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General Category => General Discussion => Topic started by: spanner on February 19, 2014, 02:52:13 PM

Title: loss of power in my CB400
Post by: spanner on February 19, 2014, 02:52:13 PM

I have had a CB 400 for about 8 years with varying levels of care and maintainance .... from overly loving and polishing to total disreagard (due to apathy and a period of poverty) back to regular but inept maintainance.

So .... with that caveat I am asking why would my bike be losing power?

Scenario:

There is a hill where I live that when I originally got the bike I would comfortably climb the hill in 4th gear or even 5th is I got a got run up but now I need to drop it all the way back to 2nd just to get up the hill.

Now I have put on some wieght but NOT THAT MUCH!

I also notice now that when I have a headwind I can not get up to 110+ kph where as I used to be able to punch through that number with gay abandon ..... not that there is any thing wrong with that of course.

All you briliant Mechanics out there  .....  what would your diagnosis be .... apart from fatal.

Title: Re: loss of power in my CB400
Post by: Biggles on February 19, 2014, 02:59:25 PM

Air cleaner?
Plugs?
Blocked injector?

Title: Re: loss of power in my CB400
Post by: spanner on February 19, 2014, 03:05:42 PM

I think the plugs are ok as they were only replaced late last year BUT the air cleaner ..... now there is a novel idea!

Title: Re: loss of power in my CB400
Post by: Pezzz on February 19, 2014, 04:05:02 PM

Check your compression too....
Internal Combustion engines come down to 3 things....
Compression, Fuel/Air Charge, and Spark.

Title: Re: loss of power in my CB400
Post by: spanner on February 19, 2014, 04:23:01 PM

Quote from: Pezzz on February 19, 2014, 04:05:02 PM

Check your compression too....

 :o

How does one check ones compresion?

Title: Re: loss of power in my CB400
Post by: Pezzz on February 19, 2014, 04:25:19 PM

With a compression gauge (about $30 from super cheap auto) and take out  your spark plugs and hold compression gauge in the plug hole while turning the motor over.
You then have to refer back to manual for what the compression should be.

Title: Re: loss of power in my CB400
Post by: spanner on February 20, 2014, 08:13:40 AM

Quote from: Pezzz on February 19, 2014, 04:25:19 PM

and hold compression gauge in the plug hole while turning   

 :eek :eek   sounds like something you do in the privacy of your own bedroom.....
 :o :crackup :rofl

Title: Re: loss of power in my CB400
Post by: saaz on February 20, 2014, 08:32:24 AM

The engine should be warm, and keep the throttle wide open to get a true reading.  Does it have carbs or EFI? Which model is it?  If it has been sitting around the fuel system can gum up, and fuel goes off.  A fresh tank of fuel and some fuel system cleaner like techron may do wonders.  New spark plugs would not hurt either.

Title: Re: loss of power in my CB400
Post by: spanner on February 20, 2014, 02:37:38 PM

definitly not stale fuel as I have been doing 100o km a week commuting!

Ill definilty be getting a compression tester and have a go ..... if for nothing else than to teach my son what I was NOT taught.

Title: Re: loss of power in my CB400
Post by: Sicman on February 20, 2014, 02:45:37 PM

Do the simple stuff first - air and fuel filters  :wink1

Title: Re: loss of power in my CB400
Post by: spanner on February 21, 2014, 09:01:43 AM

Oh definitely will do the simple stuff ..... Cause that's what I can do ..... They don't call me spanner for nothing ...... Read my reason for my nickname.

Title: Re: loss of power in my CB400
Post by: JC on May 10, 2015, 10:34:22 PM

Just wondering: did you sort out the cause of the power loss on the CB400?

Title: Re: loss of power in my CB400
Post by: spanner on May 11, 2015, 08:50:06 AM

Yep .... sorted real good. 



Scrapped!

Found out my nephew in law is/was a mechanic and he looked at it and said ...... scrap it!

So it was scrapped.

Gave it to the local tafe for some project which they were happy to have ......  don't know why though.

Title: Re: loss of power in my CB400
Post by: Jglan10 (Onesie) on May 11, 2015, 09:16:06 AM

Do you know exactly what went wrong with it I have a 2012 model

Title: Re: loss of power in my CB400
Post by: spanner on May 11, 2015, 09:47:15 AM

not exactly sure what went wrong with BUT I know the cause of it .......  poverty and a total lack of maintenance and then three years of over weight riding at top speed for over rough roads too and from the sunny coast and Roma.\


Basically treated really badly.

Title: Re: loss of power in my CB400
Post by: Jglan10 (Onesie) on May 11, 2015, 10:41:40 AM

Mine gets treated like a baby