engine loud when hot.
Seasoned HDF Member
Joined: Jan 2006
Posts: 11,463
Likes: 2,990
From: Charleston, SC
That's not quite so! Oil viscosity is a confusing subject and we have demonstrated that in various threads around HDF over the years. Unfortunately there are also umpteen websites with 'stuff' all about it, which I'm not sure clarify things very well! When 50W oil is hot I'm not sure we can be confident that it is thicker than cold 20W. 
This thread could run and run......
This thread could run and run......
EDIT: It's a "Hot 50 weight" though which will be lighter than a Cold 20 weight. It's thinning as it gets hot like all oil, but at rate more like a 50 weight oil.
You'd be surprised of the number of people that don't know what those numbers actually mean there old chap!
Last edited by lp; Jul 17, 2017 at 07:43 AM.
Seasoned HDF Member
Joined: Mar 2010
Posts: 38,310
Likes: 6,328
From: Honah Lee
Actually, if you look to the past, the clearance, especially between the piston to the cylinder, is about 1/5 what it used to be.
Most of the noise you hear is roller bearing clearance. Unlike the gliding material, half-shell bearings of a car motor, that steel to steel rollers are noisy.
Coffee makes it worst.
Do not try to fix it with tin men oil products. Those rollers roll, the best thing for them is a thin enough oil to flush them.
Especially those small needles in the input shaft of the transmission.
Most of the noise you hear is roller bearing clearance. Unlike the gliding material, half-shell bearings of a car motor, that steel to steel rollers are noisy.
Coffee makes it worst.
Do not try to fix it with tin men oil products. Those rollers roll, the best thing for them is a thin enough oil to flush them.
Especially those small needles in the input shaft of the transmission.
Seasoned HDF Member
Joined: Jan 2006
Posts: 11,463
Likes: 2,990
From: Charleston, SC
That's true. It's because the second number is stating that the oil will move like a Hot 50 weight not a Cold 50 weight.
Stellar HDF Member
Joined: May 2015
Posts: 2,091
Likes: 304
From: mid Michigan
Oil cooler & head cooler makes mine stay happy sounds about the same hot . I hated the noise before those two mods when it would get above 70 f out. Now I run 15- 50 and she purrs all summer long. I thought must the noise on these twin cams is the rockers on the vavles, but it could be bearings too, like was mentioned.
Thread Starter
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Road Warrior
Joined: Sep 2007
Posts: 1,252
Likes: 142
All very interesting info and everyone does know when oil is hot it is thinner. What gets me is this. We need lubrication. Multigrades are or were designed for cold weather startups by allowing the oil to flow in cold temps. The bike is quiet in cold temps. So if an oil that flows and or is as thick as 20 wt lubricates adequately in the cold then why not use a thicker oil when hot. We are told that 60 wt oil is not good for a motor when temps are below 80 deg. F., yet 20 wt oil cold is still thinker than 60 wt hot and it adequately lubricates. Am I spinning my wheels here? I'm trying to understand the logic behind it. My manual too says run 60 wt when operating in temps about 80 def F. and with additives like lucas that coats internal parts specifically for cold starts I'm just saying. I am not looking to start a war but given the number posts and discussions all over the internet for years now, cant someone come up with something that will keep these skoots quieter? Are you listen HD, maybe its you.
thanks guys
randy
thanks guys
randy
Club Member
Joined: Jun 2007
Posts: 45,429
Likes: 2,897
From: Bedford UK
I live close to an auto industry test site, where they test autos, bikes and other new and development vehicles for various manufacturers. I have several friends who work there and the extremes that modern vehicles are tested to way exceed what we mere mortals will normally put up with, especially cold and heat. No matter what each of us thinks of our bikes, they will survive far worst conditions than us.
If your bike is unmodified, just service it and ride. If your bike is modified from stock, make sure it is correctly tuned - then service and ride! Wear earplugs - we've been encouraged to do that since the 1970s - best tuning aid known to mankind.....
If your bike is unmodified, just service it and ride. If your bike is modified from stock, make sure it is correctly tuned - then service and ride! Wear earplugs - we've been encouraged to do that since the 1970s - best tuning aid known to mankind.....
Road Warrior
Joined: Nov 2014
Posts: 1,962
Likes: 140
From: NY
Ok I'm bored and feeling like stirring the pot. I'm running 20-60 and when the bike is cold and for the first five or seven miles, the engine sounds awesome. Shut it down and have a coffee then it sounds like a typewriter. Ok I get it, its hot but with all the BS about viscosities staying the same why the hell is a cold bike with cold oil with a greater flow rate quiet yet louder if the oil when hot supposedly is a higher number. Thermal expansion of the engine and its internal parts, making things more loose? I'm missing something here but notice, I didn't mention brands.
randy
2003 RKC
randy
2003 RKC
Ok,you say you ride only 5-7 miles with motor sounding good & quiet & then shut it down to have coffee.
Then you refire bike after coffee brk &it makes more valve/lifter &general engine noise then it did in short 5-7 mile ride.
Well the motor &esp oil did not get even close to normal full op tem in the short 5-7 mile ride before you shut it down so oil was likely still at approx 25 wt with motor still a bit warmer then stone cold when you refire the bike post coffee brk where engine clearance is a bit wider then when stone cold with oil still at lower tep & lower 20-25ish wt resulting in more overall engine noise.
It's when engine oil temp gets to approx 215-220ish deg f when using 20-60 multi visc oil that it changes from it's lower colder temp visc of 20-25wt to approx 60w grade oil at full op temp.
Hope this helped you out.
Scott
Last edited by wscott; Jul 17, 2017 at 02:25 PM.
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Cruiser
Joined: May 2016
Posts: 168
Likes: 7
From: The Great State of Ohio
when I first started riding Harley's when I was young I was amazed at all of the clattering. Now years later I seen that hasn't changed with my 01 RK. I have excepted that and just enjoy the ride. In my later years I now wear foam ear plugs most of the time to protect what hearing I have left. So I just keep my bike stock and maintained and live with the clattering.
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Road Warrior
Joined: Sep 2007
Posts: 1,252
Likes: 142
wscott, I beg to differ about it not being hot. I live exactly five miles away from this coffee shop. When I get there the rocker boxes are hot enough to not be able to put your hand on them. The bike sits for no more than ten min before I leave. I grab a small coffee, chug it down then go. I have noticed this as well on a longer ride. 15 from cold and its not too bad, shut it down for ten, heat rises you know and dispates through the whole motor and is just as hot. Shut it down for ten or so and starts to clatter. The bike having aluminum cylinders and heads will dissipate heat fast but not enough to cool it down in five or ten min. Just my observation.
The whole reason for this post originally is not really to argue or stir everyone up about oils, just wanted to know originally why after 100 + years we all just accept "they all do that" NO THEY DONT. I have been with four different identical bikes with close to the same mileage on all. Every one sounds different. Why? You can send a spacecraft past Pluto but cant figure out what the Japanese did 40 years ago. I may have to live with the clatter but I don't have to accept the excuses for it.
randy
The whole reason for this post originally is not really to argue or stir everyone up about oils, just wanted to know originally why after 100 + years we all just accept "they all do that" NO THEY DONT. I have been with four different identical bikes with close to the same mileage on all. Every one sounds different. Why? You can send a spacecraft past Pluto but cant figure out what the Japanese did 40 years ago. I may have to live with the clatter but I don't have to accept the excuses for it.
randy