Perk

~SPONSOR~
Sep 17, 2001
303
0
My cousin recently got a CRF 150R and this weekend while trailriding with his father and myself his bike started to boil over on several occasions. We were riding pretty tight, low speed terrain. While stopped and idling waiting on a slower rider, his bike started to idle pretty high and we noticed coolant spewing out from beneath the bike. After we got moving again it seemed to cool down and idle improved, but it started happening again later on in ride. Bike is bone stock and just came back from dealer after a cam recall. He is a pretty experienced rider for his age, but does not race or ride MX. Is this bike just not going to be happy trailriding in tight terrain?

Thanks,

Perk
 

mideastrider

~SPONSOR~
Jul 8, 2006
827
1
Yeah I have seen it with my son's 150 when riding some tight trails and having to sit and wait on someone to get going. But its never caused a problem. 2 or 3 oz of coolant is the most I've ever had to add and thats not been often. He races HS and does alot of trail riding.I have always used honda coolant since I got the bike new. But any good coolant should be fine.
 

KelvinKDX

LIFETIME SPONSOR
Aug 25, 2000
1,622
0
I ended up using EVANS NPG COOLANT in a KX100 that was overheating in the woods when riden slow and climbing hills. Solved the problem completely. The stuff is a non-aqueous propylene glycol concoction with a boiling point of 370 degrees F. You have to get all of the water out of the bikes system before you use the coolant.

http://www.evanscooling.com/main27.htm
 

hot125mod

Member
Jan 14, 2007
501
0
redline water wetter and water ro is the best because it is the cleanest. ro meaning reverse osmosis the way it is filtered like how dasani does theres. make sure you drain it before winter at least I have to because of good ol minnesota winters. oh yeah make it a 50/50 mix
 

Perk

~SPONSOR~
Sep 17, 2001
303
0
So this bike should be ok in a hare scrambles type environment, just try and limit the still idling?
 

KelvinKDX

LIFETIME SPONSOR
Aug 25, 2000
1,622
0
hot125mod said:
redline water wetter and water ro is the best because it is the cleanest. ro meaning reverse osmosis the way it is filtered like how dasani does theres. make sure you drain it before winter at least I have to because of good ol minnesota winters. oh yeah make it a 50/50 mix

The Redline should be an improvement over regular coolant but I do not think it will be as effiecient at cooling and reducing boil-over as the Evans NPG. The boiling point of the Redline is about 265F compared to 375F w/ the Evans. That being said the Redline should be much less expensive so I would try it first and if you still have the problems try the Evans. I had to use the Evans based upon the style of riding my wife was doing ... slow w/ lots of stopping and hill climbing.
 

KelvinKDX

LIFETIME SPONSOR
Aug 25, 2000
1,622
0
You know ... that's something to think of. What is the jetting on the bike? I have heard the the 450's come pretty lean from the factory ... not sure about the 150R's.
 

clinster

Member
Aug 20, 2023
1
0
When we picked up my son's 150R Expert (2023), the tech said that idle was set high from the factory and recommended to run it that way for a little while (like an hour), then tune it down. There's a big screw on the carb, can't miss it, and it is adjustable by hand. This adjustment may help. But as stated previously, inevitably gotta get air moving through the radiator to let convection do its thing. It is a race bike and it wants to Go-rilla!
 

Clark Jeff

Member
Sep 16, 2023
7
0
If your Honda CRF 150R is experiencing overheating issues, it's important to address the problem promptly to prevent potential engine damage. Overheating can occur for several reasons, and here are some steps you can take to diagnose and resolve the issue:

  1. Check the Coolant Level: Ensure that the coolant level in the radiator is at the appropriate level. Low coolant levels can lead to overheating. If it's low, top it up with the recommended coolant.
  2. Inspect for Leaks: Look for any signs of coolant leaks around the radiator, hoses, and water pump. Even a small leak can cause overheating over time.
  3. Radiator Blockage: Check if the radiator is blocked by debris, dirt, or mud. A blocked radiator can't effectively dissipate heat. Clean the radiator if necessary.
  4. Coolant Flow: Ensure that the coolant is circulating properly. Check the water pump and thermostat to ensure they are functioning correctly.
  5. Airflow: Make sure there's sufficient airflow to the radiator. Check for obstructions like mud or debris on the radiator fins and the area around it.
  6. Coolant Mixture: Verify that the coolant mixture is correct. It should be a 50/50 mix of coolant and distilled water. Using the wrong ratio can affect cooling efficiency.
  7. Riding Style: Avoid excessive idling and slow-speed riding for extended periods, as this can lead to overheating. Keep the bike moving to maintain airflow.
  8. Jetting: If you've made modifications to the bike's engine or exhaust, incorrect jetting can cause overheating. Ensure the carburetor is jetted correctly for your setup.
  9. Thermostat: Check if the thermostat is stuck closed, which can prevent coolant flow. If it's malfunctioning, replace it.
  10. Fan Operation: If your bike is equipped with an electric cooling fan, ensure it's working properly. Test it by letting the bike idle and monitoring if the fan kicks in as the temperature rises.
  11. Oil Level and Type: Low engine oil levels or using the wrong type of oil can contribute to overheating. Ensure the oil level is correct and use the recommended oil grade.
If you've checked these aspects and the problem persists, it's advisable to have your bike inspected by a qualified mechanic or a Honda dealership. They can perform a more thorough diagnosis and address any underlying issues that may be causing the overheating problem. Prompt attention to overheating issues is crucial to avoid engine damage.
 
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