Vintage Dirt Bike Q & A

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PostPosted: Sun Dec 31, 2017 6:14 pm 
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Joined: Mon Oct 04, 2004 5:39 pm
Posts: 5
Location: Pennsylvania
I know the deal with the early and late 125m pipes/flanges but how would an early pipe effect a late (76) engine. I have a 74 pipe with a larger inlet flange welded on to fit the late flange on my 76 125m.

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PostPosted: Sun Dec 31, 2017 10:54 pm 
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Joined: Sun Nov 30, 2008 12:10 pm
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Location: Connecticut, USA
I think you'd notice more of a mid / hi-mid powerband with the earlier pipe, as opposed to the hi-mid / top end PB of the later pipes. My '76-'78 LOP aftermarket pipe was shorter and fatter than the OEM '74 pipe and tuned for the later exhaust-port timing, so on my '74 the top end stayed about the same and mids and low end decreased.

Ray

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'74 CR125M (175cc), '75 MR175, '82 RM250Z, '08 YZ250F, '14 Zero FX electric, '14 Zero MX electric


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PostPosted: Sun Dec 31, 2017 11:20 pm 
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Joined: Mon Oct 04, 2004 5:39 pm
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Location: Pennsylvania
Thanks for the reply Ray. I got this bike with this pipe on it. I cut the stinger dpwn a little and added a universal round clamp on silencer. It could never get any bottom end out of it but it flies wide open. I'm tired of messing with the jetting.

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PostPosted: Sun Dec 31, 2017 11:59 pm 
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Location: Pennsylvania
Here is a pic
Attachment:
dsc00674.jpg
dsc00674.jpg [ 1.32 MiB | Viewed 989 times ]
sorry for the giant pic. I am trying to reduce the size of the pic on my phone.

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PostPosted: Mon Jan 01, 2018 12:13 pm 
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Joined: Sun Nov 30, 2008 12:10 pm
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Location: Connecticut, USA
Bike looks nice! I couldn't get the Clarke RC125 tank to fit on my bike (it hit the up pipe / headlight mounts / recovered seat). My repainted OEM tank fits fine everywhere, though.

My 125 had no low end either, & carb jetting seemed to make barely any difference. Turned out the LH crank bearing had partially failed and took out the seal. The MT125 head gasket I was using didn't help either (no leaks at all unlike the OEM copper one, but just killed the compression).

Ray

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'74 CR125M (175cc), '75 MR175, '82 RM250Z, '08 YZ250F, '14 Zero FX electric, '14 Zero MX electric


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PostPosted: Mon Jan 01, 2018 3:29 pm 
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Joined: Mon Oct 04, 2004 5:39 pm
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Location: Pennsylvania
The bike has alot of originality. I have the stock tank but it has failing tank liner in it. I'm told the bore is maxed out but don't know the demention of the bore (i haven't pulled it apart yet). My swingarm was welded once. Does anyone make side numberplate background stickers that fit and don't need trimmed?

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PostPosted: Tue Jan 02, 2018 2:36 pm 
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Joined: Sun Nov 30, 2008 12:10 pm
Posts: 1004
Location: Connecticut, USA
Quote:
Does anyone make side numberplate background stickers that fit and don't need trimmed?

I don't know if these are exactly the right size/shape - maybe contact them and ask:

https://www.speedandsport.com/index.php ... ckgrounds/

Ray

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'74 CR125M (175cc), '75 MR175, '82 RM250Z, '08 YZ250F, '14 Zero FX electric, '14 Zero MX electric


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PostPosted: Tue Jan 02, 2018 7:27 pm 
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Joined: Mon Oct 04, 2004 5:39 pm
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Location: Pennsylvania
Thanks for the link I'm pretty sure they are the full sized vintage number plate background...witch is bigger than the cr125m.

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