Plugs sooting up Despite top end re-build HELP PLEASE

[phil1r]

Hi Guys, beginning to loose it with my Z1R !!!
Despite a top end re build re bore and pistons still problems !!!! owned the bike 15 years now. Also fitted with Dyna ignition and Dyna S coils. The bike has always had a plug sooting up problem. To cut a long story short, in the past I had to set the carb needles to the lean point. Top circlip location. After the re build left them at this point. Plug colour not bad and ran well above 3000rpm. Up to 3000 seemed to be low on power ???
So I thought I would alter the needle settings to the standard setting. Seemed fine on the low revs and much improved for the first few miles, this was with the air filter removed. BUT after 50 miles the plugs were as black as black and could feel the performance slowing down.
These carbs must of been off at least 20 times over the years, every time checked float levels, and floats. Also tube gauges used. Most needle valves replaced as well. Standard size jets checked as well.
So any help would be appreciated.
My next step is to remove the carbs again My own thoughts are to Move the needles to the lean point again, then maybe upgrade the primary's to a larger size so power can be improved up to 3000 rpm
You're thoughts on this please, as I don't even know if i'm going down the right track.

[Robw]

I would start with taking to an experienced dyno operator and getting a picture of what is happening throughout the rev range, Then you will have a better understanding and alter accordingly.
Rob

[zed1015]

I presume the choke plunger seals have been done and all the carb 'O' rings replaced with viton equivalents ?
Especially the one on the needle jet tube .

[KeithZ1R]

You may want to get the choke plungers refurbished , its the last link in a long chain, not massively expensive but cheaper than a dyno run and you never know

[Ultim8pc]

As has been said, if not already done, refurbish the choke plungers or purchase some aftermarket replacements.
Also, you need to ensure you have double checked everything else on the bike. I wrote an article which covers this:
https://airevalleyclassics.co.uk/badrunning.html

[Al]

Discounting the things you have already covered, but including all the points raised above, a couple of things in the general landscape that can contribute to 'incomplete combustion' as below;

Overly restrictive exhaust (aftermarket or similar)
Poor quality aftermarket air filters, either blocked, too restrictive or damp.
Too cold running plugs (wrong or inapproppriate heat range)
Engine temp too low (over large oil cooler or revs too low)
Incorrect valve timing
Incorrect ignition timing (advance not working correctly or wrong range)
Fuel octane rating too high or octane additive added (ignition needs altering)
Stale fuel (being probably more than a couple of months old in todays ethanol rich environment)

You could see the above as problems or perhaps in some cases as things to manipulate to bring the situation under control.

AL

[phil1r]

Many thanks Guy's Some useful tips here. Two particular "choke plungers one" and "internal O ring TWO".
I have looked at the plungers and see no sign of wear ! can these be blanked off in any way, so to check the efficiency ?
I would like to rule these out one stage at a time. Internal O ring secondly "interesting" But I can see where you are coming from, so obviously a strip down for this.
I think any other possibility's mentioned have already been covered and checked.

[phil1r]

As has been said, if not already done, refurbish the choke plungers or purchase some aftermarket replacements.
Also, you need to ensure you have double checked everything else on the bike. I wrote an article which covers this:
https://airevalleyclassics.co.uk/badrunning.html

Can I still Buy new plungers, many thanks in advance

[phil1r]

You may want to get the choke plungers refurbished , its the last link in a long chain, not massively expensive but cheaper than a dyno run and you never know

Many thanks seems to be a popular fault

[zed1015]

Can I still Buy new plungers, many thanks in advance

No matter their visual appearance the original 40 year old seals will be leaking to some degree.
I can repair your original plungers and fit ethanol resistant Viton seals which is a one time fix and future proofs them.
Pattern ones such as Keyster items and Japanese Mikuni ones are available but neither are ethanol resistant so are on the path to failure as soon as you fit them.
The same goes for most 'O' rings found in carb kits so make sure Viton ones are used to withstand the ethanol content of our fuels.

[Mally]

Choke plungers for sure ( as has already been said more than once) , get the viton ones from Rob ( zed1015) , got them on my RD250 and made a huge difference, got them for my 900A4 , carbs are currently being rebuilt .

You can get all the viton o rings from here ( I got this link from Rob too ) ,

https://www.ebay.co.uk/itm/125076641943 ... media=COPY

I got new air screws/springs / o rings , alloy choke plunger caps , blank caps for air intake rubbers , float bowl screws and o rings too , I got viton float bowl gaskets from Aire Valley Classics also.

[Ultim8pc]

Pattern ones such as Keyster items and Japanese Mikuni ones are available but neither are ethanol resistant so are on the path to failure as soon as you fit them.

I've used Keyster repros in many bikes and carb rebuilds and sold lots and have never had problems or complaints afterwards.
I have also used your plunger refurbishment services with zero issues.

[r3sc]

It’s Rob for the choke plunger refurb every time! He does a great job!

[Ultim8pc]

It’s Rob for the choke plunger refurb every time! He does a great job!

Agreed.