Hi all,

I have been struggling like crazy to get ZX6R bike carbs set up on my pinto. They start and idle fine but are running lean and don't really pick up revs on hard acceleration. 

I've trued upping the jets to 1.8, but it spat fuel back out of the carb, went down to 1.7 which is better, but still v lean and not accelerating. 

I've read that blocking air correctors is worth trying in order to richen, but I have no idea where the air corrector is.

I've taken the air filter off and taken a pic of the jets I can see. Is this the main jet on the left and air corrector on the right? Or do I need to take the bottom of the carb off to access main jet and air corrector? 

I've tried searching the forum, lot's of talk about what to do, but I'm not 100% on what's what.

Please help!

If ZX6R carbs are anything like the ZX9R carbs in their basic layout, then the hole in the left in your picture is the air corrector for the pilot jet and the hole on the right is the air corrector for the main jet. The pilot and main jets are located in the fuel chamber on the underside of the carb.

Also dont dismiss going lower with jet size. In one set up I had 1.8. Then next was 1.4. The 1.4 was even better.

But to truly know this you need a rolling rd that can do cars / bike carb set ups. Its the only way to get the best results and worth every penny.

 

Andi

Really banging my head against the wall here. Nobody that I have contacted locally isn't interested. As soon as I mention kit car and carburettors, they say they can't help me. 

Does anyone have a contact that could help me? I have a 2.0 pinto, with megajolt ECU and ZX6R carbs, based in Maidenhead SL6. 

I've tried changing jet sizes, ignition maps, but getting the same result. As above, they idle fine and rev up nicely in the garage, but under load when driving, it doesn't rev past about 2k rpm, sounds almost like it's misfiring. 

could it be misfiring?

When under load the spark voltage goes up which can lead to breakdown in the coil or leads instead of at the end of the spark plug. You could try changing the coil pack.

I'll try anything at this stage. Another £65 though 😒

Edited August 13, 20241 yr by LewisH

Check for spilt diaphragms in the carbs and air leaks between the carbs and manifold.

Richy has a good point.

I would add an old trick checking for spark breakdown is to close up the gap in the spark plugs to about half which reduces to voltage but limits power at the highest end.

Obviously a tempory diagnostic mod.

Spray around carbs and rubbers with easy start. If it is letting in air the engine tone will change

So bit if an update, I've done a compression test and I'm getting just over 100psi in each cylinder. From what I've read, I should be getting close to 200 with a stage 3 head etc. 

The question is now, how do I find out what is giving me such low compression? I'm assuming this is the cause of low power and misfire etc. Any help much appreciated. 

It’s unusual to have equal low compression on all cylinders. Is your compression test reading accurate 

Are all cylinders the same?

Just thinking back 40 years pintos were notorious for trashing cams due to bad lubrication. Ford changed the cam spray bar to fix.

So cam cover off and examine the cam, whilst you are at it check valve gaps.

Definitely odd to have low but even readings - did you do the compression test with the throttle wide open ?  Closed throttles can give a low reading.

What about the sliders in CV carbs, should they be lifted during compression test? If left down will they restrict the airflow enough to lower the compression reading? Just a thought 🤔

On 10/3/2024 at 10:10 PM, Kerry said:

It’s unusual to have equal low compression on all cylinders. Is your compression test reading accurate 

I'm using a new compression test kit, not sure how I can verify if it is calibrated correctly?