What is a top end rebuild?
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What is a top end rebuild?
Top end rebuild means redoing just the heads. That means valve guides, check/replace valves and valve springs. Piston, cylinders, rings, crank bearings, etc. are left in tact. On the 993, this also and usually mean clearing out the SAI passages in the head and also in the cylinder head housing.
How do you tell if a 2-stroke needs a new top end?
When you see dirt in the intake, you’ll need to tear down the top end to check for damage. A damaged cylinder may need reconditioning or replating. The same goes for when you find your intake boot and airbox was not sealed properly. Anytime you find leaks, you’ll want to tear down and inspect for damage.
How often do 2 strokes need to be rebuilt?
Two Strokes: It’s also important to keep in mind that if you’re running your two-stroke on the lean side, it may need more frequent rebuild intervals. When rebuilding the top end the general time frame is every 25 hours however like we said earlier every bike is unique and rebuild times also vary with engine sizes.
How often should you rebuild top end?
Four Strokes: A four-stroke has slightly different intervals between rebuilds, the top end is generally rebuilt at the 25-30 hour mark if you’re a regular racer, and more importantly on a 250F, which is typically ridden more aggressively.
When should I do a top end rebuild?
If you’re a regular racer, and especially if you’re riding a 250 four-stroke, then you’ll want to rebuild your new top-end between the 25-30 hour mark. If you’re riding a 450, or riding the bike under an easy load majority of the time, then you’ll want to rebuild the top-end between 30-40 hours.
How often do you need to change piston on a 2-stroke?
Most modern two strokes / four stroke Motocross/Enduro motorcycles recommend piston and ring replacement at 15 hour or 5-6 race intervals. Just because the kick starter feels firm or it starts easy, it still may be time for maintenance.
When should you do a top end rebuild?
A four-stroke top end is generally rebuilt at the 25-30 hour mark if you’re a regular racer, and more importantly on a 250F, which is typically ridden more aggressively. On a 450, or if you’re riding the bike under an ‘easy’ load, then rebuilding the top end between 30-40 hours will be adequate.
How much does it cost to rebuild an engine top end?
between $2,500 and $4,000
A typical engine rebuild is between $2,500 and $4,000 in parts and labor costs. This type of engine repair might include simply replacing bearings and seals, and obviously taking the engine out and re-installing it.
