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Fuel controller for 975, Questions

Dartos

Well-known member
Lifetime Membership
I have a 2005 Carl's Cycle 975 that I have seized 3 times.
The first time I took it back and had Carl's diagnose the problem and they determined it was detonation on PTO cylinder from improper fuel. They rebuilt it and I was on my way.

Since then I have had 2 more seizures that have physically looked the same as the first. After the second one I had RkTek make me some lower compression heads and that initially appeared to work but in the end it did not cure my problem. After the third seizure I was at a crossroad as what to do. Go far deeper to fix the problem or scrap the whole thing.

Over the next year I spoke to the boys at Carl's about 15 times on what to do and how to diagnose. I also spoke to a couple other places and knowledgeable people. From that process I have decided that it was never a detonation problem from improper octane fuel as was first suspected by Carl's. Every time it seized I was at 1/4 to 1/3 throttle. I'm convinced I am having a partial throttle burn down.

Which brings me back to the original question for my application. I need more fuel mid throttle.

What fuel box have you used?
Was it on a stock or modified engine?
What do I need to know about fueling boxes?

99% of my motor tuning experience comes from the days when you tuned with an EGT, piston wash and reading plugs. Then adjust the carb from there. Im decent at tuning with carbs, don't know squat on changing fuel injection.

Any other insight or link(s) on an explanation on how these fueling boxes work would be appreciated.

As a reference this is what I have done since I decided to rebuild.
Completely tore engine down.
New Parts:
Crank end seals
Intake boots
Pistons
ALL gaskets and o-rings
Oil pump cable
Fuel filter

Other work done:
Flashed computer with latest update by Carl's
Fuel injectors cleaned and flow checked by Witch Hunter Performance
Pressurized crank case to ensure all seals are good

Cleaned rubbed touched every part in this engine.

I need to check the fuel pressure before I crank it up.
 
I would narrow the field as well to fuel pressure, leaking Intake or crank seals or injector.

Looks like u replaced it all now or recent so ur at a cross road indeed.

If U go programmer, you can get the Boondockers nitrous box. It's pretty straight fwd and easier to adjust since its visual at rpm range vs the damn lights on the dobeck boxes that screw with my eyes lol.


Sent from my iPhone using Tapatalk
 
975 issues

I recently bought a bunch of 975 parts to build one. So I am curious about your issue.

The same piston keeps seizing, just one not both ?

Fuel pressure is regulated on the stock 900 by a replaceble regulator in the fuel tank. 2 injector vs 4 run diffrent pressures. I believe the 4 injector motors have the have the higher pressure regulator.

Also diffrent injector colors deliever more fuel red blue yellow, off the top of my head I believe the red one flows more fuel. I have heard there is one other higher flow color also from a former tuner from HighMark.

It makes sense a bigger displacement needs more fuel.

Larger flow injectors with the same mapping and pressure will flow more fuel. Similiar to a larger main jet.

Is the piston on the jug with the straight in injector or the slanted steering side one ?
 
Last edited:
Yes same piston. PTO side, angled injector. Mine are the Yellow Injectors.
 
I would narrow the field as well to fuel pressure, leaking Intake or crank seals or injector.

Looks like u replaced it all now or recent so ur at a cross road indeed.

If U go programmer, you can get the Boondockers nitrous box. It's pretty straight fwd and easier to adjust since its visual at rpm range vs the damn lights on the dobeck boxes that screw with my eyes lol.


Sent from my iPhone using Tapatalk


Yeah the attitude industries box was a pain!!
 
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