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Author Topic: Honda CB450 K5 Cafe Racer.. ish  (Read 9707 times)

Offline Flugtechnik

  • Posts: 3026
  • My bike is not transportation, it is a respite
    • Nixon and Me
Re: Honda CB450 K5 Cafe Racer.. ish
« Reply #40 on: Aug 14, 2016, 23:29:41 »
This bike will not run with the choke fully closed.  With these carbs, if the choke is fully closed, you have blocked off all air flow into the carbs.  You need fuel, spark, and AIR for combustion to occur.  When I start my bike cold, I only close the choke about half way.

A cold bike tends to run lean because the fuel is not fully atomizing.  A lean bike tends to rev up.  Closing the choke lever partially restricts the air flow into the carb, causing the mixture to be richer.  I only close the choke enough to keep the engine from revving up.  I only have it partially closed for about 30 seconds.

Somewhat related to this, if you are riding and the bike starts revving up at a stop light or popping while you are riding, you are probably out of gas.  A revving engine is a sign of your mixture leaning out.  This happens when you don't have enough fuel in your carb bowls.

Next time you start the bike, tap the headers with your fingers.  They should warm up about the same.  Yes, eventually they will be so hot that you can no longer touch them.


I just pulled my pistons and found a broken ring.  I had no idea.  I just knew it was burning oil.

« Last Edit: Aug 14, 2016, 23:41:04 by Flugtechnik »

Offline bezugo

  • Posts: 53
Re: Honda CB450 K5 Cafe Racer.. ish
« Reply #41 on: Aug 15, 2016, 16:53:18 »
I see..   Still.. whoever engineered the bike probably intended for the choke to work fully closed. The butterfly has a flap with two windows for it.  Some air should pass.


I am still trying to get away without rebuilding the engine until next winter.  If i'm not causing permanent harm to the engine, then i'll let it be for the summer.
Anyway, she will never do more than a couple hundred miles until the winter.

She does exactly what you describe. Revs up at stoplights and pops especially when maintaining speed or letting go of the throttle.
I can get it to calm down by letting go of the clutch a lit bit to force the engine to lower the revs and it maintains 1,5k revs until next stoplight.

I will do a compression test as soon as possible.

Thanks a lot to all that helpped  ;)

Offline bezugo

  • Posts: 53
Re: Honda CB450 K5 Cafe Racer.. ish
« Reply #42 on: Aug 15, 2016, 16:58:40 »

I just pulled my pistons and found a broken ring.  I had no idea.  I just knew it was burning oil.



How old were those rings and pistons?

Offline Flugtechnik

  • Posts: 3026
  • My bike is not transportation, it is a respite
    • Nixon and Me
Re: Honda CB450 K5 Cafe Racer.. ish
« Reply #43 on: Aug 15, 2016, 21:06:26 »
I think I put them in in 2009?  Put a few thousand miles on them.

My bike used to rev up all the time too. Not sure what fixed it. Maybe the electronic ignition or maybe the Uni filters.

If it is running and not making awful sounds ride that bitch. Just keep an eye on the oil.


end of line

Offline bezugo

  • Posts: 53
Re: Honda CB450 K5 Cafe Racer.. ish
« Reply #44 on: Aug 15, 2016, 21:57:44 »
My bike has under 10k miles on the clock.  If it ran without it i don't know.

I will ride it as is, but that high idle has got to be fixed.  The bike is loud, and revving like crazy on stoplights gets people to close car windows and cover their ears on the sidewalk.  Embarrassing and uncomfortable.

Tomorrow i'll change the o-rings and washers on the carbs, tighten the exhausts a bit more and then make a video of how she sounds and rides.

Thanks again

Offline bezugo

  • Posts: 53
Re: Honda CB450 K5 Cafe Racer.. ish
« Reply #45 on: Aug 15, 2016, 22:44:49 »
Are those EMGO pods? If so, throw them in the trash, or do some searching for the technique to mod them so they don't restrict airflow.

I read about why they suck, but mine do not block anything.  I didn't even notice any difference between pods and no filters.

Where can i find that technique to modify them?

What i had there before starting the build was the same as no filters. Just a wire mesh stopping stones and (maybe) sand from getting in.

Should it run better without filters than with those pods?

Offline bezugo

  • Posts: 53
Re: Honda CB450 K5 Cafe Racer.. ish
« Reply #46 on: Aug 15, 2016, 23:34:33 »
This is what was there before.  I guess they're called velocity stacks.



Is this any better?

Offline bezugo

  • Posts: 53
Re: Honda CB450 K5 Cafe Racer.. ish
« Reply #47 on: Aug 18, 2016, 22:25:14 »
Today i went over a few things.

Checked the right exhaust to see where the leak was coming from.  Its oil coming from the exhaust.
There was no gasket there so i put a new one on.

Modified the baffles inside the mufflers to make them quieter.  I cut it and bent the metal to make something similar to this.



When i opened the mufflers all the glass fiber wool had gone. And just after two short drives.  I made less than 20 miles.
So i replaced it with stainless steel wool.   Hope it lasts longer.

What is normally done in this case?  Do you guys try to quieten down your exhausts?  How?

Offline bezugo

  • Posts: 53
Re: Honda CB450 K5 Cafe Racer.. ish
« Reply #48 on: Aug 20, 2016, 10:12:58 »



Sent from my iPhone using DO THE TON

Offline bezugo

  • Posts: 53
Re: Honda CB450 K5 Cafe Racer.. ish
« Reply #49 on: Aug 24, 2016, 12:00:04 »
I went over the points adjustment again and found that the right one was out of sync.
Adjusted it and now, not only it starts much easier, but I got it to idle properly at around 1200 revs.

No more spewing of oil after the new gasket.

Only thing now is that it still doesn't rev over 5000 revs
Where to look next?