Author Topic: Oil Change in CB 750 (Read 36495 times)

Bodain · « **on:** March 25, 2006, 03:54:04 PM »

I picked up the 75 CB 750 last weekend. Whenever I get one of these. I have a process order.

1 Stop the rust...... Done.
2 Check the bike out what does it need to drive it.

Need battery.... Complete
Needs new plugs... Complete
Totally clean carbs.. Complete
Clean and derust gas tank. Complete
Fix rear brake. Complete
Front brake has issues. Will require rebuild upper and lower, but I don't need to test ride.

Now it's time to start the engine. No wait.... This bike has not run since 1990.
I need to change the oil. I pull the plug on the bottom of crank case. I get about one third quart. Hmmm.
I know the 750 has external tank. I know it has a dry sump, but I'm not really sure of the procedure.
My shop manual says nothing about an oil change. I'm on this forum early this morning doing a search on a 750 oil change.
I find a lot of questions about how much,but no procedure.

Ok. I take a stab at it after talking to the local Honda dealer.

1. Drain from crankcase... You won't get much.
2. Drain from oil filter....
3. Drain from lower plug on oil tank. Now I understand why everyone says it's so messy.

Now the fill process. I fill the oil tank about up to the full mark on dip stick... I'm ready to crank the engine. I would expect the level in the tank to drop as the engine sucks it in. I hit the start button.. It runs! It's rough, but it does run. The oil level in the tank falls and I add to it. Looks good!

I start and stop the bike several more times. Looks like I got the oil procedure down. Eventually the bike fails to start.
Much trouble shooting and I determine 1 and 4 are not firing. 2 and 3 do. Swap wires. Now 1 and 4 fire. Bad coil on 1 and 4.
I'm dead in the water till I find coil replacement...

So... Does this oil change procedure sound about right???

Serge · « **Reply #1 on:** March 25, 2006, 04:15:42 PM »

I guess your bike did not have much oil left to start with ... if you did not get much from crankcase ... - serge

Jonesy · « **Reply #2 on:** March 25, 2006, 04:30:05 PM »

You essentially covered the bases. Here's how I do it (FWIW...)

Start up bike and let it run for about 10 minutes. This warms up the oil and gets things roiled up inside, but not so hot you'll burn yourself. This helps let the oil pick up crud and let it drain away with the oil, rather than having it settled out and stay in the engine.
After the bike is warmed up a bit, shut it off and put it on the center stand.
I start with the oil tank first. I remove the sidecover and temporarily undo the rear brake light switch to get it out of the way. I also crack the filler cap. Have a drain pan ready and remove the plug. I have a piece of aluminum that I bent into a small trough to keep the oil from running all over the frame.
After the tank is drained, replace and tighten the plug. Proceed on to the oil pan plug and drain the oil from there. Again, replace and tighten the plug.
Lastly, remove the oil filter housing. If all the parts are in the housing, there is a thin washer between the oil filter element and the spring. This likes to stick to the filter and before you know it, you've thrown it away. (This is probably why 90% of them are missing) In other words, when you remove the innards, don't lose it!
With the drain pan sill under the oil filter mount, crank the engine over a few times with the kick starter to get out the last remaining oil in the engine.
Wash out any sludge or particulates that have collected in the oil filter housing. Take a good look at what's in there, as any sizable bits of metal might be a warning that something's on it's way out. In some cases it's worthwhile to drop the oil pan to give it a good cleaning and look for any signs of trouble.
If you bought an oil filter kit that includes new O-rings, fit the small O-ring on the oil filter bolt and seat the big O-ring in the groove of the filter housing. Apply a bit of clean oil to the oil filter bolt O-ring to make it easier to reinsert into the housing.
With the bolt back in place, reassemble the oil filter housing with the spring first, then the washer and finally the new filter. Reinstall the filter on the engine, being careful not to overtighten the bolt.
Reinstall the sidecover over the oil tank and put the brake switch back in place.
Fill the oil tank with 3 quarts of oil. According to the owner's manual, the oil level will settle into the correct range when the engine is started. So far, I've found this to be true.
I like to hit the starter a few times with the emergency stop switch off to circulate the oil into the empty filter housing before running the engine. After doing this, fire up the bike and make sure the oil light goes out in a few seconds.

Again, this is how I like to do it. It doesn't HAVE to be done this way, but I hope it's helpful.

Japbikemike · « **Reply #3 on:** March 25, 2006, 07:35:07 PM »

Quote from: Jonesy on March 25, 2006, 04:30:05 PM

You essentially covered the bases. Here's how I do it (FWIW...)

[li]I like to hit the starter a few times with the emergency stop switch off to circulate the oil into the empty filter housing before running the engine. After doing this, fire up the bike and make sure the oil light goes out in a few seconds.[/li]
[/list]

I like to use the kick starter with the bike off to circulate the oil before starting.

jaknight · « **Reply #4 on:** March 25, 2006, 07:36:48 PM »

Hey Bodain,

Jonesy has given you a perfect sequence procedure. Couldn't be better!

   If you happen to want or need to drop your oil pan (I obviously don't know how familar you are with these bikes), just a heads up to keep track of what holes the different bolts come from; they do vary in their length.

   If you happen to need the torque specs for the different bolts:

   OIL TANK DRAIN PLUG - - - - - - 24 FT LBS (ideal median)

   CRANKCASE DRAIN PLUG - - - - - - 24 FT LBS (ideal median)

   OIL FILTER HOUSING BOLT - - - - - - 20 FT LBS (ideal median)

   OIL PAN BOLTS - - - - - - - 7 to 10 FT LBS (pick your median)

   I do hope that some of this info will help you out. Again, Jonesy's step procedure is great......
   ~ ~ ~ jaknight ~ ~ ~

toycollector10 · « **Reply #5 on:** March 25, 2006, 07:38:25 PM »

On an older bike you will probably have a lot of gunk sitting in the bottom of the oil tank.

After you have drained the oil put a screwdriver down there and see what you bring up stuck to the tip, and use a flashlight to have a look inside the tank. If it is a mess down there I recommend you pull the tank off the bike and clean it out properly.

HondaMan · « **Reply #6 on:** March 25, 2006, 08:44:57 PM »

Although the torque on the oil bolt is listed at 20 ft-lbs: for many years, I've only tightened them to (snug + 1/8 turn). This works out around 7-8 ft-lbs on a T-wrench. I've always done this because the oil filter housing distorts and locks that $%#*! bolt in something awful, often causing its destruction the next time around.

...just some experience. It won't leak if your large o-ring is new...

jaknight · « **Reply #7 on:** March 25, 2006, 10:04:12 PM »

Good Tip, HondaMan,

I will give that snug + 1/8 turn a try next time I do an oil change.

~ ~ ~ jaknight ~ ~ ~

Clyde · « **Reply #8 on:** March 27, 2006, 03:19:41 PM »

I use a length of 3" PVC pipe to help drain the tank. It is cut to suit the tank and also my oil pan
Regds Clyde

Bob Wessner · « **Reply #9 on:** March 27, 2006, 03:34:50 PM »

So simple a solution, I feel dumb

, thanks. No matter how I try, I always seem to get some oil elsewhere when draining the tank.

toycollector10 · « **Reply #10 on:** March 28, 2006, 12:37:22 AM »

Good one Clyde, so easy and simple, why didn't I think of that...1 karma

SteveD CB500F · « **Reply #11 on:** March 28, 2006, 01:22:42 AM »

Excellent.

I've put this in the FAQs: http://www.sohc4.us/forums/index.php?topic=369.msg76780#msg76780

and Karma to each of you (enjoy it while you can)

Jay B · « **Reply #12 on:** March 28, 2006, 04:16:27 AM »

Best check the points before you assume your coil is bad

Soulsk8r · « **Reply #13 on:** May 26, 2012, 01:48:43 PM »

Thanks to Jonesy for documenting his oil change procedure. It'll come in very handy tonight.

lucky · « **Reply #14 on:** May 26, 2012, 05:48:11 PM »

Quote from: Clyde on March 27, 2006, 03:19:41 PM

I use a length of 3" PVC pipe to help drain the tank. It is cut to suit the tank and also my oil pan
Regds Clyde

Sounds like a good idea!

Whaleman · « **Reply #15 on:** May 27, 2012, 10:38:22 AM »

Toycollector is correct. There is always some gunk in the bottom of the oil tank. I know I am somewhat of a nut but after I drain the oil tank I take a long stick and electrical tape a folded up paper towel to the end. With a flashlight I wipe out all the gunk. I am always suprised to see how much junk I get. I might have to make 10 of my giant paper towel swabs, but it always makes me happy to know it is clean. Dan

MCRider · « **Reply #16 on:** May 27, 2012, 10:49:48 AM »

Quote from: Serge on March 25, 2006, 04:15:42 PM

I guess your bike did not have much oil left to start with ... if you did not get much from crankcase ... - serge

\
CB750s carry very little oil in their crankcase.

Also, to the torque value question and to expand on HondaMans comments. There have been several threads here about stripping the pan drain with that much torque. I would use the tight and 1/8 turn rule on it as well. The oil tank is steel and holds a little better. Still no reason to crank it down that tight. Just fingertight and then some to squish the washer and STOP. IMO.

Old Scrambler · « **Reply #17 on:** May 27, 2012, 11:05:21 AM »

I've been changing the oil on my K3 since it was new. Plus 1 to Jonsey and others with one addition.

When all oil is drained I plug the tank and put about a cup of new oil into the tank and crank the motor for no more than 10 seconds with my deep and long pan under the bike. When this oil is drained I button everything up.

Last year I pulled my oil pan for GP and found it to be CLEAN after 70,000+ miles. And yes, I am still using the original filter-bolt but I did change the pan-plug.

Soulsk8r · « **Reply #18 on:** May 27, 2012, 11:44:43 AM »

All done, pretty good for a first timer! I think. Nothing seems to be dripping, so I guess all the bolts are back on tight enough. Next time I'll do the giant paper towel swabs in the oil tank and see what I can get out of there. I'll also try the Old Scrambler flush as well. Thanks for the tips guys, very helpful.

Greggo · « **Reply #19 on:** May 27, 2012, 02:16:34 PM »

I'll mention this because undoubtedly someone will see Jonesy's write up, it and take it as gospel. It's a great write up, but seems to perpetuate one piece of not so great advice...I'm surprised HondaMan didn't mention it in his response here, because I'm regurgitating this info from his book...

Don't kick the motor over after emptying old oil to 'drain' the little bit left over. It can create an air bubble in the oil pump. HondaMan states this can cause a lack of oil to the top end for up to a minute on first start up after the change...NOT GOOD!

Soulsk8r · « **Reply #20 on:** May 27, 2012, 02:32:12 PM »

Thanks for that pointer, I had no idea. My manual also says to operate the kick starter a few times to flush out remaining oil (my manual is for a 77 model though, not my 71). I didn't do that though, just let everything drip out.

70CB750 · « **Reply #21 on:** May 29, 2012, 07:56:33 AM »

My first oil change I dropped the pan since the drain hole was welded shut. It was good to check whats in there too - and I did it on a kickstand, thats all she had back than.

But i drilled and tapped the pan too, it is so much easier with drain hole.

RAKED71 · « **Reply #22 on:** May 29, 2012, 07:22:30 PM »

What type oil is recommended?

750K · « **Reply #23 on:** May 29, 2012, 07:34:05 PM »

^^^ that's a loaded question around here, haha. Some brand of 10-40 oil of your choice, I'm using Motul 5100 synthetic in my cb750, sexy oil as my buddies boss calls it. Haha

70CB750 · « **Reply #24 on:** May 30, 2012, 02:19:04 AM »

Nothing but sperm whale oil is good enough for my baby:)

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Author Topic: Oil Change in CB 750 (Read 36495 times)