When is it time to rebuild?

Check here for the latest and greatest engine modifications.

Moderator: hbartel

Post Reply
Bad Dawg
Posts: 388
Joined: Fri Jul 18, 2003 3:27 pm
Location: Solomon Islands

When is it time to rebuild?

Post by Bad Dawg »

My engines performance at Ashland was pathetic. All of them. Norvels and Fx's. I am wondering if my lack of basic engine skills have toasted them all. Have I run them too lean so many times that they will never run right again? I don't know. My plan for the winter is to take them all apart and check them for wear and tear and see if they need rebuilds. It is also possible I have let garbage get into the engines and caused damage that way. What should I be looking for? What are the signs of too hot runs and FOD?

NUNC AUT NUNQUAM
Mark V.
The perpetual 'newbie'
Jimbo
Posts: 1082
Joined: Sat Apr 07, 2001 11:28 pm
Location: USA

Post by Jimbo »

I'll tell you one thing I pay close attention to, dirt naps. If dirt gets in the carb I wash it out,even if it's just dust from a landing. If I stick the engine in the ground I pull it off and take it all the way apart to clean it before I run it again. Dirt and dust are engine killers. The next big killer is unbalanced props. They can kill a plain bearing engine in a hurry. One other thing is excessive RPMs. I don't turn my B engines over 17.3K. Plain bearing engines shouldn't be turned more than 15K.
1)Dirt
2)Lean runs
3)Unbalanced Props
4)Too many RPMs

Limited-B
Try it,you'll like it !
Cajun
Posts: 2020
Joined: Wed Mar 28, 2001 10:22 pm
Location: USA

Post by Cajun »

Sometimes these problems occur from just changing locations.

Jimbo and the guys from SW La. used to come to Nacogdoches for a meet and just could not get their engines to run right, even though they ran fine at home. We would in turn go to Sulphur and have the same problems with our engines.

Altitude, humidity, barometric pressure, and temperature are all a factor in how a 2 stroke/cycle engine performs. When changing from one climate to another it sometimes takes several runs to get the needles set just right again. In some cases a change of fuel is required.

If an engine has adequate compression and is not leaking air to the crankcase it should run. I have been tempted to purchase a small compression guage to measure exactly what the condition of my pistons/liners are.

CAJUN [8D]
Lone Star Combat State
AMA-CD 174052
RCCA 380
NACOGDOCHES, TEXAS
MY MIND WORKS LIKE LIGHTNING,,ONE BRILLIANT FLASH AND IT'S GONE!!
montague
Posts: 1639
Joined: Wed Feb 27, 2002 3:24 pm
Location: Maryland
Contact:

Post by montague »

If you go through the trouble of tearing down the engine, look at the piston/liner. Any vertical scratches are signs that you ate some kind of dirt. It doesn't mean the engine is trashed, just that you did get something in there. You probibly have some RPM loss from that kind of thing, but if it's small, it's not the end of the world.
I have a couple of FX's that obviously got something stuck between the piston and exhaust port, leaving scratches on the piston.

One on of them, I took a fine file and some very fine emory cloth and I deburred, the exhaust ports in the cylinder. I then took some emory cloth, put some oil on it, and put it on a flat surface, and rubbed the top of the piston, removing some of the varnish. I also went around the piston once or twice, but you really don't want to make the piston diameter smaller if you don't have to. When I put that engine back together, it had noticeably more compression, and I picked up a few RPM. It may not work for everyone, but it worked for me that time.

Oh, be sure to check all the head and backplate bolts. I had an FX and a Mag that seemed down on power and acting oddly, both turned out to have 1 or 2 loose head bolts. I've also found glowplugs that lossened themselves up.




Kirk Montague Adams
RCCA 560
http://www.MidAtlanticCombat.com - Combat in the Mid-Atlantic Region
Post Reply