Many of you have probably heard of, or even done the Yamaha R6 Throttle Tube Mod for the N400. You can purchase it here with grip pre-installed:
Short Throw Throttle w/ Grip for Yamaha, Kawasaki (OEM R6 Throttle Tube)
Norton Motorsports has a very detailed write-up with photo going over whats required to install this mod. You can read it here:
How to install an R6 throttle tube in the Kawasaki Ninja 400 / Z400
As always, when installing a race or short throw throttle tube, it's always highly recommended to install a soft pull spring at the same time. "The shorter you make the throttle throw, the harder it is to twist the throttle, since the force necessary to twist the throttle increases 1:1 as the distance decreases. So if you cut the throttle throw in half with a race throttle system, the force to pull the throttle is doubled and it starts to be annoyingly difficult to twist the throttle and your grips will start to spin." - Norton Motorsports
You can purchase the soft pull spring here:
Norton Racing Soft Pull Throttle Return Spring – Kawasaki Ninja 400 / Z400
I did the R6 throttle tube the moment I bought the bike before I ever rode my N400, since I had it on my R3 as well. I bought the soft pull spring a short time later though, and jsut got around to finally installing it (I've been riding my R3 more over the last year), and as such ran into common issues that people ask me about all the time, and I took the time to thoroughly go throw and fix them.
Many have ran into issues where even after filing and modifying the OEM housing and adjusting cables as much as possible, the throttle still is crunchy or sticks. The obvious answer is of course, pull it apart and file more until it no longer is crunchy or sticks. The next answer is of course clean and lube your throttle cables. If that still doesn't help, be sure your handlebar is clean, and you can apply a thin (by thin, I mean use a paper towel or shop towel to apply) film of grease on the handlebar under the throttle to ensure the tube itself rotates freely and smoothly.
However, some may still run into issues, and I'm here to address some that I found while installing my soft pull spring.
1. Cable Guide/Tensioner is Contacting the Tube. It's possible that the cable tensioner guide (the farthest forward cable, installed last on reassembly, has the housing side tensioner) may in fact be coming in contact at times with the throttle tube itself. I cut the guide/tensioner shorter (the bit that sits inside the housing) and filed it down to be smooth. I filed mine more so the cut portion was flat after these photos, but for illustration here's the piece I'm talking about.
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2. Throttle Tube Contacting the Sides of the OEM Housing. If you try rotating the throttle inside the housing before reassembly, you may notice the tube contacting the sides of the OEM housing, if this is the case, remove the tube, and either file or sand with a fine tooth or grit the sides of the throttle tube until it no longer contacts the inside of the housing when rotated with cables attached. Be careful, as you don't want to remove too much material, you can also slightly sand or file the sides of the OEM housing to also create clearance. It's important that every surface be smooth though so it isn't crunchy and slides easily. You can again apply a very thin film of grease with a shop towel or even cable lube to assist in smooth operation on these surfaces.
3. When Reassembling Don't Over Tighten the OEM Housing Screws. This may seem simple, but it's something often done. When reassembling, tighten the top screw first using a JIS screwdriver (It's a Japanese Motorcycle, keep rounding out screws on your bike? Get a JIS Screwdriver set. This is the one I've used for years, and have two sets of: Hozan JIS-5 JIS Screwdriver Set (NEW 3rd Gen.) ), then when you tighten the second screw (lower screw) go until the throttle catches when twisted, then back off slowly until it doesn't. If you've already followed the write up, and everything above, it shouldn't need more than a quarter to a half turn out before the throttle returns (provided the cables are tensioned correctly). This will still be more than enough to hold the housing in place firmly, and will prevent any binding on the housing.
4. Cable Routing and Tensioning. This one should have already been addressed long before this point, so if you haven't addressed this, it's on you completely. However, it's the most common issue, so I'm hammering this one till it's dead. Make sure your cables are routed correctly, no kinks or sharp curves, free and clear especially from full handlebar lock both left and right. If you have aftermarket clip-ons like I do, routing may need changed or adjusted. Tensioning will always change with this mod, wether you have OEM or aftermarket handlebars. Think you set tension correctly but still not working? Go to either extreme on both tensioners! This means 4 different configurations (maxed out tension positions). Then find where it needs to sit on both. You always adjust the throttle body side tensioner first, then the housing side tensioner.
5. I've Done Everthing in the Write up, and Above, Still Catches When Reassembled! If you've reached this point and are still having issues, go over and double, or triple check everything again, because chances are you missed something, or didn't tension or route correctly, or didn't file enough. If you've gone through all of this multiple times, then take it to shop and have them do it.
Hope this helps those out there who are having issues with the Yamaha R6 Throttle Tube Mod.
Short Throw Throttle w/ Grip for Yamaha, Kawasaki (OEM R6 Throttle Tube)
Norton Motorsports has a very detailed write-up with photo going over whats required to install this mod. You can read it here:
How to install an R6 throttle tube in the Kawasaki Ninja 400 / Z400
As always, when installing a race or short throw throttle tube, it's always highly recommended to install a soft pull spring at the same time. "The shorter you make the throttle throw, the harder it is to twist the throttle, since the force necessary to twist the throttle increases 1:1 as the distance decreases. So if you cut the throttle throw in half with a race throttle system, the force to pull the throttle is doubled and it starts to be annoyingly difficult to twist the throttle and your grips will start to spin." - Norton Motorsports
You can purchase the soft pull spring here:
Norton Racing Soft Pull Throttle Return Spring – Kawasaki Ninja 400 / Z400
I did the R6 throttle tube the moment I bought the bike before I ever rode my N400, since I had it on my R3 as well. I bought the soft pull spring a short time later though, and jsut got around to finally installing it (I've been riding my R3 more over the last year), and as such ran into common issues that people ask me about all the time, and I took the time to thoroughly go throw and fix them.
Many have ran into issues where even after filing and modifying the OEM housing and adjusting cables as much as possible, the throttle still is crunchy or sticks. The obvious answer is of course, pull it apart and file more until it no longer is crunchy or sticks. The next answer is of course clean and lube your throttle cables. If that still doesn't help, be sure your handlebar is clean, and you can apply a thin (by thin, I mean use a paper towel or shop towel to apply) film of grease on the handlebar under the throttle to ensure the tube itself rotates freely and smoothly.
However, some may still run into issues, and I'm here to address some that I found while installing my soft pull spring.
1. Cable Guide/Tensioner is Contacting the Tube. It's possible that the cable tensioner guide (the farthest forward cable, installed last on reassembly, has the housing side tensioner) may in fact be coming in contact at times with the throttle tube itself. I cut the guide/tensioner shorter (the bit that sits inside the housing) and filed it down to be smooth. I filed mine more so the cut portion was flat after these photos, but for illustration here's the piece I'm talking about.
2. Throttle Tube Contacting the Sides of the OEM Housing. If you try rotating the throttle inside the housing before reassembly, you may notice the tube contacting the sides of the OEM housing, if this is the case, remove the tube, and either file or sand with a fine tooth or grit the sides of the throttle tube until it no longer contacts the inside of the housing when rotated with cables attached. Be careful, as you don't want to remove too much material, you can also slightly sand or file the sides of the OEM housing to also create clearance. It's important that every surface be smooth though so it isn't crunchy and slides easily. You can again apply a very thin film of grease with a shop towel or even cable lube to assist in smooth operation on these surfaces.
3. When Reassembling Don't Over Tighten the OEM Housing Screws. This may seem simple, but it's something often done. When reassembling, tighten the top screw first using a JIS screwdriver (It's a Japanese Motorcycle, keep rounding out screws on your bike? Get a JIS Screwdriver set. This is the one I've used for years, and have two sets of: Hozan JIS-5 JIS Screwdriver Set (NEW 3rd Gen.) ), then when you tighten the second screw (lower screw) go until the throttle catches when twisted, then back off slowly until it doesn't. If you've already followed the write up, and everything above, it shouldn't need more than a quarter to a half turn out before the throttle returns (provided the cables are tensioned correctly). This will still be more than enough to hold the housing in place firmly, and will prevent any binding on the housing.
4. Cable Routing and Tensioning. This one should have already been addressed long before this point, so if you haven't addressed this, it's on you completely. However, it's the most common issue, so I'm hammering this one till it's dead. Make sure your cables are routed correctly, no kinks or sharp curves, free and clear especially from full handlebar lock both left and right. If you have aftermarket clip-ons like I do, routing may need changed or adjusted. Tensioning will always change with this mod, wether you have OEM or aftermarket handlebars. Think you set tension correctly but still not working? Go to either extreme on both tensioners! This means 4 different configurations (maxed out tension positions). Then find where it needs to sit on both. You always adjust the throttle body side tensioner first, then the housing side tensioner.
5. I've Done Everthing in the Write up, and Above, Still Catches When Reassembled! If you've reached this point and are still having issues, go over and double, or triple check everything again, because chances are you missed something, or didn't tension or route correctly, or didn't file enough. If you've gone through all of this multiple times, then take it to shop and have them do it.
Hope this helps those out there who are having issues with the Yamaha R6 Throttle Tube Mod.
