Author Topic: Oil & fuel FAQ  (Read 30373 times)

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Offline Harry

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Oil & fuel FAQ
« on: April 08, 2005, 01:45:28 AM »
Which oil should I use in my SOHC4?
10-40w MINERAL oil is what Honda recommends. When these bikes were first sold, the API oil rating and formulation level was SD or SE. 20W-50 MINERAL oil can be used on older, worn motors. Don’t use synthetics. Synthetics have a reputation for a high detergent action. That is, if you have an old engine that has some sludge or deposits internally, the synthetic will sometimes remove it in chunks. There is some risk of plugging or restricting the oil pickup
screen, which would starve the engine of oil. It also affects some old seals adversely causing them to leak (from shrinkage if I remember correctly) and often leads to clutch slippage (see Clutch FAQ for clutch slippage comments).

Article on Oil: www.yft.org/tex_vfr/tech/oil.htm (Mick750F)

Motorcycle Oil Filters Exposed!: www.tobycreek.org/oil_filters/index.shtml (Mick750F)

Which fuel should I use in my SOHC4?
Many SOHC4s have a relatively low compression of 9:1 and the manual typically recommends low octane fuels: 91 octane is roughly equal to 87 pump octane in the US. Most unleaded gasoline today is rated at 87 octane, which is sufficient for engines with compression ratios of up to about 9 to 1. Higher-octane gasoline requires more heat and pressure to ignite, meaning it's actually harder to ignite. The primary characteristic of higher-octane fuels is longer hydrocarbon molecules. These are stable and more difficult to ignite, but when they do ignite they burn slower, producing higher cylinder pressures. To capitalize on higher-octane fuel, the engine must be set up with more compression and in many cases, more ignition timing. The higher octane gasoline you use, the slower the fuel will burn, and the cooler your car will run......with the potential for this fuel to leave carbon deposits in the engine. The residue of unburned hydrocarbon becomes a deposit, and potentially a "hot spot.” So the same high octane fuel which should prevent "pinging" and at the same time give a cleaner motor (at least according to the Shell ads I have seen) could actually give a dirtier motor and the possibility of pinging due to predetonation induced by hot carbon deposits.
High and low octane fuels have for all practical purposes the same potential energy per volume. Use the lowest-octane fuel on which the engine will run cleanly and efficiently. By burning the fuel more efficiently more of the potential energy will be used, and the engine should run hotter. If you have good high compression (perhaps because your firing chamber is full of soot ;-)), you need to run higher octane or you'll get pre-ignition and eventually detonation, which will rob your bike of its rideability and you of your money to fix it. If you are using low octane (or old) fuel you may experience pinking: change to a higher octane. Otherwise, if you continue to experience pinking, you may need to change your ignition timing. If my memory serves me correctly, you may need to delay timing, as pinking is caused by early combustion, which is before the piston has actually reached TDC.

There is an oil leak coming from my shifter seal – how do I change it?
1. Undo the bolt on the back of gearchange (foot) lever. 2. Make a mental note of the usual position of the gearchange lever, and then pull it straight off of its splined gearchange shaft. 3. Undo the bolts on the left-side engine case that covers the front sprocket for the chain, and pull the cover straight off. There is no gasket or oil behind this cover. Just the chain sprocket. 4. Using needlenose pliers or a similar tool, try to grab the old O-ring shaped Oil Seal and pull it out from it's insert on the side of crankcase body. Do not scrape or damage the seal insert area. Slide the Oil Seal outwards along the gearchange shaft to remove it. Even if this Oil Seal looks good, discard it. This Oil Seal MUST fit snugly, otherwise oil will continue to leak out from behind the gearchange shaft. Oil is intended to squirt through a small channel from inside the crankcase into a hollow ridge on the backside of the Oil Seal in order to keep the gearchange shaft constantly lubricated. Remember, the old Oil Seal may have hardened or changed shape slightly over time. 5. Install a new Honda O-ring Oil Seal (approx $5.00). It might help to find a hollow rod (like the handle of a hydraulic jack) slightly longer than the gearchange shaft in order to lightly tap the new Oil Seal into its insert. The Oil Seal should fit almost flush inside crankcase insert. 6. Re-install the engine case (cover). 7. Prior to re-installing the gearchange lever, slide a rubber spacer (similar to a garden hose washer) onto the gearchange shaft right up against the engine case. THEN install the gearchange lever. This will limit lateral (sideways) movement of the gearchange shaft, thus reducing the chance of the new oil seal from getting caught up on the shaft and gradually pulled out of its insert. Make sure that the gearchange lever can still move freely up and down - just not sideways.


« Last Edit: October 03, 2005, 08:33:53 AM by SteveD CB500F »
Harry Teicher, member #3,  Denmark....no, NOT the capital of Sweden.

Offline SteveD CB500F

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Offline SteveD CB500F

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Oil Filters / 17mm bolts / Spring & Washer Missing? (with Pix)
« Reply #2 on: November 12, 2005, 07:57:29 AM »
Here's a FAQ based on recent threads about buying oil filters and the various o-rings, washers and springs that you need.

  • Do I need the o-rings?
  • Will I get the o-rings?
  • What's a 17mm bolt and do I need one?
  • Handbook shows a spring and washer - do I need them?

So, here goes:

  • Unless you damage the o-rings (unlikely), you don't actually need to change them at each oil change.
    "In the Old Days" (?) you went to you Honda Dealer and bought an oil filter. It came with the large o-ring for the filter cover and the small o-ring for the filter bolt.  Nowadays, you buy a filter from DSS and you get - a filter (that's all). I want to hear from others who've bought different makes of filter and what they contain (with photos please)
  • There have been many posts about how to remove the oil filter cover as the small 12mm bolt head is knackered. A long, long time ago (the 70's) this was a problem fixed by using an aftermarket 17mm oil filter bolt.  As long as you use a hex socket head you'll be fine. One word of warning - don't get carried away with your super new 17mm oil filter bolt and over tighten it (just because you can...)
    See additional info from Mike Nixon:
    Steve -- Saw your oil filter bolt item in the oil FAQ.   A comment.  Many people don't know that honda actually put a 17mm oil filter bolt on the first year model 750.  There is even a bulletin about it if I remember correctly.   They found that the bolt was routinely overtightened (buckling the case and resulting in oil leaks), so when the oil filter case was updated for the second model year (the original case did not have cooling fins, these were added later) the bolt head was resized to the later 12mm to prevent overtightening.  As a tech, I remember strongly advising against the use of these aftermarket 17mm headed bolts.
    and from Bryan Jones:
    Yes Steve Honda UK tech reps also advised not fitting the 17 mm headed bolt as it was easy for a "numnuts" to way over tighten and strip the threads out of the crankcase and there was no helicoil for that so new cases were called for. We used to sell the bolts and when not working for a franchised dealer fit them but when working for a Honda dealer we would only fit Honda ones even though the spares sold the aftermarket ones, That way we kept the dealership! Cheers Bryan
    Springs and Washers:
    The spring keeps the oil filter pushed hard up against the crankcase and the washer stops the spring from digging into the little rubber bit in the middle of the filter. It's not recommended to run without a spring. The washers tend to stick to the filter when you remove it and many get thrown away :o

    The washer is 29mm OD and 20mm ID and 1mm thickness

    Oil filter element spring retainer OEM part number 15415-300-000
    Oil spring seat washer OEM part number 15414-300-000
« Last Edit: March 23, 2008, 01:13:04 AM by SteveD CB500F »
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Offline SteveD CB500F

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Fuel / Gas Cap Pins by Hondaman
« Reply #3 on: November 21, 2007, 03:17:48 AM »
These fit all the 1968-1980 bikes with flip caps, (based on the feedback I've been getting). The kit contains both 1 screw cut to size and another, full-length screw, just in case something unusual shows up. I haven't heard of any problems: they probably fit Kaws, Suzys and Yammers, too.

They are made from stainless steel, non-sparking screws with acorn nuts and washers, all in a satin finish. You can remove and install at will, if you have the right size of Allen wrench. They come in a "kit" with one screw cut to fit the SOHC4 tanks and one full-length, in case you have other ideas for it.

Drop Hondaman a PM or email him on mgparisATconcentric.net for current pricing info. Part of the price goes back to SOHC4 to help support the site for all of us.

« Last Edit: May 12, 2009, 11:08:12 PM by SteveD CB500F »
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Offline SteveD CB500F

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Latest Update
« Reply #4 on: March 23, 2008, 01:14:08 AM »
Updated 23rd March 2008

Added info on oil filter spring and washer.
SOHC4 Member #2393
2015 Tiger 800 XRT
1971 CB500K0 (US Model)