Same-day shipping cutoff: Noon Pacific Time

TM40 ProCycle Installation Guide

You finally purchased a TM40 Carburetor for your DR650, or are at least thinking about doing it. Congratulations! So, for the next few minutes I beg you to forget that I work at ProCycle. Never heard of the place. I am just a regular Joe that ordered this carb from the web site. I had a modified airbox with an aftermarket filter and the stock exhaust. Yeah, stock exhaust. I really like the quiet factor so I can just about ride past the wildlife in the woods without spooking them. When my order arrived it was all there in one box; a new set of throttle cables (shorter inner cables than stock), a baggie full of jets and a complete instruction packet.


  • Being your average male,  I started by pulling out the old carb and cables.  Along with the carb came the secondary filter and the bar mounted choke lever. Before starting the actual installation I decided that a quick peek at the instructions wouldn't be a bad thing.  The first good tip was to remove the rear brake reservoir from the frame. This allowed me space to get my fingers in to finagle the new TM into place from the right side of the motorcycle.  That extra room really is important. You can remove this little plastic reservoir now like they recommend, or call them up later and order a new one as you will probably break it off somewhere during the installation process.
  • Next they told me to trim the two little centering tabs off the rubber portion of the intake manifold. The TM40 doesn't have anything there to use those and it really needs the room. OK, so another good point taken. The next step in the instructions recommended spraying a bit of WD40 (or some other lubricant) in the two rubber boots that the carb slides into. The TM40 is just a bit longer (or wider) from intake to exhaust than the stocker (stock is 98.13 mm, TM40 is 105.10 mm) and a bit of lubricant goes a long way in making it easier to squeeze the TM into that smaller space. This is the toughest part of the installation. In fact it is the only thing that is tough.
  • Squeezing the TM40 into the airbox boot can take a few minutes. I found the easiest thing to do was remove the rear clamp, lubricate each boot and start by sliding the front all the way in as far as possible. Once the front is in, wiggle and move the rear part of the carb around and GENTLY work the boot outside the carb with a small screwdriver.  DO NOT put a hole in your boot, that would be a bad thing! Once you have the airbox boot around the carb, you can put the clamp back on. Be sure you get the clamp all the way around the carb so you have a good seal. Tighten the front and rear clamps good and snug and your new TM40 installation is just about complete!
  • So you have the new throttle cables routed correctly, all the slack removed from them and tightened down at the carb as well as at the adjuster. Adjust the cable free-play to a minimum and make sure the throttle will snap closed by itself at the left and right steering lock positions. This is very important!
  • Let's finish up the final few steps and button up the entire program: connect the fuel valve vacuum hose to the vacuum port on the front right hand side of the TM, then connect the vacuum hose to the fuel petcock (if you have the stock petcock); replace the rear brake reservoir, fuel tank, seat and side panels.
  • Next is the start-up procedure: turn the petcock to 'PRIME' (if you are using the stock Suzuki petcock, or 'ON' if using a non-vacuum petcock); pull the choke knob out (if you used the TM40 knob) or pull the stock bar lever back, and hit the starter button. (Allow me just a moment to say that if you have an oversize IMS tank like I do, reaching that choke knob is now a like reaching behind the work bench for that bolt you just dropped and really need. It is not fun. Thankfully they have a remote choke cable kit that turns it back into a snap. Takes just a few minutes to install and you will be happy you did.)
  • It took my DR about 3 seconds to start for the first time with the TM. Just thumped right to life and was ready to go! It now requires the choke for about 15 - 30 seconds, even when cold, and is ready to motor away. You will probably have to adjust the idle once it warms up, but with the big knob poking out the left side of the carb, that is no problem.
  • With the bike warmed up, put on your helmet, jacket and gloves and go for a test ride. Be prepared though! This is no longer your old DR. This is the bike you have always wanted. Remember, I am NOT writing this as a ProCycle employee. I installed this carb on my bike just last night (October 5, 2011) and the difference was AMAZING! This became the motorcycle I thought it would be when I bought it. It now pulls from way down low (where the CV carb would not allow it) clear to the top. There is no hesitation, no stuttering going down the freeway, just nice smooth power everywhere!
  • Take a few minutes and adjust the idle mixture screw. Once you have fully warmed the bike up, turn the idle mixture screw inwards (clockwise) until the idle speed starts to drop or it becomes slightly rough. Then screw the screw out (counter-clockwise) until the idle just smooths out. You have just found the happy spot!
  • All motorcycles were not created equal. Each motorcycle is slightly different than the next and jetting that works on one motorcycle may be slightly off on another. The same is the case with the TM40. Though we do our best to get the jetting just right for your bike, it may need some slight adjustments to make it absolutely perfect on your motorcycle. Included with each TM40 is a copy of the tuning manual that will cover how to make changes in detail.