CBR 400 Running on 2 cylinders at start up and for 15 minutes into ride and then runs on 4 cylinder

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Bowches
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CBR 400 Running on 2 cylinders at start up and for 15 minutes into ride and then runs on 4 cylinder

Post by Bowches » Thu Jan 25, 2018 9:29 pm

Hi Everyone

Recently three days ago. The CBR 400 took a long time to start up. It was running like a scooter or single cylinder bike (Because of the sound).

And then after 15 minutes into the ride, I could feel the other two cylinders starting to kick in. And then 17 mins into the ride, the CBR 400 was running like normal again.

I had done a valve clearance check on 13 November 2017. I had taken out that rubber piece that you put the HT spark plug caps through as I found it hard to fit back in and out of laziness did not put it back on.

Now could there be something wrong with the spark plug caps or HT LEADS COIL? This morning as well I had a tricky time starting the bike and in the evening today (it is warmer today), when I started the CBR 400 in the afternoon, it started well and all 4 cylinders were running fine.

Maybe I must buy Ignition Coil caps?? I have attached an Image in this message showing the big Rubber piece I am talking about.

This is why I just prefer to keep the CBR 400 stock these days as I am using it for commuting and IT MUST BE RELIABLE!

https://postimg.org/image/6avtahi6j/

dunkenb
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Re: CBR 400 Running on 2 cylinders at start up and for 15 minutes into ride and then runs on 4 cylinder

Post by dunkenb » Thu Jan 25, 2018 11:05 pm

Which cylinders don’t run when you start it up?


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CB1pod70
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Re: CBR 400 Running on 2 cylinders at start up and for 15 minutes into ride and then runs on 4 cylinder

Post by CB1pod70 » Fri Jan 26, 2018 12:42 pm

It is likely that there is water sitting around the plug caps or inside the connections between the HT lead & coil causing a short circuit. As the engine warmed up the water will have evaporated and the plugs started working again. Also check the wiring going to the coils, you may have knocked them loose when removing the cam cover

the large cover is a pain but it is there to stop hot air rising and mixing with the cold air going into the airbox. Not a problem at this time of year but you really want to re-fit when the weather starts getting warmer

As another check, which cylinders were not firing? Number 1 is the outside cylinder on left (as you sit on the bike). Depending on which cylinders are the problem, it may be an issue with one of the coils.

Bowches
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Re: CBR 400 Running on 2 cylinders at start up and for 15 minutes into ride and then runs on 4 cylinder

Post by Bowches » Tue Jan 30, 2018 9:08 am

I do not know which Cylinders are not running. But 100% it is running on one or two cylinders at start up.

This morning was two degrees and The battery went flat trying to start it. I had to take the train.

It nearly started though. Also a few flames kept bursting out of the exhaust.

What shall I do? Remove the HT coils and clean it? I am definetely putting back that Rubber cover lol.

Otherwise I will buy a HT coils on Ebay from another CBR 400. Taking out the Rubber piece was silly thing to do. The mechanic should have known that.

Im gonna try to leave it as stock as possible

Bowches
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Re: CBR 400 Running on 2 cylinders at start up and for 15 minutes into ride and then runs on 4 cylinder

Post by Bowches » Wed Jan 31, 2018 9:01 pm

Great news I fixed the problem.... The HT coils were upside down when I checked the Haynes Manual. I also put back the Rubber piece covering the rocker/cam shaft cover.

The outer cylinder on the throttle side had the coils stretching so much to go inside the cylinder, but now it fits perfectly.

I'm not sure but I think this was turned upside when I had the valve clearance check done. But anyway I turned it upside down today and connected it and it fit perfectly, I did not have to stretch any of the coils to fit onto the spark plugs.

Let me see how it goes for a week. :peace:

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Davez29
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Re: CBR 400 Running on 2 cylinders at start up and for 15 minutes into ride and then runs on 4 cylinder

Post by Davez29 » Thu Feb 01, 2018 9:07 pm

Hi everyone.

Glad you got it sorted, im amazed it worked on four cylinders after it warmed up at one point, as you said..

As long as you have fitted them correctly and ever get similar problems, check that individual plug caps and leads are screwed in tight.
If that does not help read the Haynes section 5.2, take the coils off and check the resistance of the coils, leads and plugs caps.

It may be worth sourcing new leads and plug caps.

I checked mine a while back and found three plug caps loose and one with the wrong resistance. Luckily I had a spare set of good coils I could take a plug cap from. I found those cheap Chinese copy plug caps didn't give the correct resistance, so maybe pass on them if you see them on ebay.

I have mentioned it before but buy a cheap infared gun thermometer, then if the bike seems to be missing on one you can quickly pinpoint which cylinder it is by pointing it along the headers. Better than trying to work it out burning your fingers on something that maybe 50c to 100+c

cbr400rrn
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Re: CBR 400 Running on 2 cylinders at start up and for 15 minutes into ride and then runs on 4 cylinder

Post by cbr400rrn » Thu Feb 01, 2018 11:35 pm

The headers must surely get hotter than 100*c n what's wrong with burning your fingers? I've done it many a time. Seriously buying one of the cheap infrared guns is a good idea

Bowches
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Re: CBR 400 Running on 2 cylinders at start up and for 15 minutes into ride and then runs on 4 cylinder

Post by Bowches » Fri Feb 02, 2018 10:57 am

Yea Just removing the HT coils and plugging them back on the spark plugs seems to have done the business.

Its running very nicely now. Alot more crisp and responsive!

Thank goodness for that. I know its a 27 year old bike G reg 1990....but I really need it to be reliable.

Bowches
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Re: CBR 400 Running on 2 cylinders at start up and for 15 minutes into ride and then runs on 4 cylinder

Post by Bowches » Wed Feb 07, 2018 5:30 pm

Davez29 wrote:
Thu Feb 01, 2018 9:07 pm
Hi everyone.

Glad you got it sorted, im amazed it worked on four cylinders after it warmed up at one point, as you said..

As long as you have fitted them correctly and ever get similar problems, check that individual plug caps and leads are screwed in tight.
If that does not help read the Haynes section 5.2, take the coils off and check the resistance of the coils, leads and plugs caps.

It may be worth sourcing new leads and plug caps.

I checked mine a while back and found three plug caps loose and one with the wrong resistance. Luckily I had a spare set of good coils I could take a plug cap from. I found those cheap Chinese copy plug caps didn't give the correct resistance, so maybe pass on them if you see them on ebay.

I have mentioned it before but buy a cheap infared gun thermometer, then if the bike seems to be missing on one you can quickly pinpoint which cylinder it is by pointing it along the headers. Better than trying to work it out burning your fingers on something that maybe 50c to 100+c
Thanks for your help as always and everyone else

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Davez29
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Re: CBR 400 Running on 2 cylinders at start up and for 15 minutes into ride and then runs on 4 cylinder

Post by Davez29 » Thu Feb 08, 2018 9:43 pm

cbr400rrn wrote:
Thu Feb 01, 2018 11:35 pm
The headers must surely get hotter than 100*c n what's wrong with burning your fingers? I've done it many a time. Seriously buying one of the cheap infrared guns is a good idea
Yes I do think they do get a lot hotter but could not remember the range. In fact I think it was 100c which was cooler than the rest. Thats hot to touch and im sure not many people could distinguish between 100 and 200 degrees by touch. Much simpler with the olde thermometer.


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