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.
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How many hours is a 250 2 stroke top end?
My current bike is an ’02 KX250. I typically get 35-40 hours on a top-end, the rings and piston will be right on the edge of still being in spec at that time. My first crank lasted approx. 200 hours before the lower rod bearing began developing play.
When should I do a top end rebuild 2 stroke?
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 long does it take to top end a dirt bike?
Dirt Bike Maintenance 2 Stroke A top end rebuild may need to be done as often as every 10-20 hours if you’re riding aggressively and constantly in the high RPM range. However, mild trail riding might only require a top-end rebuild every 100-200 hours.
How many hours is a top end?
How many hours on a 2 stroke top end? A 2-stroke piston can last over a hundred hours if the bike was casually ridden and properly maintained, but an aggressive motocross racer can wear out a top-end in less than 20 hours of ride time.
How often do you rebuild a 2 stroke?
You need to do that every year. The amount of time depends on how hard you are working. 50 hours or motorcross type riding is what you should rebuild. If you act like your in a race and mix 32:1, you should only need to rebuild once a year.
How far can you ride a 2 stroke?
You can tour long-distance on a 2-stroke motorcycle as long as you ensure it does not overheat. Many riders have done thousands of miles on 2-stroke motorcycles. However, 2-stroke motorcycles are not made for constant engine speeds and it may be difficult to find good quality 2-stroke oil at garages.
How long does a bottom end last on a 2 stroke?
It really depends on how you ride and how well you maintain your 2 stroke dirt bike. You may have to rebuild the bottom end every other time you rebuild the top-end. On the flip side, you may get 500+ hours on the stock bottom-end. The harder you ride (high RPM), the shorter it will last.
How many hours does a YZ125 have?
We have seen up to 35-40 hours on a YZ125 top end but that’s stretching it a bit far and we wouldn’t recommend prolonging standard maintenance that long.
How much does a top end rebuild cost for a 2 stroke?
How Much Does It Cost To Rebuild A Top-End 2 Stroke? The cost of rebuilding a 2 stroke dirt bike top end can vary from under $50 to $500+. It depends on what parts need to be replaced and if you’re doing the rebuild yourself or paying someone else to do the work.
How do you break in a 2 stroke engine after rebuilding?
At first start up, keep the engine just above idle and give it a few revs up and down. This power on and power off RPM breaks in the piston and rings evenly on the intake and exhaust sides. If air cooled, once the engine builds up heat where it becomes too hot to touch, shut the engine off.
What is good compression on a 2 stroke dirt bike?
Good compression is 150-160 PSI. A 125cc 2-stroke dirt bike should have at least 140 PSI and about 180 with a fresh top-end. A 250cc 2 stroke should have 170 PSI or more and 210 PSI when new. A 500cc 2 stroke should have at least 140 PSI of compression and 170 PSI for good performance.
Is 50 hours a lot on a dirt bike?
It is around 100+ hours that you need to start thinking about valves, top end, bottom end, new bearings, etc, etc. Of course, this varies with quality and frequency of maintenance and riding conditions. Some may need valves and such at 50 hrs, some may need the work done at 200 hrs.
Why does my 2 stroke have no compression?
The most likely reason why a two-stroke engine has lost compression is an issue with the piston or piston rings. The piston is the part of the engine that creates the compression needed to run. If there is a crack in the piston, air can escape and cause a lack of compression.
What Causes 2 stroke piston slap?
The most common noise associated with a two-stroke top end is a metallic slap. This is commonly referred to as piston slap, and is a result of the piston rocking back and forth in the cylinder bore as it reciprocates. … Left unattended, excessive piston slap can result in failure of the piston skirt.
How many hours is a lot for a 4 stroke dirt bike?
A 4 stroke top-end can last 500+ hours of casual riding if it’s properly maintained. You can also wear out a top-end in less than 20 hours if you’re riding it hard and constantly hitting the rev limiter.
How do you read a 2 stroke piston?
Is it easy to rebuild a 2 stroke engine?
Periodically, if you own a two-stroke, there will come a point where you need to rebuild the top end of your engine. … While two-stroke engines are relatively simple mechanical devices, rebuilding them requires knowledge of how they work, attention to detail, and a systematic approach.
What does top end rebuild mean?
just the heads Top end rebuild means just the heads. It means valve guides, check/replace valves, and valve springs. There are Piston, cylinders, rings, crank bearings and so on. They are in tact. The passages in the head and the cylinder head housing are usually cleared out on the 993.
What is in a top end rebuild kit?
Description. This rebuild kit includes the following items: 2 PTFE Piston Rings, 2 Large White PTFE Cylinder Gaskets, 4 Shaft Seals, 12 Green Cylinder Gaskets, 2 Cylinder O-Rings, and 2 Long Allen Screws.
Is it hard to ride a 2 stroke?
Although 2-strokes are lighter, that doesn’t always mean they are easier to ride. Handling ability will ultimately depend on the rider’s ability and their personal preference. That being said, two-strokes can be harder to ride because they demand more work from the rider.
How many miles can you go on a dirt bike?
Anything over 20,000 miles is usually considered high mileage for a dirt bike. A dirt bike is ridden 3,000 miles per year on average. However high mileage is less important for a dirt bike and it’s far more important how that bike was cared for during its life.
Can you drive 2 strokes on the road?
In the US, you can ride any street legal, registered motorcycle on any public road. This includes 2 strokes that were legal in the year they were manufactured, such as Yamaha’s RZ350. There are many 2 stroke street legal scooters of more recent vintage as well.
How long does a yz250 top end last?
It might last 60-70 hours before kaboom, but for best performance, you are probably looking at about 30 hours.
How do you check compression on a 2 stroke?
How long is bottom end on YZ125?
You could see 200 + hours easy on a bottom end.
How often do you service a YZ125?
Clean Air Filter every ride or two. Change the Tranny oil (ATF) every 2-3 rides. Keep Super Premium Gas mixed wiht a high quality oil at 32:1. Every year, have a top end done.
Are YZ125 reliable?
These are still considered some of the best motocross bikes, especially the 1999 model. They are fast, reliable, and are just a great overall bike.
