SY250R Heatshield

[pmk]

When I got this SY, there was evidence of the previous owner burning traces of riding gear onto the exhaust headpipe.

During my informal dismantle and reassembly, I scrubbed that headpipe to remove all traces of burnt on gear, oil spooge stains and carbon builup at the headpipe slip joint into the exhaust mid box.

After several hours of riding the SY, it was apparent that even I was leaving burnt riding gear traces onto the headpipe.

Being frugal, I waited on some leftover high temp epoxy, then rounded up some scraps of carbon cloth.  In a short bit of time, I fabricated my copycat heatshield.  Mounting is simple, two high temp silicone bands between the carbon and stainless headpipe, everything held secure with two worm clamps.

Hope it lasts a while and gets the job done.

 

Edited April 5, 2018 by pmk

[pmk]

2 hours ago, oni nou said:

That looks like a very professional tidy job.....my heat shield is made of old bits of burnt riding pants but I could do with one of those to help stop the gouges and scrapes caused by rocks on the front pipe.

I was working on building a burnt pants heatshield also.  Was not sure the cost of pants was justified so I made this.

As for neat and tidy, thanks.

[markparrish]

that's a really neat job and great idea - well made! Did you mould it over the header to get the correct shape? If so, what did you use as a release agent?

[pmk]

1 hour ago, markparrish said:

that's a really neat job and great idea - well made! Did you mould it over the header to get the correct shape? If so, what did you use as a release agent?

Mark, as an aircraft repair tech with specialized in composites I cheated and was lazy building it, knowing what I could get away with.

The headpipe was washed and scrubbed clean with Simple Green soap and Scotchbrite to remove residue from the burnt pants.  Next I placed masking tape over the metal surface and drew lines of about the shape and location I wanted.  Over the masking tape I placed a layer of high temp very flexible silicone rubber sheet, 1/8” thick. A helper positioned and held the rubber sheet in place while rolling it also around the curves, as this was done, the entire rubber sheet was wrapped in black plastic electrical tape.  The tape was wrapped tightly.  The silicone sheet provided the uniform air gap between the metal pipe and the carbon guard.  I rough cut three sections of carbon cloth approximately to size but adequately oversize.  On plastic sheet, I drew the actual cut boundaries for the carbon cloth.  Epoxy was mixed, then the three plies were stacked while pouring epoxy between the layers.  This epoxy / carbon stack was worked while between two layers of plastic film sheet.  Using a Bondo squeegy, the epoxy was worked into the carbon fabric, and all the air was removed.  Once ready, the entire stack of wet carbon was cut between the plastic film sheets on the previously drawn template lines.  The lower plastic film was peeled away, and the entire stack of carbon was positioned onto the headpipe that was positioned in a vice by clamping the flange, but was over a trash bucket to limit the mesh if drips happened.  Once positioned, the upper plastic film was peeled off while carfully draping the wetted carbon.  Once positioned, the entire carbon layup was covered in peel ply, then worked by hand to comform to the shape. Then cured.

The headpipe was not mold release waxed, I very carfully cut through the cured carbon into the 1/8” silicone sheet with a curting wheel, then the carbon guard came off with black tape stuck on the inside.  This tape easily peeled off and the tape on the headpipe removed easily.  The edges were final trimmed, then everything was wet sanded with 600.  Total time spent, maybe an hour.

[pmk]

Wanted to add, the white line in the carbon is a tracer.  Tracers are an option in some carbon fabrics and are an indicator of the fabrics direction in regards to what is known as the warp.  In critical repairs, fabric direction is called out.  Bummer the tracer is there, but I was not too concerned, just saving the pants from burning.

[pauls320]

Great write up and pics of the new shield   I wonder if the stainless clamps could be fastened to the backside of the shield with a few short rivets on each and still secure effectively...and then silicone wrap between clamp and pipe??

[markparrish]

Thanks for such a detailed write up - as you have access to the materials (and clearly, the knowhow!)  it makes sense to use them! I am sure it would be possible using your information and some similar materials to make a similar accessory in a normal home workshop but hard to achieve that quality without lots of practice - very  nice.

Thanks again, Mark

[pmk]

2 hours ago, markparrish said:

Thanks for such a detailed write up - as you have access to the materials (and clearly, the knowhow!)  it makes sense to use them! I am sure it would be possible using your information and some similar materials to make a similar accessory in a normal home workshop but hard to achieve that quality without lots of practice - very  nice.

Thanks again, Mark

Practice helps.  If it were something I needed many of, say a production run, it would be more involved as I would make a mold.  The mold would allow easier fabrication and a more glossy finish, plus repeatable edge trims.

This morning I helped a friend rebuild his leaky MAR fuel tank.  Pretty much reskinned the original fibreglass with new materials.  More work than the exhaust guard, but worthwhile.

Next for the Scorpa SY will be a carbon guard / access cover for the silencer.  Going for the carbon appearance, but will not dent, and should allow repacking without welding.

[pmk]

2 hours ago, pauls320 said:

Great write up and pics of the new shield   I wonder if the stainless clamps could be fastened to the backside of the shield with a few short rivets on each and still secure effectively...and then silicone wrap between clamp and pipe??

Planned to be riveted if this works well.  Need to find some #3 monel solid rivets to attach the clamp to the carbon.  Putting the silicone sheet between the clamp and pipe should keep it from loosening.