How many rebuilds their own engines

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1/15/2019 8:31 PM

kpersonius264 wrote:

I can do my own top ends (2 or 4 stroke), clutch assembly. I replaced a shift shaft and a water pump seal once, but I have ...more

Ktm65 is Soooo easy. Learn on one of them

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1/15/2019 8:59 PM

Been doing this sport for over 35 years now , and I'm ashamed to admit , I've never split my cases. I can tear them down to the bare frame , do top ends with my eye's closed. I have always been paranoid about doing the bottom end myself. Tearing into these newer types of suspension scares me off as well. Even though at the track I can ( and enjoy ) tuning in my suspension.

I have to find me a boat anchor motor ( engine HB !!! ) and learn how to it properly.

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And there goes Jeffro. One of God's own prototypes. A super high-powered mutant of some kind never even considered for mass production. Too weird to live, and too rare to die.

Pimpin' Ho's , Rollin' fatty's......drinkin' beers , beers , beers!! ~ Ja

1/15/2019 9:51 PM

I'm not surprised by the results of this poll. I know one of my favorite aspects of the sport is how maintenance intensive it is. A night spent changing oil, washing filters, or greasing suspension is a great way to relax and spend some time to yourself. Plus getting comments on your bike mean so much more if you're the one that maintains it.

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1/15/2019 10:12 PM

Tarz483 wrote:

Imo there should have been an option for an answer that said, i pay to have my things repaired.
I wish i knew how but i was ...more

If you'd like to learn, see if you can find an auto shop class in your area. In San Diego, I remember seeing them available at some night schools a few years ago. Once you learn the fundamentals, it'll all start making sense, and motorcycle and car engines are similar.

The first time you do a top end it'll take a long time. The second time, probably 1/4th as long.
Just be careful, and if in doubt ask someone or post questions here.

Good luck!

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1/15/2019 10:28 PM

kpersonius264 wrote:

I can do my own top ends (2 or 4 stroke), clutch assembly. I replaced a shift shaft and a water pump seal once, but I have ...more

Just take your time, and create a system to remember how the parts go back together. Take pictures as you disassemble.

I split the cases on my YZ80 when I was a teenager and put one part back on backwards. It was a plate that kept a bearing in place. On my test ride, it allowed the shaft to move, and OUCH!! a few broken gears and such, and I got to do it a second time.

All in all it was a great experience. Just be meticulous, and it'll be alright.

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1/16/2019 12:06 AM

I love wrenching on bikes and have always done basic stuff including top ends.
But it has only been the last few years that I've learned to do full motors. I wish I had
been doing them long ago! Also have taken it upon myself to do some suspension
re-valving and wheel lacing. Lacing wheels, in particular, can be almost zen like.
I take my time, crank up Pink Floyd and those babies come out perfect AF!

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1/16/2019 12:14 AM
Edited Date/Time: 1/16/2019 12:16 AM

I use to. Now i buy a second bike when it goes on sale and swap the whole engine out. Then i sell the parts and recoup my money. This saves time and it ends up costing 0 out of my wallet in the long run. I have not paid for a dirt bike or parts since 2007 by doing things this way.

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1/16/2019 2:26 AM

I've done 2 stroke top ends and clutches. I've never split cases or worked on or even owned a 4 stroke but I'm confident I could do it with a good service manual .

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1/16/2019 3:23 AM

FWYT wrote:

I love wrenching on bikes and have always done basic stuff including top ends.
But it has only been the last few years that ...more

How good is a fresh true wheel you built yourself?

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1/16/2019 3:57 AM

kpersonius264 wrote:

I can do my own top ends (2 or 4 stroke), clutch assembly. I replaced a shift shaft and a water pump seal once, but I have ...more

This is me as well, gong to do a crank this winter to on a 2 stroke hopefully. Good luck on your 125

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1/16/2019 4:35 AM
Edited Date/Time: 1/16/2019 9:47 AM

Here's a tip when splitting cases. Take a pic of the shift fork layout including its configuration on the shift drum. The rest is easy. On a fourstroke. Make sure you don't lose or forget the orings that sits in between the cases. Also the dowel pin

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1/16/2019 5:54 AM

Did top ends on my GT80 at 10-11 years old. Did quite a few small block Chevy's in high school and shortly after from top to bottom. Had a BW Super T10 apart in my bedroom at 18...damn that gear lube stunk up the house. Split cases on my 82 RM250, early 20's. Can probably do a 74 CR125 and 250 case split with my eyes closed. Done a few Briggs engines along the way. Not scared...I have f'd up more expensive things.


laughing

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1/16/2019 6:04 AM
Edited Date/Time: 1/16/2019 6:05 AM

My current project. Rebuilding a junk ass Yamaha transmission. Still have no idea why this failed. Weak 3rd gear I guess. Didn’t even make it 50 hours. And unfortunately I can find damage on 7 gears. The metal shavings mulched the bearings.

I will be having the cases put together by my local suspension and engine guy. I don’t have all of the tools to get the bearings in and out correctly or press the crank in and don’t want to risk half assing this.

Between all of the transmission parts (and I do mean all), a new OE crank, new top end, head mod, and labor, it will end up being close to $2k to do it all.

Photo

Photo

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1/16/2019 7:21 AM

hillbilly wrote:

This guy gets it

An ENGINE !

Not a motor, and I rebuild my own but the rest in my area bring their ENGINE s to me

Matt Fisher wrote:

You're right!

However, we should probably let those folks know that make motor oil, along with the Harley Davidson Motor ...more

drt410 wrote:

Bam

Motors plug into the wall,engines don't

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1/16/2019 7:40 AM

Matt Fisher wrote:

You're right!

However, we should probably let those folks know that make motor oil, along with the Harley Davidson Motor ...more

hillbilly wrote:

I just hAte hearing a nascar guy say " i blowed my motor"

BobPA wrote:

Why do you hate when they say it, because they are correct?

mo·tor
/ˈmōdər/Submit
noun
noun: motor; plural noun: motors
1.
a ...more

To most performance engine builders, it's like the basic training mantra "This is my rifle, this is my gun..." . Gun is technically correct, but to call it a gun is not acceptable. Smokey Yunick discussed this at length in several of his articles and books. He blamed Banjo Matthews (a chassis builder) for introducing the term "motor" into NASCAR; thereafter, making many of the NASCAR drivers/mechanics/fans appear ignorant in other racing circles (like Indy, Can-Am, etc). Imagine an F1 guy saying, "We lost a motor." "WTF is he talking about, is his car electric powered?"

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1/16/2019 7:58 AM

JBecker 72 wrote:

My current project. Rebuilding a junk ass Yamaha transmission. Still have no idea why this failed. Weak 3rd gear I guess. Didn ...more

Yes, 3rd gear in a YZ 250 is about as reliable as the valves in a '02-'05 CRF engine. Seen them do it much earlier than 50hrs in the past too.

Adding to costline's post, I always install the shift forks back into their gear sets and wrap a rubber band around the ends of the shafts and twist it around the forks to hold everything together in its place until it's time to reinstall.

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1/16/2019 9:00 AM

FWYT wrote:

I love wrenching on bikes and have always done basic stuff including top ends.
But it has only been the last few years that ...more

Jrewing wrote:

How good is a fresh true wheel you built yourself?

Primo!!!

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1/16/2019 9:53 AM

On my next personal rebuild. I want to rebuild my crank myself. Heads I just send out. Shop in az is cost effective and do work i could never do at home unless you have a newen.

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1/16/2019 10:08 AM

JBecker 72 wrote:

My current project. Rebuilding a junk ass Yamaha transmission. Still have no idea why this failed. Weak 3rd gear I guess. Didn ...more

You might look into a yz426F 3rd, if it's close on the gearing side it's probably more reliable gear than putting a YZ gear back in it. People have been putting WR426F gears in YZ's for years.

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1/16/2019 10:17 AM

My first MX bike was a blown up 98 YZ250, I rebuilt it myself without a manual at 16 years old. Everything went surprisingly well except I was super worried about stripping bolts and I didn't get enough torque on the cylinder nuts. While riding it started puking coolant out the base gasket.... I just rode it to my truck, cranked them down, and dumped my drinking water into it. Had that bike for 2 years and learned a lot about mechanical maintenance. FYI don't put 15wt fork oil in a modern bike. I had so many tank slappers on that bike...

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1/16/2019 1:47 PM

Top ends are fine but bottom end work goes to our friend-mechanic

I've split a few 110 cases for output shafts and cranks, but not alone

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"What happens to your hands when you crash?"
"I put my hands up real quick to protect my sunglasses"

1/16/2019 2:49 PM
Edited Date/Time: 1/16/2019 2:54 PM

Both top ends, but only a 4 stroke with a manual. I need to know valve clearances, chain timing, spring tolerances, etc.

I would be hesitant to split cases without a manual but with a manual it's straight forward. I've done it but only because I've split my cases before. I'll never do engine work on a bike I've never worked on without a manual to reference.

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1/16/2019 3:49 PM

aFACEdismembered wrote:

Both top ends, but only a 4 stroke with a manual. I need to know valve clearances, chain timing, spring tolerances, etc.

I ...more

I always get nervouse when I don;t hae a manual but most times you can find assembly breakdowns online. Torque specs for internals is another headache if you don't have one.
That said I've done more than I can count over the years and there are similarities to most modern bikes. I always layout parts in order of disassembly on cookie pans. Sometimes take pics if needed. The more systematic you can be the easier stuff goes back together. The Dollar Store is great for parts organization stuff..........

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1/16/2019 4:52 PM

Two strokes only for me.
Four strokes are evil. I don't wanna ride one, look at one or work on one.

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Braaapin' aint easy.

1/16/2019 5:05 PM
Edited Date/Time: 1/16/2019 5:06 PM

Also easy way to know configuration of case screws or inner clutch cover screws. All screws will should be equal in length when pushed in not tightened. I never record which hole mutiple screws go into. I just find the easiest to remember a short screw and make the rest are equal

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