Bike Carbs on S4

[miked]

Carbs fitted

Return spring mechanism

Vac take off for carb balance

Fitting of Kawasaki ZX9R carbs to 2 Litre Zetec Silvertop Dunnell 185Bhp engine to replace 45 Spanish Webers and Dunnell ECU.

Purchased a set of Keihin CVK type C - year 99 carbs with centre pull throttle and TPS.
From Ebay for £125. Nice condition. Stripped, cleaned and fitted new float valve assembly's. Also changed "O" rings on the fuel input Tee's.
Bought adjustable needles to replace fixed needles for rolling road session. I believe that small washers can be fitted under the head of the standard ones if richness is required. The adjustable set is only £16.00. The float valves and brass part about £40.
Removed coolant circuit pipes (prevents icing on bikes), like the issues with Strombergs also being CD. Apparently no issues when used on car duty.

Bought Danst Engineering alloy manifold bespoke for the engine. Really nice job. About £220.00 This includes fuel resistant hoses and stainless clips.

New gasket £15.

I cut about 8mm off the inlet manifold stubs and about the same off the hoses to move the carbs closer to the head and give more clearance for the Pipercross cold airbox.
Initially the side of the airbox was fouling on the U part of the bonnet receiver.
In the end I cut into the side of the airbox, opened it and kicked it in. See photo of cut and alloy brackets and rivets.
Bought cold airbox kit from Danst with their spun alloy velocity stacks, back plate and alloy spacer to mount stacks on. About £330. Also has intergral filter and large input hose to route into the nose.
These stacks replace the bike plastic ones and move the back plate nearer to the head.

Bike carbs have a circular cable pull with two cables nipples spaces and slots. One to open the butterflies and one to pull shut. Very safe and positive.
I tried one pull cable first but on the first test run the engine was not shutting down quickly enough when changing gears.

Dan who owns Danst is really helpful and easy to talk to. It was his confidence and friendly supply of information that encouraged me to do this. 

The car started straight away and settled into a tickover. This was with throttle plates set on the bench by rack of the eye. Idle screws set at 2.5. Unchanged main jets and idle jets. Start point only. 40 mm carb size with 155 main jets.
I had Danst fit a vac port at the rear of the manifold plus 4 bottom ports for the Carbtune. Since the air box limits some clearance underneath, I have added 4 rubber pipes and made a little brass fitting with 4 input hose tails and 4 blanks. Sits near the cam cover. The blanks are removed and the normal Carbtune hose tails are screwed in to allow easy connection and balance. 
I had a problem with a bug when writing this and lost a lot. Even with copy and paste. Seems you can't write too much at once. So bit at a time.

The bike carbs have butterfly adjustment between 1 and 2 and also 3 and 4. Then middle adjustment between (1 & 2) and (3 & 4). Therefore with the adaptor ports the Carbtune dialed in within seconds.

Nodiz
I changed out an obsolete (unsupported) ECU from Dunnell as nobody could get into program or record any settings, if it failed. An updated unit was very expensive when you consider it is only doing spark advance. Hence the Nodiz at £299.
I had no problems with this apart from voltage drop on the car. Will discuss later.
The Nodiz comes bespoke for the Zetec with coil pack lead and plug, speed pick up lead and plug. The TPS wiring is there but a plug is required for your particular carbs.
Dan gave me a second hand one.
I bought more pins and populated the plug with a few more features.
I picked up the coolant temperature and also gave outputs to run the tacho and the cooling fan.

I normally have a separate earth conductor run out on previous cars, but had not done it on this one as it has always spun over well even with a 2 litre motor. On this one I have good engine straps and also well earthed chassis in the boot. However, the Nodiz would only spark with the plugs out. The loading under compression was the straw that broke the camels back in terms of voltage drop. To crush a walnut with a sledge hammer I ran out two power conductors. A neg direct to the engine and a pos to the front starter terminal. Pre egngaged ! About 35mm conductors as I recall.
I also ran out two 4 mm conductor direct from the battery to the Nodiz with a relay fired by the ignition supply. After this it never failed and the engine spins even faster.
The Nodiz has two flashing LED's that show the coil pack signals. This is helpful as these went out under cranking with the volt drop problems.

Anyway, besides this problem i have not even plugged into the Nodiz yet to program the fan output parameters. It runs on the base map. Saying that, I have been more busy sorting out the choke and throttle cables.
A bike only has limited throttle movement. Also the mech is feather light under the foot. To correct this I have moved the clevis pick up towards the pivot to magnify the pedal travel. This worked fine but upon test driving the return was slugish causing the revs to linger and give poor gear changes. With bikes having two cables, one to pull throttle on and one to pull it off, i decided to add a return cable with an adjustable spring anchor. I made up a mechanism and cable. This works well on the test drives.
So now I need to get the bonnet on and do some runs taking into account that the mixture is not set correctly.
It does however run very nicely and revs through.
Will report back when i have checked the plug colours and ran further.

[The Veg]

Interesting- would love to see some pics!

[miked]

See updates with photos and description. In have added a lot more detai

[greg40green]

Bike carbs on my 1964 Lotus Elan S1.

Mmmmm now there's a thought.

Gives me something to do whilst we are all on lock down.
Beats decorating.

Looks fantastic Mike , hopefully they preform better than twin forties.

[miked]

The Lotus police will be after you mate.
I'll get 2 years. Life for you on an S1

[Briggs1]

nice, what transmission are you using? Stock frame?

[miked]

2000e gearbox with MKF close ratio heavy duty gearset. 3.55 diff with LSD and alloy nose. Billeted diff outputs and hub shafts.

Spyder frame. First one done by our late friend John Pelly.

[miked]

I had to cancel my rolling road session in the days prior to the lockdown. So Nodiz base Zetec map and same jetting and needle position as when the carbs were on the bike. Since my service light is on my normal car and racking up miles, i went out for the shopping in the Elan. Save a quick run around the block it has not even been warmed up properly .
Unbelievable, smooth sharp response and really smooth delivery under light throttle. Due to the position of the idle mixture screws I have not even had a go at them. I think can just about detect it coming off idle mixture and going to needle jet under very light throttle. With cold airbox fitted it is very quiet regards induction. No smells or black smoking. I look fowrard to hopefully getting it to the tuner in Bradford sometime in the future. No worries about driving it there.

[jono]

Looking great Mike, you car was an absolute blast to drive on the Webers so I can't wait to have a go with this set up - you will get me hooked again.

Hope to see you and others here for the intended Duns trip this year if we manage to get out of the wretched 'lockdown' and promise me a blast up through the Borders

[miked]

Look forward to it Jon. You are blessed with those roads. And the village micro pub.

[miked]

I managed to take the car to the rolling road. Very pleased with Danst Engineering. Very helpful and professional. Nice set up.
I gave up some horses to keep my new airbox. With no airbox and longers velocity stack there was a good bit more to be had. It was making 182 with the airbox off and short stacks. I do not like rakes of induction noise.
Look at that torque.
Drove back via Skipton and Clitheroe. It was a blast, very free revving and lively. My friend followed and it was burning very clean. Even on the way there, nothing of significance.
The jets were downsized from the bike settings. Needles stayed same and ignition advanced somewhat from the Nodiz Zetec base map.
I can see a track day coming up in the future.
PS. Big maintence carried our before. New TTR diff mounts and poly torque rod bushes.

[nmauduit]

wow, congratulations ! I'm impressed not only by the daring adaptation (I would have initially thought that bike carbs would be a limitation on a 2l engine aiming at 180+ hp, but apparently they do the job), but also by the apparently very rapid success (while I erred for ages with just slightly modified Webers)... and of course astonishing torque curve !

I understand this kind of engine is not meant to rev higher than 6500? I definitely need to learn more about these modern swaps, would it only to keep alive a car without original engine (though I'm trying to reduce the list of long term projects)...

[miked]

It is a Dunnell tuned 185 engine that was set up for 45 Webers. It was fitted with a cold airbox in the car so who knows what it was developing after coming off the factory dyno at 185. I have an old correspondence from Mr Dunnell that says about a range of up to cut out at 7300. Talking to Dan, today, he said it was pretty pointless going past the 6k mark as everything was happening before. I was somewhat nervous about extreme rpm. I did remove long stacks from the webers so it is good to know that the bike carbs were going to be capable with longer stacks and decent breathing. I did take a bit of a leap of faith and even sold the webers to do this.

[nmauduit]

interesting... my initial thought on max power was a gut feeling of intake restriction of the motorcycle engine on a 2l , I suspect this is why you get a plateau around 6k rpm (there is a correspondance between breathing rate and power, and 185hp is quite something for a bike while a 2l could exceed 200 without extreme effort, considering the rule of thumb of 100hp/l of a tuned engine in the sixties)

[69S4]

185hp is quite something for a bike

The last of the carb ZX9's were putting out around 150bhp. The current 1L ones (with F.I.) are touching 200. That, plus 200kg weight, means crazy crazy on the road, but people buy them.