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Author Topic: First engine failure  (Read 385 times)

Online zcarlson12

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First engine failure
« on: June 15, 2017, 08:37:19 AM »
I had my first engine failure in 17 years of racing Memorial weekend at a race. It was running extremely well for the first practice and even better in the second but something went wrong right after landing from a small ski jump. I had little to no throttle response and it sounded terrible so I shut it down immediately. Got it back to the pit and the guys from Koster Racing were right next door and asked if they could help. Told them what happened and started it up and immediately shut it down so they could hear what was going on. We all figured it was probably the top rod bearing but it was actually what you see in the pictures. I should have known it was on the last leg since it was running better than it ever has. Any ideas as to why this happened? My piston, bore, clutch, transmission, cases everything was fine except obviously the crank. Throwing a new piston kit, crank and crank bearings in just to be safe as well as a water pump rebuild kit with one of Ryan's impeller shafts while it's apart. Specs are

ESR 310 trx7 clean up
72.25 bore and piston
50:1 Amsoil dominator in VP 110 fuel
BR9EIX plug gapped at .22
HP trans oil in the bottom end
LRD pipe and silencer
38 a/s #6 slide 48 pilot 172 main DGH needle
Roughly 20 hours on top end and complete bottom end was done in 2015
Laeger 310R

Online Skeans1

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Re: First engine failure
« Reply #1 on: June 15, 2017, 09:36:27 AM »
What brand of crank Zac?

Online zcarlson12

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Re: First engine failure
« Reply #2 on: June 15, 2017, 09:38:10 AM »
Hot Rods stock 89 length. Came in the yellow box not the red and white.
Laeger 310R

Online Skeans1

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Re: First engine failure
« Reply #3 on: June 15, 2017, 10:59:22 AM »
Almost looks like it was shock loaded

Offline rablack21

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Re: First engine failure
« Reply #4 on: June 15, 2017, 12:42:21 PM »
How many hours you think you had on the crank? How many races?
« Last Edit: June 15, 2017, 12:44:37 PM by rablack21 »

Online zcarlson12

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Re: First engine failure
« Reply #5 on: June 15, 2017, 06:11:17 PM »
12+ so 24+ motos and practices probably just as many times. It definitely had some time on it now that I'm breaking it down. I guess I know the life  expectancy for the future haha.

Also, went to put the top end on today and noticed Eddie didn't send the top end gasket kit and extra base gasket. Called him up and he is over nighting it for me. Great customer service!
Laeger 310R

Online The norm

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Re: First engine failure
« Reply #6 on: June 15, 2017, 09:25:21 PM »
Man sorry about your R! I have not personally seen a crank shaft break, but I have delt with several broken pump and gearbox shafts. I'm my experience as a power plant mechanic I have seen where vibration will break a shaft. Hopefully you get it back on the track.


Loren
I had a BDT motor once.....It SUCKED!
Currently: Hybrid Engineering 310 stroker built by Pete

Offline F-Red

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Re: First engine failure
« Reply #7 on: June 16, 2017, 03:38:54 PM »
I guess I know the life  expectancy for the future haha.

Also, went to put the top end on today and noticed Eddie didn't send the top end gasket kit and extra base gasket. Called him up and he is over nighting it for me. Great customer service!

Sorry for your misfortune. But as for ESR, Eddie once sent me the wrong size, reed spacer block. He sent the right one, next day. Great customer service!  ;)
LONG LIVE THE "R\'s"

Offline Phoenix843

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Re: First engine failure
« Reply #8 on: June 16, 2017, 09:03:27 PM »
Sorry it happened, seems like you got a lot of use out of it though. Like you said now you know how long it will last.

Offline Langbolt

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Re: First engine failure
« Reply #9 on: June 18, 2017, 08:31:31 PM »
Check the rivets on your flywheel.....if they're loose the magneto won't be balanced and the harmonics will break your crank like yours did. Are you running a Stock Flywheel ?

Online zcarlson12

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Re: First engine failure
« Reply #10 on: June 19, 2017, 12:02:39 PM »
Thanks everyone for your input. Langbolt I'll check the rivets on the flywheel tonight. Stock ignition and flywheel.
Laeger 310R

Offline StrokedAZ

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Re: First engine failure
« Reply #11 on: June 23, 2017, 10:55:45 AM »
That sucks man.  Hope they get it up and running for you. 
86 TRX 250R