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Rebuild time

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So the trusty old RM died today 👍

Was having a great time riding greasy trail with the new Vortex in the traction mode. Stalled out on a hillclimb, go to kickstart, no compression. Manage to bump start it down the hill and get it within 2 miles of home before Bowaaah. Push kickstarter over by hand and get a binding by the time I get to the end of the stroke. Somethings broken in there.

No biggie, I was planning on replating and rebuilding my crank anyways this winter. Thats why I let this Wiseco piston go so long, it was coming up on 100hrs. I was doing a bit of a piston experiment. How long can one last? :smashpc:

There's only a couple weeks left of riding season, I was hoping it was going to make it, but thats all she wrote.

So now with a nice new cylinder and crank I'm going to say rings every 25hrs, piston every 50.

I'll tear her down tonight and get some pics.

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Senior expert...... thats alot of hours for someone that fast...

I run 40-50hrs MX on the Wiseco and then rebuild the top end.

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Senior expert...... thats alot of hours for someone that fast...

I run 40-50hrs MX on the Wiseco and then rebuild the top end.

Yeah I knew it was time a while ago but by the time I got the piston kit I thought I'd only be riding another 20hrs or so before rebuild. Didn't really want to put a new piston in as I need to put a new one in when I replate anyways. Cylinder was workable when I rebuilt the bike last yr, but really on it's last legs. I plan on rebuilding the crank and new main bearings anyways, so I figured I couldn't really do any harm running her till she blew.

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Well the piston wasn't even the culprit, in fact it took the abuse like a trooper. Big end bearing failed. I guess thats why I was planning on rebuilding the crank. Last time I checked it 45hrs ago it was well in spec.

oct11036.jpg

oct11040.jpg

oct11043.jpg

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did you clean that piston?

if not, what ratio are you running? i'd say too lean and that would also explane why your big end broke

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time for a phathead!

That was actually my thought. You ever run one?

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did you clean that piston?

if not, what ratio are you running? i'd say too lean and that would also explane why your big end broke

No didn't clean it. Run Amsoil Interceptor at 32:1. The Interceptor keeps it clean.

Crank is highly likely original, I put 100 hard hrs on it. I'm not really shocked it decided it was time to go bye bye.

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did you clean that piston?

if not, what ratio are you running? i'd say too lean and that would also explane why your big end broke

You could be right. There was not enough residual oil in the crank. I guess I'll start running 25:1.

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if you were going high compression could you machine that head down and use it? or is it just screwed? I had a thought to send an old beat up head to EG when I do my 295 to have as a high compression head, if it would work.

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if you were going high compression could you machine that head down and use it? or is it just screwed? I had a thought to send an old beat up head to EG when I do my 295 to have as a high compression head, if it would work.

You could clean it up and use it. But I talked to my machine shop and they want $150 to reconfigure a head. might as well get a Phathead for $170 and have a choice of compression.

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So it was the left side crank seal. Must of just gone, there was the tiniest of spooge starting to exit the seal. My plug also looks a good colour underneath but a bit of a white top coating. Thought so last night but confirmed with better light today.

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OK. Now I know your RM is your baby. Resting its parts on its blankie! Priceless. Really, what's the baby gonna think when he or she nuzzles up to the blankie and it smells like premixed gas and antifreeze?LOL!

As for the head, I tried a Phathead on my KTM, Hated it! The stupid orings that seal the combustion chamber kept blowing.:smashpc:

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That was actually my thought. You ever run one?

im running one now and love the adjustability, just make sure to pack the orings in with some lithium grease to ensure a good strong seal.

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OK. Now I know your RM is your baby. Resting its parts on its blankie! Priceless. Really, what's the baby gonna think when he or she nuzzles up to the blankie and it smells like premixed gas and antifreeze?LOL!

As for the head, I tried a Phathead on my KTM, Hated it! The stupid orings that seal the combustion chamber kept blowing.:smashpc:

The boys bike is the KTM 50 so he already loves the smell of premix in the mornings 👍

Well I had already bit the bullet on a phathead.I liked the idea of interchangable compression and cheap repaceable domes if one gets destroyed in scenarios like this. Searching all the threads on TT I could find was 90% positive. I think I remember one other guy on a KTM complaining of Oring blowout. Which bike did you have it on? They only show it on KTM's up to 125's now.

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I wont get into the whole scamsoil thing, thats another story.....

My kid runs the Phathead on his RM85 and its awesome... no problems at all...

Good luck with the rebuild 👍

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