Removing the radiator bypass hose?

[Arne]

I was re-reading a bit of stuff on racers and I noticed that someone said to remove the radiator bypass hose from the crank to the cylinders and implied that this should be blocked off.

Why are they saying that? Doesn't seem to make sense to me....

Any thoughts?

[rngdng]

If they were running without a thermostat, I can see it, but for normal use, I wouldn't do it. I don't see any gain in that......



:ame

[water cooled]

I clipped this from the "Buffalo Possessed" site which I'm sure most folks have seen and read.

I measured and purchased plugs to cap off both ends and eliminate the hose in between although I have not completed the mod. I will probably do this during the winter when I take the engine back out and pull the barrel off for mapping.

It certainly isnt done for weight savings but from my experience, the stock hose seems to get in the way when you start increasing the size of the carbs. Because I wasnt certain about performing the mod either, I just re-routed a different type of hose to go around the middle carb without collapsing.

I could really do without having the hose in the way if it is unnecessary...and according to the Buffalo Possessed site, the hose is unnecessary (at least for racing). I agree with Lane, for everyday use, I would leave the bypass hose in place.


K. Cooling System

The Suzuki cooling system needs little attention, but it will need some modification. Remove the water by-pass from case to head. Replaced the water pump if it has seen more than 3000 miles, and also pre-1975 pumps with pump Kit #17400-31830. Use water only with water pump lubricant, about 4 oz. Water pump lubricant can be purchased in any auto supply house. Suitable oil can also be used in the same proportion. Suzuki Bars Leak can also be used if any minute leaks occur, but care should be taken because if repeated often, it may clog the radiator. To save weight, the radiator filler can be welded directly atop the right side of the radiator and all extra plumbing can be removed.

The cooling system of the GT-750 is over design. It is too good. Although we left the radiator alone, size wise, on our superbike, we did cut down on our G.P. machine. Operating temperature of the engine must be around 185° to 190°, but the system will keep it at 180° to 185° so we upped the thermostat. Next season we will make the radiator as small as it is on the G.P. bike, thus losing weight and providing proper engine temperature. We will then go back to the 180° thermostat. Although a thermostat may be labeled to open at, say, 180°, it may vary to such an extent that may open as early as 176° or as late as 189°, so if you have the same error at 185°, your high level may be 194° bringing you closer to disaster should the thermostat fail, and sometimes they do.

[GT Tim]

This may sound really dumb, but if the cooling system is too efficient, couldn't you pinch closed or otherwise defeat (solder shut) some of the passages in the radiator, thus reducing the overall effective cooling surface and achieve the same results? If a higher operating temperature is your goal and the bike is happier there? This is what I gather from the above post, I could be missing the point altogether, however...

[diamondj]

Seems like you could do the old tractor trailer trick and cover a portion of the radiator with cardboard, plate aluminum, plexiglass, etc.... and increase the operating temperature a bit......

[rngdng]

Here in the Southeast, I think I'll let mine run as cool as it will. In summertime traffic, I could really use the fan from the J/K bikes.



Lane

[Suzukidave]

Hummm , the bypass does allow the coolant to flow around the cylinder for more even warm up .

[Arne]

Here in the Southeast, I think I'll let mine run as cool as it will. In summertime traffic, I could really use the fan from the J/K bikes.



Lane

Really? This is twice in the last week I've heard of the fans kicking on, but I thought the cooling system was originally set up to not need the fan.

Is your radiator flushed?

I'm curious because I'm trying to figure out if I should mount a fan on my project bike with my smaller than stock radiator.... hmmmm.... maybe I'll just leave the option open and watch the temperature to see what it does.

I think I'll leave my bypass hose hooked up, it doesn't weigh much and can be routed around stuff fairly easily.

I'd like to see what the fin temperature is on some of these KH750's sometime.

Thanks! Arne

[Suzukidave]

Arne , on my GTX-R i used a Honda V65 Sabre radiator and it does good to keep up with temps until i get into stop and go traffic and then the fan kicks on , so i am glad i put a fan on mine . http://suzukidave.myphotos.cc/suzukidav ... C00084.JPG

[water cooled]

I need a sanity check here on my understanding of the cooling sytem...

The suction side of the water pump is drawing coolant primarily from the lower front of the barrel. With the thermostat closed, it can't draw from the radiator. Coolant is also drawn down the Bypass from the upper back side of the barrel near the center cylinder. Coolant from the primary suction mixes together with the coolant from the Bypass and moves through the pump and flows under pressure into the lower backside of the barrel.

Since the cylinders get hot up top first, the primary suction inlet is pulling lower temperature coolant from lower-front of the barrel and the Bypass is pulling higher temperature coolant from the top near the center cylinder as the engine warms up. The bypass is drawing the fluid at the highest fluid temperature and returning it to the lower temperature backside of the barrel.With the bypass hose removed, the coolant at the top of the cylinder gets up to temperature faster than with the bypass installed.

So, my question is: does the difference in temperature gradient from the top to the bottom of the barrel adversley affect the performance or hP output during the time that the thermostat is closed.? It seems to me that the inside cylinder walls will heat up the same due to the combustion process and any difference in temperature gradient along the water jacket created by removing the bypass hose will resolve itself once the thermostat is opened.

Here is system description from Suzuki:
[/url] http://kawtriple.com/tripleed/dalegt750/sr53.jpg
[url]

[Suzukidave]

The coolant enters thru 3 openings in the lower front of the block goes around and exits out the top thru the bypass when cold or to the radiator when the top part of the thermostat opens . When cold the coolant just goes round and round from the block to the pump and back up to the block , when the coolant gets warm enough the bypass closes off and the top opens allowing the coolant to go to the radiator .

[water cooled]

Thanks Dave,

Looks like I had it backwards. It didnt seem like the Bypass was large enough to fully supply the inlet. Thanks for clarifying. How did the cooling system work on the Buffalo Possessed with the bypass removed and a thermostat in place...The pump must be drawing coolant from somewhere other than the bypass....

[rngdng]

Thermostat bypasses keep the waterpump full. Without the bypass, there could be little to no water actually in the pump which would fry the sealing surfaces. There's another reason to keep the bypass, UNLESS you want to run without the thermostat.


Lane

[tz375]

For a street bike, leave the bypass and thermostat alone.

I would treat the "possessed" article as an interesting piece of nostalgia - contains some good points and some inaccuracies. When the TZ came out, Yamaha used to say that normal temp was 80C, but modern TZs run at 55-65C with smaller cooling passages.

if it's really cold, we just add a couple of strips of duct tape to shroud part of the fins.

For a drag bike, I would have thought - NO water and get towed back, or remove the radiator and loop the outlet back to the intake or use a very small radiator just to be safe.