Misfire when cold, fine once up to temperature

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Vaughn
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Joined: Sun May 12, 2013 7:10 pm
My Bike: Zxr400

Misfire when cold, fine once up to temperature

Post by Vaughn »

Hello
My 400 has been sat in the garage for the last couple of months and she has developed a misfire when the engine is cold, it runs on the choke but as soon as I touch the throttle it dies.
When the engine gets some heat into it the misfire seems to go away and I can rev it up no problem, although I haven't ridden it because I'm in the final stages of getting my license. The fuel in it is not that old so I don't think that's the problem and I do get her running every few weeks and get her warmed up so the fan kicks in.

When I bought the bike there was no misfire, I decided to put a new set of plugs in so ordered exactly what was in there, gapped to the guage in the manual and torqued the plugs.
I have had the air filter out, cleaned and re oiled but apart from that I haven't done anything that should cause a misfire or to run rich.

I let the exhaust pipes heat up a little and checked but they all seemed to be hot, although I can't find my infra red thermometer gun at the moment so couldn't tell for sure if one was cooler than the others.
I then removed and checked the plugs again and cylinder 1 is running rich with sooty deposits on the plug but the other 3 cylinders were fine but with a slight bit of wetness to the plugs but they looked clean.
I checked each cylinder for a spark with the corresponding lead and all sparks seem fine.

Ok so it's obvious my problem is with cylinder 1 running too rich, but like I mentioned I haven't changed any settings or touched anything else and when I got the bike there was no misfire.
The only difference is when I got the bike the plugs were finger tight so this could have leaned out the 1st cylinder.

Ok so after a bit of brainstorming and searching the web I have come to the decision I must be having electrical problems, maybe a faulty coil??
The plug caps have seen better days and so have the leads, after a bit of searching around I've come up with a parts list worth £200 as the plug caps are like rocking horse pooh.
I have priced up the stick coil mod, parts from a cbr 600 and they come to £60 so might give that a try.

I'm just worried that won't correct the problem.
Also while I was reading around the forum I noticed somebody mentioned what way round the wires to the coil are and mine are completely opposite to what he wrote, I can't remember exactly off the top of my head but it was something like green to 2+3 red to 1+4, well mine were the exact opposite of what he wrote.

I was wondering if somebody would be good enough to post a picture showing the coils and the order of the leads so I can compare, or at least point me in the write direction
Thanks for reading
ross46
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Re: Misfire when cold, fine once up to temperature

Post by ross46 »

If you think its a faulty coil then swap them over? See if the misfire moves to a different cylinder, I'll take a picture for you tomorrow as im in there anyway changing some seals, have you balanced the carbs? Checked valve clearances? I had a misfire on one cylinder and it turned out the main jet had fallen out of the holder! Where abouts are you located?
Vaughn
Posts: 243
Joined: Sun May 12, 2013 7:10 pm
My Bike: Zxr400

Re: Misfire when cold, fine once up to temperature

Post by Vaughn »

ross46 wrote:If you think its a faulty coil then swap them over? See if the misfire moves to a different cylinder, I'll take a picture for you tomorrow as im in there anyway changing some seals, have you balanced the carbs? Checked valve clearances? I had a misfire on one cylinder and it turned out the main jet had fallen out of the holder! Where abouts are you located?
Cheers bud ill try that. No haven't balanced carbs and haven't checked clearances yet either. I have 3 sets of feeler gauges and they are all different from each other so I don't trust them and won't be doing clearances until I find a set I can trust.
I'm in Poole in Dorset
I'm tempted to get the carbs off and give them a good cleanup, might get myself one of them ultrasonic cleaners first, there's a couple of shops in the area that sell them but they are for jewellery, I want to find a bigger one for engine parts and stuff
ross46
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Re: Misfire when cold, fine once up to temperature

Post by ross46 »

Just ask banner, his come out lovely and clean, get banner to clean them and get a seal kit of maelstrom, they'll be lovely afterwards
Vaughn
Posts: 243
Joined: Sun May 12, 2013 7:10 pm
My Bike: Zxr400

Re: Misfire when cold, fine once up to temperature

Post by Vaughn »

ross46 wrote:Just ask banner, his come out lovely and clean, get banner to clean them and get a seal kit of maelstrom, they'll be lovely afterwards
Funny enough I was reading the post about maelstroms seals, I thought at the time I should get a set of them.
I've bookmarked the website so when the money situations a bit better in the next couple of weeks I'll order them up

Thinking about buying a sonic cleaner, looking at one big enough to get engine blocks and crankcases into, again when the money is there I'll buy that bad boy, watched a couple of videos of them in action, well impressed hopefully be powerful enough to wash the stains out of my pants from when I first go out on the 400 lol

I've drained the carbs completely for now and emptied all the fuel from the lines, my plan is on Thursday if I pass my test to get some carb cleaner in there then refill the tank and flush it out a bit by undoing the drain valves under the carbs then take it out for a spin and see if it miraculously goes away, hopefully it might just be where she's been sat for a while.
I've got some fuel system cleaner to put in
Also got some stick coils and loom on there way so maybe if i can bung them on maybe that might fix it

Till Thursday she is staying in the garage untouched
Vaughn
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Re: Misfire when cold, fine once up to temperature

Post by Vaughn »

The more I think about it the more I think the spark plugs were loose for a reason, I think they were left like that to lean the bike out.
I reckon a serious overhaul could be on the cards
ross46
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Re: Misfire when cold, fine once up to temperature

Post by ross46 »

just been reading through that thread. my personal view- someone would leave spark plugs loose even if they are chavs, if somebody knew enough about bike to think through the fuel system to leave the spark plugs loose would cause more harm than good. have you torqued up the plugs? no helicoil? i would just out it to how it should be... spaark plugs cleaned and torqued, oil, filter,coolant flush and change, check/replace air filter, check clutch, check brakes, pads etc, check/clean/lube linkages and bearings clean carbs, new seals, compression test and then the final jetting
Vaughn
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Joined: Sun May 12, 2013 7:10 pm
My Bike: Zxr400

Re: Misfire when cold, fine once up to temperature

Post by Vaughn »

Right so I've been out today and bought a sonic cleaner, some m3 washers (just in case) and a vernier caliper.

Got home whipped the carbs off and now I'm having a smoke and a coffee before I get cracking.
These carbs are in a bit of a state I think. Before when I flushed them out with carb cleaner it came out red so kept flushing till clear, drained the carbs again today and guess what it came out red again lol, just wondering what surprises are gonna be lurking.
I'll get some pics up as I'm stripping them down
Vaughn
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Re: Misfire when cold, fine once up to temperature

Post by Vaughn »

Right so here is the bottom of the airbox
ImageUploadedByTapatalk1378556975.071521.jpg
Float bowls
ImageUploadedByTapatalk1378556996.304436.jpg
Filthy dirty carb
ImageUploadedByTapatalk1378557012.337906.jpg
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Vaughn
Posts: 243
Joined: Sun May 12, 2013 7:10 pm
My Bike: Zxr400

Re: Misfire when cold, fine once up to temperature

Post by Vaughn »

These rubber seals have disintegrated too so I'm gonna have to get me a carb seal kit ordered pronto
ImageUploadedByTapatalk1378557291.771764.jpg
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Vaughn
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Joined: Sun May 12, 2013 7:10 pm
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Re: Misfire when cold, fine once up to temperature

Post by Vaughn »

That's 1 carb cleaned, just finishing off all the jets and things
ImageUploadedByTapatalk1378559412.969106.jpg
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KwakKwak
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Re: Misfire when cold, fine once up to temperature

Post by KwakKwak »

Used the Viton kit in mine, only non oem part I used, it is good quality, fits perfectly, I only needed certain seals, carbs weren't too bad, bear in mind though the delivery takes about two weeks, worth it though as the price is very competitive.
Like I said in the hello post, keep it off the road until you've sorted it, patience, patience, patience!
If its running like toad, and cutting out alot, basically just becomes dangerous, as I found out on mine, trying to concentrate approaching a roundabout, head on a swivel, and trying to keep the engine running just becomes silly.
I reckon your parts bill is going up, as did mine, enjoy your ciggie and coffee :smt002 , been there, remember, patience!
Does the low seat height reflect the low intelligence? Easier to get an asshole onto.
Vaughn
Posts: 243
Joined: Sun May 12, 2013 7:10 pm
My Bike: Zxr400

Re: Misfire when cold, fine once up to temperature

Post by Vaughn »

All done and back together for now, got a new seal kit ordered so when that turns up ill clean it all again one last time and get it back together
ImageUploadedByTapatalk1378584290.185819.jpg
Got a bit of wear on one of the needles, worth replacing??
ImageUploadedByTapatalk1378584396.955962.jpg
Does anyone know where I can get a couple of these washers,
ImageUploadedByTapatalk1378584440.039880.jpg
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Vaughn
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Joined: Sun May 12, 2013 7:10 pm
My Bike: Zxr400

Re: Misfire when cold, fine once up to temperature

Post by Vaughn »

Think I have one of these springs missing as well
ImageUploadedByTapatalk1378584534.689746.jpg
I'm not sure if it's missing or is there not meant to be one between the middle carbs??
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ross46
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Re: Misfire when cold, fine once up to temperature

Post by ross46 »

i have a set of stock needles for sale if you need them, will have been sonicated by banner and i dont need them as i have dynojets, make me an offer and they're yours, the red stuff can either be crap from the tank, iron oxide (rust) is red, hence why blood is red as it contains iron in the haem group (weird fact) also sometimes the carb cleaner sprays can be weird colours, i had one which was red once sprayed, put in a new fuel filter and check/clean the tank.
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