950 Supermoto Turbo Build Thread

[snowhawk jockey]

Originally Posted by Maineroads

What do you do for a living Tommy?

Now, Now, don't go blowing Tommy's cover like that! He is just a regular joe with a motorcycle in his garage and some curiosity about taping a whistle on the back of said moto. Let the man work, the rest of us are drooling for the next pics/post... dreaming that this build-along produces a dyno chart and black streaks coming out the driveway!

Lots of experienced technique and knowledge on display, no doubt!

[CBR-ELEVENTY-TEN]

This is a good one.

Might I suggest that a mod sticky this thread???

[omnivore]

Tommy. Once you get the header back to the turbo, I think you should take it to an exhaust manufacturer and have it jigged up. I think many people would buy them, who are riding SM, SMR, and possibly even SE, who would like to do a single muffler for weight savings and leaving room for Ned's auxillary fuel tank, would be all over a header like this.....even without the power snail hanging back there. Besides it takes the exhaust out of harm's way, and leaves mucho room for a skidplate/bashplate.

[Willis]

I need more!

[snowhawk jockey]

Originally Posted by omnivore

Tommy. Once you get the header back to the turbo, I think you should take it to an exhaust manufacturer and have it jigged up. I think many people would buy them, who are riding SM, SMR, and possibly even SE, who would like to do a single muffler for weight savings and leaving room for Ned's auxillary fuel tank, would be all over a header like this.....even without the power snail hanging back there. Besides it takes the exhaust out of harm's way, and leaves mucho room for a skidplate/bashplate.

The ADV or SE headers bolt right up to an SM or SMR(same exhaust). The standard ADV 2-into-1 conversion process can then be done for a single muffler. The fringe benefit to ADV pipes are the added ground clearance!!
This is FangFactor's bike, he is in Australia:



A stock SM header is an easy single side conversion, it is already a single pipe at the end...
I took my 2-onto-1 to a well known exhaust mfg and they said that there isn't enough of an SM market to even recover their tooling costs. The name brands do business in the thousands of pieces and not dozens.


ETA: pics

[Tommy_J]

Maineroads,

It feels like two lifetimes ago but I was a race car fabricator/engineer as a young guy, six years in motorsports, including Indycar. As fifty gets closer I, like many, seem drawn to revisit what was fun decades before. That's a big part of the reason for turboing a bike that was already near perfection. Anyway, back to the build.

A turbo inlet flange was cut from 3/8 plate. Unfortunately its mild steel so it will need some coating. I didn't want to loose the weekend to get stainless.

The header was extended back towards the turbo.

.

This piece will get sectioned later for a slip joint. On a V motor there must be a way to separate the pipes.



Here the tire clearance is being checked with a straight edge. I really cut it close by tucking the turbo in this tight. Its not as bad as looks here though. The straightedge is leaning well forward of the closest point.

[Tommy_J]

Originally Posted by snowhawk jockey

The ADV or SE headers bolt right up to an SM or SMR(same exhaust). The standard ADV 2-into-1 conversion process can then be done for a single muffler. The fringe benefit to ADV pipes are the added ground clearance!!

A stock SM header is an easy single side conversion, it is already a single pipe at the end...
I took my 2-onto-1 to a well known exhaust mfg and they said that there isn't enough of an SM market to even recover their tooling costs. The name brands do business in the thousands of pieces and not dozens.

It would have been great to get some SE pipes but those didn't fit the budget. Plus, I wanted to try something different.

KTM routed the rear cylinder's pipe down through the swingarm and looped it back up. That makes the pipe lengths more equal, for even cylinder scavenging. For a turbo this scavenging is less important and maintaining high exhaust gas velocity is more important. So, I'm going to build the rear cylinder's pipe shooting straight toward the turbo.

[MODNROD]

Originally Posted by Tommy_J

I was a race car fabricator as a young guy, six years in motorsports, including Indycar. As fifty gets closer I, like many, seem drawn to revisit what was fun decades before.

I thought the project looked cool. Being in a very similar age/position, I rekn helps restore some of the fun.




This piece will get sectioned later for a slip joint. On a V motor there must be a way to separate the pipes.

Please, please, please don't be offended by the look of the rusty pipes in the pictures included in this link (I had to use what I had, not what I wished........then rode the thing for 1000's of Km tuning and just enjoying it!), but if you scroll down to pic #3, the upwards pipe to the back cylinder goes into a slip joint, no sealer, no clamps, no leaks.
That's how I did it, might give you some ideas.

http://www.bikeboy.org/daves4r.html


Please continue, enjoying the build very much!

[Tommy_J]

We think alike Modnrod. I plan the same kind of no-clamp slip joint. Turbo charged light aircraft use this set up because its reliable and light. Since the inside pipe runs hotter it expands to make a good seal.

A diametrical clearance of .005" to .008" should seal well when hot but also allow some movement. I measured the pieces from the cut up KTM header and four Ducati mufflers and found pieces that have this clearance.

[Tommy_J]

Fitting the tubes for the aft cylinder was a slow process for a few reasons. There was no fudge factor, a couple of turns were crammed into a tight space, and there was no spare tubing if I screwed up. Worst of all, both tubes were curved at the intersection.

This tube barely misses the cam chain tensioner boss and goes too close to the brake line to leave unprotected. I wish I has an SE around to see how KTM dealt with this.

.

Same approach as before, the joints were taped in place as an initial test fit. When things looked good joint was tack welded.



Here a little persuasion is used to adjust the gap for the tack weld.



So far so good.



here is where it gets more challenging. A guess was taken as to the shape of the miter for the Y joint.



After about an hour of gradual trimming the joint looks good from the outside.

[Tommy_J]

Still working on this Y joint. I snapped the tack weld at the cylinder fitting to make a tiny adjustment. That's an example why everything should be tacked together first.



Once everything was fit nicely it was time to mark and cut the hole in the other tube.









All tacked up except for the 90 into the turbo.

[D.T.]

[cpallen]

Originally Posted by D.T.

Wow.

[Ultra54]

I wonder if you will have to brace it when you finally weld it solid due to heat distortion? I suppose you could make a mach V to bolt the flanges down to.

[Tommy_J]

Ultra, you're right about the distortion. Half way through welding the Y joint it pulled quite a bit. It's because the Y joint beads are all to one side of the tube. The plan is to weld up the forward end almost completely and then break the tacks by the turbo and re-aim the last section of pipe.

Here is the slip joint. That gap is supposed to be there. It allows the pipes to grow when they get hot. It should also let the pipes move if the subframe flexes down, like from a jump. The proximity of the brake line is clearly a problem that needs to be sorted out.




Formed some tabs for the slip joint by folding some stainless around a #2 phillips screwdriver



Cut tabs to length and smooged as needed




Brazed the tabs on to minimize distortion of the slip joint. Its a really good fit. The bolt may get swapped for a shorter one with a stronger spring, if I can find one in the junk drawer.