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Old 08-30-2009, 12:53 PM   #1
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Default How many of you....

change out the rod after engine break-in?

I've never done it but I'm thinking about it for the engine I'm running right now. It's got about 1 1/2 to 2 gallons on it now so it's pretty well broken in. I'm interested in hearing other folks thoughts on whether or not replacing the rod will add to the engine's lifetime. Thanks.
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Old 08-30-2009, 12:58 PM   #2
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I dont although its good insurance on a high dollar mill
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Old 08-30-2009, 01:10 PM   #3
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You should at least pull the engine and remove the
backplate and check to see how much wear (slop)
there is in the lower con rod bushing. Remember to
have the piston at or near T.D.C. when you pull the
backplate from the engine. You will break the piston
skirt on some engines if you don't have the piston up
out of the way. I check my engines after every gallon
of fuel or after running an engine really hard all weekend
long.
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Old 08-30-2009, 03:15 PM   #4
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I very rarely every change my rod. When I break in a motor I always heat it up so there is not as much pressure on the rod journal and crank pin. This is due to the heat expanding the piston and sleeve therefore the pich not be as tight.
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Old 08-30-2009, 04:13 PM   #5
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Nope, I leave them in as long as I can.

I pull the backplate and check the conrod nearly every time I pull the engine for clutch maintenance. If there isn't any play I leave it in.

I only run Novarossi and Picco engines.
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Old 08-30-2009, 04:23 PM   #6
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In the past you didn't need to (though it was still a good idea) because the motors were not all that tight and broke in fairly quick. Some of todays motors are just ridiculously tight and should get a rod after break-in and maybe one race. It really depends on the motor though. If it was so tight when new that the thing was constantly locking up on you, change it now.
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Old 08-30-2009, 05:20 PM   #7
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I never used to.... but I do now!



That's from my AB Modded JPX .21... Expensive mistake.

-Howard
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Old 08-30-2009, 05:42 PM   #8
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I got to replace my .21 v spec ....2.5 gals. and it started losing tune.....pulled the engine and sure enough there was some slop in the rod, not much but just enough to probably make it run goofy. I will be breaking in another v-spec tomorrow and I will replace the rod with a SPEED rod as soon as I get a gallon through it. I will let you guys know if it helps,.....could not believe it actually had visible slop in the rod!!!
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Old 08-30-2009, 06:38 PM   #9
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Quote:
Originally Posted by Joey Platinum View Post
I got to replace my .21 v spec ....2.5 gals. and it started losing tune.....pulled the engine and sure enough there was some slop in the rod, not much but just enough to probably make it run goofy. I will be breaking in another v-spec tomorrow and I will replace the rod with a SPEED rod as soon as I get a gallon through it. I will let you guys know if it helps,.....could not believe it actually had visible slop in the rod!!!
Keep that old rod you remove after a gallon. Every time you buy a Vspec pop that rod in so that your allways useing that same rod for breakin and the first gallon. Then when your done with that pop the rod that came with the engine back in. (I think the Jx21 rod is the same as the speeds, but $10 cheaper)

A good way to save rods on the OS mills, not really needed with NR's.

Do you like the OS better than your GRP? Easier to tune isn't it.
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Old 08-30-2009, 08:29 PM   #10
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Quote:
Originally Posted by pur3evil View Post
I never used to.... but I do now!



That's from my AB Modded JPX .21... Expensive mistake.

-Howard

Pics are worth a 1000 words.

we had a Clockwork Jpx Poop the rod today as well.
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Old 08-31-2009, 06:42 AM   #11
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Quote:
Originally Posted by Zerodefect View Post
Keep that old rod you remove after a gallon. Every time you buy a Vspec pop that rod in so that your allways useing that same rod for breakin and the first gallon. Then when your done with that pop the rod that came with the engine back in. (I think the Jx21 rod is the same as the speeds, but $10 cheaper)

A good way to save rods on the OS mills, not really needed with NR's.

Do you like the OS better than your GRP? Easier to tune isn't it.
That is very close to what I do. I use all OS engines so all the rods fit. I have the same standard v-spec rod I use to break in engines then I pop the new one in after the break in and initail race tune. The v-specs in particular are very rough on rods on break in. Also always use the speed/ninja rod the oiling hole keeps that bushing cooler and stops them from getting sloppy. Also always use new ones of those cheap clips that hold in the wrist pin. They are cheap to replace and trust me from experience they don't hold well the second time around.
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Old 08-31-2009, 07:06 AM   #12
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Quote:
Originally Posted by pur3evil View Post
I never used to.... but I do now!

..Removed the pic..

That's from my AB Modded JPX .21... Expensive mistake.

-Howard
YIKES! Is that the bushing all in pieces? That's gotta be detonation, right?
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Old 08-31-2009, 07:07 AM   #13
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I dont like opening my engines up. I feel like every time I do I increase the chances of causing trouble.
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Old 08-31-2009, 07:14 AM   #14
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Quote:
Originally Posted by Zerodefect View Post
Keep that old rod you remove after a gallon. Every time you buy a Vspec pop that rod in so that your allways useing that same rod for breakin and the first gallon. Then when your done with that pop the rod that came with the engine back in. (I think the Jx21 rod is the same as the speeds, but $10 cheaper)

A good way to save rods on the OS mills, not really needed with NR's.

Do you like the OS better than your GRP? Easier to tune isn't it.
I like that idea. Thanks. I'll probably try to keep a "break-in" rod around from now on. Plus that forces you to tear down and inspect the new engine which is a good idea but something that I rarely do.
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Old 08-31-2009, 07:57 AM   #15
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I do it too, it's an age-old trick. 5L => new rod. Keep reusing the old one to break in the new motors, chuck it in the bin when there's too much play as too much play means improper lubing of the crank pin.

Paul
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