Piston Head Pitting

[canadiansavage]

hi i was wondering if anyone knew what causes a never opened k4.6 to have pitting on the piston head? i have run, maybe, 3/4 a gallon through the engine, and i recently took her apart and noticed the pitting on the piston head.

could this be a cause of over-heating? the glowplug seems to be working fine, its the same one the engine came with. i try to run the engine rich, because i am a newbie, and i want to put a good length of time on her before rebuilding her.

anyone else run into this problem?

 

[windjammr]

some things that might do it are a lean condition or geting dirt down the glo plug hole,running to hot of a plug there are many.what sort of temps are you runnig at?

 

[canadiansavage]

i try to keep it at around 250-300MAX, i have occasionally run it at 320 a few times, but not for very long. i have the venom on board temp gauage, so i can reference the highest temp when i bring it back to me to check. how long should it take for the engine to get past its optimal heat? i usually run it at an outside temp of 20 to 24 degrees C.

but between destroying 2 clutch bells because the mesh was off and a busted oil damper, i haven't given her much attention. lol, stupid savage! but right now I'm waiting to get time off work to get a new clutch, then go back to factory on my settings and bring her up to speed again.

by the way, do you knw how to mesh up a metal spur and clutch bell? lol, I'm such a noob!

 

[puckamahow racing]

I think your runnin a lil lean myself thats some high temps ya got there!IMO anyway

 

[Shaun]

yes it sounds to me like you may have been running a little lean as 320 degrees is to hot, hpi reccomends not getting the temps over 250 degress but thats just a guideline and some engines do run a bit hotter but 320 is pretty extreme!!

 

[Blazer X]

Without a doubt a lean conditon. My lrp was suffering from this. I figured out the HSN oring was letting air slip by. My piston and head button look like they were sandblasted.

 

[SunkenMetal]

If you are running lean, more oxygen is burning in your engine, oxygen is an oxidizer, and aluminum oxidizes fast so i would agree with people that you are running lean, or you have an air leak in your carb. check the all the O-rings in your carb and motor, if they are cracked replace them, if they are dry get some type of O-ring lubricant to help seal them, if they arent sealing...

 

[windjammr]

https://www.hpisavageforum.com/forums/showthread.php?t=2137
try this for setting the mesh

 

[scrogathon]

btw how is the Motor running? what does it sound like and is there lots of blue smoke?

http://ca.youtube.com/watch?v=4Nt5tA3vRl0

http://ca.youtube.com/watch?v=prX0OeQLrbw

 

[canadiansavage]

in hindsight, no, not lots of blue smoke, but smoke when it started out, then little to none in the higher rpm's. it sounded kinda angry? I'm not quite sure of the sound.

sometimes, the engine was also had a high rev; it would sputter in the high rpm when i stopped her to idle. ive re-set her back to factory settings so i can re-calibrate where my needles need to be. yea, i barely had it out for like 5 min and she would heat up really fast. i should have realized sooner.

i just got a new 49T plastic spur to mesh with a 17T hardened clutch. I'm tired of throwing money at something that i don't fully understand how to do properly, lol.

i have one more noob question, when I'm screwing in the screw to fasten the clutch bell on the fly-wheel of the motor, should i screw it completely tight, so the flywheel and clutch bell move as one? or should i ease up just before the clutch bell starts to bind with the fly-wheel, letting the clutch bell spin freely, without the flywheel moving?
(ive usually let the CB move free of the flywheel, but ive never been sure if this was OK or not)

Thanks guys, you've all been a great help!!!

 

[Bankrupter]

i have one more noob question, when I'm screwing in the screw to fasten the clutch bell on the fly-wheel of the motor, should i screw it completely tight, so the flywheel and clutch bell move as one? or should i ease up just before the clutch bell starts to bind with the fly-wheel, letting the clutch bell spin freely, without the flywheel moving?
(ive usually let the CB move free of the flywheel, but ive never been sure if this was OK or not)

Thanks guys, you've all been a great help!!!

Sounds like it has a washer/shim touching the outer race of one of the bearings or it has been over shimmed. With the screw all the way tight. The clutch bell should have a very slight amount of back and forth play and spin freely.

 

[HopIt]

There should be a thrust washer that fits between the flywheel nut and the CB. Check the bearings are ok, and run with as little friction as possible. Some people even flush out the factory grease in the CB bearings with a much thinner lube to help this. Then after the CB there is a brass spacer, then you fit the screw in the end of the crank shaft.
Hope this helps.