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Author Topic: Bottom end maintenance schedule.  (Read 3451 times)

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Offline Stusmoke

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Bottom end maintenance schedule.
« on: June 27, 2013, 01:46:06 AM »
What time frame does everyone use? Thanks in advance.
« Last Edit: December 31, 1969, 04:00:00 PM by ' »

Offline TotalNZ

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Bottom end maintenance schedule.
« Reply #1 on: June 27, 2013, 07:52:05 AM »
Well i just split my cases for the first time after 100 hours and everything is in real good condition. I'm going to do all the bearings while it's apart but they really don't need it. It really depends on how good you are with your maintenance though, if you don't clean your airfilter enough or change your trans oil enough then your motor will wear out faster.
I change trans oil after every race meeting or every second practice session and filter after every ride and i'm happy to leave my bottom end for 150 hours. This in a 300 though, a 125 would need done more often.
You can check side play on your bigend with feeler gauges at each rebuild and check your mains for play by giving the flywheel a good shake once in awhile to keep an eye on things.
« Last Edit: December 31, 1969, 04:00:00 PM by ' »

Offline Stusmoke

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Bottom end maintenance schedule.
« Reply #2 on: June 27, 2013, 08:27:56 AM »
Well i just split my cases for the first time after 100 hours and everything is in real good condition. I'm going to do all the bearings while it's apart but they really don't need it. It really depends on how good you are with your maintenance though, if you don't clean your airfilter enough or change your trans oil enough then your motor will wear out faster.
I change trans oil after every race meeting or every second practice session and filter after every ride and i'm happy to leave my bottom end for 150 hours. This in a 300 though, a 125 would need done more often.
You can check side play on your bigend with feeler gauges at each rebuild and check your mains for play by giving the flywheel a good shake once in awhile to keep an eye on things.
Cheers mate. So bearings @ 100 hours on your 300 is the playing it safe and a 250 wouldnt be much different. By sticking feeling gauges in the big ends amd going by the clearance that the manual states is how ill know when its time for a new crank assembly. Thanks mate

Any other opinions welcome cheers.
« Last Edit: December 31, 1969, 04:00:00 PM by ' »

Offline TotalNZ

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Bottom end maintenance schedule.
« Reply #3 on: June 27, 2013, 10:20:37 AM »
yeah, 100 hours is playing it pretty safe definitely. At 100 hours all my bearings are in great shape with no real signs of wear at all. Could probably go much much longer especially if you're mostly trail riding.
I've actually got some microblue mains for her this time so that could push service life out even further.
« Last Edit: December 31, 1969, 04:00:00 PM by ' »

Offline VintageBlueSmoke

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Bottom end maintenance schedule.
« Reply #4 on: June 27, 2013, 10:23:19 AM »
At the end/before the beginning of the racing season.
« Last Edit: December 31, 1969, 04:00:00 PM by ' »
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Offline gpnewhouse7

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Bottom end maintenance schedule.
« Reply #5 on: June 29, 2013, 12:06:46 PM »
New top end when I buy the bike and then again between race seasons.
Fix the bottom when it stops working.

The bottom ends can last forever on my yz85 I used to run it with a dirty air filter and never changed the oil in the gearbox the whole time I had it. I had it 3 years it did three top ends and the bottom was still fine when I sold it.

My rm125 had the bottom end replaced just after I got it along with the top end, I then cleaned the filter after every ride and changed the oil after every three rides and the bottom end went again six months later.
« Last Edit: December 31, 1969, 04:00:00 PM by ' »

Offline arnego2

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Bottom end maintenance schedule.
« Reply #6 on: June 30, 2013, 01:18:50 PM »
There is a relation between riding style and premix ratio in regards to bottom end changes.
Coming from bottom end changes at 150 hours due to necessity at 40 to 50:1 premix level and no premix fallout in the crank I now run over 200 hours on one crank with all in spec @ a premix ratio of 20:1 and a 2mm fallout of premix in the crank.

A higher premix ratio gives you more life to your bearings and a way better ring-seal. All IMO of course :) 
« Last Edit: December 31, 1969, 04:00:00 PM by ' »

Offline scotty dog

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Bottom end maintenance schedule.
« Reply #7 on: July 05, 2013, 10:52:17 PM »
If you can afford to Stu and your keeping the bike for the next season, I would do it at the end of each season. I used to do 2 rings and piston/ring each year and never had a failure and I rode pretty much both days every weekend and a couple during the week, but I used to trade in for a new one every year too
« Last Edit: December 31, 1969, 04:00:00 PM by ' »
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