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Not so secret Weapon

3610 Views 35 Replies 13 Participants Last post by  jbranson
Here's a pic of my solution to any heat issues on my 175. Almost a mini radiator...might even have to cover part of it on cool days. All "AN" fittings, braided lines. Should be able to beat the crap out of the bike with no worries.

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Super Deeeeelux!

"You know you've achieved perfection in design, not when you have nothing more to add, but when you have nothing more to take away".

Antoine de Saint-Exupery 1900-1944
Hey JB,

You mentioned you are having heat issues. Just curious, do you have an oil temp gauge or are you seeing some oil type burn marks or discoloration when you tear down the motor? Wondering what I should be on the look out for.

That does look nice. Did you give any thought to putting some kind of crash bars around it. With two crashes per race you may have to do something special to be able to finish and still keep the oil on the inside.

I put a Triumph Trident oil cooler on my 500 Bobber as I had to use a Triumph Cub oil tank because of the rigid rear section; mounted it next to the front frame downtube. I'll take some pics of it next week and post them.

It's a long way from being done, but it's coming along nicely. Last night I solved the tail light/license plate issue as I wanted the rear fender clean, so wanted to do the along-side the rear wheel thing. Came up with what I believe is a first. I used a Triumph connecting rod; made up a frame lug for the big end using a piece of tailpipe that goes over the exhaust spigot and then necks down. I radiused out the frame end, then brazed a trans' gear inside the end that the rod clamps on, looks cool. Welded that on the frame, then clamped the big end on the lug with the rod matching the kick that I made the side pipes at. I then stuck the "grudgeon" pin in the small end and cut the skirt off a piston and slid that on the protruding end of the wrist pin. That will hold my tail light on the backend, and my sideways license plate mount on the backside of the piston. Something different.

I'm going to set up a search on ebay for car hood ornaments in hope of finding something I can attach to the lower triple tree to mount my headlight on. This thing is fun to work on because there are few rules for this style bike.

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I started out with Mobil 1 coming out of the engine smelling bad and being too dark. Switched to Royal Purple...a similar synthetic with different additives...would smell bad..but because of the color I couldn't tell if it was burnt...noticed this at Mosport. Switched to Red Line ester based synthetic which is supposed be good to about 550 degrees. It's not burning so far. The engine comes back from a race hot enough to sizzle spit everywhere on the engine, everywhere...which means at least about 240 degrees. Ten minutes still sizzles spit...which means overall engine temp is probably in the 300+ degree range...with hotter spots I'm sure.
The rocker pad end of the rocker arms turn BLUE....I'm thinking that's too hot. So far the chrome is not coming off of them, wear is what I would expect with the cam and springs I use. Cylinder walls show more scuffing than I'd like and the piston bottom is picking up more burn't oil than I like to see.
I compare my engine to Mary's engine which is much closer to stock and has run so far for 2 years and still looks new inside.

Believe me I was thinking about crashes when I set up the cooler. The supply lines are well protected where they enter the engine and the cooler is mounted such that I shouldn't have to worry unless I hit a wall straight on 50+ mph. I could drop the bike on either side and it wouldn't touch anything with oil in it.

I could probably have gone with a cooler a bit smaller...but I figure it's better to have one too big and have to cover it up with some tape on cool days rather than have one too small. I've changed the mounting from what is shown in the pics to a mounting where the ports are facing up..this will keep the oil from draining out of the cooler when the engine is shut down and will let air purge from the system easier. But it makes the lines a bit longer. The AN lines and fittings will cost more than the cooler did. I did some research on oil temps first and was impressed with the info on how much longer an engine will last if oil temps are kept in the proper range. It seemed to be the opinion of many engine builders that oil coolers are an absolute necessity on any type of race engine. I've noticed that just about every modern water cooled sport bike has an oil cooler.

Doug, send pics of your cooler setup...I'm interested in every setup I can look at.
And....Mad Max called.....he wants his bike back.
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Where were you planning on making the feed lins enter and exit the motor? Do you feel comfortable with the oil pressure availible to fill the cooler? Somewhere I have some pictures of where a guy plumbed cooler lines into a Superhawk motor if that is of use to you. Probably already where you are planning to put them.
See pic below. That's the main supply oil passage from the pump...goes through a passage in the side cover. I drilled and threaded the middle section of the passage and installed a plug. This forces the oil out the first oil...though the cooler...back into the same passage through the second hole...then on to the oiling system as normal.
The oil pressure on these engines is not particularly high at all...but volume does seem to be ok if the flow is fairly unrestricted. The oil cooler offers little or no restriction..although there will be a pressure drop through the's moot because the down stream restrictions are greater than that of the cooler...meaning the resistance to flow through the cooler is way less than that of the downstream system.

I have changed the cooler mounting to point the supply lines UP, this will keep the cooler full of oil during shut down and prevent having to refill the cooler on startup every time. I have no worries about the pump making enough pressure to make the climb to the oil cooler...the reason these engines have low oil pressure is not the pump...but the type of supply system they have...many places for oil to just flow out of bearings and into the sump...the cam bearings are probably the only place in the engine where there is enough restriction in flow to develop upstream oil pressure.

It gets complicated....but, believe it or not...I have a couple of years of schooling on hydraulics, hydro-dynamics, heat transfer and fluid flow. Which means I know enough to really screw things up :)

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If anyone can do it properly I have no doubt it will be Clever Dog Racing's fluid dynamics division. I didn't know if the inherent low pressure would be enough. The Superhawk cooler had fittings welded into the block using the gallery that runs across, just below the cylinders. That center of that passage gets bypassed but wouldn't matter.
Of course this cooler occupied the majority of the time I spent while driving around on the lawn mower and I completely spaced on checking the 175 for similar passages after the mower broke and I nearly pulled a John Hopkins nutty kicking at it. Big weekend for BFD
Of course this cooler occupied the majority of the time I spent while driving around on the lawn mower and I completely spaced on checking the 175 for similar passages after the mower broke and I nearly pulled a John Hopkins nutty kicking at it. Big weekend for BFD
That's the funniest post I've read in a long time. I can't picture you kicking anything BFD; the image of you kicking at your mower is simply hilarious. I felt like a tool laughing that hard at work. "Big weekend"; that's awesome.

That is about how I did it on my last 350. I just made up a fitting on the lathe that was long enough that it blocked off the oil passage where it made the 90 degree turn in the clutch cover, then I put the cooler return line in about where you have yours. I wasn't clever enough to think about putting the cooler fittings on top, so I did have to fill the cooler on start up. I didn't notice any issues. I raced that engine for a couple of years after that and didn't have any oil related problems. Dropped valves from over revving and parts falling off aren't oil related are they? I think I need to fit a cooler to my current 350 race engine too. I think I will point the lines up this time.

Vintage racing - old guys on old bikes
I don't KNOW that there would be any problems with the ports down...I've mounted them that way in the past on other bikes but most of those were tube and fin coolers...this being a plate and fin cooler it would probably like to gather air up top in the cooler and trap it there. With tube and fin all the oil flows through a single tube so it's kind of easy for the oil to flush out the air. With plate and fin you have two oil plenums on either side of the cooler with numerous thin plates that provide a passage between...since the oil can choose the easiest path to might just flow through the lower plates and leave the top plates full of air. Wouldn't be an issue on a high flow system like a car...might be on my bike though. Plus this type of cooler holds more oil...hence it would take longer to fill up on a cold start if it drained back...which by the way I don't know if it would do anyway. Figured better safe and than sorry.

The 175's have the same large oil gallery in the upper case behind the cylinders. Feeds the top end, the main bearings and crosses over to supply the left side top end. Not sure if it's the same on the SuperHawk...but if you tap in on that gallery on a 175 it allows uncooled oil to flow up to the right side top end feed because that would be on the "hot" side of the cooler. The main gallery would have to be blocked or restricted in the middle to induce the pressure differential needed to drive any substantial amount of oil through the cooler. Fluid flow is almost identical to electrical chooses the path of least if the main gallery was unrestricted then it would just flow through there without going through the cooler...since the cooler is mounted higher and has more "Head Loss"....a term meaning resistance to flow.

I wanted somewhat more than an oil cooler...I wanted to be as close as I could come to a "oil cooled" engine. So I wanted full pump flow going straight through the cooler before it goes anywhere else. I also carefully bored out all the oil passages between the pump and the main gallery about 15-20%. It should flow more oil after all these mods than it did before I installed the cooler.

Right now just waiting for some new fittings to come...I screwed up on the port fitting size. Just a little dremel work to do to the pump outlet area and I should be good to go.

BTW...I spent the last two days "splitting" my Cub Cadet garden tractor to replace a differential seal. Huge filthy pain the ass. But it's all back together and mowing again. I was about ready to start kicking it too.
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i reckon that an oil cooler for a cb 350 wouldn't do much when all i do is race at nhis for 8 lap races. besides .... i change my oil after every race weekend. not that i am dissing your progress. it is very cool.

Not really the 8 laps that concerns me much. It's practice, then an 8 lap race 20 minutes later, then a 20 min break and another 8 lap race, without time for the engine to cool off much in between.
My 175 is modified way beyond the typical it gets much hotter, much faster, a it's running about 11,000+ rpm all the time. Even two laps with oil that's too hot is harmful to the engine.

I change the oil every event also...always a good idea.

I change my oil almost every event with the 175 as well. I put the waste oil in a can by Bransons trailer labeled "Red Line".

Hi Branson... I like your cooler. I haven't repsonded to any emails or sent any cause I'm up in Maine working on the barn. I need to figure out the "in and out" of your setup. All my British stuff was easy to setup cause everything was external.

Aaron...are you spooging in that oil too? Cause it works great!

How's the barn coming? I assume you are taking pictures so you can post progress pics.

I'll do the mods to your engine cover for $1000. In fact...I'll install an entire system on your bike for $1000.....+/- $2000.
I've updated my website with a complete summary of the oil cooler installation on my bike.

All the R&D is done for you...just follow the directions to have your own cool running 175.....assuming the freakin thing works that is. It's been pressure tested and oil is flowing to the engine...I'll test it for actual cooling in the next couple of weeks.

Whatch out she's gonna blow! ! !

Very nicely detailed write up. Thanks. Two questions, first why nylon oil lines, and more specifically why not stainless steel lines? Was it due to weight?
Second, should you saftey wire the long mounting bolts that hold the cooler to the mount?

That's pretty nifty. The same principles would apply to a 160 sloper right?

What are the most vulnerable aspects of these engines? I'm assuming (based on your hard work here) that excessive heat/warpage on the top end?

No go on the Paddy 175's. I'll look around at Mid-Ohio. How much're you looking to spend? You're just after the top ends right?

Honda go sideways!
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