Two Dead Cylinders??

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gempip
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Two Dead Cylinders??

#1 Post by gempip » Wed Jul 04, 2007 6:37 pm

Hi Gang, Need a bit of advice here, I have bought a very tidy 1982 Honda CB 750F2, Bol d Or, I thought riding it home that the carbs were badly out of sync but on investigating I find that the two nearside pots are not firing, i.e. no spark at the leads. The bike has been standing unrun for some time, (which is why the 2nd left carb is leaking I reckon) Anyway any help, advice welcome. Cheers. John :smt002

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Kwackerz
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#2 Post by Kwackerz » Wed Jul 04, 2007 6:39 pm

swap the coils about, see if the problem follows the move?
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gempip
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#3 Post by gempip » Wed Jul 04, 2007 9:37 pm

Kwackerz wrote:swap the coils about, see if the problem follows the move?
Will do Kwackerz, Thanks. :smt001
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woody
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#4 Post by woody » Thu Jul 05, 2007 10:44 am

I had this on my old ratty bandit, I just sprayed everything with UB40 and it cleared it

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Aladinsaneuk
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#5 Post by Aladinsaneuk » Thu Jul 05, 2007 11:05 am

eh???
UB 40????

soft brummie reggae has that kind of effect???

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woody
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#6 Post by woody » Thu Jul 05, 2007 11:09 am

Yup its 'rock steady' now............... :smt004

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Kwackerz
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#7 Post by Kwackerz » Thu Jul 05, 2007 7:07 pm

:smt005 :smt005
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#8 Post by Falcopops » Fri Jul 06, 2007 11:04 am

Yup 1st thought would be a dead coil.

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gempip
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#9 Post by gempip » Fri Jul 06, 2007 11:57 am

:smt009 A bit of of a problem now, have had the left hand coil and leads checked and its o.k. SO I wonder where to go from there, The right hand side is o.k. and firing. :smt017 :smt017

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Aladinsaneuk
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#10 Post by Aladinsaneuk » Fri Jul 06, 2007 12:10 pm

swop spark plus over - is unusual for them to fail but....

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Falcopops
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Re: Two Dead Cylinders??

#11 Post by Falcopops » Fri Jul 06, 2007 12:37 pm

gempip wrote:the two nearside pots are not firing
Didn't read your 1st post properly.

If it isn't the plugs then:-

It's usual for the outside two and inside two pots to run from a coil each and there's a lazy spark in the pot that isn't on the compression stroke.

Unless I'm wrong abut the way this bike works then both the coils must have been good as proved, but it's odd that one spark works and the other doesn't. Does this bike's ignition sequence work as I think?

Perhaps the low tension side is at fault, points or pickups?

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#12 Post by Kwackerz » Fri Jul 06, 2007 12:49 pm

The glaring problem is that it's a Honda.

:smt002 :smt002 :smt003
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falcomunky
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#13 Post by falcomunky » Fri Jul 06, 2007 3:17 pm

Nailed it K. :smt003
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#14 Post by Trumpeteer » Sat Jul 07, 2007 3:11 pm

New plugs first, no point in pissing about, they can fail under compression.
Is there a spark at the plugs now?
If so replace and check if the suspect headers are getting hot? If not spray easy start direct into the carb inlets of those not getting hot. If they then fire and get hot you know its fuelling and time to check if those carbs are getting juice by removing drain plugs.....

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gempip
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#15 Post by gempip » Sat Jul 07, 2007 6:09 pm

Trumpeteer wrote:New plugs first, no point in pissing about, they can fail under compression.
Is there a spark at the plugs now?
If so replace and check if the suspect headers are getting hot? If not spray easy start direct into the carb inlets of those not getting hot. If they then fire and get hot you know its fuelling and time to check if those carbs are getting juice by removing drain plugs.....


Hi, Thanks for all that, The situation now is that I have got it down now to one potheader is cold after firing up and on that one (a) the plug dosnt seem to spark (although they are supposed to be new plugs and the coil/s has been tested as positive) and the carb that feeds that one is flooding all the time. So I will try another plug and see where we go from there. I suppose the bike being stood for a long time before I got it dosnt help. :smt017
The Time is Now!!!

Red 1995 VFR750 - I luvs it.

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