Engine Noise.

jsouthard · Oct 14, 2008

This is my first Norton. First British.

I followed the other guys lead and posted my bike on youtube.com

The engine seems aggressively loud. I have adjusted the tappets. Is this normal? or should i take the head apart and start looking at the valves?

your help is appreciated!

http://www.youtube.com/watch?v=_jbpDdmYoPI

dgwilson · Oct 14, 2008

What noise annoys an oyster?

Engine noise is subjective. It depends what you are used to. If the engine is running ok and the noise is not getting louder then I would say everything is OK. I bought my Norton in 1977 and had to remove the head for new valves & guides after reassembling and riding it sounded noisy in the valve push rod area I rode it until 1993 when a oil scraper ring collapsed. after fixing it all up with new valves etc again it still sounds noisy but is running as good as ever. I changed my helmet and that made a noticable difference in engine noises that could be heard while riding. But she keeps on running. With engine running on the sidestand it all sounds pretty acceptable.
Mine is a mk11 interstate with the metal timing chain tensioner which adds to the general running noise. Later models have a rubber contact pad that rubs on the chain and apparently reduces noise.

tpeever · Oct 14, 2008

jsouthard said:
This is my first Norton. First British.

I followed the other guys lead and posted my bike on youtube.com

The engine seems aggressively loud. I have adjusted the tappets. Is this normal? or should i take the head apart and start looking at the valves?

your help is appreciated!

http://www.youtube.com/watch?v=_jbpDdmYoPI

It sounds pretty clanky to me. I think I would be hesitant to run it much more until you figure out what is going on. Can you run it side-by-side with a buddy's Commando to compare? What do you know about the history of the bike including engine rebuilds etc? I read somewhere a while ago that one can use a stethoscope (like physicians use) to diagnose engine problems. You can listen to the top and bottom parts of the engine to try to narrow it down.

dgwilson · Oct 15, 2008

a noisy noise annoys an oyster

After listening to the video clip:
I instantly think maybe one carby is out of tune or pilot air blocked, or maybe a burnt exhaust valve. The blue pipe on one cylinder could indicate this cylinder doing all the work & running hot or a burnt valve letting burnt gas into the exhaust? try a compression check. to see if both cylinders have the same compression.

Scooter62 · Oct 15, 2008

I think DGwilson is on to something. It might be the clutch or primary chain but to diagnose the problem get a stethoscope or make one with a piece of tubing and a bolt and listen at various places to see if you can find the source of the major noise.
The british bikes were the original "chattering class" but yours sounds a bit too noisy and erratic. If the carbs are synced and you still have the points ignition check the timing on both sides to make sure its the same.

jsouthard · Oct 15, 2008

Thanks for the input.

Its a single mikuni carb so the engine should be getting an even mixture. Up close its seems to be the valves. I haven't taken apart a head before and just wanted to make sure its not a "normal" sound before i start ripping the bike apart.

The weird thing.... It runs amazing. 900 rpm idle. 4500 rpm's and 65 mph. Exhaust sounds dead on. Clutch is smooth and has no problem finding neutral. one kick, every time. 2 minute choke warm up and the bike is ready to roll.

Its just the noise that has been getting me. I'm not a mechanic AT ALL. but i want to do all the work myself. The hesitancy to take the head apart is because i know that to fix one thing i tend to break three. literally.

Thanks again!

cash · Oct 15, 2008

I agree with ludwig the chain can and will transmit a lot of noise. The valve adjuster can wear a dent/groove in the top of the valve stem giving a false clearance, and worn guides can rattle too.
Cash

79x100 · Oct 15, 2008

It sounds very tappety, especially on the right hand cylinder. Are you sure that you haven't got a false reading somewhere ?

If it were mine and a double check of the tappets didn't reveal anything, I would pull the top end off but this is a bit of a fiddle the first time (trying to support the head with one hand as you attempt to feed four oily pushrods into spaces where they don't really want to go !)

Is there another Commando owner in the area who could give you a hand ?

If you do lift the head, it would probably make sense to remove the cylinder as well and have a look at the cam and followers.

JimC · Oct 15, 2008

I agree, you definitely have too much noise. It may come from any number of places. The usual suspect, valve train, is a good place to start. Once you ascertain valve clearances are correct, the next thing would be to check for correct valve lift. This can be done without removing the head. A worn or loose cam chain can be very noisy, also.

Listening to the video sounds somewhat like piston noise. Checking this would require the head to be removed. Visual of the piston tops and cylinder walls might reveal something.

tpeever · Oct 15, 2008

JimC said:
Listening to the video sounds somewhat like piston noise. Checking this would require the head to be removed. Visual of the piston tops and cylinder walls might reveal something.

I think so too. I think you need to pull the head and cylinder to check. It sounds like one of the pistons may possibly be contacting the cylinder walls. Could ring gaps be too small?

ML · Oct 15, 2008

May be worthwhile checking there is no contact between the left exhaust header and the underside of the primary chain case. Had a recent top end rebuild and on idle it sounded like a main bearing or clutch centre had gone, turned out to be the header pipe knocking against the primary case. Simple adjustment of the pipe fixed that.

Mick

Ron Hulton · Oct 16, 2008

A long time ago i took a small 12 volt bulb and attached 4 foot wire leads to it. It makes for a great inspection lamp when wanting to look INSIDE the cylinder. Just pop the plug out and drop the bulb in and you have a great view . Damaged rings can generally be detected by doing a simple compression check. Just a thought before you rip it all apart .

Hang on to the light ... you'll use it for many years to come. I carry it as part of my tool kit. It is smaller and much brighter than a flashlight and plugs nicely into the auxillary 12 v socket on the right side and 4 ft. leads allow you to access the bike end to end.

mikegray660 · Oct 16, 2008

Ron Hulton said:
A long time ago i took a small 12 volt bulb and attached 4 foot wire leads to it. It makes for a great inspection lamp when wanting to look INSIDE the cylinder. Just pop the plug out and drop the bulb in and you have a great view . Damaged rings can generally be detected by doing a simple compression check. Just a thought before you rip it all apart .

Hang on to the light ... you'll use it for many years to come. I carry it as part of my tool kit. It is smaller and much brighter than a flashlight and plugs nicely into the auxillary 12 v socket on the right side and 4 ft. leads allow you to access the bike end to end.

crafty-me likes!

batrider · Oct 17, 2008

You can't tell a thing from a tinny recording like this. There are no lows just highs. Some years clank more than others. It sounds pretty normal to me.

Russ

Keith1069 · Oct 17, 2008

It does sound out of tune but the noise is typical at least to my mind. If anyone has a copy of the National Motorcycle Museum rebuild DVD try listening to Norman White's NEW Production Racer motor (with it's PW3 cam presumably) Not clanky but very 'tappetty and ringy' if that makes sense. Would try to upload it but it's a VOB file and is copyright. Don't want it getting on YT!

jsouthard · Oct 27, 2008

An update.

I just got the head off. One bent push rod and the others where scratched dent and worn down. This was the noise issue.

thanks for all your advice and help!

joe

Ron L · Oct 28, 2008

Joe,
Any idea what caused the damage? Pushrods don't just bend on their own. A recent mishandled head removal? Missed shift?
There might be further damage. If it was from over-rev (missed shift) you might want to check the valves to make sure they aren't bent and are sealing properly.

Cookie · Oct 28, 2008

This was years ago but it seems like whan I missed a shift and bent a push rod I had marks on the piston from the contact.

jsouthard · Oct 28, 2008

I'm still VERY new to this and not a mechanic.

Because of early carb problems i can't remember if it sounded this way when i bought it this spring.

This is the first head removal since i got it. I don't have the tools to take the spindles out or the valves. I may have Norbsa rebuild the head since he's close to me and the seasons over.

I want to do the work myself but with a lack of tools and when i start reading about "regrinding valves" i start to get nervous.

I'll post some pictures of the pushrods and the pistons. You guys may be able to tell me which direction to go.

jsouthard · Oct 28, 2008

Engine Noise.

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