Drumnagorrach
Tuned and Synch'ed
Chaps.
Need a bit of advice, my 1988 Cali 3 Dresser,has developed an annoying rattle that resonates through the fairing,all attempts to find the source have failed.
The vibration occurs just under 2000 rpm both on the way up and on the overun. I can run the engine up to the resonance out of gear where it seems to be a little lower say around 1300 rpm ,but it doesnt resonate on the side stand. Nothing is loose around that area ,so I have to assume that it's the angle of lean that prevents the noise.
I can hear noise from behind the cylinders,this noise is very transient and only occurs within a few hundred rpm .
Not being able to find anything loose ,I have to believe that it could be piston or little end noise ,and the vibration from it is finding other bits of the bike to resonate.
So does the frequency match up to any known vibraton patches that these engines develop.
My engine has covered 75,000 miles ,pulls very well ,doesn't smoke or rattle in any other rev bands and the vibration can not be felt when riding.
The noise I observed ,when stationary wasn't rattly /mettalic,more knocking,but as I mentioned only for a very narrow rev band between 1300 and 1900 .
Ideas
Lee
Update. Brought my stethoscope home from work ( not a doctor,I use it for listening to steam traps )
The noise wasn't coming from the engine,but the frame and exhaust !! Dooh.
front lower side stand bolt was making contact with the nearside downpipe. Cut 1/4 " off ,jobs a good un.
I guess that 1800 rpm is the first harmonic of the downpipe,that would lead me to think 3600 is the second ?
Is 3600 max torque on my small valve engine ? it would fit in .
Need a bit of advice, my 1988 Cali 3 Dresser,has developed an annoying rattle that resonates through the fairing,all attempts to find the source have failed.
The vibration occurs just under 2000 rpm both on the way up and on the overun. I can run the engine up to the resonance out of gear where it seems to be a little lower say around 1300 rpm ,but it doesnt resonate on the side stand. Nothing is loose around that area ,so I have to assume that it's the angle of lean that prevents the noise.
I can hear noise from behind the cylinders,this noise is very transient and only occurs within a few hundred rpm .
Not being able to find anything loose ,I have to believe that it could be piston or little end noise ,and the vibration from it is finding other bits of the bike to resonate.
So does the frequency match up to any known vibraton patches that these engines develop.
My engine has covered 75,000 miles ,pulls very well ,doesn't smoke or rattle in any other rev bands and the vibration can not be felt when riding.
The noise I observed ,when stationary wasn't rattly /mettalic,more knocking,but as I mentioned only for a very narrow rev band between 1300 and 1900 .
Ideas
Lee
Update. Brought my stethoscope home from work ( not a doctor,I use it for listening to steam traps )
The noise wasn't coming from the engine,but the frame and exhaust !! Dooh.
front lower side stand bolt was making contact with the nearside downpipe. Cut 1/4 " off ,jobs a good un.
I guess that 1800 rpm is the first harmonic of the downpipe,that would lead me to think 3600 is the second ?
Is 3600 max torque on my small valve engine ? it would fit in .