Hi all,

I'm going to get my car run up on a rolling road and check with a wide band lamda,Is this a sensible way of setting up fuelling correctly,The car is running at the minute but I think it's running rich,It's running on carbs and I have a very basic knowledge on fuelling regarding main jets,float levels etc.The guy who owns the rollong road has no experience at all with bike engines but says I can use his rollers if I know how to set the car up myself.

Any info here guys would be superb.

Craig

Wich engine is it we are talking about?
Original carbs?
Original air box or?

Guessing here: Original CV carbs and not original airbox.
If so, then the CV carbs will lift throttles in not an very crisp way and slightly moore mod to needle/throttle set up needs to be done.

BUT, rolling road with AFR sensor will be an good baseline tool.

As above, more info needed. However if you are running a foam filter, and free flowing exhaust, you really need to invest in a Dynojet kit, this comes with a new set of adjustable needles, and a selection of main jets.

Al.



Originally posted by craig_007
Hi all,

I'm going to get my car run up on a rolling road and check with a wide band lamda,Is this a sensible way of setting up fuelling correctly,The car is running at the minute but I think it's running rich,It's running on carbs and I have a very basic knowledge on fuelling regarding main jets,float levels etc.The guy who owns the rollong road has no experience at all with bike engines but says I can use his rollers if I know how to set the car up myself.

Any info here guys would be superb.

Craig

Cheers guys,

It's the old ZX10 I have with the orginal CV carbs,I already have a dyno jet kit fitted,It's got the orginal airbox aswell modded to fit with a cone filter on the end of it,Currently I'm running 140 main jets and I've lowered the float level so there is more fuel.

I done a track day with it a few months back but as I said it was set up by myself in the garge !!! When I removed the plugs they looked very black which I am led to believe is a sign on running very rich !!!

As I say,My knowledge of bike engine tuning/setting up is limited but I do know the basics !!! I think !!

quote:

---

Originally posted by craig_007
I've lowered the float level so there is more fuel.

As I say,My knowledge of bike engine tuning/setting up is limited but I do know the basics !!! I think !!

---

By lowering the float heigh I mean,Orginal float height was 17mm from carb base to bottom of float,I have now set this to 14mm thus allowing more fuel to overcome the fuel starvation that I was getting when set at standard.
On the airbox the orginal filter was removed and airbox altered to suit installation on a BEC,Using airbox in standard form is no use as the airbox is designed to get air from the fairings this is not possible on a BEC,So the cone filter is in and fitted where it can get cold air direct !

Dyno jet is fitted as per instruction,Again using the stage 3 settings the standard airbox with standard filter again needs removing,Stage 3 settings are free flow filter and free flow exhaust utilising the 140 mains.

My airbox set up is not to dissimilar to the pipercross remote filter set up !!

Ok, you have raised the float heights but to a level which seems excessive. A 3mm increase is quite a lot and could cause a few problems with flooding. Are you sure that you were suffering with fuel starvation due to the float heights or was it due to something else?

Firstly, I would reduce the float height to 16mm if you're sure that is where your starvation issues stemmed from and fit some new plugs so that you can hopefully get a reasonable reading. Then, do a plug chop to see what's going on with the mains. If it's still rich (and I suspect that it may be as a single large cone filter probably doesn't have the filter area of a Pipercross sausage filter) jet it down a bit. How much depends on how rich it appears from the plug chop. Then, once you're somewhere near with the mains can you start playing with needle heights - if it feels woolly at part throttle, drop the needles. If it starts misfiring, raise them.

I hope that this gives you somewhere to start from!

Thanks for the reply Coose,

Raised the needles,I got you,I described it the wrong way!!

The reason I did infact raise them was due to it missing,I did try a few main jets but as soon as I hit 6K revs it would die of death and start to miss but when raised it went well enough,I will try lowering the float height to 16mm and see how I get on,I'm gonna try and get it on the rollers over the weekend and see how the fuelling is !!

Thanks agin for your help

No worries! I didn't mean to sound harsh with my first response, but it's very easy to get it horribly wrong if you're not sure what you're doing and have terminal meltdown.....

Just make small changes and you should be ok - as you're running rich you're on the safe side!