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Old 08-22-2013, 03:42 PM   #1216
Powderaddict
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Ugh, still having issues overheating. Like where the coolant boils over and runs out the overflow line.

I've done the following:

- Burped the coolant tank several times
- Replaced the Radiator cap twice
- Checked the oil for coolant (oil came out clean)
- Wired the fan to a toggle switch, fan runs all the time (helped a bit)

So as long as I'm moving at a good clip, the bike is fine. But when stopped, the temperature climbs drastically. Like it will go from normal to way into the red at a stop light. When stopped, if I rev it up, it pushes the coolant through and drops the temp, which the fan toggle switch has helped with.

A couple things:
- This bike has a 330 kit in it. Awesome, I love it. I can keep up at 75 all day long. The previous owner stated it had heating issues, but he drilled a small hole through the thermostat, and that it took care of the heating issues. Apparently not. He's telling me to drill a second hole of the same size. Does this make sense to anyone? What would this accomplish?
- I can smell the faint smell of coolant from the right radiator. I can't find any leaks, anywhere. I suspect there may be a small hole or crack somewhere in the radiator. There's no visible signs, just the smell. It's not strong, but strongest right where the fan draws air through the radiator. I am going to replace the right side radiator.

I want to feel confident my bike will not overheat if I am in stop and go traffic. I'd like to ride to Denver, but don't want to ride in Denver until I get this issue fixed.

So a couple questions:

1. Does the hole in the thermostat make sense to anyone? I think I'll replace the thermostat while going through everything. The one that's in there is supposedly pretty new, but who knows. The previous owner was pretty adamant about drilling the hole through the thermostat as solving his overheating issue with the 330cc engine.

2. Do you know if the radiator from any year will swap in? I have an 89, and have found conflicting info. There's one for a 99 on ebay right now, but their little part guide says it won't fit.

3. Revving the engine seems to push the coolant through while at a stop where idling doesn't. Might that indicate any other problems?

4. Any other ideas?

Thanks!
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Old 08-22-2013, 04:13 PM   #1217
XDragRacer
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You may just be paying the price of the 330 cc bit-bore hop-up!

The water pump, etc., were NOT designed to handle the heat load of a 330 cc engine at idle. Rather, a 250 cc engine.

Drilling a hole in the thermostat sounds like a fool's errand to me; when the thermostat reaches its threshold temperature, IT OPENS FULLY! What good would another (one weep hole exists OEM, IMHO) small hole do, when the thermostat is CLOSED?

Your problem, I gather, occurs when the coolant is HOT; during these moments, the thermostat is completely OPEN. Don't see another small hole helping anything.

Think about it: You've INCREASED the possible volume of combustible mixture by unit time by approximately 30 per cent; does it make sense that extra combustion, at idle, without additional air flow or coolant circulation, may not be able to keep up with the heat load?

Further, I'm not familiar with your 330 kit. Unless extraordinary steps were taken, regarding piston design, cylinder/head/gasket dimensioning, the COMPRESSION RATIO could be increased . . . by how much? Again, 30 per cent. The higher CR suggests possible higher combustion chamber temperatures.

Heat control/stabilization has been a problem of hop-up eternally; ask someone who raised the compression ratio of his flathead Ford V-8!

Regrettably, there may be no free lunch; the additional displacement may require heat management compensation by--additional radiator capacity, a more robust water pump, an enhanced cooling fan . . . hey, what about TWO cooling fans?

As things stand, I'd consider you're ahead of the game--you have increased power, and safe, stable engine temperature operation at speed. Without significant cooling system modifications (never mind the hole in the thermostat), you may have to nurse it through idling intervals, on a hot day.

That said, still--congratulations on your performance improvement!

-----------------------------

I'll try to answer one question:
Quote:
3. Revving the engine seems to push the coolant through while at a stop where idling doesn't. Might that indicate any other problems?
No, IMHO. Revving the engine makes the water pump turn faster, circulating a greater volume of water per unit time, available to cool the engine, again, IMHO.
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Old 08-22-2013, 05:33 PM   #1218
kidflyr
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Quote:
Originally Posted by Powderaddict View Post
1. Does the hole in the thermostat make sense to anyone? I think I'll replace the thermostat while going through everything. The one that's in there is supposedly pretty new, but who knows. The previous owner was pretty adamant about drilling the hole through the thermostat as solving his overheating issue with the 330cc engine.

2. Do you know if the radiator from any year will swap in? I have an 89, and have found conflicting info. There's one for a 99 on ebay right now, but their little part guide says it won't fit.

3. Revving the engine seems to push the coolant through while at a stop where idling doesn't. Might that indicate any other problems?

4. Any other ideas?

Thanks!
1. drilling a hole in the thermostat will allow more coolant past the T-stat before the engine is up to the thermostat's rated temperature. This means that the bike will take a slight amount longer to warm up from a cold start, and may take a few seconds longer to heat up at idle after traveling at speed. If the PO was using the bike on trails, with sustained rpms or on roads with few stops, I imagine he could become convinced of "Problem solved!" after drilling a little hole.

2. Radiator from any year should swap in. Different colored plastics and the wimpier, NOx-emmision friendlier cams of later model-years are the most major changes the bike got over the years from Kawasaki.

3. See XDragRacer's post.

4. Run a more watery mix in the radiator: if you're running 50/50 water/antifreeze, try 80%water/20% antifreeze, or just distilled water and a corrosion inhibitor.

Consider a coolant additive, such as water wetter. The main selling point of such additives is that they lower coolant temperatures.

Remove or chop the fender, or run a smaller one like the acerbis supermoto fender (I mounted one, it made crosswinds much less of an issue also) or UFO superbike low mount fender. Any of these will allow more air to the radiator, though mainly at speed.

Patman mod. Again, this one helps mainly at speed, seems to help the fan exhaust stay separated from the air flowing into the radiator at a stop too.

Higher pressure radiator cap. I wouldn't try this until you're confident of your radiator's structural integrity, and I'd get new hoses on there for peace of mind. This will increase the boiling point of whatever coolant you use, keeping it as a liquid and in the radiator doing it's duty up to a higher temperature.

Lower temperature thermostat: it will open sooner, allowing coolant to flow through the radiator beginning at a lower temperature, slowing the onset of the problem. Not perfect, but more elegant than drilling a hole in the thermostat.

Run without a thermostat: I would consider this a last resort because it would subject the cylinder and head to rapid temperature swings and likely run too cool on the highway, but it would allow maximum flow that the coolant pump can offer by removing any obstruction from the thermostat or its "frame". You'd need to replace the thermostat with an O-ring like watt-man does with his Thermo-Bob kit.

watt-man has done some thorough testing on the 650 in the realm of the cooling system, and much of it is transferable to our KLR250's:
http://watt-man.com/uploads/Margin.pdf

Send an e-mail or make a phone call to Greg at Cycle Works Racing in PA. His shop is the only one I'm aware of that offers a 330cc kit. http://cycleworksracing.net/
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kidflyr screwed with this post 08-22-2013 at 05:38 PM
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Old 08-22-2013, 06:57 PM   #1219
ChromeSux
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Have you checked the hose routing, one time i worked on my KLR250 hooked the coolant hoses up backwards at the motor, dont laugh, it was easy to do, i had the same type problem, as long as i was going along at a good clip things were fine.

Came home that afternoon and studied the situation and realized what i had done, what made it so easy to mix up the hoses, is they fit just fine backwards.
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Old 08-22-2013, 07:20 PM   #1220
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For powderaddict:

I believe these are correct. It's how the bike came and I have no cooling issues.



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http://advrider.com/forums/showthread.php?t=1003485
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Old 08-22-2013, 07:21 PM   #1221
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I know, the header needs attention. I'll get there eventually.




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COBDR and UTBDR on my klx250:

http://advrider.com/forums/showthread.php?t=1003485
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Old 08-22-2013, 07:23 PM   #1222
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I see how easy it would be to reverse them. These are correct for sure thought. It's actually stamped on the water pump cover which outlet goes to the cylinder.




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Old 08-22-2013, 09:00 PM   #1223
Powderaddict
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Thanks for all the replies. Some good tips here.
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Old 08-22-2013, 11:40 PM   #1224
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Over Heating 330

I have the same 330 in an 89, makes for a great bike.

My daughter rode it to Alaska last year and we started having heating problems after about 6600 miles. Seemed to be losing water but couldn't find a leak. Eventually toasted a crank bearing. Rebuilt and replaced the bearings and have some major clicking going on inside but that is a different issue.

I replaced the carb with one from a KLX and it has the choke on the side - so I removed the overflow bottle, cause it was in the way of the choke. What riding I have done with it I have not had any heating issues since the rebuild. I haven't ridden it in stop and go traffic yet, but running around the hills and what not no problems that have come to the surface.
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Old 08-23-2013, 04:30 PM   #1225
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Quote:
Originally Posted by kidflyr View Post
Send an e-mail or make a phone call to Greg at Cycle Works Racing in PA. His shop is the only one I'm aware of that offers a 330cc kit. http://cycleworksracing.net/
I emailed him and he suggested installing a KX500 radiator.

Reading many threads on many sites (thanks, internet!) I am starting to wonder about the head gasket. Others have chased down similar issues and have wound up at the head gasket, even though there wasn't really any signs in the oil.

I hope not, I'm not a great mechanic, and while the price of the part wouldn't be an issue, the price of labor might. Is this a pretty straight forward process, or is it pretty involved?
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Old 08-23-2013, 06:41 PM   #1226
XDragRacer
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Quote:
Originally Posted by Powderaddict View Post
I emailed him and he suggested installing a KX500 radiator.

Reading many threads on many sites (thanks, internet!) I am starting to wonder about the head gasket.?
I think a leaking head gasket would produce more symptoms than you've experienced, i.e., more than overheating on idle.

The kit developer's suggestion, augment the radiator capacity by replacement with a larger one, may be worthwhile.

Otherwise, you can baby it when forced to run at idle; e.g., rev the engine as necessary, take cool-down breaks.

Maybe it can be done, but . . . asking a cooling system designed for 250 cc to keep a 330 cc engine within safe temperatures, "from DC to daylight," from idle to WOT, may be a too-tall order.
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Old 08-23-2013, 06:47 PM   #1227
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Quote:
Originally Posted by XDragRacer View Post
I think a leaking head gasket would produce more symptoms than you've experienced, i.e., more than overheating on idle.

The kit developer's suggestion, augment the radiator capacity by replacement with a larger one, may be worthwhile.

Otherwise, you can baby it when forced to run at idle; e.g., rev the engine as necessary, take cool-down breaks.

Maybe it can be done, but . . . asking a cooling system designed for 250 cc to keep a 330 cc engine within safe temperatures, "from DC to daylight," from idle to WOT, may be a too-tall order.
It seems like it wouldn't be too difficult to put in the better radiators, so I'll do that regardless. But the way that the coolant keeps boiling dumping it out the overflow tank may be a sign. Either way, it does seem like a good idea to upgrade the cooling capacity.
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Old 08-23-2013, 11:50 PM   #1228
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Just a thought, but if I'm remembering correctly, the 1st generation KLR650 has its radiator and fan on the left side of the bike, possibly making the addition of a 650 fan wired in parallel with the existing fan something worth exploring.
Additionally I have heard some positive reviews of some waterproofed computer cooling fans that an eBay seller is marketing as auxiliary cooling for dirt bikes and other motorcycles. Such an option would put less amperage draw on the bike's wimpy stator, compared to the 650 fan. I don't remember the seller's screen name though :(
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Old 08-24-2013, 12:36 PM   #1229
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Ok, I checked the coolant lines, they are correct.

I also just checked the level of coolant, it's pretty low. Which I topped it off really recently. It is spitting coolant out the overflow tank once it gets to operating temperature. Not a continuous flow, but more in spurts.

When I pulled off the radiator cap I noticed small flecks of what looks like copper. So if they used a copper head gasket when putting in the new engine, which are known to fail quickly, that might make sense. I've been looking all over the interwebs, and found a couple threads with symptoms that mirror mine where the head gasket ended up being the issue. Not a huge leak, just enough to make the cooling system malfunction.

I can do basic stuff, but I'm nervous to get into it. I just ordered the manual, hopefully a head gasket is a job I can tackle.
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Old 08-24-2013, 01:50 PM   #1230
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Top end is pretty easy, just take your time and make notes, take photos, study the shop manual, you will be fine.

Good luck
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