One more thread on an oil cooler mod

[Kyler]

I have a Period 3 (P3) vintage road racing sidecar. It uses a GS 750 motor.



I blew up the '77 motor in it at Mid-Ohio. I've since then bought two more motors (a '80 and a '81). One is a spare for the next time .

Due to the very high revs and marginal air flow, IMHO an oil cooler is required. I've read most of the threads here about an oil cooler mod but want to try something different with these new motors.

I'm thinking of making an aluminum tube to replace the oil filter. I'd make the tube actually contact the filer cover so that I can redirect oil out the oil pressure switch hole and then drill a hole in the center of the cover to bring back the cool oil. I'd add an external filter and install an oil temp/pressure switch suite as well as an motor cutoff switch tied to the pressure sensor.

What do you guys think?

[Kyler]

Yup, 'tis I. Hack racing is big in the north east and out west. Most road racing sidecar nuts are Canadian and not far from you.

I guess I didn't explain my idea well. I'd mount the cooler in the hack where it can get airflow. The idea I expressed above seemed like an easier way to get the oil out of the motor and back in without modifying the cases.

Here's a better picture. The oil cooler is on the left in front of the gas tank where it gets air.

[niclpnut]

How about something like this?



you can tap and purchase fittings from any hardware store. Route the hoses how you want them, then mount the cooler or one like it.


I can't remember if the cover is modified on the reverse side to direct the oil flow or not. i recently sold this one that was mounted on a GS 11000. The filter plate is basically the same less the sending unit.


More info on oil cooler adaptation to a GS 1100 can be found here :http://www.theflyingbanana.com/oil-cooler.htm It uses the lower oil gallery bolts to feed the cooler and lists ideas to modifly flow to route the oil correctly and into the cooler.

You might be able to utilize some of the info gleaned from there to help in your mod.

[rapidray]

I HIGHLY recommend you NOT use the 80-82, 16 valve motors!!! Use the 3rd gen 83 or the 85 700 motors. You WILL have issues with rod & main bearings racing the 2nd gen 750s! I know this as FACT!!! Ray.

[niclpnut]

This is one that i almost got, but missed the bid last minute:

Said he used an 82 750 cover tapped with fittings http://www.ebay.com/itm/1982-SUZUKI-...p2047675.l2557:
Don't know if I believe that since most of the 750 covers I've seen are flat on the reverse side.



You'll notive the configure of the inside of the cover:

The semi closed gallery with the notch is needed to direct the oil flow properly.

Nic

[Kyler]

I HIGHLY recommend you NOT use the 80-82, 16 valve motors!!! Use the 3rd gen 83 or the 85 700 motors. You WILL have issues with rod & main bearings racing the 2nd gen 750s! I know this as FACT!!! Ray.

Unfortunately the rules limit me to 1982 and earlier

[Kyler]

You'll notive the configure of the inside of the cover:

The semi closed gallery with the notch is needed to direct the oil flow properly.

Nic

Thats sorta what I had in mind but what I don't understand on those pictures is how does that redirect oil to the cooler? Looks like both fittings are on the same side of the oil flow.

[niclpnut]

Look at the flyingbanana site. Helps to explain it.

Nic

[GSScoobie]

How about building a box with tubes through it to add under the oil pan like they make for automotive transmissions?

[Kyler]

How about building a box with tubes through it to add under the oil pan like they make for automotive transmissions?

I have a drip pan there with oil absorbent mat (required) for when you blow the motor. Sidecar racing is really tough on the old motors and they have a bad tendency to puke. The other racers aren't fond of oil on the track.

[80GS1000]

Are you using a 2 or 4 valve motor?

[SqDancerLynn1]

The 80-81 is a 4 valve motor and has a high pressure oiling system. If you are determined to use them ? You need to shim the oil pressure relief and add a top end oilier. They were good for eating the exhaust cams. They don't have near the dependability of the 2 valve motor 77-79 in extreme use. At the least take the top end off and clean all of the oil passages & run synthetic oil

[Guest]

The 80-81 is a 4 valve motor and has a high pressure oiling system. If you are determined to use them ? You need to shim the oil pressure relief and add a top end oilier. They were good for eating the exhaust cams. They don't have near the dependability of the 2 valve motor 77-79 in extreme use. At the least take the top end off and clean all of the oil passages & run synthetic oil

Or run the earlier 8 valve motor, the 16 valve is not that durable

[Kyler]

The 80-81 is a 4 valve motor and has a high pressure oiling system. If you are determined to use them ? You need to shim the oil pressure relief and add a top end oilier. They were good for eating the exhaust cams. They don't have near the dependability of the 2 valve motor 77-79 in extreme use. At the least take the top end off and clean all of the oil passages & run synthetic oil

Unless one of you guys want to buy them from me I'm stuck using them. Anyone near Frederick MD want a bike and spare motor?

[Kyler]

I think I have it figured out. The measurements work out nicely and I won't have to turn a custom filter replacement on the lathe. A simple aluminum tube can be cut to fit.

The tube the filter fits over is 19.6mm or roughly 3/4". The filter replacement tube therefore needs an ID of 3/4".



The cover has a recessed hole that has an ID of 21.6mm or roughly 7/8". Therefore the filter replacement tube therefore needs an OD of 7/8".



McMaster-Carr sells a high-pressure aluminum tube with those dimensions - voila! Length is roughly 3" and I'll play with that till I get it right. I'll seal the ends with Grey Permatex.

Now then for the plumbing.



JB Weld is pretty incredible stuff. I have a CR500 motor that grenaded and I repaired the busted case internals with JB Weld. That motor is now on its second overhaul and the JB Weld is still looking fine.

So I'll take JB Weld, fill-in the center recess to make a fitting boss for the return line; and create a fitting boss in the corner for the output line. The oil then would flow from the engine, fill the cavity where the filter used to set, be forced out the output line, through and external filter, through the external oil cooler and be returned into the center of the cover where the tube would direct it back into the motor.

Now then, the line where the oil enters the filter cavity is about 14mm. which is roughly 9/16". I think I can get by using a -8 AN line and 3/8" NPT fittings. According to my well worn machinists manual, 3/8? NPT is compatible with up to ?8 AN (1/2? hard line). It is slightly less but 1/2" NPT is just HUGE! I don't think there is enough room in the cover for that.

I'll put the oil pressure sensor inline with the external lines and put the temperature sensor in the existing pressure sensor hole.