Yamaha DT 125R 1994 project

[claws]

@jonne123 giannelli probably.

[Calum]

Or BigOne

[jonne123]

My ported suzuki pv moped: https://www.youtube.com/watch?v=Ds1trRkr22g

[jonne123]

So i had little worn rear tire so this happened... little backfire also. https://www.youtube.com/watch?v=GruRc--3zNA

[jonne123]

So i had engine failure and said what the heck i will rebuild it. and tune the bike up. Pictures coming!

[Calum]

Wow, why did the engine fail?

[SpookDog]

@Calum
Check out his pootube vid, then ask yourself why you asked ...
Sorry, did I miss your dry humour?

[Calum]

@SpookDog no I did see the video. Still though, a little burnout never hurt anyone

[jonne123]

So basically i was just revving the hell of it for about 20 seconds went driving and felt weird. Engine stalled kickstart stuck.

So i opened the engine and there was bearing pieces over piston so rod bearing failure. There was sand in engine via bad air filter from previous owner. Also the piston was ridden about 1500km and the ring cap was 0,7mm on the top one and 0,5mm bottom one. And the needle bearing was shot. So the engine would have failed eventually. I think i know now what the werid side noise was.
https://i.imgur.com/jsw8S7K.jpg

https://youtu.be/GrOBDzHtQpY

[SpookDog]

@jonne123 said in Yamaha DT 125R 1994 project:

So basically i was just revving the hell of it for about 20 seconds went driving and felt weird. Engine stalled kickstart stuck

Is called seizure by heat or lack of oil. Or screaming from cold start. Or all of the above...

“There was sand in engine via bad air filter from previous owner. “

Bad you never checked as well though bud (the filter) bike stuff 101

The rest is lost in translation, to me.

[jonne123]

Well it had rebuild top end and i changed the filter right away but didn´t realise that there was sand in the intake until month ago i cleaned it. Also the engine was making weird side noise probably from crankshaft. There was oil and mixture was rich.

[SpookDog]

@Calum
Totally! I like to burn out my back tyre though. Not my engine ...

[SpookDog]

@jonne123
Sorry dude! Don’t take me to heart. I’m on my 4th beer! I don’t mean to come across as patronising ...

[jonne123]

But i didnt do a burnout.

[SpookDog]

@jonne123
YouTube & your back tyre says otherwise!

An engine rebuild is always around the corner on a second hand bike, no matter what the previous owner says. If you do as good a job with the engine as you did with the rest of the bike, you’ll end up with a good, tight bike. Just run it in on less than 90% throttle!! ...

[jonne123]

Yeah... But it was like month after burnout. The engine has always made weird side noise. But it would really been sad if it happened during next summer. The bearing would failed. Also the needle bearing is totally worn and piston rings. Remember to clean your air filter!

But now plans for the project:

-Fix rust and paint some parts.

-Clean aluminium parts.

-Fix engine

-Replace worn parts.

-Sticker kit or wrap for plastic parts.

-Possible some tuning parts.

I´m open for suggestions!

[Calum]

@jonne123 Fix the engine is the first point of call. Find out why it failed as well.

[jonne123]

I know that the crankshaft bearing failed. But there could be something else like a bearing.

[Calum]

@jonne123 Yes, but WHY did the crank bearing fail?

There is no point in rebuilding it if you don't understand why it failed.

[SpookDog]

@Calum
I’m guessing that the weird side noise was worn out main bearings ...

@jonne123
I’d replace every bearing and seal in the engine, crank conrod as well, and if you’re gonna do that you might as well do the bore and piston rings @ least...