Z900 with Vance and Hines Exhaust

[Phil50]

hi All

Been a while since posting. Took that long to get the bike up and running after "thecatswhiskersofz900" had been at it.

For anyones information if you get oil in the airbox get an oil pressure gauge and when it stops working you know you have a blocked oilway!!!!!!!

So if you send your engine parts off for cleaning and someone else is putting your bike back together make sure he knows what he is doing.

DUH. Like clean and check all oilways before re-assembly, or actually test rides it before taking the bastard money.

Well its taught me a lesson.

Anyway to the current and last hurdle/problem with this demon bike.

There seems to be very little data or knowledge about the correct jets, settings etc of the carbs with a Vance and hines exhaust.

I rang Vance and Hines direct and they had no clue and were not very interested at all.

The usual sell and forget company.

So I won't recommend their products again

I have 26mm Standard mikunis and had a slight flat spot about 2300 to 2800 rpm.

I removed the standard 115 and put 120 in and the bike could hardly pull 50mph.

So I purchased a Keyster 161n kit which has all the right parts and fitted it all back to standard 115.

Set thumbwheel to 2mm gap and slides to 0.6mm per the book.

Vaccum was 8.7 to 8.9 for all 4 so left that alone

Now the flat spot is even worse. Though if I get to 4200 rpm to 6000 rpm bike goes like an express train.

Plugs look a bit pale so was thinking next trick to try was take circlip to next position for a richer mixture at lower speed.


I have heard that one bloke with the new brand original patent 4 into 4 pipes needed 120 main up a notch and 17.5 to 2.0 idle jet in order to get going.

Worth a try but where does one get these 2.0 jets from if needed.

Suggestions please?

ta
Phil

[zed1015]

Carbs really shouldn't need much alteration at all with just the addition of a pipe.
Go up to 117.5 on the mains and you probably need to richen up the mix going off the pilot circuit to the needle as that is where the fueling gap is.
Try adjusting the pilot mix on the mixture screw half a turn first to see if you get an improvement and try lifting the needle a notch to bring the needle jet in earlier to fill the gap.
Larger pilots jets can be bought from Allens.

[Phil50]

Ta Zed

I have gone down a notch on the needle from 3 to 2. It started OK and felt smoother once it had warmed up. Sadly the rain stopped a test today.

Who or what is "Allens".


Need more info here

[ADRIAN H]

Allens stock and sell carburettors and repair kits and jets etc. Type Allens carburettors in Google and you get their web page.

[warren3200gt]

Allens performancen http://www.allensperformance.co.uk/shop/

[RALPHARAMA]

Rather than just experimenting with suck it and see, your best bet would be to stick it on a dyno. A simple dyno run doesn't cost much and will give you some seriously useful info about your fuelling.

One is making the assumption that you have established with a strobe that the ignition timing is cock on?

[Phil50]

Thanks Ralph

I have been unable to find anyone in the UK who has a dyno and charges less than £200 with no guarantee they can see the problem.

I live in West London and there is no one here.

I went out for a ride today and had to adjust the air screw to 1 and 1/2 it should be 1 and 3/8 so tomorrow I will stick the circlip back on position 3 and go to 117.5 main jet.

30 years ago I never had to do anything other than play with the main jet and I already know 120 is too much for the Vance and Hines.

It ran very well today but felt "new", but then it has only done 750 miles since a total rebuild.

Timing is strobed and spot on thanks

Phil

[RALPHARAMA]

Around this neck of the woods you pay in the region of £30-40 for a Dyno run. You don't want to be getting them to fiddle with it, just tell you what it's doing wrong at what throttle openings. eg up to 1/4 throttle ish you are running mostly on the pilot circuits which can be fine tuned with the pilot screw, between that and 1/2 throttle the mixture is controlled by the needle and over that you're on the mains. Don't confuse a dyno run with getting them to tune your bike! There's a world of difference.

Old farts of our age aren't usually running on mains much of the time, so most of the tuning is done on the needles and pilot screws.

For a starter for ten it's best to slightly enrichen the pilot circuit and maybe raise the needles by one slot and leave the mains as standard or maybe one size up.

You're a braver man than me to ride a bike in London; it scares the shit out of me going to the Ace once a year

[FOZ1A]

Try Steve Jordan Motorcycles in Great Bookham, near Leatherhead M25 J9, knows his stuff and all round good bloke!

foz

[Ginger Bear]

PDQ Motorcycle Developments in Taplow ain't far from you.

I had my first ever experience of being in the dyno room there around 20 years ago.

http://pdq1.com/

[njwmct]

I'm running a Harris 4 into 1 on my Z1000 MKII

I found the following:

1 size up on pilot jet gave me a smooth idle #17.5

Main jet standard #105

At standard needle clip position - bike was flat in the mid range.

Lifting the needle 1 clip position got rid of the flat spot but the revs would hang & not settle down to a nice idle.

The solution was to use some small washers which effectively mean that you are moving the needle position by half a groove. (these washers are available from Allens Performance)

So the needle has been lifted by half a notch from standard, pilot jets up one size & main jet standard.

The bike now runs like a dream - perfect idle, no flat spots & pulls like a train

[Phil50]

Many thanks guys

Taplow mans Dyno booked till September, LEatherhead man not available yet.

ho hum

ta all.
Phil

[ADRIAN H]

Where are you ?
Could phone Debbens Performance- Ringwood. Hampshire. Just a thought.

[Phil50]

thanks ,njwmct

I also have a pair of Z1000 carbs and they are a different carb altogether.

On the Z900 you have a mixture screw. On the Z1000 Carbs you do not.

Underneath the carb on a Z1000 is a "Volume" screw adjuster.

The air mix is done inside the carb on this one.

I have the standard 17.5 pilot, 115 Main and needle in slot 3. Its a pig now.

It seems to like slot 2 better but then it has no guts below 4000 rpm and runs over rich.

I had the Z1000 carbs a few years ago and the bike ran well with a Harris exhaust back then also. It was bit lean and I could never rev it past 7000 rpm.

I could have put bigger main jet but bought Z900 carbs from a crook instead.

Anyway I have found a Dyno man now and he builds Zed's for Santa pod etc so its off to him a week wednesday for 4 hours. About £220 they reckon but the bike will be fixed.

If it is not the bike is for sale via this Forum.

All it needs now is the carbs sorting or another set of carbs.

I am not spending another bloody penny.

The only thing that is not new is the frame, the wheels, the casings, crank and conrods, head and cam cover threads alll stainless steel inserts.



The carbs have been "done" by a leading expert so why do they not fucking work?

I warn you guys do NOT send your carbs to anyone for any work unless they are going to fit them onto a Z900 after the work to test them.

thanks for the info guys
Phil