overheating, i need better coolant? maybe a fan?

74 replies to this topic
  • tribalbc

Posted April 28, 2009 - 06:38 AM


i heared the boysen water pump kit works wonders on the bikes, im going to be ordering it tonight when i get off of work..

and man i never thought this thread was going to have so much good information..:banghead:

The Boyesen does work wonders. I gave it the ultimate test this weekend riding an extremely ugly Hare Scramble. Basically the whole race was 1st gear hell, BIG wet roots an rocks. There was 1 hill that was bottlenecked with a whole wack of riders. LMS kind of terrain. Took me 20mins to get up that hill, spinning and pushing the whole way.
Bikes overheating all around me and I didn't even get a burp in the puke tank :banghead:

I've been using mine a year now racing Hare Scrambles and give it 2 thumbs up :banghead:

  • grayracer513

Posted April 28, 2009 - 09:58 AM


Gray does the Boysen water pump/impeller kit really help?

I can't really judge that. I don't personally have a problem with the stock water pump (except the shaft sucks), and I don't know anyone who has used one. Since I'm not over heating due to poor circulation at all, I don't think improving the circulation will help me any.

what's you're opinion on the two2cool?

People say it works. The company refuses to say how, or what effect it has on the lubricity or other aspects of the engine oil, or to publish any lab data demonstrating the veracity of any of their claims, so I refuse to use it. No opinion, I guess.

  • swatdoc

Posted April 28, 2009 - 05:06 PM


For the supercooler setup, i haveit on my bike, but i put it on before i ever rode it the first time. Now, a guy i know in hawaii that has a WR street legal was having overheating problems when stopping at lights and in traffic - he put the supercooler on his bike and told me it made a noticable difference. 3rd hand info, but i've only heard good things.

  • rexbond007

Posted April 28, 2009 - 05:41 PM


i heared the boysen water pump kit works wonders on the bikes, im going to be ordering it tonight when i get off of work..

and man i never thought this thread was going to have so much good information..:banghead:

I have one been running it for two months now and like it

  • swatdoc

Posted May 13, 2009 - 05:54 PM


King Quad - thanks a bunch for the ebay link to the Spal fans - that's the exact model I was looking to get, and at less than half retail price, with free shipping! I ordered one just now!

  • BC3

Posted May 13, 2009 - 07:58 PM


Another option is to fit an overflow tank into your cooling circuit. Motion Pro make one that fits on the fork leg behind the front number plate. Another option is to fit the overflow tank from a WR. I have used both, the WR tank on my 400 and the Motion Pro tank on my CR250.

The tank allows for your radiator to blow off and when it cools again, to draw the coolant back in.

At very slow speeds the YZ will always boil over, the best solution is to minimise riding at slow speeds, and to catch the coolant it expels (as explained above).

Very good advice....Just to add one comment......The system is set up to where it will cool under normal racing conditions BUT if you lose ANY FLUID at all you will have a over heating problem so the catch can is a great idea

  • LumpyBoy

Posted July 28, 2009 - 11:18 AM


Just stumbled on this thread. I have a SPAL puller fan on my KTM SXF. If anyone needs info, PM me. There's a great thread on KTMTalk with pics and everything (computer fans have been used with great success as well). I doubt a fan is going to work on the '08 YZF given its limited aftermarket stator output but perhaps it will work if you aren't running any other electronics. You can zip tie the fan to your radiator and run a thermo switch so it goes on around 170-190 degrees (depending on which switch you buy). You'll need a full DC system of course.

Visit the ThumperTalk Store for the lowest prices on motorcycle / ATV parts and accessories - Guaranteed
  • swatdoc

Posted July 28, 2009 - 11:54 AM


when I get around to hooking up my fan, I'm gonna wire it so it's on the same switch as my headlight - so either one or the other is on. pull up to a red light - hit the switch - headlight off and fan on. switch back when the light turns green and i'm moving again. my lighting system is strictly battery powered until (if) someone ever comes out with a reliable stator for our bikes.

  • LumpyBoy

Posted July 28, 2009 - 06:23 PM


Good idea Swat. Only need a two position toggle. Position 1 connects the regular light circuit (I have a Sicass Racing switch cluster so I could still turn off the light if I want to) and position 2 turns on the fan. You have a nice bike and while zip tying the SPAL fan to the radiator sounds ghetto, it's actually quite sano. Of course, I have BPD guards on my sxf rads and that is what I used to attach the zip ties. I don't need guards on my YZ so I'll have to figure out another mounting setup. Some folks have used threaded aluminum dowels that they insert through the fins.

Oh, and there are now 2 hours of ride time on the Proracing stator. Too early to tell yet.

  • ReedRulz

Posted July 28, 2009 - 06:43 PM


I use yamacool and never spew coolant and never have to add any coolant.

  • Pukeballs

Posted July 29, 2009 - 01:02 PM


I use the engine ice and installed the boyesen water pump and impeller on my '05. This combo works great for me since I ride in a hotter climate (so cal deserts) and I've never boiled over.

  • motoman88

Posted July 29, 2009 - 07:44 PM


"well the reason i think i boil over faster than everybody else is that i got a lot of work done to my motor
that would cause for more heat.. "

I dont know if any one has asked since I didnt read all the replies, but what Octane gas are you running. When you begin working on the motor and upping the compression you MUST run a higher octane to avoid pre detonation, which will cause your motor to over heat. Also you can go into exhaust wrap and wrap your header since alot of heat is coming off the header and is near the radiators. You can even wrap your radiator in very few places to deflect heat. I hope this helps.

  • roylo

Posted September 27, 2009 - 04:16 AM


Id thought Id add my question here instead of starting a new thread. Bike is a 08 YZ450

My radiator level usually stays just above the core. But the weather is starting to warm up over here and I find the level going just under the core now after every ride.
I want to try a 1.3 bar pressure cap and see how things go. My question is, is this fairly safe to use and wont harm the engine?

  • davidl9999

Posted October 03, 2009 - 07:27 PM


Using a higher pressure cap is generally fine. The weak link is the radiator tank seams, not the engine (at least in my experience). Not cheap to fix if one fails, but don't know anyone that's happened to on current bikes.

Something to think about - if you're racing the bike, then you should be doing maintenance between each race - including refilling whatever puked out of the rads during the last moto - so the point of the coolant going below the top of the cores is kind of moot as long as the engine is still running fine at the end of each moto. If you're riding trails for fun or for hours at a time, then having full tanks is helpful and you might want to consider adding a puke tank like on the WR. That way the rads are always full.

  • Parrot

Posted October 04, 2009 - 01:07 AM


I have the Boysen Water pump kit , the wr catch tank, and running the polypropylene in the bike. The bike of mine does over heat, due to the type of riding I do. I just have to wait till the catch tank draws the coolant back into the radiators. Some times I just use some of my drinking water on the radiator external skin to help it cool sooner. Air flow is needed which I am not giving the bike. On tight trails this setup is fine, I ride a lot of rocky washes, that have never been ridden. Many are even more technical than 5MOH, and is real slow going.
I am using the bike for riding it was not designed for. So I have to live with the quirks such as over heating.
I really enjoy this thread, hits home.

Related Content


Is it worth it? (Cam and High compression piston) by macgi77

Dirt Bike   Make / Model Specific   Honda   CRF 150/230 F/L
  • Hot  36 replies

Need help by Goforaride

Dirt Bike   Dirt Bike Technical Forums   Suspension
  • Hot  68 replies
WR Camshaft Swap Info - last post by jamesm113

WR Camshaft Swap Info

  • 0 replies

Snake pit oct 30th by The Anvil

Dirt Bike   Dirt Bike Regional Discussion   California
  • Hot  35 replies

yz250x vs 450 4t comparisons (preferably desert riding) needed by JakeNorthrupYZ450F

Dirt Bike   Make / Model Specific   Yamaha   Yamaha 2-Stroke
  • 9 replies

Join Our Community!

Even if you don't want to post, registered members get access to tools that make finding & following the good stuff easier.

If you enjoyed reading about "" here in the ThumperTalk archive, you'll LOVE our community. Come join ThumperTalk today!

The views and opinions expressed on this page are strictly those of the author, and have not been reviewed or approved by ThumperTalk.