Offroad-Express

So I have had some Mikuni quad carbs lying around for aaages. Last week finally went to the engineering shop to get the manifold fabbed.

Talking to a mate with 2 sets on his rover V8, and we decided the Vit needs a cam at the same time.

I know Low range has a couple of aftermarket cams, but we have decided to specify our own.

The quad carbs will not have a plenum chamber until they branch from the snorkel. So the motor will be like four motorbikes bolted together.

I've got 4.24 t case gears, and 5.83 ring gears, so she revs at slow speed. Got coby extractors, so breathing out won't be a prob.

Will shave the head to get some more compression. Might do some head work, porting, polishing, open it up a bit.

Kind of thinking that we might set up the carbs and cam for go fast in 4wd high, as the gears are low as.

The jetting I have initial jets of 160 mains, may need to play with the needle for mid range.

I don't care at all about fuel economy.

The truck is not currently WOFed and will probably stay that way.

Thoughts and comments on the configuration of the cam?

Don't neccesarily just want low down torque (have gears for that).

Have a chat to Henry at Auckland Cams.
He's very knowledgeable and an off-roader and to top it off he's a suzuki nut!

Might be a bad combo those two by the sounds of it.

Killer zooks in the hills screaming...

Although on reflection most zooks are giant killers and do best with the valves bouncing!!

Thanks

Looking at running the most lift I can,

Thinking about increasing lobe separation angle, and advancing timing.
Really not sure about what duration right now.

Important to bear in mind the (awesome) th180 / trimatic auto box.

With the torque converter, my understanding is that if it slips because the engine revs are higher than the trans, then the converter acts as a torque multiplier.

Correct me if I am wrong on this. The best part of this project for me is the learning process.

Is anyone aware of adjustable timing gear for G16a?

On carbs, the runner length is important for ensuring the fuel is aspirated, and reading around, there is significant tuning available in terms of torque curve from changing the trumpet length. The trick here will be getting this right as we will be making a manifold to go to the snork.

Jetting, will start by enlarging mains to 160 ish

It is important to have fuel pressure right, I have a fuel pressure reg and gauge already installed for this. KB from Gecko cycles recommends 4psi.

I will post pics as soon as I have something to show. Anyone interested can check out the gecko cycles samurai page.

There is also the Myside Harley carb set up available.

your playing with lots of black magic and science there mate good luck with the experiment

derk wrote:your playing with lots of black magic and science there mate good luck with the experiment

Thanks,
Looking to share everything I learn on this, the carbs can be had for $100-200.

First time doing any head work for me, so will maybe post on this too.

Other than the TBI and MPFI standard set ups, which can easily handle a bit of boost from a supercharger or turbo, I am aware of, myside, side draft Harley manifold, LPG, weber, Holley, and GSXR quads (plus the standard single mikuni carbs from factory). There was one good tech page that I saw where the dude ran GSXR quads with a turbo on.

Looking at the 1300 vs 1600 standard mikuni, there seems to be quite a bit of difference.

If you are reading/following, and I am on a tangent, or flat out wrong, please put me straight!