Author Topic: Cb 550 ss spain  (Read 12798 times)

Offline murdock

  • SOHC Member
  • Posts: 195
    • View Profile
Re: Cb 550 ss spain
« Reply #60 on: April 04, 2021, 03:00:29 PM »
I'm sorry, I have not understood, is this?

Offline murdock

  • SOHC Member
  • Posts: 195
    • View Profile
Re: Cb 550 ss spain
« Reply #61 on: April 04, 2021, 03:06:10 PM »
lo que si he visto es que en todos los cilindros y en todas las alturas o posiciones ,siempre con la falda del piston
 numero 1 tengo el mismo gap que en la foto , varia muy , muy poco

what I have seen is that in all cylinders and in all heights or positions, always with the piston skirt
 number 1 I have the same gap as in the photo, it varies very, very little
« Last Edit: April 04, 2021, 04:59:55 PM by murdock »

Offline murdock

  • SOHC Member
  • Posts: 195
    • View Profile
Re: Cb 550 ss spain
« Reply #62 on: April 04, 2021, 05:02:41 PM »
sorry, I have modified the above message that came out in Spanish

Offline Bryanj

  • Grogu
  • *
  • Posts: 10694
    • View Profile
Re: Cb 550 ss spain
« Reply #63 on: April 04, 2021, 05:22:34 PM »
How big a feeler gauge can you get into the gap between bottom of piston and cast liner at one of points of yellow arrow? If over .002 inch (.08mm) piston or bore or both is worn

Offline murdock

  • SOHC Member
  • Posts: 195
    • View Profile
Re: Cb 550 ss spain
« Reply #64 on: April 04, 2021, 06:02:42 PM »
thus 0.010, mm but in the other direction does not enter 0.04 mm

Offline murdock

  • SOHC Member
  • Posts: 195
    • View Profile
Re: Cb 550 ss spain
« Reply #65 on: April 04, 2021, 06:12:27 PM »
from left to right 0.10 mm, from top to bottom ???

Offline Bryanj

  • Grogu
  • *
  • Posts: 10694
    • View Profile
Re: Cb 550 ss spain
« Reply #66 on: April 04, 2021, 06:55:15 PM »
You did not listen, the only one that matters is the one at right angles to the wristpin (your smaller number)which seems within limit.
Piston are manufactured oval in the fist place so the measurement along wristpin is irrelevant.

0.04 mm is about 0.0015 thou so within tolerance for re use
If the ring gaps in bore are within tollerance you are good to go
« Last Edit: April 04, 2021, 07:00:00 PM by Bryanj »

Offline murdock

  • SOHC Member
  • Posts: 195
    • View Profile
Re: Cb 550 ss spain
« Reply #67 on: April 04, 2021, 07:07:45 PM »
I got into this mess because I couldn't get more than 100 psi of compression, so it was just the rings? You think that with honing and new rings I could get at least 60 psi more, changing the primary chain, bearings, shock absorbers, seals it is already decided that I will do it, but I also thought that I should change pistons and rings

Offline Bryanj

  • Grogu
  • *
  • Posts: 10694
    • View Profile
Re: Cb 550 ss spain
« Reply #68 on: April 04, 2021, 08:15:45 PM »
I think probably your compression gauge is not too good and/or the valves are leaking.
Try standing the head on the inlet ports and filling the exhaust ports with petrol to see if the exhaust valves leak then after that turn it over stand it on the exhaust ports and fill the inlets.
In both cases the gasket surface will be vertical with a set of ports on the top

Offline murdock

  • SOHC Member
  • Posts: 195
    • View Profile
Re: Cb 550 ss spain
« Reply #69 on: April 04, 2021, 08:40:20 PM »
Today I did that test with wd 40, not a leak, the exhaust had a lot of carbon, but they did not leak, the intake ones do not leak and they are very clean and the meter is perfect, I have many, I work with hydraulics and pneumatics every day

Offline murdock

  • SOHC Member
  • Posts: 195
    • View Profile
Re: Cb 550 ss spain
« Reply #70 on: April 04, 2021, 09:11:36 PM »
the kick start no longer offered any resistance, it did not exceed 120 k / h on the highway, I know it was a bit rich but not much, with 100 jets, velocity stacs and quite open exhaust, maybe it was because of the gap in the rings , or reverse rings,
now it doesn't matter
It will be very entertaining to rebuild the engine, I guess this week I'll open it

Thank you very much for your assistance

Offline K2-K6

  • Grogu
  • *
  • Posts: 5234
    • View Profile
Re: Cb 550 ss spain
« Reply #71 on: April 04, 2021, 10:07:49 PM »
As Bryan has said,  you need to measure piston skirt to bore clearance at front or back of piston, not at the side underneath rist pin.

Also, put the barrel upside down and let the piston go all the way down to the end of bore. If you measure them right at the bottom of the barrel,  then it won't show much wear as the piston rings don't travel that far down. 

Likely with velocity stacks that the rings will be worn as no dust is filtered very effectively.  Just depends whether bores are too.  If it runs rich as well that won't help the rings as it washes oil from the bores to increase wear.

Offline Bryanj

  • Grogu
  • *
  • Posts: 10694
    • View Profile
Re: Cb 550 ss spain
« Reply #72 on: April 04, 2021, 10:36:13 PM »
I dont doubt your proficience in tool use but to get a proper reading you need a short hose on the compression tester as a long hose increases the final volume by a marked amount reducing the max compression figure. A better diagnostic test for a small petrol engine is a leak down test where you put the piston on tdc compression and force air invia the plug hole then measure the % pressure drop listening for where the air leaks

Offline murdock

  • SOHC Member
  • Posts: 195
    • View Profile
Re: Cb 550 ss spain
« Reply #73 on: April 05, 2021, 06:49:15 AM »

ok, that sounds good, I'll try next time, thanks for the tip

Offline murdock

  • SOHC Member
  • Posts: 195
    • View Profile
Re: Cb 550 ss spain
« Reply #74 on: April 05, 2021, 11:30:35 AM »
maybe this is the way to do it ???

 

SimplePortal 2.3.5 © 2008-2012, SimplePortal