Missfire at 5000rpm - two years to solve
02-07-2009, 02:22 PM
#1
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Squid
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Join Date: Oct 2008
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Missfire at 5000rpm - two years to solve
Im posting this just for anyones information, if they ever come across this problem as it had me stumped for nearly two years.
This will only apply to a Japanese Domestic model VTR of 97/99 vintage, but in case anyone reading this has, or may get a bike from Japan, here goes.
In New Zealand, many, many bikes are imported directly from Japan - both domestic market models and export market models...which are generally unrestricted.
My VTR was a Japanese Domestic model, which have carb restrictors ( easily removed) and a 180 kph speedo, along with a restriction to 175kph.
This speed restriction is common to most, if not all Japan Domestic bikes, ( and cars too) irrespective of manufacturer, and racers will all be familiar with de-restriction means.
My bike had a misfire, on the front pot, at about 5000rpm - ie about half red line engine speed. It started and ran perfectly, in all other respects, except it would not rev without a misfire over 5000rpm.
Without going into the trial and errors of trying to fix this problem, including it spending a month at the local Honda dealership, who also could not solve the problem, we tried all the possibilities short of changing the wiring loom.
Then a friend loaned me a POSH FAITH RED REV , which is a Japanese market de-restriction device. It has 2 x 6P plugs that fit it between the 6P on the wiring loom, and the 6P from the instruments. It also has 1 x single red wire, that has a single female bullet connector. We could not work out where this single wire attaches to...being red it may be 12V + but I was not game to plug it in without being 100% certain.
It turns out that there is a ORANGE / BLUE single wire in the wiring loom that it connects to. Where this OR/BL wire goes, I still have to find out, but most liely the computer.
This wire had been tucked back into the housing of the loom and was not apparent at any time over the two years - ie I didnt know it was there.
This OR/BL wire attaches, normally to a single wire from the instruments.
My bike must have originally had a de-restrictor on it in Japan, and when sold for export someone had removed it -and the bike had come from Japan with this wire having been removed, and the OR / BL wire tucked back into the loom...ie not connected back to its "mate"
The additon of the RED REV here, FIXED the misfire...so if anyone comes across this problem, the symptom is that if that OR/BL is not attached to its "mate" from the insruments, the bike will missfire...on the front pot only.
I still have yet to discover just what colour this wire is, and where it attaches into the instrument housing but that will be easy when I find another stock bike to check out...probably to the speedo.
oh - and over the 2 years, one can ride a VTR all the time at under 5k rpm , it must have saved me getting the odd ticket ...5k is still 140 kph on the open road
Grant
NZ
This will only apply to a Japanese Domestic model VTR of 97/99 vintage, but in case anyone reading this has, or may get a bike from Japan, here goes.
In New Zealand, many, many bikes are imported directly from Japan - both domestic market models and export market models...which are generally unrestricted.
My VTR was a Japanese Domestic model, which have carb restrictors ( easily removed) and a 180 kph speedo, along with a restriction to 175kph.
This speed restriction is common to most, if not all Japan Domestic bikes, ( and cars too) irrespective of manufacturer, and racers will all be familiar with de-restriction means.
My bike had a misfire, on the front pot, at about 5000rpm - ie about half red line engine speed. It started and ran perfectly, in all other respects, except it would not rev without a misfire over 5000rpm.
Without going into the trial and errors of trying to fix this problem, including it spending a month at the local Honda dealership, who also could not solve the problem, we tried all the possibilities short of changing the wiring loom.
Then a friend loaned me a POSH FAITH RED REV , which is a Japanese market de-restriction device. It has 2 x 6P plugs that fit it between the 6P on the wiring loom, and the 6P from the instruments. It also has 1 x single red wire, that has a single female bullet connector. We could not work out where this single wire attaches to...being red it may be 12V + but I was not game to plug it in without being 100% certain.
It turns out that there is a ORANGE / BLUE single wire in the wiring loom that it connects to. Where this OR/BL wire goes, I still have to find out, but most liely the computer.
This wire had been tucked back into the housing of the loom and was not apparent at any time over the two years - ie I didnt know it was there.
This OR/BL wire attaches, normally to a single wire from the instruments.
My bike must have originally had a de-restrictor on it in Japan, and when sold for export someone had removed it -and the bike had come from Japan with this wire having been removed, and the OR / BL wire tucked back into the loom...ie not connected back to its "mate"
The additon of the RED REV here, FIXED the misfire...so if anyone comes across this problem, the symptom is that if that OR/BL is not attached to its "mate" from the insruments, the bike will missfire...on the front pot only.
I still have yet to discover just what colour this wire is, and where it attaches into the instrument housing but that will be easy when I find another stock bike to check out...probably to the speedo.
oh - and over the 2 years, one can ride a VTR all the time at under 5k rpm , it must have saved me getting the odd ticket ...5k is still 140 kph on the open road
Grant
NZ
Last edited by grantm; 02-07-2009 at 02:33 PM. Reason: typo
02-09-2009, 04:59 AM
#3
ole dirty bastard
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