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2 stroke XR 70

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Well today me and the guys were kicking around the idea of a 2-stroke pit bike. We have a old 1999 YZ125 motor that needs a top end rebuild. The XR just blew up a few days ago as well. We laughed at it but so we started to get curious of if this may actually work. Well do any of you guys of anybody who's done this before?

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it will definitely be very difficult to do this not having the undercarriage that the yz has on the frame. You're going to have make some heavy duty motor mounts and frame gussets. If you want help feel free to pm me, I'm pretty good with custom fab work.[

Edited by 110Tim

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It would be more fun to bolt a 140cc pit bike motor into the 70cc chassis 

 

Piranha 140cc Engine
fits Pit Bikes and other Minis
Part No: WHS-1143
Location: 0H

iiiPiranha140ccPitBikeEngine_1.jpg&h=250

 

Piranha 140cc Engine
YX140cc 
This is our best selling engine 
Top performance and economy all in one 
Super sturdy and Very strong running engine
Latest Version available with larger kicker shaft and all most current improvements

Front Drive Sprocket Included

See picture for parts included , only as pictured.

Great Replacment engine or for builds & Projects.
Includes:
Engine 
Intake
CDI
Coil 
Harness 
Kicker
Shifter

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Well today me and the guys were kicking around the idea of a 2-stroke pit bike. We have a old 1999 YZ125 motor that needs a top end rebuild. The XR just blew up a few days ago as well. We laughed at it but so we started to get curious of if this may actually work. Well do any of you guys of anybody who's done this before?

In the 70's Jim Pomeroy's mechanic put a 250 Bultaco motor in an xr 75 frame.

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Mounting the radiators and keeping them protected will be interesting to do without making it look like a hack job. If you do this be sure to make a build thread!

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In the 70's Jim Pomeroy's mechanic put a 250 Bultaco motor in an xr 75 frame.

 

 

look at an xr75 frame and then look at a xr70 frame.   not to hard to put a diff engine in the xr75

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look at an xr75 frame and then look at a xr70 frame. not to hard to put a diff engine in the xr75

Sorry, misread the title. And shoehorning that 250 motor in the 75 was probably harder than you imagine.

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Sorry, misread the title. And shoehorning that 250 motor in the 75 was probably harder than you imagine.

oh i know it wasnt easy but was easier than trying to put a yz125 engine in the xr70

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What are you talking about doing, combining the two motors? Engine swap? Be more specific

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Think he wonts to turn the motor into a 2 stroke 70?? If so probably sound like a ds80 lol. We bolted 110 pit bike motor loom and bits onto a act50 or cta50 honda 3 wheeler bolted right in good bit of fun

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Maybe it's just because I was born on Earth, but doesn't this idea seem outta this world?

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Maybe it's just because I was born on Earth, but doesn't this idea seem outta this world?

I think trailboy got into Daddy's liquor closet a few nights ago.  Either that or it was a plant by TT to generate conversation for hits.  Happens on the Pro Racing forum all the time.

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I think trailboy got into Daddy's liquor closet a few nights ago. Either that or it was a plant by TT to generate conversation for hits. Happens on the Pro Racing forum all the time.

It was just an idea that me and the guys laughed about wile taking a break. The Yz engine needs a rebuild anyway and the Xr just blew up so we were just kicking the idea around of somehow mounting it into the frame, but after some chalking out lines and taking measurements, we'd have a better time building our own brand of bike from the two.

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It was just an idea that me and the guys laughed about wile taking a break. The Yz engine needs a rebuild anyway and the Xr just blew up so we were just kicking the idea around of somehow mounting it into the frame, but after some chalking out lines and taking measurements, we'd have a better time building our own brand of bike from the two.

There is a hot rodding magazine that says you can out anything in anything and they are correct.  it would be a cool project if you have the time and the skills.

 

However, no more drinky poo with the guys when it comes bike fixing ideas.

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There is a hot rodding magazine that says you can out anything in anything and they are correct. it would be a cool project if you have the time and the skills.

However, no more drinky poo with the guys when it comes bike fixing ideas.

Haha ya right. For now, my kx needs my attention. Whole lot of parts and not much time to be put in expecaly with school projects in a diesel academy, it's hard to get any side project done.

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Y'all wanna know a secret. You can buy a ttr and itll never blow up lol jk. But you can swap a yz head out with a ttr its easy just need radiators and bigger head bolts

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And ttrs are cheap bit seriously....they DONT BLOW UP. I've tried to blow one up it ran dry on oil its got over 1,000 hours on it without maintenance and it runs fine. Wtf if it was a crf 125 itd been dead long ago

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TTRs are awesome woods bikes. My buddy has one and the thing is a boat. It float over almost everything when it comes to enduro so trailing.

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Y'all wanna know a secret. You can buy a ttr and itll never blow up lol jk. But you can swap a yz head out with a ttr its easy just need radiators and bigger head bolts

A yz head with a ttr head? I hope you don't mean cylinder head? I really hope I'm just understanding you wrong.

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A yz head with a ttr head? I hope you don't mean cylinder head? I really hope I'm just understanding you wrong.

no dude he knows what he's talking about. Hahahah I already tried to tell him he was wrong with the ttr stuff and he flipped out. Lmfao
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