Tag: Carburettors

A Few Things…

Additional work has been completed since the suspension rebuild, none worthy of a single blog post, but here goes;

Front Springs

After I had replaced the rear springs as (see the previous post), It can only help to replace the front rusty, flaky ones too. I picked some 250lb  springs up from Protech then, it was a simple job; remove the retaining bolts – viciously cut off the old springs with an angle grinder, then slip on the new (shorter) springs and re-installing. The ride height was matched side to side but needs another look as the whole car seems a bit low.

After a couple of drives with the new springs – the car bucked around a little when on bumpy surfaces – so I clicked the dampers down one level all-around. 
MAP Sensor Damper
When completing the Ignition system a couple of years back, a Danst Engineering damper was added to smooth out the pulses created by the intake system and provide a good reading to the MAP sensor. I fitted it below the inlet manifold sort of hanging on the vacuum lines. Then after watching a youtube video from Japan about a Toyota AE86, and seeing a nice setup, I decided to copy it. Basically, the damper was moved to the edge of the cam cover fastened by p-clips and plumbed in with fresh silicone hoses.
Look, I’ve added an arrow to help you spot it!

More Wheels
When I got my current tyres fitted (Nankang NS2R), the man in the workshop noted that one rear wheel had hit something pretty hard and dented the OSR wheel rim (inside and out) – this presents itself as a rumble at higher speeds. 
This gave me an excuse to find more wheels (again) after waiting and watching I found some 13inch Minilite replicas (these cars are supposed to handle better on 13’s) I collected them and got them on – the car feels lighter on its toes and I think they look great!
I’ll probably go back to the 15inch wheels for another year or so to wear the tyres out, then get some new 13inch tyres and switch to these full time.

Carburettor Rebuild…

So,

I decided that it might improve the WOT(Wide Open Throttle) running by giving the ZX9R B carbs a rebuild.

As a bit of a grounding I watched this fellas videos on  You Tube.

Here’s what I found during the rebuild process.

The inlet manifold take-off pipes for the Megajolt MAP (Manifold Absolute Pressure) sensor were a bit loose – one was off completely – I pushed them all on tightly.

The float heights in the carbs were not even – they should all be 14mm, only 1 was – I reset them by bending the little tags on the float.

I increased the jet size to 1.6mm as per many recommendations. To richen the mid throttle range I raised the needles by adding a washer below each needle stop.

a few little back bits were found knocking about near the jets and needle valves – maybe plastic or hard rubber, i cleared these out.

After a clean up and rebuild – refit – I put them on the car and started it, but fuel came out of every orifice (even the venturi).

Stripping them once more drove me to replace the float needles and seats – reading through some forums I heard that the varnish in worn carbs keeps these things sealing, and that after cleaning this off – if they are worn troubles can arise.

I also replaced the float bowl rubber gaskets to ensure good sealing.

They looked glorious;

2nd Try – the carbs went back in quickly and the car started 1st time, alas though they still leaked fuel – from the overflow pipes – I remedied this by dropping the fuel pressure through the Filter King to around 2psi – at 3 psi the fuel must have been pushing the float valves open.

I found at part to  mid throttle the car is feels like it has more torque and the exhaust note is wetter – this I think is due to raising the needles.

It was still unhappy at WOT though – so maybe going for different main jets once more is the key.

I’m looking forward to balancing them and giving the car a good test in some dry weather to get an opinion.