4k Missing At High Rpm?

[DearmanKE]

ok my ke70 misses when u rev it out, like 4.5k and up

it valve bounces

 

today i checked the timeing and it was fairly advanced so i wound it back abit, this made it miss even more and sounded like it was valve bounceing at about 5k, i don't think it was tho i think it was just missing heaps.

 

i also reset the points to .018inch

 

would the points effect this much, because i set the points before setting the timeing which is the reason i had to wind back my timeing to stop it pinging its arse off, but now it misses alot at high rpm, it already did before but not to this extent.

 

i also mucked around with the mixture abit, but that didnt have any effect on it

 

ps it also misses a bit on idle

Edited July 2, 2008 by Shizotimang

[Taz_Rx]

Yeah try closing the points gap up a bit and see if that helps.

 

Are your plugs good?

 

Arcing coil or plug leads can also cause serious misses, so if you can swap some leads between cars etc you could eliminate this problem. Or just buy a set of Bosch super sport plug leads from supercheap for like $20. :D

[DearmanKE]

yeah i put newish bosch leads on at same time

 

and bosch dizzy cap done less than 100 k's, i think leads were replaced at same time aswell, (this is off another car)

 

not sure how good my plugs are, theya re probs full of gunk, don't have a sp spanner tho,

 

i might try closeing the gap up in a minute

 

 

note for anyone turning over there motor with a wrench, once u have done it, don't forget to take the wrench off

 

i started the car with it on(because I'm forgettful) and it undid the bolt on the end of the crank in a matter of a second

 

 

edit. hmm before i do anything else I'm gunna put my old leads on, i know the bosch ones are new but the bit that goes to the plug just doesnt seam longe nough, that could be arcing.... probs not tho

Edited July 2, 2008 by Shizotimang

[Taz_Rx]

haha thats how I undo the crank pulley bolt, but with the coil lead removed so it won't start. :D

 

I've got a spark plug tool I bought from supercheap for like $7. Double sized end and a T handle. They also have a uni joint in them, which does get a bit slogged out, but only allows you to do up the spark plug as tight as you need to. Shit quality toll....but highly recommended!! :yes:

[DearmanKE]

tryed old leads, same result,

 

went back to good leads, same thing

 

set points again

was then missing at 2.5k and above would only rev up to 3k,

 

looked at points again, wow thats really big oops...

 

set them again useing .014 inch guage(to allow for slight error)

 

runs abit better now, still misses at high rpm but not so much, still misses a bit before 5 which id like to get rid of, and idles a little better now. less missing

 

i need one of the spark plug tools,

i gotta go to work in abit, else id go grab one n check the plugs,

 

whats the best way to service the plugs? will probs do it 2moro, whats the gap?

 

also what sieze sp spanner do i need? i might get one on way to work??

Edited July 2, 2008 by Shizotimang

[Redwarf]

Plugs. Buy NGK's. :D

[Taz_Rx]

Yeah NGK's FTW, bosch plug are shit! Stock 4k plugs are bp5ey. Gap is 0.8mm

 

You need a bigger (19mm IIRC) spark plug tool.

[Damon550]

i had a half dead spark plug it would miss and fart at like 3000 revs so i would make the spark jump and it ran fine but as soon as i put the lead back on it would miss

[DearmanKE]

checked my plugs there all fine,

 

this problem seams to have fixed itself now,

 

may have just been shit in the carby or something that needed a good thrashing to get rid of, even tho i give it a good thrashing most places i go lol

[marvis]

Points gap fine? I had this issue and it was with the points gap. Should be a 0.4mm from memory.

 

Timing might be an issue.. Stock is 8deg but trying running it 12+ depending on mods.. Just set it, take it for a drive, then do it a bit more etc.

 

fun fun.

[1dirty30]

Hi.

I've had a similar problem with my 4k. Its missing once it gets past 80km/h but not all the time and is genrally fine once past 110km/h. I've replaced the plugs, fuel filter, distributer leads and points to no avail? where do i go from here?

[Evan G]

Posted 02 July 2008 - 04:15 PM

[Taz_Rx]

Proof he actually searched e so all good! ;)

[altezzaclub]

maybe carb-

 

If about 80kph is where the 2nd choke adds to the 1st choke it might run lean for a while. Difficult to check with a vac controlled throttle.

 

A run with an oxy sensor to check the mixture would tell you.