How to Shave Your Dirt Bike Seat

I originally wrote this article for CRFsOnly.com’s forum, where it was turned into a sticky “How To” on that site. I have since taken photos of another seat that I have done, cleaned up some of the typos from the original article (while introducing more I am sure), and made other relevant adjustments.

BEFORE YOU BEGIN: Shaving your dirt bike seat is a one-way ticket. You may be able to take more off, but you cannot put more back on. A shaved seat is a good alternative, or addition to, lowering your bike by using a lowering link or internal suspension work. I can pretty much guarantee that it will not look stock, and it will make your seat harder. If you have a KTM, the latter will not matter much as you are already sitting on a plank.

For me, I have found that shaving the seat provides a wider base that is actually more comfortable than some stock width foams. I also like that I can ‘roll’ the edges of the foam by sanding it for an even more custom fit. The largest advantage is the ability to ‘save myself’ from some embarrassing (or painful) tip-overs because my feet are a bit closer to the ground. Still, a shaved seat is not for everyone and it can be costly if you mess up.

If you decide to take the plunge, take your time and remember, you can take more foam off but you cannot put more foam on. Okay, technically you could add foam, but we will stay away from that one for this article.

Things you need:

  • 120-180 grit sand paper (for power sander or sanding block)
  • 60 grit sand paper (for use by hand)
  • Electrical tape (optional)
  • Flat blade screwdriver
  • GOOD permanent markers, 2 colors
  • Hammer and punch (maybe)
  • Long, sharp knife, or electric carving (preferred) knife
  • Masking tape
  • Pliers
  • Power sander (preferred) or sanding block
  • Ruler (preferably something with some flex)
  • Sharp scissors
  • Shoe Goop (or similar flexible adhesive)
  • Spray paint (any color, just not the same as the seat foam)
  • Staple gun (I use an electric unit)
  • Stiff, thin wire

 

Step One, Remove the Original Seat Cover

Unbolt and remove the seat, and place it on a sturdy work surface. Being careful to not tear the seat cover, use a flat blade screwdriver and lift up each staple. Ideally, you should try to lift each staple evenly rather than only lifting one side. If you can lift the staples evenly they will likely pull out the remainder of the way by hand, else you will need to use pliers and pull them out of the seat plan. Set the cover aside.

Step Two, Find the Depth of the Seat Pan

If you take too much foam off the pan you will undoubtedly split the foam. Suffice to say, this would be a very bad thing.

To find the seat pan, I use wire and pierce the foam until I find the pan. If this is your first shave job, I recommend you mark the pan from the side by taking a piece of stiff, thin wire and poke it through the side of the foam so as to find the top of the seat pan. Try to put the wire straight in, being careful not to wiggle it. Once you are sure that you have the wire straight in from the side and at the top of the seat pan, take the permanent marker and  mark the hole so you know where the top of the pan is for that section. Make additional holes and marks as needed until you have marked the pan about every 4 inches. When you are done, you should be able to look at the seat from the side and visualize where the pan is inside the foam.

Advanced route: If you have already comfortable shaving seats or confident in what you are doing, You can insert the wire from just about any direction and note the depth. Again, I do not recommend this for everyone.

Step Three, Mark the Pan

Skip this step if you took the advanced route in Step Two

Using the ruler or a steady hand, connect all the dots from the wire marks with the permanent marker. Make sure you understand THIS IS NOT THE MAX SHAVE DEPTH. If you shave to this point, you have ruined the seat for sure.

Step Four (optional), Mark the Original Logo Location

If you have a logo on the seat cover and still want to see it after you put it back on, you will need to mark its original location. The best way to do this is place the cover back on the foam and roll the side up until you get to the bottom of the logo. Make a mark on the foam indicating this bottom position, then continue to roll the cover until you get to the top of the logo, and mark that position as well. Make additional marks for the beginning and end of the logo. BE SURE TO ONLY MARK ONE SIDE OF THE SEAT.

See Step Five for a photo of the logo marking.

Step Five, Mark the Cut Line

I have a couple of different methods for doing this. For me, it really comes down to the seat that I am working with. For the newer style (nearly flat) seats, precision is a must as the foam has very little give, which will translate to very noticeable/wavy cut lines if you are not near exact in your measurements. For the older style seats that lip up at the tank, you should have more foam to work with so you can be a bit loser with your marks.

For both methods I recommend you put the seat back on the bike. Take the electrical tape and mark the seat where you think you want to cut it. The electrical tape is flexible enough to make some nice curves, and will not stick to the foam so much that it ruins the foam when you take it off. This process is a bit of trial-and-error and is very subjective to your preferences.

Tip: I I highly recommend you do not cut the front 3, or rear 1-2 inches of the seat foam for 2 reasons:

  1. The seams on seat cover, or sewn curves, will still fit as intended
  2. Cutting to close to the edges, especially the front, will make taking the slack out of the cover very hard.

Once you have the tape where you want it, make a small mark every couple of inches on the ‘cut’ side of the tape. The ‘cut’ side is the side that you intend to shave down to later. If you are not going the precise route, you can go ahead and just mark the entire tape before you remove it.


If you are going the precise route, measure from the factory shape lines down to the tape mark on one side of the seat, then measure the same distance on the other side of the seat and make an adjustment mark if needed. The point here is to make sure that you have marks that are the same distance from the factory shape lines on both sides of the seat. Once you have the measurement marks, go ahead and connect the dots.

Step Six (optional), Finish Marking the Logo Location

If you did Step Four, then you have a logo mark on only one side of the seat. You now need to estimate where the logo will land after you put the cover back on. Unfortunately, all I can do here is provide a bit of guidance as it really is a subjective process. What I do is measure from the factory curve line on the foam to the top of the logo mark that I made in Step 4, then measure that same amount from the ‘cut line’ on the opposite side and draw the logo location. Sometimes you may need to decide if having the logo look good is more important than the shape of your seat. If in doubt and looks are important, get a seat cover without a logo.

See the first photo in Step Eight for the final logo marking. Note it is in a different spot relative to the seat pan line in the second photo of Step Eight.

Step Seven, Start Cutting

Using a sharp knife, or better yet, an electric carving knife (best method), make thin cuts in the foam. Go slow so as to avoid tearing the foam. Keep taking material as you work towards the cut line, being sure to stop before you are on the line.

Tip: Pay attention to what the foam is doing. Some parts of the foam will already have splits that require you to go really slow (especially if you have used the seat), others will just split regardless of how careful you are. Just keep the damage to a minimum and fix it in Step Eleven.

Step Eight, Sand Sand Sand

At this point you have a piece of foam that would not be very pleasant to sit on because it is a bit choppy. It should also be a bit shy of your ideal height. Translation, you have some sanding to do. To get started, LIGHTLY mist the top of the foam with spray paint. Try to keep from coating anything below the cut line. Let the paint dry to the point that it does not come off on your fingers, and will not clog the sand paper. The dry time should be very quick unless you are working in the cold or used more paint than you should have.

Using the 120-180 sand paper, start sanding the foam using a power sander or sanding block. The paint acts as a ‘guide coat’ for sanding. As you sand, you will have parts of the foam stay colored while other parts become free of paint. The objective is to work the high spots until they blend with the low spots, while also leveling out the seat. Take your time. Apply more guide coat if needed.

Tip: Save some of the sanding dust for Step Eleven.



Step Nine, Test Fit and Adjust

Once you feel that you have sanded things smooth, go ahead and put the seat back on the bike for a test fit. Pay close attention to the dimensions of the seat and note any areas that need to be sanded further as adjustments. Also take note of the curving of the front and rear of the seat, and sand the foam to give it a nice contour / flow if desired.

Step Ten, Round the Sides

You now will want to round the side of the foam so that it has a comfortable feel. Take the masking tape and tape the top of the seat foam a little bit inside from the new foam line. Unlike the electrical tape, masking tape will stick to the foam well enough so that it should not peel back when hit with the sand paper. The amount that you round-off is up to you, but I suggest 3/8-1/2 inch as a start. To make things easier, I like to take a marker and color in the area that I want to curve, with the marker acting as the ‘guide coat.’

Once you have the curve marked, take the 60 grit sand paper and sand the curve by hand. Follow up with 120-180 grit to smooth things out.

Step Eleven (optional), Fill the Cracks

If you have small cracks in the foam, you can probably just leave them alone. For bigger tears and voids, gently score them with 60 grit sand paper, then fill them with shoe goop (flexible glue). While the shoe goop is still very fresh, liberally cover the glue with sanding dust from Step Eight, and gently push the glue and dust into the crack/void. Repeat this process a couple of times while gently working the glue/dust into the crack. Don’t worry about perfection; all you want to do is get enough of a mix in to keep the foam from having a soft spot later. The most important thing is to not make a tear worse. Top with a little more glue and dust if needed. Remember, only the big cracks/voids need attention.

After the fill dries thoroughly, hit them with some sand paper if needed.


Step Twelve, Re-install the Cover

Tip: Do not start this step until the glue from Step Eleven is completely dry!

Refit the cover onto the foam. Starting at the front, then rear, staple the cover. You staples should be about 1/2 inch apart. Some spots are hard to get the gun to rest completely against the pan so the staples may be high, although with some practice you may be able to get them all to seat. If necessary, use a punch and hammer to tap the staples in the remainder of the way, or at least get them to lay flat. Staples that are very bent should be removed and replaced.

Once you have the front and rear in place, start about 1/3 of the way back from the front and pull the cover taught against the pan and staple it, followed immediately by pulling and stapling directly across on the other side. Work forward and backward on the seat repeating this pull/staple process. If needed, remove staples and re-position the cover.

Tip: Be sure that you staple far enough in on the pan so that the staples do not poke out the side of the cover.



Step Thirteen, Trim Excess Cover

Once the cover is secured, you will have a sizable amount of excess material that should be trimmed back using a sharp pair of scissors. If your seat has mounting tabs like the Honda cover shown, be sure to refrain from trimming too much around the tabs else the cover may roll up and expose the seat pan.

Step Fourteen, Bolt-on and Go Ride

You did it! Time to bolt that gem on and go ride!

First photo is a Honda with the old style seat. The second photo is a KTM with a new style seat. Both of the photos are the ‘after’ photos of the seat foams shown in this tutorial.


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