occasional fault/missfire

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Prospector
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Joined: Thu Dec 16, 2010 2:51 pm

occasional fault/missfire

Post by Prospector »

I have been working on a friends firestorm that has been causing him problems with a missfire and only running on one cylinder .
I checked the valve timing and clearences all ok the battery was a bit flat so charged it using the optimate, it tried to fire up but still running on one cylinder both spark plugs have been replaced and checked for spark both ok so I tried again it started on one cylinder the front one and when I tried the rear cylinder with a little ht tester I have it was not producing a spark although it had been earlier, so an irritating little intermittant fault, I checked for any bad connection in the loom but everything seemed to be ok.
I tried starting it again and away it went firing on both cylinders and sounding great I dont know what I may have touched to cause the problem to go away but obviously something is not as it should be.
So I was wondering if anyone on here has had similar problems and what the cure was, at the moment I am thinking that the rear coil may be breaking down and so tempted to replace the coil trouble is its not my money I would be spending and am loathe to buy a new coil if it does not cure the problem.
We are off to spain in a couple of months and want the bike to be reliable any advice help would be appreciated. Jack
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benny hedges
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Re: occasional fault/missfire

Post by benny hedges »

more than likely hes trapped a fuel line underthe tank.
other things to check... the 16 pin plug in the brain under the seat, behind the back lamp.
the wires to & from the ignition module on top of that.
check theres no corrosion where the coils bolt to the frame - fire it up in a dark garage & look for ht tracking under the tank
the rear coil is under the rt hand tail piece, just behind the tank... check the wires are secure.

but bet it's the fuel lines.
if the tank has been off and placed on the subframe, he's probably turned it round instead of turning it back, thus putting a twist in the pipes.

i find when mine is about to run out of fuel it only runs on the front cylinder.

oh and try bypassing the clutch & sidestand switches.
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Prospector
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Re: occasional fault/missfire

Post by Prospector »

Hi Benny thanks for the reply , It is not fuel related both pipes are kink free and the vacumm pipe is correctly positioned, the rear cylinder does seem to be the problem I fired it up again today and it was running only on the front cylinder I tried my little spark tester to see if there was any spark at the rear ht lead initially no spark present I moved the wiring loom around as much as I could where the rear coil gets its supply from there was a backfire and the engine picked up and been running well since it was ticking over very slowly so turned it up so that it now ticks over about 1100 .
I pulled the connectors apart looking for any signs of corrosion but nothing not even anything that felt loose enough to cause a bad connection
Its really cold here at the moment and the battery is feeling the effects of it as it is quickly wound down trying to start it.
I tried looking for arcing in the dark but there was nothing visible.
I will let it cool down again then try it later tonight. Jack
tony.mon
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Re: occasional fault/missfire

Post by tony.mon »

Try temporarily swapping the coils around to see if the misfire also changes.
I know the lead lengths will be wrong but I'm sure you could rig something on a temporary basis.
If the misfire moves to the other cylinder have a look at the plug cap- it has a suppressor built-in.

If not, it could be the plug, possibly?

And if the problem remains on the rear cylinder after coil and plug swaps (not both at the same time, or you won't know which causes the problem) then you'll need to strip the carbs for a thorough clean.
It's not falling off, it's an upgrade opportunity.
13yearsVTRrider
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Re: occasional fault/missfire

Post by 13yearsVTRrider »

My VTR1000F3 has 45000miles on the clock and gets ridden as long as ambient temperature are over 3 or 4 degrees C. A couple of days ago I was riding home from work in the pouring rain, and at the end of the trip it went onto one cylinder. I used the car the next day.
In the garage the following evening, I pulled off the the plug lead to the front cylinder to find it was still wet .
The problem was caused by the drain hole at the bottom of the sparkplug recess in the cyl.head being blocked , and not allowing the water etc. to clear. The short front mudguard allows all the mud and salt to plaster the front and top of the head and camcovers . There is a seal moulded into the plug cap which should prevent this muck from getting any further down the recess, but it does not stop the dirt from getting forced in via the outlet for the drain hole.
The outlet for the drain hole is just below and to the nearside (left side when sitting on the bike) of the exhaust port -it's about 6mm dia at this point, but further in it reduces in diameter.
This means the gap between the sparkplug and the bore of the recess can fill up with mud etc which dries and goes hard, eventually blocking the drainhole.

You can imagine what happens if you remove the plug without thoroughly cleaning this out.

The solution is to insert a screwdriver with a 3mm dia shank into the hole below the exhaust port and ream the dirt out. You can check whether it's worked by pouring cleaning fluid or WD40 down around the plug - it should come out of the drainhole and be easily visible.

The next task is to thoroughly clean all the muck out before removing the plug. Jizer and a pressure washer is probably the easiest solution.

Otherwise, a super reliable machine as long as you change the cam chain tensioners every 16 thousand miles. My last VTR expired at 47000miles due to cct failure.

Hope this is of some use.
tony.mon
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Re: occasional fault/missfire

Post by tony.mon »

Good helpful first post, well done. :thumbup:
It's not falling off, it's an upgrade opportunity.
13yearsVTRrider
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Re: occasional fault/missfire

Post by 13yearsVTRrider »

Glad to be of some use!! :D
The problem is made worse if the plug cap isn't pushed down as far as it will go - the seal then won't prevent water reaching the plug from the top. Sounds obvious but it's easy to do if you are distracted by wife or kids! :Argue:
Here's a question for everyone - why did Honda fit a smaller battery to the later models with the HISS system - (which drains the battery)?
My first machine had a 10Ah battery - I think the current one has an 8Ah, which is physically smaller heightwise. There's a big block of rubber packing in the battery carrier to raise the battery so the leads reach the terminals.
If you take the packing out you can fit a 10Ah battery. Forces the use of a trickle charger otherwise if the 'bike isn't ridden every day.
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sirch345
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Re: occasional fault/missfire

Post by sirch345 »

13yearsVTRrider wrote: Here's a question for everyone - why did Honda fit a smaller battery to the later models with the HISS system - (which drains the battery)?
My first machine had a 10Ah battery - I think the current one has an 8Ah, which is physically smaller heightwise. There's a big block of rubber packing in the battery carrier to raise the battery so the leads reach the terminals.
If you take the packing out you can fit a 10Ah battery. Forces the use of a trickle charger otherwise if the 'bike isn't ridden every day.
I have often wondered why the later models had a smaller battery too. Lighter and cheaper perhaps :?:

A mod which quite a few have done on here is fit a bigger amp hour battery to the earlier models, (if you can as you say remove the packing from the carrier to fit the earlier bigger battery then this mod could be done on the later models too) a battery that is meant for the Honda Varadero XL1000. It's approx 15mm taller but is a 12amp hr battery. It means removing the battery carrier top thats the only down side, but it makes the engine turn over better for starting in the cold winter months.

Chris.
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benny hedges
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Re: occasional fault/missfire

Post by benny hedges »

if you shop around you can get a 14ah the same size as the 12.
i now have the same battery in all 3 bikes so i keep one on the shelf charged up just in case.
didnt know the later model had a 8ah though. every day's a schoolday
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sirch345
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Re: occasional fault/missfire

Post by sirch345 »

benny hedges wrote:if you shop around you can get a 14ah the same size as the 12.
Benny, can you please point me in the right direction to the same size 14ah battery :?:

Chris.
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benny hedges
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Re: occasional fault/missfire

Post by benny hedges »

sirch345 wrote:
benny hedges wrote:if you shop around you can get a 14ah the same size as the 12.
Benny, can you please point me in the right direction to the same size 14ah battery :?:

Chris.
its a Yuasa YTX16-BS or equivalent.
the height is like +25mm but it does fit with the cover off. :thumbup:
thats the one i have in my cbx, storm & zxr, my spare one is a ytx14 i think, which is 12ah and about 10mm shorter but the other dimensions are the same.

just noticed you can now get a YTX20CH-BS 18ah battery which will fit the storm.
the only difference is height at 161mm, instead of the standard 133mm, but it will fit without modding the cables if you remove the lid.
the 14ah i have is 160mm tall and there is plenty of room between the battery & seat.... if i was to replace it i'd go for the 18.
i'd say that would be the best option, but will be a lot heavier than the std jobby lol
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Gerrit
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Re: occasional fault/missfire

Post by Gerrit »

Replace the Spark Plug caps

I was battling with a intermittent misfire for months, and eventually, I found the problem in the Spark Plug Caps.

There is a resistor in the cap, that fails, and causes all the drama.

I replaced mine with NGK caps, and the bike has never been better.

Have a look at the photo below...if you remove the rubber sheath, you can unscrew the cap, to reveal the resistor and the spring that conducts the current down to the plug.

The spring was corroded and the resistor was dead.

me thinks this is a fix to many peoples problems.

Image

Regards,
Gerrit
http://www.cornerspeed.co.za
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sirch345
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Re: occasional fault/missfire

Post by sirch345 »

benny hedges wrote:
sirch345 wrote:
benny hedges wrote:if you shop around you can get a 14ah the same size as the 12.
Benny, can you please point me in the right direction to the same size 14ah battery :?:

Chris.
its a Yuasa YTX16-BS or equivalent.
the height is like +25mm but it does fit with the cover off. :thumbup:
thats the one i have in my cbx, storm & zxr, my spare one is a ytx14 i think, which is 12ah and about 10mm shorter but the other dimensions are the same.

just noticed you can now get a YTX20CH-BS 18ah battery which will fit the storm.
the only difference is height at 161mm, instead of the standard 133mm, but it will fit without modding the cables if you remove the lid.
the 14ah i have is 160mm tall and there is plenty of room between the battery & seat.... if i was to replace it i'd go for the 18.
i'd say that would be the best option, but will be a lot heavier than the std jobby lol
As I thought Benny not the same size entirely as the Varadero battery dimensions. Interesting though to know all the same that a YTX16-BS will still fit with the battery cover removed.

Chris.
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benny hedges
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Re: occasional fault/missfire

Post by benny hedges »

sirch345 wrote:
As I thought Benny not the same size entirely as the Varadero battery dimensions. Interesting though to know all the same that a YTX16-BS will still fit with the battery cover removed.

Chris.
yeh but if youre going to go for the 14ah you might as well get the 18 (ytx20ch-bs) as it's the same size as the 14.
thats what ill be getting next time i need a battery.
but the shipping weight is 12 lb lol..... 8O

*be sure to quote the CH if you order one as the ytx20bs is 187mm tall & wont fit.
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AMCQ46
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Re: occasional fault/missfire

Post by AMCQ46 »

Gerrit wrote:Replace the Spark Plug caps

I was battling with a intermittent misfire for months, and eventually, I found the problem in the Spark Plug Caps.

There is a resistor in the cap, that fails, and causes all the drama.

I replaced mine with NGK caps, and the bike has never been better.

Have a look at the photo below...if you remove the rubber sheath, you can unscrew the cap, to reveal the resistor and the spring that conducts the current down to the plug.

The spring was corroded and the resistor was dead.

me thinks this is a fix to many peoples problems.


Regards,
Gerrit
http://www.cornerspeed.co.za
Good info Gerrit.........what do the NGK plug caps look like, and can you put the sheath back on to keep the crap out?
AMcQ
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