4K Won't Idle?

[luk3333]

I see this is a common thread after a quick elgoog search, and I'm at my wits end. What happened was it was idling fine, then I was mucking around with the carb and when I assembled it all again it won't idle unless the choke is on. It starts fine, but then gets leaner and leaner until it stalls. I have an AFR gauge, so i know it is leaning out and not flooding.

 

I have:

- Checked timing

- swapped to spare and visually inspected both fuel pumps

- checked flow, cranked for 10 seconds about 20ml or less came out, not sure if this is usual, it seems pretty low. When idling, on and off choke, plenty of fuel comes out the return hose.

- Tried two different carburettors, one I have fiddled with, another I purchased thinking my fiddling had done the damage. The second one appears to have never been opened or cleaned but it apparently idled before it was removed. Both stock Aisans.

- Blow through rubber lines with air compressor

- Tried bypassing fuel filter

- Twiddling idle speed and mixture; has no effect once it starts leaning out.

- Leaning on the intake doesn't affect revs, this is how I found a dodgy intake gasket once before.

- No vac leaks, I have checked with aerosol, and swapped all the vac hose with spare and tried plugging them up. No effect.

- Fuel solenoid definitely works, if I unplug it the car completely stalls. I can also hear it tick open/shut.

- Looking down the carb, I can see fuel coming out the primary throat normally when revved. Accelerator pump also works normally.

- On the carburettor I fiddled with, I went back and blew out all the jets I could find, and checked the needle and float weren't stuck.

 

With half choke on it idles at ~14.7 but at quite high revs. I would have thought it would be richer. Full choke; rich and screaming.

 

If anyone has a diagram showing the idle jet, so I can make sure I've got it clear that would be helpful. It appears to be a problem with the idle circuit I think. I suspected the bowl not filling fast enough on idle, but it barely uses any fuel on idle and it can be brought back to life with a rev/ opening primary, which wouldn't make sense if the bowl was empty.

 

Someone please help me solve my mystery!

[altezzaclub]

plenty of fuel comes out the return hose.

 

Leaning on the intake doesn't affect revs/I have checked with aerosol

Those neatly sort out fuel supply and leak problems.

 

If its a problem with the idle circuit it would be unlucky to have it happen with both carbs.

 

I was mucking around with the carb

What did this involve?? It will tell you what stopped it idling. I assume you have check-tightened all the bolts on the manifold in case leaning on it wasn't enough. You might need to remove the manifolds and check the gasket for breaks I think, seeing both carbs suffer the same problem.

 

You can alter the half-choke idle speed and leave it to just richen the mixture, but that won't solve the problem.

[luk3333]

Yeah, its drivable, I just prefer to know it's working right. I pulled the jets out to blow them out, and basically just had a look at all the parts and tried to get some idea of it worked. I'm not sure exactly which is the idle jet still. A video I watched referred to a long thin one next to the accelerator pump as a "slow jet", is that it?

[altezzaclub]

Here-

 

Drawn on for another thread, but those are the jets.

[towbar65]

Hi there,

Just wanted to write something on my experience.

Have had my 5k ke11 for 15 years. Love it. Just put in a fresh 5K and rebuilt the K50 gearbox. Big fun.

About 3 years ago I put in 2inch ehaust, extractors, geared starter and a life changing Weber 32/36 downdraft From a redline distributer in Seattle. High Aussie dollar made it around 400 bucks from memory for the kit.

My only advice. Find a mountain and throw the Aisan carbs off it. I tried kits, jetting, multiple tear downs and am convinced that they are indeed SHIT. Sorry but true.

The redline Weber was pre jetted for a 3/4/5K and after mounting the adapter plates and installing carb (custom throttle cable) which was straight forward, I was amazed it started right up and has run perfectly without a single adjustment. The only thing I've done with this latest engine change is port the 3K manifold to the adapter plate which made it even smoother.

Want perfect idle, transition and top end? I can't see any alternative.

Hope this is of value and not just further agrivating your hard trouble shooting.

Cheers

[GJM85]

Problems occur with the Aisan carbs when the throttle shafts wear out causing a continuous vacuum leak.