Knock, knock......
- Thread starter PaulE
- Start date
I tore down my '91 motor in 2007 and replaced the crankshaft and rod big-end bearings. The bike ran great but after about an hour of riding and it was thoroughly warmed (I live in FLorida, so it was WARMED), I would feel/hear a sort of thumping from the engine. Long story short, I stopped using synthetic oils and switched to Castrol GTX 20W-50 and the thumping stopped. The thumping only seemed to appear after riding a while on really hot days...
That sounds a lot like what I'm getting. It only knocks when hot (when the oil has thinned a bit).
My bike had, i'm assuming, regular oil in it when I bought it. On the advice of a mechanic, I switched to Amsoil 10W40 ($100). But no improvement in the knock.
Maybe I should drain the Amsoil and try 20W50.
Why did you find it necessary to change the crank and bearings in the first place?
My bike had, i'm assuming, regular oil in it when I bought it. On the advice of a mechanic, I switched to Amsoil 10W40 ($100). But no improvement in the knock.
Maybe I should drain the Amsoil and try 20W50.
Why did you find it necessary to change the crank and bearings in the first place?
Andrew Shadow
Site Supporter
Assuming that the correct oil is being used and that the correct oil isn't 20W50 for your conditions, changing to 20W50 oil to stop the knocking sound is treating the symptom not the cause. If changing oil stops the knock, the thought occurs that it might be worth finding a gauge and checking the oil pressure to make sure that there isn't an oil delivery problem before tearing it open. At least you will know whether or not you need to look more closely at the oil pump when you are in there. One would hope that the low oil pressure light would illuminate if there was a problem but who knows, there could be a defect in that system, so it might also be worth checking that the oil pressure sensing circuit and light are functioning correctly while you're at it.
I can't disagree with anything you are saying.
I'm pretty sure that heavier oil will eliminate or at least reduce the knock.
An oil pressure check is also a good idea.
Does anyone know where the oil pressure sender is, and what a good oil pressure reading would be?
Uncle Phil
Site Supporter
Right side near the back - it screws into the bottom end of the engine.
You may have to remove the low cowling and lower fairing to get at it.
Take a good flashlight, remove the side inspection cowling and see if you can see it.
Number 5 is the switch (HPN- 35500-MJ4-024) -
ReSTored
Site Supporter
You might want to join st-riders as it can also be a great source of info
Andrew Shadow
Site Supporter
Hey, it's me again.
I finally got around to doing a compression test and oil pressure test, hot.
Compression is between 170 and 180 PSI on all cylinders except #2 takes a little longer to get up there.
Oddly oil pressure seems to increase a bit as the engine warms up.
Cold, 30 PSI @ idle and 45 PSI @ 5000 RPM
Fully warmed up (175 F at the thermostat housing) 18 PSI @ idle and 55 PSI @ 5000 RPM.
So we're definitely at the lower end of the spec. The oil is Amsoil 10W40.
I took some video as the knock was becoming audible with the bike being hot.
At 1100 RPM the frequency is approx. 500 knocks per minute, comparing to a metronome app on my phone.
Not sure if there is any significance in that but I thought I'd throw it out there
I tried to insert the clip but it looks like MP4's are taboo.
I still believe I'm looking at a teardown for my winter project.
Will keep you all posted.
I finally got around to doing a compression test and oil pressure test, hot.
Compression is between 170 and 180 PSI on all cylinders except #2 takes a little longer to get up there.
Oddly oil pressure seems to increase a bit as the engine warms up.
Cold, 30 PSI @ idle and 45 PSI @ 5000 RPM
Fully warmed up (175 F at the thermostat housing) 18 PSI @ idle and 55 PSI @ 5000 RPM.
So we're definitely at the lower end of the spec. The oil is Amsoil 10W40.
I took some video as the knock was becoming audible with the bike being hot.
At 1100 RPM the frequency is approx. 500 knocks per minute, comparing to a metronome app on my phone.
Not sure if there is any significance in that but I thought I'd throw it out there
I tried to insert the clip but it looks like MP4's are taboo.
I still believe I'm looking at a teardown for my winter project.
Will keep you all posted.
I synched and synched again perfectly, but when really hot, I could feel an odd cylinder while slipping the clutch. I finally got round to tweaking the pilot screws and it's fine now. It was a bit of an ordeal, which I won't go into here...!
I'm willing to try anything before removing the engine, but I think the marginal oil pressure is telling me something I really didn't want to hear.
I have already synced the carbs and I'm confident that they are all pretty close.
When I had the carbs off, they were all spotless. I turned all the pilot screws out 2 turns as was suggested on this forum.
I am in the process of making a bendy pilot screw adjuster. I'll post how I did it here (if it works). I'm using Stainless aircraft cable for the bendy part, and 1/4" brake line squished into a "D" shape using the chuck of a small lathe.
I have already synced the carbs and I'm confident that they are all pretty close.
When I had the carbs off, they were all spotless. I turned all the pilot screws out 2 turns as was suggested on this forum.
I am in the process of making a bendy pilot screw adjuster. I'll post how I did it here (if it works). I'm using Stainless aircraft cable for the bendy part, and 1/4" brake line squished into a "D" shape using the chuck of a small lathe.
Hello again. Looking for some advice on ST1100 engine removal.
I'm 4 days into the part of Alan's video, where he says "and the engine drops nicely down oth the wooden blocks.
A question for Uncle Phil. If I remove the alternator, can I re-install the engine in the frame with the alternator bolted back into the engine?
The areas that I am having difficulty with are;
The alternator and the shifter tab welded to the frame under it.
The rear tab on the frame that receives the removable frame section interferes with the engine case, preventing the engine from being moved to the left.
The lower RH threaded tab that the sits just below the RH cam sprocket hits on the frame preventing me from moving it forward more than about 3/4".
Thanks in advance.
I'm 4 days into the part of Alan's video, where he says "and the engine drops nicely down oth the wooden blocks.
A question for Uncle Phil. If I remove the alternator, can I re-install the engine in the frame with the alternator bolted back into the engine?
The areas that I am having difficulty with are;
The alternator and the shifter tab welded to the frame under it.
The rear tab on the frame that receives the removable frame section interferes with the engine case, preventing the engine from being moved to the left.
The lower RH threaded tab that the sits just below the RH cam sprocket hits on the frame preventing me from moving it forward more than about 3/4".
Thanks in advance.
Uncle Phil
Site Supporter
I know exactly what you are talking about on the rear tab and the shifter tab - they make removal and installation a royal pain in the anatomy.
A little more thought on the engineering side and it would be a lot easier!
Yes, if you remove the alternator to get it out you can reinstall the alternator before you reinstall the engine.
My only caution is when you remove it be careful and not pull out the drive gear as it is a royal pain to try to get back in.
Look carefully at where you pry to get the alternator out.
You will have to reach the lower alternator bolt (there are 3 ) from the bottom.
My engine didn't 'drop nicely down' either time - it sort of fell out of the frame once I got it the right place.
Getting it back it is real 'challenge' but pay very close attention as to where Mr. Millyard places his lift straps - it make a lot of difference as I found out.
If the strap on the left head is not positioned properly - around the engine and where the top of it goes - it will lift the entire engine instead of swinging the left head up into the frame.
A little more thought on the engineering side and it would be a lot easier!
Yes, if you remove the alternator to get it out you can reinstall the alternator before you reinstall the engine.
My only caution is when you remove it be careful and not pull out the drive gear as it is a royal pain to try to get back in.
Look carefully at where you pry to get the alternator out.
You will have to reach the lower alternator bolt (there are 3 ) from the bottom.
My engine didn't 'drop nicely down' either time - it sort of fell out of the frame once I got it the right place.
Getting it back it is real 'challenge' but pay very close attention as to where Mr. Millyard places his lift straps - it make a lot of difference as I found out.
If the strap on the left head is not positioned properly - around the engine and where the top of it goes - it will lift the entire engine instead of swinging the left head up into the frame.
Uncle Phil
Site Supporter
You want to pry on the alternator flange not the gear drive flange.
Hard to see when it is in place.
Hallelujah, it's out!! Once I loosened the alternator it practically leapt onto a foot thick pile of moving blankets.
And yes, I figured out what part to leave on the engine, actually Alans video shows it quite nicely.
Once again Phil, I owe you!!
Cheers,
Paul
And yes, I figured out what part to leave on the engine, actually Alans video shows it quite nicely.
Once again Phil, I owe you!!
Cheers,
Paul
Uncle Phil
Site Supporter
Glad you got the easy part done!
I found that removing the alternator gives you a lot more 'working' room.
I don't know if you could install the engine without it and put it back in once the engine is in place or not.
I just didn't want to get the engine back in without it then find out I couldn't reinstall the alternator without removing the swingarm.
But it would make engine reinstallation a lot easier!
I found that removing the alternator gives you a lot more 'working' room.
I don't know if you could install the engine without it and put it back in once the engine is in place or not.
I just didn't want to get the engine back in without it then find out I couldn't reinstall the alternator without removing the swingarm.
But it would make engine reinstallation a lot easier!
Uncle Phil
Site Supporter
It looked like that to me also - you might have to have it sort of in place before you move the engine in.
As I said, I just didn't want to go through the hassle of trying it and then having to pull the engine again if I was wrong.