM26's.
Re: A4 carbs help
Posted: Sun Mar 30, 2025 10:24 am
Author: Mally
zed1015 wrote:I do use these cheap long bristle soft brass wire brushes on the bodies to get in all the nooks and crannies which gives them a light natural sheen without scratching the surface.
https://www.ebay.co.uk/itm/126808760232 ... FJEfos0tSGThis is the recent result on the Racecrafters carbs.
DSC00426.JPG
Thats what I'am after !! got a few of those that fit into the Dremel flexi chuck.
Ordered some of this too , will post up the results.
https://www.frost.co.uk/new-h-102-alumi ... qmEALw_wcB
Re: A4 carbs help
Posted: Sun Mar 30, 2025 10:25 am
Author: Mally
warren3200gt wrote:Or you go the other extreme

20180808_171620.jpg
Been there a few years back when I got them vapour blasted , not as shiny as those though

Re: A4 carbs help
Posted: Sun Mar 30, 2025 10:26 am
Author: Mally
gray wrote:I know this sounds a bit daft ... but brass bristle brush and tomato ketchup - it's apparently mildly acidic but washes off easily
Yeah , brown sauce and old pennies , remember how that cleaned them up , ta.
Re: A4 carbs help
Posted: Sun Mar 30, 2025 10:45 am
Author: Mally
DeadZedDave wrote:Looks like a thorough rebuild. Can I please just check / confirm pic.4 shows a packet marked 4 x 120....
Are you running 120 Main jets ? and 17.5 pilots ?
With an air box or with individual pod filters ?
This would be useful information to confirm thanks !
No problem , yeah 120 mains, 17.5 pilots and needle up one notch on those VM26SS .
Harris 4/1 , K & N filter in standard airbox but without the tube baffle ( mono shocked rear end so no space to fit.) 1015 Hepolites fitted. Full Dyna ignition /coils, Taylor leads.
Been running it like that for years ,no issues. But as yet to see how it goes now everything is as good as it can be again. Bought the 117.5's as now the carbs been rebuilt as a contingency. Standard is 115 main with 17.5 pilots , with needle on 3.
Re: A4 carbs help
Posted: Sun Mar 30, 2025 11:12 am
Author: Mally
So carbs now done...... now this has happened !
Tank liner de laminating .... will start a new thread for this.
Re: A4 carbs help
Posted: Sun Mar 30, 2025 11:38 am
Author: DeadZedDave
Thanks for confirming those jet sizes Mally - good info for other members looking for jetting advice.
Before Air Corrector Kits turned up 120 Mains and 17.5 pilots was the way most of us went with a 4 into 1 and K&N's (or bellmouths).
Its a good starting point especially with VM26's.
Some disagree !
My own recollection is that it works well - thanks for confirming your own experience.
Re: A4 carbs help
Posted: Sun Mar 30, 2025 4:35 pm
Author: Mally
No problem , its cheap nylon jets I had ( been in for years !!!)
Now with genuine Mikuni parts it might make a difference but deffo 120's .