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Author Topic: Engine smoking  (Read 2789 times)

Offline yozzer74

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Engine smoking
« on: October 17, 2016, 02:04:15 PM »
Hi I've just done about 20 miles on bike noticed she smoking a lot .I thought it may have been because of just rebuilding engine .but I think it's getting worse .it's kicking a little oil out of the breather pipe on crank case too .video attached https://youtu.be/jGkBzsxAnXE
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Offline yozzer74

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Re: Engine smoking
« Reply #1 on: October 17, 2016, 02:06:10 PM »
Any ideas what's wrong
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Offline philgresty

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Re: Engine smoking
« Reply #2 on: October 17, 2016, 03:23:21 PM »
looks like piston ring blow by to me. did you replace the piston rings with the rebuild?
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Offline yozzer74

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Re: Engine smoking
« Reply #3 on: October 17, 2016, 03:38:49 PM »
Yeah I changed rings new valve guides seals recur seats
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Offline MrDavo

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Re: Engine smoking
« Reply #4 on: October 17, 2016, 03:42:22 PM »
The rings might just need bedding in, don't tear it down again just yet.
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Offline yozzer74

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Re: Engine smoking
« Reply #5 on: October 17, 2016, 03:45:44 PM »
Do we think putting different oil in will help
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Offline tom400f

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Re: Engine smoking
« Reply #6 on: October 17, 2016, 04:06:49 PM »
20 miles today or 20 miles since rebuilding it?

What is the colour of the plugs? Consistent across all cyls?

What oil are you using? Doubt it will make any difference. Just to say I am using the Europarts semi-synth diesel stuff discussed on here without any apparent problems.

Edit: Watched the rebuild video - must say, lovely work.
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Offline Bryanj

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Re: Engine smoking
« Reply #7 on: October 17, 2016, 04:07:17 PM »
what oil is in it?
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Offline Johnwebley

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Re: Engine smoking
« Reply #8 on: October 17, 2016, 04:15:22 PM »
after an engine rebuild,you should use the most basic mineral oil,
it helps the motor bed in,also a bit of firm acceleration and then shutting the throttle helps the ring to seal,

 the smoke looks either the pump is not scavenging ,or the rings are not bedded in,or the valve stem seals are leaking

check the plugs,see if they all show oily tips,
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Offline yozzer74

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Re: Engine smoking
« Reply #9 on: October 17, 2016, 04:21:44 PM »
The plugs are black  .this is the oil [ Guests cannot view attachments ]
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Online K2-K6

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Re: Engine smoking
« Reply #10 on: October 17, 2016, 04:39:01 PM »
Did you prep the bores at all by glaze busting them to allow running in of new rings?
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Offline Johnwebley

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Re: Engine smoking
« Reply #11 on: October 17, 2016, 04:51:17 PM »
try a basic oil,
  the better oil prevents the parts bedding in,

http://www.sparesworld.co.uk/10w40-Mineral-Engine-Oil-5ltr.html

  you may find it cheaper,but don't use any synthetic till the motor is well run in
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Offline philgresty

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Re: Engine smoking
« Reply #12 on: October 17, 2016, 04:52:50 PM »
looks like car oil, might not be the best for the wet clutch in your cb.
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Offline yozzer74

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Re: Engine smoking
« Reply #13 on: October 17, 2016, 05:27:02 PM »
I had bores crossed hatched I think they call it .yeah it's car oil
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Offline UK Pete

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Re: Engine smoking
« Reply #14 on: October 17, 2016, 05:32:31 PM »
Hey yozzer, my F2 smoked like a pig after the rebuild, then after about 100 miles it started to run clear  until nothing so it could just be bedding in, btw these old bikes really do f=ck with your head, it can be so frustrating, but stick with it fella
pete
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