How to: 1/5 throttle for your GSXR (R1 swap)

I've found the breakthroughs on BARF to be very useful. I'd like to give a little something back.

Note: I'm writing this out of passion on 2 hours of sleep. Please bear with me. I'll be sure to edit in the morning.

What this is:

This procedure describes how to replace the stock throttle grip assembly on a GSXR with the grip from a Yamaha R1.



Why the hell would anyone want to do that?:

Both the R1 and the GSXR have a 1/4 turn throttle in stock form. When installed, the R1 grip effectively converts your GSXR to a 1/5 turn throttle setup.

If you use the grip from a 2004 Yamaha R6, you will end up with a 1/6 throttle. However, this installation process is more complex, and the shorter throw may be of dubious benefit.


What's the point?:

On the street, there isn't much of one.

On the track, I've discovered that in can be tricky perform a smooth roll from braking, to cracking the throttle, to Wide Open Throttle (WOT) during cornering. Due to the risk of upsetting the bike, I'd rather not have to adjust my wrist at any point during this maneuver.

For those of you who like to wheelie, this modification should make things a tad simpler.

During subdued riding, you should barely notice the difference. However, your bike will feel noticeably more responsive to aggressive throttle input.


What's the risk:

Screwing things up is pretty difficult. If you follow these directions closely, this procedure is fairly simple. If you're careless, your throttle might stick.

Swapping to a R1 throttle will result in a little more free play side to side, and a tid bit of bar showing between the grip and the bar end. No one will notice.

Since no parts on your bike need to be cut or drilled, swapping back is trivial if you don't like the change, and the overall cost is minimal.


What model GSX-R does this work on?

I'm using an 04 GSX-R 600. This should work for any 600 or 750 with a 1/4 turn throttle. (Can someone please confirm?)


What do you need?

8mm, 10mm, and 12mm crescent wrenches.
Phillips Head Screwdriver.
4mm and 5mm Allen wrenches (hex head wrenches)
A container or baggie to hold parts.

The throttle grip assembly for a 2004 Yamaha R1 ($15, Part# 4YR-26240-02-00)

Optionally:

Cable Lube (Now is a good time to do it.)

If you care about having matching grips:
The clutch side grip from a Yamaha R1 ($8, Part# 4YR-26241-02-00.)
Grip glue


More complex:

If you want to do the 1/6 throttle mod, use the grips from a R6 instead:
Throttle ($8, Part #5SL-26240-01-00)
Left Grip ($8, Part #4YR-26241-01-00)
6mm drill bit (which works out to be about 15/64ths of an inch.)
A drill

For the R6 mod, you will need to drill the throttle grip assembly, otherwise your throttle cables will be too short.

Full procedure to follow.

This was one of the first (and only) mods I did to my '06 600 using an '04 R1 throttle tube because it was WORK to get to WFO. Awesome mod and super cheep!!

1. MAKE SURE YOUR BIKE IS STABLE! We will be removing bar ends, which can require a lot of force. A rear spool stand is recommended. If you are using your side stand, make sure to put the bike in gear.


2. Remove your bar ends. On my bike, one of them is held in with a Phillips head screw, the other with a 5mm Allen bolt. I guess the previous owner wasn't being honest when he said it the bike had never been down.

Tips:
- Loosen the screw on the bar end just a little bit. If the whole bar end pulls out easily at this point, great.
- You can remove the bolt completely, and leave the large rubber grommet in place. We don't actually need to remove it. Be careful about using this procedure, as the nut behind the grommet may not hold in place if the bolt is removed.


3. Remove your seat, and lift the tank. Use the prop included under your seat to support the tank.


4. Remove the clamp that holds your throttle side handle switch assembily wires.



5. Loosen your throttle cables and remove them from the throttle body.


It's hard to tell in this picture, but I'm holding a 10mm crescent wrench on a long nut.

Tips:
- Loosen only the 10mm nut closest to the front of the bike. Once loosened about 1cm, you should be able to remove the cable from it's bracket.


6. Remove the two screws holding your handle switch assembly together.



Tips:
- You will need a bigger screwdriver than I show here.
- You may want to remove the ram air tube. I didn't have to.


7. Open the handle switch assembly and remove your stock throttle grip.



Tips:
- Be slow and deliberate. You do not have to force anything here.
- It's not necessary to pull things quite so far apart... But it sure is fun.
- You may have to turn the handlebars and pull the throttle and electrical cables through their brackets in order to get everything wide enough apart.


8. Remove the old grip. Compare to the new grip.

Awesome. Bet it took you longer to type this up than to do

9. Now would be a great time to lube your cables! You will have to remove the screw holding the cables to the handle switch assembly with a 3mm Allen wrench. Once you're finished, put the cables back the way they were before this step.


10. Loosen your throttle cable as much as possible at the grip using a 10mm and a 8mm crescent wrench.



Tips:
- Loosen the 10mm nut as far as it will go.
- Follow suit with the 8mm nut.
- Do not tighten things down at this point.


OPTIONAL:
Now would be a great time to install grip heaters!


11. Remove the funky plastic ring on the R1 grip. This ring serves no purpose on the outside of the handle switch assembly, and if you put it on the inside, it will cause your throttle to stick (Very dangerous!)



IF YOU ARE USING THE R6 THROTTLE:
You must drill a new hole in order to attach your throttle cables. The stock GSX-R cables are barely long enough for the R1 mod, and will certainly not be long enough for the R6 throttle.

I opted to go the R1 route, so I can't describe this step in detail. Use common sense and everything should go smoothly.



Tips:
- You may want to add 2 holes, evenly spaced about 1cm apart. This will make your job easier if you find you need more slack or have too much.


12. Install the R1 throttle. It should go on the same way your GSXR grip came off.

Tips:
- Slide the R1 grip up your clip-ons before connecting the cables.
- The top cable goes over the grip.
- The bottom cable goes under the grip.
- Remember that you can pull on the cable from the other (throttle body) end in order to add or remove slack!


13. Close up the handle switch assembly.

View attachment 236200

Tips:
- The assembly must go in exactly the same location it came from. There is a small, easily missed pin in the bottom of the assembly that locks it in place to the clip-ons once everything is tightened.
- Do not force things. If it doesn't seem to fit, figure out why.


OPTIONAL:

Now is a great time to loosen your master cylinder, rotate your brake lever down. I find this position slightly more comfortable, and less prone to catching my fingers when I go to brake. Adjust the clutch lever similarly.


14. Set the throttle cables to their loosest position at the throttle body side. There are 3 nuts at this end. Simply back the 12 mm nut in the center as close to the 10mm nut as it will go. Don't worry about the outer 12 mm nut.

Attach the throttle cables to your throttle body. Start with the bottom one.



Tips:
- Once the cable is connected to the throttle cam, hold the outer 12 mm nut, and tighten the long 10mm nut as far as it will go using your fingers. Then tighten the center 12mm nut towards the outer 12mm nut.
- Repeat this procedure for the top throttle cable.
- Make sure not to mix up the cables!

When you're done, it should look similar to this:



15: Perform the final cable adjustment using the 8mm and 10mm nuts next to the throttle grip.



16: Check your throttle for smooth operation. This step is critical!

Tips:
- You should be able to open your throttle all the way with minimal effort.
- You should feel as though your are twisting a spring.
- You should not feel any resistance at all.
- The throttle should snap shut the instant you let it go.
- There should be about 1mm (5-10 degrees) of free play in the throttle.
- Make sure it turns the correct direction.

If the throttle sticks at all, try loosening all the cables. You should be able to see a small bit of slack in the cables near the throttle body (see the previous image.)

If you have loosened everything as much as possible, and still have no slack, you may have to drill a hole in your throttle grip assembly. See the note about the R6 throttle.

If you have far too much free play (probably because you drilled a looser cable anchor in the throttle,) simply loosen the 10 mm nut near the throttle body, and tighten the center 12mm nut towards the outer 12 mm nut until things feel right.


17: Double check that everything is secure, and feels normal.

18. Remove the tank prop, and lower the tank. No need to bolt it down yet.

19. Start the bike. Keep your finger on the kill switch.

20. Make sure everything is adjusted correctly.

- Your idle speed should not have changed.
- Move your handlebars from side to side. Your engine speed should not change.
- You should have free play in the throttle no matter where the bars are pointed.
- Blip the throttle and make sure nothing binds as you move the bars.


OPTIONAL:
Now is a great time to adjust your idle speed if necessary.


21. Stop the bike and bolt everything back together.

- Make sure all throttle freeplay adjuster bolts are tight (two by the throttle body, one by the grip.)
- Re-attach your the clamp that holds your handle switch assembily wire.
- Make sure your brake and clutch levers are secure.
- Bolt down the tank.
- Bolt down your seat.
- Double check your tank and especially your seat by tugging on them.

22. Have a great ride!

Tips:
- Remember your kill switch in case anything strange happens.
- Try not to get a ticket.
- If you wheelie, make sure it's on purpose.

23. Let me know how it went!

FrigginChi said:

Awesome. Bet it took you longer to type this up than to do

Click to expand...

You hit the nail on the head. The process is really easy, once you know the gotchas.

I actually ended up doing everything twice in order to figure out what to do with that damned plastic R1 ring.

I performed a very similar mod on my 1999 R6, installing a throttle tube from an '02 R1 for a quicker throttle action.

I may do the same for my K6. Great tutorial!

Burning1 said:

11. Remove the funky plastic ring on the R1 grip. This ring serves no purpose on the outside of the handle switch assembly, and if you put it on the inside, it will cause your throttle to stick (Very dangerous!)
View attachment 236202

Click to expand...

You should edit this.

Actually, having a plastic ring between the housing and the rubber grip greatly reduce the stiction between the two parts. I try to add this feature whenever doing throttle swaps. Double delrin rings are the ultimate. I cut these from sheet stock.

Also, you should add that a thin film of aviation control cable grease should be applied between the throttle tube and the bar for super slick opperation.

pvd said:

You should edit this.

Actually, having a plastic ring between the housing and the rubber grip greatly reduce the stiction between the two parts. I try to add this feature whenever doing throttle swaps. Double delrin rings are the ultimate. I cut these from sheet stock.

Also, you should add that a thin film of aviation control cable grease should be applied between the throttle tube and the bar for super slick opperation.

Click to expand...

Unfortunately, the one that comes with the R1 grip is just slightly too wide, and causes very noticeable drag on the throttle. I considered coating the ring with lube, but I didn't trust it as a long term solution. I'm not sure it would have solved the problem either.

I'll add a note about derin rings. I assume doing so will mean removing the grip from the throttle tube?

Great point on greasing the bar!