Radiator Guards = Overheating????

[Sandjunky]

My engine was bogging so bad today on some relatively small hills that I usually kill. It's like the brakes were on and I could'nt get the RPMs up with the clutch. The only thing that has changed is the set of Devol Radiator Guards and ASV levers that I installed since my last ride. The temperature outside was nice, my jetting has never been an issue, and my air filter had one ride on it. I checked my plug and it looks like it is running a little lean, but the engine was not popping. Is there any possibility that the radiator guards restrict too much air flow and caused the engine to get too hot? I never smelled antifreeze or burning engine smells and the bike ran great until I hit the hills and then it would lose power.

Thanks

 

[Spine_Thrust]

Take your pipe off and check for blow-by on the piston. What oil are you using?

 

[Sandjunky]

I run Maxima SuperM and 91 octane @ 32:1. I haven't checked for blow-by, but it seems to have good compression. It starts on the first kick and feels like it has plenty of compression when I push the kick starter through a revolution.

 

[NO HAND]

I run devol rad guards too and personnaly I only have good things to say about this product but I've read it may reduce cooling capacity up to 20%. The stock plastic fins that we remove to fit the rad guard are there to channel the air towards the rad.

 

[Sandjunky]

Thanks No Hand. I like the guards, but if they reduce horsepower due to overheating I can't see the benefit of using them. I may change the jetting to run it a little richer to see if that helps. I figured that if I have always ran it a little lean before, then that 20% reduction in cooling could be pretty drastic. I need to richen it up if I'm going to be climbing hills anyway. I don't want to burn a piston.

 

[JST122]

If you cant seem to figure out the problem then I would recommend putting the stock Radiator Shrouds and fin guards back on and see if it makes a differenece. If it runs better under the stock conditions, then you will know what the problem is and if it doesnt then you can puty the aftermarket parts back on and continue troubleshooting.

 

[Rcannon]

Thanks No Hand. I like the guards, but if they reduce horsepower due to overheating I can't see the benefit of using them. I may change the jetting to run it a little richer to see if that helps. I figured that if I have always ran it a little lean before, then that 20% reduction in cooling could be pretty drastic. I need to richen it up if I'm going to be climbing hills anyway. I don't want to burn a piston.

Is it possible you knocked a wire loose on your coil as you were installing the guards? I cannot see the slight amount of extra heat causing problems?

I once chased a similar problem. To make a long story short, I cracked the porcelan on a spark plug..............

 

[Sandjunky]

I changed the Main jet from a 160 to a 162, and replaced the sparkplug with a new iridium tip NKG. I double checked the coolant and it is clean and full. I ran it down the street and it still runs fine, but I won't know if it is better until I hit the hills next week.

It sucks that I have to take the carb off to change the main jet. Time consuming.

 

[Sandjunky]

Update:
OK, so I replaced the stock plug BR8ECMVX with a BR9EIX, which a colder plug, and I changed the Main jet from a 160 to a 162. I ran it today and it did much better on the hills. After a few hill climbs it was pretty hot, but never felt like it was bogging. I ran it pretty hard down a sandwash and it seemed to get pretty hot. I smelled antifreeze. On the way back it seemed to have a little pre-ignition but it wasn't constant. So here are my options... Jet it a little richer, run a colder plug, or remove the Devol radiator guards and sacrifice radiator protection for better cooling.

Any other ideas?

 

[i_955]

Cut some slots in the guards to allow better breathing.
You'll still have the extra strength and a steady hand with a file will make it look pro.

 

[hndarida4life]

i god the same guards all they have done was good for me i had a rock hit them and dent it but the rad is still good which i am happy about cause i dont have 300 dollars for ne ones so i dont think its the guards.

 

[elcamino12sec]

One thing, if your float is not adjusted properly, when your bike is at an incline it may be running out of fuel causing it to bog. Next time it does this, stop and make the bike sit level for a moment and then run it in the power band, if it pulls insted of bog than thats what your problem is, if is still boggs than Im not quite sure what to tell you, hope this helps.

 

[john stu]

i have run devol guards on a 95 cr250,99yz400 "hot running four stroke"and 2002 cr250 i didnt notice any of them running hottor than stock and never boiled any of them......but i could see them restricking a small amount of air flow with the loss of the louvers so i guess its possable