fitting an oil cooler

[streetfighter_danny]

im going to be fitting an oil cooler to my kr1s street fighter.do i need to fit a non return valve on the return feed to the sump?

also has anyone fitted an electric water pump?

cheers danny.

[Garry]

i'm all for innovation but why would you wan't to do that?

[scooble]

to cool your gearbox?

[streetfighter_danny]

i'm all for innovation but why would you wan't to do that?

fit an oil cooler to cool the oil and helps prelong the gear box..
as for the water pump,by fitting this i can then run a much smaller rad as the coolent is circulting quicker and also your supposed to gain around 1bhp as your releiving a little stress off the crank from driving the mechanical pump.dont know if the hp gain is true though.

danny.

[falconman]

I've been riding 2 strokes for over 35 years and have never seen/heard of a heat related trans problem that required a cooler. Next, you are quite incorrect on your thinking of the rad system. Decreasing the size of the rad and speeding up the coolant is going to overheat your engine. Reducing the rad area and the time the coolant spends there will greatly reduce the ability of the system to dissipate the heat. Half of the job of the thermostat is to slow the coolant so it has time to dissipate it's heat. That's why when removing the thermostat you need to slow the coolant back down by installing a restricter plate.

[ScottaKR]

I've been riding 2 strokes for over 35 years and have never seen/heard of a heat related trans problem that required a cooler. Next, you are quite incorrect on your thinking of the rad system. Decreasing the size of the rad and speeding up the coolant is going to overheat your engine. Reducing the rad area and the time the coolant spends there will greatly reduce the ability of the system to dissipate the heat. Half of the job of the thermostat is to slow the coolant so it has time to dissipate it's heat. That's why when removing the thermostat you need to slow the coolant back down by installing a restricter plate.

What he said.

In reality Danny, the KR needs a larger rad to keep it cool. Riding a stock KR1 in anything much over 30c temps will find the rad at it's limit just cruising, let alone if you want to give it the beans.

[TwoStroke Institute]

Don't believe anyone who says it can't be done, yep you'll need that non return valve and the electric water pump has been done and gains a fair bit more than 1 HP especialy with the small radiator(use a dirt bike one)
Sounds wicked.

[streetfighter_danny]

Don't believe anyone who says it can't be done, yep you'll need that non return valve and the electric water pump has been done and gains a fair bit more than 1 HP especialy with the small radiator(use a dirt bike one)
Sounds wicked.

cheers for that...more than 1 bhp,very interesting

[smithyrc30]

fit an oil cooler to cool the oil and helps prelong the gear box..
as for the water pump,by fitting this i can then run a much smaller rad as the coolent is circulting quicker and also your supposed to gain around 1bhp as your releiving a little stress off the crank from driving the mechanical pump.dont know if the hp gain is true though.

danny.

Erm, you will need to fit a pump if you want to move the oil from the gear box through the cooler and back to the gearbox again. You will need a lot more oil as well.

I do not think a smaller radiator is the way to go for the following reasons.
1: the volume of coolant is the time constant that you have before you overheat your engine. If you reduce the amount of coolant, you lower the time constant. Coolant has a fixed specific heat capacity, once you have put all the energy it can store into itself, it will change sate (boil). The amount of energy you put in depends on how much power you are asking the engine to develop. (throttle opening) Roughly one third of the energy in the fuel goes to the water, one third to the exhaust in heat and one third to the piston crowns.
2: While adding an electric water pump instead of the mechanical one might seem like a good idea, it only makes sense in a power equation if you look at managing it, ie turning it off when the coolant temperature is lower than desired. If you run it all the time you have just exchanged one energy conversion for another. The mechanical one takes power from the crankshaft directly, the system losses here are the pump seal friction, the gear losses and the water pump efficiency. The electric one is powered by the battery, which is charged by the alternator which gets its energy from the crankshaft. The system losses here are alternator efficiency, battery efficiency and the same water pump losses as the mechanical pump.
3: The rate of heat transfer out of a radiator depends on
a: the air flow through it which is controlled by the fin density, the number of coolant tubes and its thickness. Bigger numbers on any of these means more air side pressure drop, (more aero drag) lower numbers is less drag.
b: the water flow through the system. Bigger cross section tubes means less water side pressure drop, more tubes is less pressure drop. The length of the tubes is very important to the cooling as is the ratio of tube cross section area to surface area. The heat form the coolant can only get to the air around the radiator through the tube wall. If the tube is too big the water will flow through too fast to enable the heat to get to the tube. If it is too small the water flow will be low, and the coolant in the radiator will be very cool while the coolant in the engine will be very hot.

Also increasing the coolant velocity is very bad for friction and hence pumping losses. So in short with a smaller coolant volume, you have lower thermal capacity, meaning the pump has to work harder, which takes more energy and the system is in a state that is much closer to boiling than it was before. Added to that the only benefit you have added is the (small) change in aero drag (on a KR the radiator is unnoticeable below 100kmh) and the very slight reduction in overall weight.

To improve the cooling on the bike I would suggest that fitting a larger volume radiator and an electric pump with a controller would be a much better way to go. (There is a reason that GP bikes have those huge radiators)

I might be mistaken, but I cannot recall ever seeing a motor cycle two stroke engine with a gear box oil cooler. Not even an NSR 500

[mgtkr1]

well, i must say its a first foir me to hear of an oil cooler on a stroker. tbh i dont see any point, however the water pumpo idea is a good proven idea. a bigger rad is a must on a kr, rgv on makes for a good cheap alternative. not sure why you would want to cool the gearbox oil?? the gearbox isnt known to be particularly vunerable on the kr unlike the rg500/rgv ect. even bikes makes much more power/torque seem to cope easily. was talking to a bloke about kr's/tz yams and comparing road based bits(kr1s) to tz yams (proper racing bike). the kr gearbox is, if anything over engineered for the hp. irc, not a million miles away from tz yams in size re the width of gears ect. as for hp gains, theres a lot more that can be done for considerably more power at less cost. just need patience and resources. just look at some of the tuning threads. std pipes are good, when the motors in bits, rework the cases, remove sharp egdes, even up the ports and general tidying up around the transfer tunnels ect alond with some work on the head/squish will transform your motor.

[streetfighter_danny]

taking onboard all this useful information guys..this is my first 2/ build and im used to building big v twins and jap inline 4s..this is a totally new area for me..

great advice though as i dont really know much about kr1 engines..

thanks danny.

[mgtkr1]

before owning a kr i was always under the false impression that the motor was inferior to the rgv and aswell as been slower, was more prone to going bang. this info came from a rgv racer (anti kr)!!
after reading team sparrow, then owning a few kr1s myself i realised the stories about the kr been inferior (engine wise atleast) where bollox. its easy to be misleasd by the fact the kr isnt a v twin (which is a good thing btw). a good kr is quick and dead reliable, a good rgv can be quick but no where near as reliable. the rgv is a moped under its peak power compared to the kr. a fantastic little unit. ask mj how many times he has blown his bike up!!! not many and mj has been known to run his bikes on old (read bloody ancient) pistons/crank ect. his bike is a seriously fast proddie 250 btw. any questions will be answred on here, a great bunch of lads/lasses. some stunning bikes aswell

[KwakOn]

Don't believe anyone who says it can't be done, yep you'll need that non return valve and the electric water pump has been done and gains a fair bit more than 1 HP especialy with the small radiator(use a dirt bike one)
Sounds wicked.

bit of a wind up maybe,

If you want more power there are better things to do than pump the oil, this would waste power whatever way you do it.

As its a streetfighter maybe the oil cooler is for bling in which case just leave it disconnected and save a bit of work.

If you were going to install a waterpump for the power gain I honestly dont think you could notice the difference on the road. It would deliver at the top end I expect and also help the motor rev more freely (running total loss electrics is better for this maybe).

For a streetfighter folk usually want more torque (wheelies and drag) rather than bhp for top speed (no fairing - bit windy) so maybe consider things like:

K&N's with no airbox (unrestricted) and bigger jets, #145 or more,

Blown airbox i.e. Supercharger (my favourite idea personally),

Run premix and use the Lube injectors to add octane booster or Nitrous

Obviously you will use better gearing (sprockets) for low down power i.e. 14fr 46re.

Of course there is a very limited amount of extra power to gain in the low revs because it is a two-stroke and is only really working once the Power Valves open, 6 or 7 thou RPM.

keep us posted and pics too

[falconman]

Well I never said it couldn't be done. I think everyone here who is telling him not to do it is just trying to save him some time, pain and more that a couple of quid having been down similar roads. My post was based on the philosophy that there are 2 main reasons to mod a vehicle. 1- for more performance and 2- to impress someone. Let's look at #1. Decreasing the cooling ability will make the bike overheat quite quickly leading to detonation then melted pistons (££££). Yes an electric pump will increase power due to less drag but there is more to consider in the system as a whole. Anyone who is familiar with the needs/weaknesses of a 2 stroke will know the suggested mods are probably not the best but if he wants to do it he has every right to. Most people learn more from a failure than a success. Now on to #2. At the bike meet everyone there who is "in the know" will understand that the mods were not in the vehicles best interest and will most likely voice that opinion in a taunting manner. Now, if his ultimate goal was to land that certain bird down at Ace's she is certainly not going to ride a guy that everyone is calling a muppet. We're just trying to help the guy out.

[scooble]

Now, if his ultimate goal was to land that certain bird down at Ace's she is certainly not going to ride a guy that everyone is calling a muppet. We're just trying to help the guy out.

perhaps he likes muppets;