Need opinion on engine please.
Posted: Thu Sep 26, 2019 1:44 am
My 79 CBX with a 81 school motor has been a perfect running machine for the 3 years since I have owed it. The carbs were done by Mr. Nixon a few years back and it starts on the first tick etc. But....The other day I started it up after sitting for just a couple weeks, (Always on the center stand) and it seemed to run fine. Took it for a test ride and around 4100 RPM I detected a slight hesitation and a noticeable crack like back fire sort of sound from the left exhaust. The engine was warm and the issue occurs at about 4100 RPM to about 4500 RPM whenever the throttle is held steady in that regime. It seems to run smooth above 5000 RPM and below about 4000 RPM.
I did a heat gun on the exhaust and the #2 was about 60 degrees colder than the rest. *Sources tell me that that is well within the range. I swapped plugs with the
# 1 # 2 cylinders and no improvement. I have yet to check the OEM paper filter but that is my next step. Now, before I start tearing carbs apart, chasing sparks, etc, is this indicative of any known issue that comes to mind. Please feel free to jump in here if you have any thoughts or remedies or just opinions. anything would be helpful at this point.
Data:
- 79 CBX SS with 81 engine.
-Carbs tuned done to perfection about 2-3 years ago.
-Valves shimmed about the same time carbs done.
-Plugs not changed.
-Using Lucas oil safeguard Ethanol Fuel Conditioner.
-Regular oil changes.
-I ride it about 3 time a month.
-Always on the center stand.
-Glass fuel filter.
-Motobatt battery.
-Tims CBX alternator installed.
Thanks in advance for any help.
Cheers,
Sky
PS: I have been real busy with a high level restoration of a 1975 Suzuki GT750.
Blog is here:
http://www.kettleclinic.co.uk/kcforum/v ... =6&t=12043
-
My CBX:
https://www.youtube.com/watch?v=kZEMXpomCZU
I did a heat gun on the exhaust and the #2 was about 60 degrees colder than the rest. *Sources tell me that that is well within the range. I swapped plugs with the
# 1 # 2 cylinders and no improvement. I have yet to check the OEM paper filter but that is my next step. Now, before I start tearing carbs apart, chasing sparks, etc, is this indicative of any known issue that comes to mind. Please feel free to jump in here if you have any thoughts or remedies or just opinions. anything would be helpful at this point.
Data:
- 79 CBX SS with 81 engine.
-Carbs tuned done to perfection about 2-3 years ago.
-Valves shimmed about the same time carbs done.
-Plugs not changed.
-Using Lucas oil safeguard Ethanol Fuel Conditioner.
-Regular oil changes.
-I ride it about 3 time a month.
-Always on the center stand.
-Glass fuel filter.
-Motobatt battery.
-Tims CBX alternator installed.
Thanks in advance for any help.
Cheers,
Sky
PS: I have been real busy with a high level restoration of a 1975 Suzuki GT750.
Blog is here:
http://www.kettleclinic.co.uk/kcforum/v ... =6&t=12043
-
My CBX:
https://www.youtube.com/watch?v=kZEMXpomCZU