Stock 4K Idle Problem

[biglad]

Hey guys

I recently bought a ke70 with a standard 4k. When its cold it idles ok but as it warms up it starts to missfire on idle. It revs up, accellerates and decellerates fine without a problem and doesnt blow smoke, but after driving for a few minutes then stopping at a set of lights it almost dies and I have to keep the revs up to keep it running.

I have checked for vacuum leaks, used carby cleaner etc but havent

[biglad]

Phone internet sucks. As i was saying i haven't fiddled with the mixture screws and it idles at about 1000 when it decides to idle itself. Can anyone give me an idea of what is up with it?

Cheers

[SLO-030]

Sounds like it might be a blown headgasket.

[B.L.Z.BUB]

Service it and get the timing done.

[Evan G]

vacuum leaaakkkk

[biglad]

Thanks for the advice guys. I think ill service it and get it tuned professionally. Its a pretty strong 4k so i don't think it would be a blown head gasket. Do you fine gentlemen know a good carby tuner in sutherland shire?

[ke70dave]

Sounds like it might be a blown headgasket.

 

care to share with us how you came to this conclusion. as i don't see any evidence from the description that this could be possible...not saying its not possible but i can't see how you can draw that conclusion?

 

do what bubbles said. service it.

 

1: pull plugs, clean, re gap

2: carby clean the crap out of it (engine running, rev the guts out of it and spray in the carby cleaner straight down the barrell of carbys) check for vac leaks while your at it too.

3: reset points (possibly replace if burnt out)

4: possibly replace the capacitor thing on the dizzy too, can't recall what it is called, but its cheap to buy.

4: set the base timing as best as you can to get it running.

5: tune carby, no need to get it done by a pro, cost to much, buy a k motor book and read the tuning section, theres only 2 screws on the standard carby, you can't go wrong.

6: reset base timing again.

[altezzaclub]

Running OK when cold then not running when warmed up suggests its too rich at idle.

 

Re-setting the idle mixture screw might fix it straight away. That's just screwing the mixture screw in and out again to get the highest, smoothest idle and then re-setting the idle speed screw to the idle speed you want. Must be done warm.

 

Another one would be float height too high, but that is less likely.

 

Have you measured how much fuel it uses? It should use less than 8L/100km around town.

 

Go over it as KE70dave said, a general tune that you can do at home yourself. These are dead simple cars.

[jaygore]

this sounds very similar to my issue... So I will keep an eye on this one and see what happens

 

and I get nowhere near 8l/100km around town I'm lucky to get 250kms out of a tank, twin webbers obviously don't help but I would have thought at least 350kms a tank would have been a decent target =\My dad and I have messed around with the mixture screws and so on, but just cannot get it right =\

[altezzaclub]

I'm lucky to get 250kms out of a tank, twin webbers obviously don't help

 

ROFLMAO !! I read "I'm lucky to get 250Km" and thought -

 

"Gee that's bad!"

 

then I read the rest and cracked up! There's nothing worse that DCOEs for using fuel, but that power and noise is soo addictive!

 

Have you had the jets changed to suit the motor? Slap an oxygen sensor on it and you'll probably find it running rich 80% of the time. You've got main jets, air jets, emulsion tubes, idle jets, pump jets... and they all need to be right for that motor. Don't forget the float levels too.

[jaygore]

:blinks: sooo much and i don't understand any of it haha! I think I will take it in to get tuned properly at some point haha...

 

But the noise is addictive, wayyy to addictive! haha

[altezzaclub]

Go to a racetrack when clubmans racing is on and chat to guys there about who is a good tuner locally.

 

If not, chase some mad old Italian backyard garage who does old Fiats/Lancias etc as they will know Weber tuning backwards and have a shitload of jets to try.

 

It should end up smooth and sweet with no flat spots, but roar when your foot is flat. Round-town should turn in 8.5-9L/100km. You can make Webers very fuel-efficient.

 

If you pop the little round top off you can take the jets out and look at the sizes. The top one is the air jet, should be around 180, the middle tube is the emulsion tube, say an F9 or F6 or F15, and the bottom one is the main fuel jet, should be around 115. All 4 sets will be the same. (well, the certainly should be!)

Edited February 15, 2011 by altezzaclub

[biglad]

Good info :) ill do the tuneup asap

[TomoKE55]

Ive got the same problem, a mate suggested the carby base gasket or manifold gasket could be blown. Got some in the shed so i'll chuck them in tomorrow and let you know what happens (if it stops raining :bash: )

Edited February 18, 2011 by TomoKE55