Misfire when cold, fine once up to temperature

Moderator: Moderators

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 »

Good shout, I'll order some straight away
Well the rubbers have cooled and hardened now, they slip on and off perfectly.
I think I'll fit the bottom of the airbox to the carbs before I put the carbs on the bike, then I can make sure it's sealed properly.
The o rings between the carbs and box have seen better days too, at €4.50 each I think I'll just use silicon to make a better seal
ross46
Restricted
Restricted
Posts: 825
Joined: Fri Aug 26, 2011 9:31 pm
My Bike: zxr 400 l6

Re: Misfire when cold, fine once up to temperature

Post by ross46 »

Don't know how the h model airbox fits but on the L model there is a square recessed on the carb plate, I've sealed it with silicon and it's been fine
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 »

I notice there is a difference between my airbox and the new model ones, the bottom bit that bolts to the carbs is all one piece on mine but it seems on the newer models the plate can be unbolted, presumably to make it easier to align the rubbers into the carbs.
The big question is will a new airbox fit an old bike, I can't see why not, it looks similar, I'll keep my eyes peeled for one of them in the future.

Just ordered a rocker cover gasket and pulsar cover gasket, oh yeah forgot feeler guages I'll do that in a sec.

I've decided I'm gonna drain the cooling system and flush it through with water, then I can remove the top hose out of the way when it comes to doing clearances.

That's tomorrow's job list sorted,
remove fairings and find a safe place for them,
drain and flush cooling system,
remove plug caps, leads and coils and get the bike on paddock stands in a suitable place in the garage.
Might even whip the rocker cover off if I get time and have a peek inside

Been thinking when I have done the clearances I will drain the oil and probably pour some clean oil through it while the rocker cover is off.
Get a new oil filter on there as well.

This is getting really involved now, wish I had done all this before, I even thought about it but decided to leave it till I've ridden the bike and do it gradually. Now it's all go lol

I really hope after all this I fix the problem
ross46
Restricted
Restricted
Posts: 825
Joined: Fri Aug 26, 2011 9:31 pm
My Bike: zxr 400 l6

Re: Misfire when cold, fine once up to temperature

Post by ross46 »

I've now got access to the laser cutter again so I can cut the 3 engine cover gaskets, doing them for £20 for all 3, took long enough to get them drawn on the cad/cam software! About 20 hours!
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 »

Nice, is that the clutch cover gasket, pulsar gasket and sump gasket?? Might have to get you to cut me a set.

Any news on the needles??
ross46
Restricted
Restricted
Posts: 825
Joined: Fri Aug 26, 2011 9:31 pm
My Bike: zxr 400 l6

Re: Misfire when cold, fine once up to temperature

Post by ross46 »

Clutch, pulse and generator, never looked into clutch, if its bigger than a4 its awkward to do, but I can do it if there is enough interest
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 »

Hmm well I've ordered a pulsar gasket anyway, but I could do with a set of all 3 of them.
I will get the clutch housing off at some point and check it over, money's a bit tight at the moment though after buying so much stuff over the last few days so might have to give you a shout in a week or two if that's ok.


Been looking in the manual and it says my bike should have n77c needles but mine are n77r
Wonder if the r stands for racing
The manual is for h2 though mine is h1 so they either changed the needles in that year or my needles aren't standard I guess.
Come to think of it one of the plastic covers on the carb had L and a year written on it, that got washed off in the sonification, I just assumed someone had replaced the plastic, I'm wondering now if someone changed the whole carbs though
Damn it I thought I took a picture of the writing but I can't find it
ross46
Restricted
Restricted
Posts: 825
Joined: Fri Aug 26, 2011 9:31 pm
My Bike: zxr 400 l6

Re: Misfire when cold, fine once up to temperature

Post by ross46 »

thats fine, just put some on my bike, fit lovely, and no leaks! Makes a change on this bike confuddled
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 »

Hahaha, well if yours is anything like mine then it's no wonder it leaks the bloody thing seems to be held together with silicon, spent a bit of time in the garage today and got the rocker cover off, it was sealed with silicon lol, even the spark plug tubes were siliconed, just as well I ordered all new gaskets for the top and bottom of plug tubes and new rocker cover gasket too.
I'll get a picture up tomorrow so you can see all the silicon in the rocker housing, my battery died as I was taking pictures and I hadn't got as far as the rocker cover by then.


Right so it looks like I've opened pandoras box, found a problem
ImageUploadedByTapatalk1378843801.859902.jpg
As you can just make out one of the exhaust bolts for cylinder 2 has snapped off, that would explain why I could hear the exhaust leaking, all bolts look knackered so might be time to fit some new ones.

Drained the cooling system as well, the water was thick brown, take a look at the expansion tank
ImageUploadedByTapatalk1378844034.442328.jpg
I was trying to get a better pic but it was at this point my battery died, there was brown sludge in the bottom so got that all cleaned out, gonna flush the rad tomorrow.

I wanted to get a picture of the cam chain tensioner on here to see if you think the chain needs replacing, I'll get a pic after work tomorrow.

I have a bad feeling I'm gonna need to replace some valves, hopefully be able to just change the shims but after what I've seen I have a bad feeling.

Would I be right in thinking that as the timing chain stretches it will change the clearances on the valves making them go out of sync?? Then when you fit a new chain it lines the cams up better and changes clearances again?? Does that make sense
You do not have the required permissions to view the files attached to this post.
ross46
Restricted
Restricted
Posts: 825
Joined: Fri Aug 26, 2011 9:31 pm
My Bike: zxr 400 l6

Re: Misfire when cold, fine once up to temperature

Post by ross46 »

Not unless its gone, if its not broke dont fix it, my cam chain went and you could hear it rattling, take the pulsar gasket off and take a picture of the tensioner, I probably sound like im plugging my new gaskets, but i can change the document and cut lots of one gasket as when doing cam chain and bits like that you seem to end up taking the cover off constantly so you sometimes need more than one pulse cover, im doing them individually if people ask, at half of oem
User avatar
banner001
Track day God
Track day God
Posts: 2585
Joined: Sat Sep 24, 2011 3:27 pm
My Bike: ZXR400 L4
Location: Nuneaton

Re: Misfire when cold, fine once up to temperature

Post by banner001 »

Vaughn wrote:Would I be right in thinking that as the timing chain stretches it will change the clearances on the valves making them go out of sync?? Then when you fit a new chain it lines the cams up better and changes clearances again?? Does that make sense
yes...to a point, a "stretched" chain might only add 0.5-1cm MAX to the length of the chain, im just guessing here, but i reckon a zxr400 chain to be about 90cm total length, so at the very most you are adding 1% to the total length so you are retarding your inlet by at most 3.6 degrees, more likely its 2-3 degrees which given the probable state of most peoples cylinder head, and the amount of dirt welded to the valves/seats is going to do pretty much nothing, there will be a difference but its going to be unnoticible.

it is possible (aparently) to increase the midrange by dropping one tooth on the inlet sprocket, this is a 6 degree change and presumably the bike still works...so 2-3 degrees will do comparitively nothing.

on a tuned bike it would be a whole different story.
UK ZXR400 L3 (1993) - Fully restored and on the roads, my green beast!
JPN ZXR250 A2 (1990) - Revs to 19,200rpm... 'nuff said :smt003
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:Not unless its gone, if its not broke dont fix it, my cam chain went and you could hear it rattling, take the pulsar gasket off and take a picture of the tensioner, I probably sound like im plugging my new gaskets, but i can change the document and cut lots of one gasket as when doing cam chain and bits like that you seem to end up taking the cover off constantly so you sometimes need more than one pulse cover, im doing them individually if people ask, at half of oem
I found some pictures in a thread of cam chains and tensioners, looks like mine is fine, tensioner is in the middle of travel.

Yeah I'll have a set of them gaskets off of you, maybe tomorrow or next Thursday ill have to let you know
banner001 wrote:
Vaughn wrote:Would I be right in thinking that as the timing chain stretches it will change the clearances on the valves making them go out of sync?? Then when you fit a new chain it lines the cams up better and changes clearances again?? Does that make sense
yes...to a point, a "stretched" chain might only add 0.5-1cm MAX to the length of the chain, im just guessing here, but i reckon a zxr400 chain to be about 90cm total length, so at the very most you are adding 1% to the total length so you are retarding your inlet by at most 3.6 degrees, more likely its 2-3 degrees which given the probable state of most peoples cylinder head, and the amount of dirt welded to the valves/seats is going to do pretty much nothing, there will be a difference but its going to be unnoticible.

it is possible (aparently) to increase the midrange by dropping one tooth on the inlet sprocket, this is a 6 degree change and presumably the bike still works...so 2-3 degrees will do comparitively nothing.

on a tuned bike it would be a whole different story.
Good answer thanks for that, that's put my mind at ease,
So after fitting a new timing chain it would be wise to check valve clearances then
User avatar
banner001
Track day God
Track day God
Posts: 2585
Joined: Sat Sep 24, 2011 3:27 pm
My Bike: ZXR400 L4
Location: Nuneaton

Re: Misfire when cold, fine once up to temperature

Post by banner001 »

Vaughn wrote:
ross46 wrote:So after fitting a new timing chain it would be wise to check valve clearances then
yes, and every 6000 miles afterwards :D
UK ZXR400 L3 (1993) - Fully restored and on the roads, my green beast!
JPN ZXR250 A2 (1990) - Revs to 19,200rpm... 'nuff said :smt003
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 »

banner001 wrote:
Vaughn wrote:
ross46 wrote:So after fitting a new timing chain it would be wise to check valve clearances then
yes, and every 6000 miles afterwards :D
Brilliant, good advice thanks
I've read into the subject a bit and it seems a lot of the hot starting problems are caused by wrong clearances so it is well worth keeping on top of it in my eyes. Gonna make myself up a clearance/shim chart as per mori's instructions

Just got home and having a smoke and a coffee then I'm off out into the garage, gonna get the water pump and thermostat out for a clean and flush the engine with water. Got my new foam today as well so I'll get the snorkel packed again and put the airbox back together

Running out of things to do now, just waiting on parts to turn up

I'll get a picture of the cc tensioner as well, I'm pretty sure it's fine but I would like a second opinion.

Still waiting for another set of feeler guages so can't do my clearances yet :-(
Vaughn
Posts: 243
Joined: Sun May 12, 2013 7:10 pm
My Bike: Zxr400

Misfire when cold, fine once up to temperature

Post by Vaughn »

Right so just got back in from the garage and oh what a night it's been.

Here's the cam chain tensioner
ImageUploadedByTapatalk1378924499.925965.jpg
I think it looks alright but I'm not sure about those metal filings magnetised to the bolt on the right of the tensioner

Got the water pimp off and cleaned, it wasn't too bad just a little bit brown and gunky, in the manual the thermostat looks easy to get too but on the bike it's a different story so gave up with that idea,
Got a hosepipe and flushed the whole system through till it came out clear instead, even took the cylinder drain screws out. So that's a nice clean cooling system ticked off my list. Tomorrow when everything is dry I've just got to put a little bit of silicon on the water pump housing and refit and that's that sorted.

I had a go at the exhaust manifold bolts to try and get them off without breaking, snapped the other bolt in cylinder 2 but the rest came undone fine, I started to take the rad off to get better access to remove the exhaust system but my belly started rumbling and I gave up

Tomorrow I'll get the rad and exhaust off and see what can be done with the manifold bolts, the 2 snapped ones are showing a fair bit of thread so there might be some hope yet.
Thinking maybe I should replace them all with stainless bolts. Just worried about snapping one off in the head

I might start a new thread because this is drifting way off the point of just a misfire.
Maybe a things I have done to my bike thread.
I'll keep this one clean for any progress with the misfire
You do not have the required permissions to view the files attached to this post.
Post Reply