40W No Kick

Hey all, only posted a couple times but I search the site frequently. I’m slowly (very) bringing my ’70 Fastback to life after sitting in storage for many years. Still some things to conquer, but now that I have fixed the dragging clutch, rebuilt the carbs, have new Avons, sorted some electrical gremlins, etc. she runs and handles well.

However, I’m curious about something. In an only partially successful attempt to reduce wet-sumping I used 40w oil (non-detergent as recommended somewhere). The problem then was that the kick start lever didn’t want to budge unless all the stars were perfectly aligned in relation to TDC (that’s my assumption anyway). So, taking the advice of some folks on this site, I changed to 20W-50 (Castrol conventional 4 stroke) and she kicks-over consistently fine now when given a good deliberate kick.

My curiosity question is this. Given that I’m draining the sump before cranking, what specific area(s) in the oil circulation system do you reckon was objecting to the 40W?? I’m envisaging some tiny orifice somewhere that the higher viscosity oil just couldn’t squeeze through quick enough!? I’m on the Texas Gulf Coast and the weather has been mild, so it’s not due to temperature (although everyone is all excited about the approaching polar vortex).

Any feedback or other comments appreciated.

Thanks….

40W is way thicker than I ever tried. I did use 50W racing oil and that was fine for the summer.

My first guess would be the sump but you said you drained it. Maybe it was just the oil in the timing cover. That 40W stuff must have been like molasses.

I ran straight racing 50 Pennzoil in my Norton most of its life all year round, a old American use to import Pennzoil here but he past away and the Pennzoil that is sold here now is made in AUS and is not the same, but we don't get real cold winters here in my state, I never had any problems running straight 50 and no problems kicking it when it was cold, but then my Norton don't have any problems wet sumping, only if I let it sit for over 6 months or more, in over 45 years of ownership it has only wet sumped 2 time, we get very hot summers here and my Norton loved the straight 50 so straight 40 should be OK but then everyone has their own opinion on what oil to use and what works great for one might not work for others, I also use a Lochart oil cooler all year round without a themo on all my old British bikes, but of course that also opens a can of worms with others on here, but it works for me and my Norton was a every day rider for 38 years with over 160K miles on it, I also run STP in my oil and that also opens another can of worms here.

Ashley

Any chance that the kickstart mechanism is locking up when you stand on it? And that you are attributing this to sumping??

I have owned my Atlas from new. Back in the 1960's, most Brit bike owners followed the Owner's Manuals and used non detergent 50W in summer, and 40W winter.

Whenever the outdoor temperature was less than 40F., I found kick-over using 40W was a problematic affair, ..... too sluggish to get the magneto to fire, I had to lay the bike up in a heated environment to get started. But then, I had no desire to ride when the temp. was less than 40F.

In the Houston environment, I would not expect 40W to be a stopper to starting. Your description of the bike's behavior 40W vs 20W-50 does not register as I would expect.

Thus, I have no answer to your predicament, except that it seems to be out of character based on my experience.

Slick

How bad is it wet sumping, check oil level in tank. I have an Atlas that will empty the oil tank over winter. When you kick it you are trying to compress the small amount air and a lot of oil. Almost rock solid. I always thought you could push out oil seals if you were to continue with out draining sump first. Just my thoughts.

I'm across the bay from Corpus Christi and have always run 20-50, and yes it will fill the sump if it sits for a couple of months. I just run it at least once or twice per week when weather prevents going on the road. Have 25,000 or so on my motor so I don't piddle too much with what's always worked.
Straight viscosity oil is always thick until it gets hot. I don't care for the stuff except maybe for chain lube.

God I hate retyping old stories again and again....
50W has been my staple for ever, except if I do an oil change before the bike is parked for the winter season. 40W in the fall...winter
15 degrees at Thanksgiving and I got my combat fired up for a trip to a friends for T dinner. 150psi pegged on the gauge if I revved it...It was a low wet sumping engine up to that point with under 20K miles.
Now I watch the oil in my log splitter (8.5hp briggs and straton) so I can burn wood and heat the shop. 100% steady fire since early December.

V-Twin 20W50. I used to use straight 50 but the V-Twin is great. As far as I'm concerned oil is oil. I know some will disagree. No oil is bad, some oil is better, enough oil is best.

Stephen Hill said:

Any chance that the kickstart mechanism is locking up when you stand on it? And that you are attributing this to sumping??

Click to expand...

Stephen, thanks for the feedback. I'm thinking it's not a mechanical issue as so far the mechanism handles a strong kick and cranks the engine fine with the 20w-50. The bike does wet-sump rather quickly, but I've been checking/draining the sump of any oil before starting just to make sure that wasn't the issue. I'm mostly just curious as to folk's hypothesis, if any, as to why the kickstarter wouldn't budge with the 40w even when the sump is empty. Thanks.

dynodave said:

God I hate retyping old stories again and again...

Click to expand...

If there was only a solution for that.

Interestingly, Norman White recommends 40W in his book.
Hard to believe that the oil alone is causing kickstarting problems.
Is the crankcase breather free and clear?

dynodave said:

God I hate retyping old stories again and again....
50W has been my staple for ever, except if I do an oil change before the bike is parked for the winter season. 40W in the fall...winter
15 degrees at Thanksgiving and I got my combat fired up for a trip to a friends for T dinner. 150psi pegged on the gauge if I revved it...It was a low wet sumping engine up to that point with under 20K miles.
Now I watch the oil in my log splitter (8.5hp briggs and straton) so I can burn wood and heat the shop. 100% steady fire since early December.

Click to expand...

Dave
Come into the modern age, copy and paste from an earlier one!

dobba99 said:

Dave
Come into the modern age, copy and paste from an earlier one!

Click to expand...

Good advice=NO
SEARCH-FIND-copy-paste
search is good if the search program is properly selective "search dydnodave cold oil story????
yeah right.....2462 submissions to date

I have to move my kickstart lever counter clockwise a couple of teeth on the shaft to make cold engine kick starting easier. If my lever is close to straight up, it is difficult to kick over a cold engine. Mostly my short legs to blame, and that getting old crap.

A tight spot in your primary chain can make it harder to kick over the motor when cold, and in general. Maybe the stars were not aligning when you had the thicker oil in there. (Side note: A overly tight primary chain makes shifts inconsistent.)

Maybe check the primary chain tension all the way around a few times, and try moving your start lever counterclockwise a tooth or two. If you have a belt drive, obviously checking the primary chain is out.

To fully rule out the mechanical part at the gearbox... Pull in the clutch lever and push down on the kick start lever with your starting leg a few times. If your kick start lever moves freely with no glitches, all good. Kick harder. If it does not, you have a mechanical problem with the kick start parts in the gearbox. Well, that's my logic anyway.

I fixed the old Norton motor wet sump thing. I could park it for years now and it would not wet sump. Draining my sump before starting required taking my exhaust headers off. I got real tired if that.

RWS,
Early spring and late fall I use Kendal Titanium 20-50, riding North of the 49th parallel. Summer I switch to straight weight 50 Kendal Titanium. Never had issues with kicking the bike over unless it was real cold and the bike has wet sumped from sitting over a couple of months during the winter lay down. then it would take a few more kicks till the pots fire. Your problem may lie elsewhere.
Cheers,
Tom

dynodave said:

Good advice=NO
SEARCH-FIND-copy-paste
search is good if the search program is properly selective "search dydnodave cold oil story????
yeah right.....2462 submissions to date

Click to expand...

If i have found myself retelling any story or missive more than once, i type it up in Word or Notepad (Notepad would be the better for this as it can be read by almost every other program) Actually it would pay in spades if you got into the habit of doing all your posts on here, first in a word processing program and then copy and pasting into this forum. A little housekeeping with the saved files under there own folder and finding any file becomes a matter of seconds. With 2462 posts to date, if kept on file under relevant folders, finding 'cold oil post' would be a cinch and you can then use the same post,file, story across other forums.
In fact, copying all your relevant posts from here, to there own folders on your own computer would not be a bad idea at all.

Well folks, now you've got me doubting my own self. I'm half-tempted to refill it with 40w and give it a kick just to restore faith in myself (and I'll let you know if I do!).

Thanks everyone for your input, it's all much appreciated.

what is best oil for commando?

make sure you are in neutral