OldMiniBikes exhaust

oldsledz

Active Member
#1
Anyone have a photo of any of the exhaust pipes that OldMiniBikes sells for the blue clone engines.

I want to see what one will work on a big frame Ruttman, I think I want one with a screw on muffler.

A photo with the exhaust on the bike is what I am looking for. Thanks
 

TomH

New Member
#4
As you can see, it is about an inch lower then the tank, and without any modifications, I had to modify mine, it comes out on the centerline of the OHC on the valve cover
 

oldsledz

Active Member
#5
Thanks TomH and Dragbikemini the photos were just what I needed, I went with the standard one and it fits the bike perfect.

Have you guys run your bike much with this set up? I am wondering if I will need a jam nut to keep the muffler from vibrating off?
 

JamnJM

New Member
#6
Here's a problem that I ran into with that header but on a Predator engine (same gaskets used), The rear nut can not be used.... I had to grind the header, buy metric allen bolts and grind the bolt heads to get it to work:


Plus they use a round tube to the d port:


Otherwise a good header, I just wanted you know what I had found out.....

Plus here's a photo with that header and a AC VW pea shooter muffler tip on it....just slit the pea shooter tip for clamp to tighten:

 

oldsledz

Active Member
#7
I was able to get the rear nut on mine, I had to start the rear one first it just barley touched the pipe but I was able to turn it with a wrench.
 
#8
I have welded up and then abaondoned so many pieces and parts of headers because its not easy at all to make them work they way you want AND fit.

There is a good reason why you want a header like the OldMiniBikes one with a round hole.
Not all heads have exactly the same shape and angle to the port depending on the casting used.

OldMiniBikes does you a favour!

My only beef with there header is I am not fussy about the angle it exits the head because that makes blending the header to the port more time consuming.

And my other beef is The OldMiniBikes headers make mine look bad lol.
Fine piece of kit there !
 
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JamnJM

New Member
#9
My old Nascar 4 cylinder race engine builder also is a long time header designer.....I have been thinking of tapping his ideas on a header for these..... :rolleyes:
 
#10
I would be very curious to hear a pro's thoughts on header design for these motors.

It seems everyone loves a stepped header, but that seems counter intuitive to me since as the exhaust gets further from the valve, it cools off, and thus contracts, so having a progressively larger exhaust pipe just doesn't seem to make sense.

I'm also curious about header length and how it affects performance for our use.
 
#12
I was able to get the rear nut on mine, I had to start the rear one first it just barley touched the pipe but I was able to turn it with a wrench.
Yep. Me Too...on my Predator, got the rear nut on and tightened with open end wrench. Also, I drilled out the holes in the header flange a bit to ease mounting.
 
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