oil cooler lines

[motorman]

Hi guys and gals, it's me again with another question. I have now accumulated enough parts to retrofit my "79 Special with an aftermarket oil cooler. The radiator that I have is a Lockhart brand, double row cooler that supposedly was marketed for the XS 1100. However, both ports (in and out) on this radiator are only 1/4" ID. Is this sufficient for proper engine oiling or should I look for a radiator with larger ports? Thanks for your help, Steve.

[79XS11F]

My after market cooler is also Lockhart. I don't think the inside DIA of the hoses I am using is much larger then 1/4 inch. I have mine installed so the oil supply from the block behind the head goes to the cooler and then back to the head. If you go this way pre fill the cooler and the lines before final hook up and running the bike.
Rob

[skids]

I can tell you that the stock hoses on the 81H are much larger outside diameter than the apparent size of the fittings at the adapter plate. Sorry, I cant tell you what the actual ID of the fittings are, but I would bet they are close to 1/4 inch.

[John]

I run the Lockhart on mine also. I am using 3/8 ID cloth braided hose, similar to OEM, from the adapter plate to the cooler. The fittings in the plate are 45 degree, 1/4 pipe to 3/8 hose (barb) type fitting. The cooler has the fittings built in and they are 3/8 hose type also, all secured with hose clamps. The ID of the hoses is amost double that of the oil pipe that supplies the cams, where you have your cooler tied in. In that cofiguration you could possibly loose oil pressure to the cams by routing through the cooler first. When I first bought my bike it was set up that same way, but I swapped it with one from an XS 850 Special, that I modded the hoses to fit an 11. I didn't like the idea of coming off the oil pipe, just too small an ID for my liking.

[motorman]

Thanks for the input so far. I will be using an adapter plate from an old 850, and after looking at the Lockhart radiator I was concerned about the possibility of insufficient oil volume. I know that 3/8" passages will flow nearly double the volume of !/4" passages at the same pressure. I certainly don't want to oil starve the bottom end of the engine. What size are the factory cooler lines and passages? Steve.

[John]

You will have a little problem using a plate from an 850 with out doing some mods to the steel lines that are bolted to the plate. I had the same set up on my bike, only I used the 850 cooler also. You will see that the steel lines are bolted to the plate, and the hoses are crimped to the steel lines. They are formed to fit an 850, and will not fit the 1100. You will need the lines from the 850 cooler lines to be able to get the fittings. They are not pipe fittings, but when you get the plate, you will see attached. You will need to cut the steel lines from the hoses, and then attach your hose to the lines. I had a problem with one of the hoses blowing off of the steel line, so I had brazed a raised lip onto the end of the line, so the hose wouldn't slip of any more. I still have that set up some where around here.

[planedick]

Oil lines...

The oil pump would be hard pressed to keep a 1/4" line full if it were open. The 1/4" line should be adequate as the volume isn't all that much. For instance, a missing rod bearing, would let out so much oil there would be no pressure left and the oil hole in the crank is less that 1/8" dia.

[motorman]

Thanks again for your input. I believe that I will go with what I have and monitor the results. If my oil pressure increases significantly then I will know that there is too much restriction in the new part of the system and deal with it accordingly. Steve.