Common Question

Why Cams Break

Engine Break-In Procedures

Valve Lash

Top End Oilers

Plumbing Your Oil Lines

Email Hank

 

MY ENGINE JUST BLEW UP! WHO'S AT FAULT?

To a Professional engine building and rebuilding facility, no news is usually good news. When you don't hear from a customer for quite some time, it is safe to think everything is OK and his engine is doing him a fine job. However there are those who do have problems and here comes the bad news. "I just had you rebuild my engine three races ago and it broke the intake cam. You will warrant this won't you? It's only three races old? " or, "I just had you rebuild my engine and it broke #2 rod, about one inch from the wrist pin. What did you do to my engine to cause this? I only had a few races on it!"

All of us, and I am speaking for most of the major engine rebuilders of Legend engines, have experienced engine failures of one type or another. We go out of our way to go that extra mile for a customer to help control engine failures, but they still happen. Cam breakage, Rod failure, broken Crankshaft, spun Rod Bearings, Cam Cap Bolts pulled out of the head, Oil Pump splines worn out and on and on! Does that make your chosen engine builder at fault? In our experience, 99% of the time the answer is no!

If we magnaflux the crankshaft and connecting rods during a rebuild and they check out ok, that doesn't mean they will not break. They were not cracked at the time they were checked and that can change in a few laps. First and foremost everyone needs to keep in mind this engine is sold new with no expressed warranty from 600 Racing, Inc. or the Yamaha Motor Co. How then can a experienced engine rebuild facility do what the manufacturer or the seller of the product cannot do? Most reliable engine builders, including myself will warrant their work. By that we mean if it broke due to our assembly techniques or improper machining we will take care of it. As for parts, you cannot guarantee a part not to break, the manufacturer doesn't, let alone your engine builder. These XJ and FJ motors are very durable, but they were not intended for this kind of application. They do a remarkable job and it is amazing that they hold up under the abuse they receive.

There are many procedures you can do that will add to the longevity of your engine. These are not small block Chevys and Fords, which are water-cooled and can take much more abuse. These are Hi Performance air cooled motorcycle engines and require TLC if you want them to perform week in and week out. How many of you would take your family car out and turn it up around 8,000 rpm every weekend for four months? How many of you think it would last that long? Not many I bet, but you do expect your Legend car to hold up no matter what! Guess what; they can break, then what? Who is at fault? Who can you blame it on? Folks, it doesn't work that way. I know of no one who comes to mind that will guarantee a race engine not to break or fail. If they do then they're setting themselves up for a huge financial loss. First off, practice after practice, test after test, will wear your engine out. Coupled with the heat and continual high rpm, how can you expect so much from your engine ? Don't abuse them anymore than you have to! Limit your practice time and learn the cooling techniques that will add to the life of your engine.

Remember, the engine rebuilder you choose, should be reputable and noted for building good engines. He is just as upset as you that your engine broke. It is his workmanship and name at stake and he doesn't want it to happen to you. This is racing and engine failures are to be expected. They happen in all forms of racing and will happen in Legend racing. They are not bullet proof! If you want that, you need a police vest.

Hank Scott Racing Services