07' Boiled over!!!

desertgasser300

desertgasser300

Banned
Managed to boil over my 07' 300 yesterday,

Altitude of 2500 ft.
Temps. 100F

40 pilot
second clip from bottom on a CEK needle
175 main

1.4 bar (new) rad cap

This is a first for me and was extremely surprised by this. It was a long, loose and rocky hill climb. Mostly second gear for the climb in the pipe. Crested the hill and noticed it boiling. Let it cool down, lost maybe 8 oz. of fluid. Once it cooled off it never boiled again finished the last 50 miles of the ride.
 
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Were you slipping the clutch a lot? On my Orange bikes that was THE quickest way to get them hot.
If you find that it is boiling over more than it used to, it may be the new rad cap. You wouldn't be the first to be let down by a brand new unit.
 
Plus one.

If this has only just started in conjunction with the new rad cap then thats where I'd be looking first.

Anything else changed?
 
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Der....I meant a 175 main.

It has never boiled before or even on the return trip later that day.
Wasn't slipping the clutch, it has a rekluse in it.

I did forget to mention that as I let it cool I dropped the needle to the middle clip. It would burble a bit in the mid, but as long as it didn't boil I was o.k. with that. The rad cap is new, but like 2 months of use new.

My concern for all of this is the enduro I have coming up this Sunday. 50 miles in 3000 to 6000 elevation with temps in the highs 80's to mid 90's
 
Double check the cap if you can. Have a look in the rad with the engine running and make sure there is good water movement. Maybe check the water pump impeller just to be safe.

Do you run a catch tank? Any chance the rad was over filled and just spat its load? Or was it really really boiling. Any other signs of lean running? Hanging idle? Any air leaks? Carb boots, LHS main seal?
 
It may be a combination of the conditions and being borderline lean in the midrange with that needle. That needle is smooth because its little tight with fuel. For your race at higher altitude it may be fine.
 
GMP, you maybe right. I have mostly riden at around 1100ft with the needle where it is but the single track I ride there I never really get on it like I did the other day on that hill. I didn't realize that particular needle was so lean. Maybe the reason why I see very little smoke and virtually no spooge with that needle setting. I think I would rather be a bit rich then to lean. Spark plugs are cheaper then a top end!

I have the upgraded billet impellor and it is moving water through the rads.
 
I just plotted it out graphically. CEK#2 is very lean particularly so at 1/4 to 1/2 throttle. For example most people here are running 38 N3CH#2 172/175 for altitude. Comparing to 40 CEK#2 175 they are very similar from 1/2 throttle to WOT. The CEK is around 11% leaner at 1/4 throttle though.
 
V
Jakobi said:
I just plotted it out graphically. CEK#2 is very lean particularly so at 1/4 to 1/2 throttle. For example most people here are running 38 N3CH#2 172/175 for altitude. Comparing to 40 CEK#2 175 they are very similar from 1/2 throttle to WOT. The CEK is around 11% leaner at 1/4 throttle though.
Click to expand...

You blow my mind how knowledgable you are on jetting..

The CEK what it came back with from RB designs.
 
desertgasser300 said:
V

You blow my mind how knowledgable you are on jetting..
Click to expand...

..I'm using JDs jetting spreadsheet. LOL! Not much skill on my behalf. I don't think I'm very knowledgable at all. Definately not an expert. Just a noob who has had a bit of time to play around and report the findings.

If it was boarderline lean going a clip richer should help it out. My experience is like Glenn said. Going leaner will continue to make throttle control crisper but it will also get smoother as it won't be making the same power under load.
 
Wish I was Racing

desertgasser300 said:
Coolant is two months old.

I think I might leave the jetting where it is now for this weekends race. Its not a fast trail, more technical and rocky.

Andoman, curious if you are entered this weekend?
Click to expand...

I wish. I work out of town 3-4 days a week. So I only race/epic ride 3 or 4 times a year. Most all of my riding is local a couple of times a week. I'm in Payson and only have to ride 1 mile down a dirt road from my drive-way to the trail.

Another thought about your overheating: I had a Rekluse in my Orange 540. With normal plate wear and the resultant installed gap increase, I noticed the bike regularly running hot before I ever noticed the clutch slipping more than usual.
 
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What Rekluse do you have? I had the z start on my kx250 and it def made things hotter because I could never get full engagement at v low revs so on tech climbs I could not chug. But I am guessing that if you had just fitted it and then it started boiling you would already have your answer and would not be asking here :-/
 
Four strokes are a bit different with respect to clutch slipping influencing overheating. They run at a much higher temperature than a two stroke, much closer to the boiling point even in a normal situation.
 
Mine was on a kx250 2t with z-start, not even the pro, believe they have progressed a bit since then. On some of the rocky climbs we do here the clutch cover would sizzle if you poured water on at the top and most bikes boiled on the way up. Have since done the same mountain on the GG and only steamed (was riding with orange bikes so hardly a boil in comparison!) in the last hundred meters or so. Really made me question myself why I ever tried to endorize an mx bike!
 
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