Mikuni VM28 TM28 Flat Slide 28mm Carburetor

Additional Information

• I'm looking for a replacement carb for my 1983 Yamaha Riva 180 do you know if this will work?
  

  This carb is an aftermarket carburetor and not designed as a direct replacement for any original equipment carburetor, including the Riva. However, it is possible that it can be adapted to work on the Riva. Listed below are a few things you need to consider when attempting a conversion:
  
  1. What size is my current carb? You want to be in the same ball park as your current carburetor. Too big a carburetor will not make you bike faster - it will make it run worse. You will, more than likely, also have to experiment with the jetting to get the bike to run optimally.
  2. Will this new carb fit? Check the dimensions of your current carb and compare it to the dimensions in the listing. Size is important!
  3. Will this carb fit my manifold and air filter boot? This carb has a 33mm spigot that fits into a rubber manifold adapter. Your bike also has a rubber manifold too, but you need to check your current carb to see if the spigot (the part that fits into the rubber adapter on the manifold) is 33mm as well. If not, an adapter will have to be machined. The intake bell on this carb is 44mm. That is the part that mounts to the rubber boot on your air cleaner. If it's close in size, you can sometimes find ways to easily adapt this boot to fit. It is not as critical as the intake spigot.
  4. Will my throttle cable work? This carb uses a single pull cable. Can your cable be adapted to work with this or will you need a aftermarket throttle and cable as well?
  5. Can I get to the choke? I can answer this for you. No. The engine is hidden under cowling. It uses a remote choke. Sometimes, the existing choke cable can be adapted to work with the TM28 choke mechanism. We also sell a remote cable that is 8-10 inches long. You might be able to mount this on your cowling.
  
  These are things that must be taken into consideration before buying an aftermarket carburetor.

  Answer by: rick c (Admin) on Mar 23, 2017 9:28:00 AM

• I have a Yamaha BW200 which has been modified with increase compression, mild exhaust porting, 30mm intake port matching, 30mm intake boot and less restrictive exhaust. The stock carb is a 28mm round slide. The intake boot can accommodate up to 30mm. I understand a flat slide flows more than a round slide, so between this 28mm flat slide or the 30mm round slide which would be a better option? Also, for a reference point, the stock main jet is a 120 in the Teikei carb. How does this translate to a Mikuni?

  Mikuni's VM28-418 flat slide carb is a more advanced carb than Mikuni 28mm round slide carb (VM28-49). Which carb is best for you really depends on fit. On many applications there is not enough room on the top for the flat slide and that is why the round slide is used. The flat slide carbs are generally a bit taller than the round slide. In this case, the flat slide is 135mm top to bottom, and the round slide is 122mm.
  Your biggest issue with going to an aftermarket carb may be the intake spigot because you mentioned your carb has a 30mm ID at the boot Both of these carbs have a 35mm OD at the spigot. Perhaps a larger flange adapter will mount to your head. I have provided a link for a 35mm spigot adapter below:
  http://www.nichecycle.com/ncs/mikuni/flanges-adapters/m-vm28-200k-adaptor-rubber-flange-to-spigot-26-28mm-by-mikuni.html
  The intake bell is also sized the same on both carbs at 44mm.
  Both carbs are excellent, but I believe ultimately fit will be the most important consideration.
  I have attached a link to a guide I wrote on choosing an aftermarket carbs. I think this may be helpful to you:
  http://www.vintagebikebuilder.com/choosing-aftermarket-carbs.html
  Once you have the carb, you can attempt to match your stock jetting as closely as possible. But, you may have to do some testing to determine the optimal jetting for your bike. With that in mind, I have also attached a link to a MIkuni tuning and jetting guide I wrote:
  http://www.vintagebikebuilder.com/mikuni-tuning-and-jetting-guide.html
  I do not have a guide that compares Mikuni jetting to the jetting of other carbs. You could possibly use jet drills to measure the jetting of the Teikei carb and compare it to various MIkuni main jets to find a similar size.

  Answer by: rick c (Admin) on Nov 18, 2019 12:02:00 PM

• Is the VM28-418 suitable for use on the Honda XR200r? If so do you recommend any specific installation instructions?

  We have never installed a carb on an XR200R, so I have very limited info to offer. There are other things to consider, such as how it will be mounted, along with physical size for installation, but I think I would try to go a little larger than a 28mm. Having no real world experience with installing on that model, please take this suggestion with a grain of salt. I'd probably go with a VM30.

  Answer by: Web Support (Admin) on Mar 24, 2022 12:12:00 PM

• I'm looking for the needle jet chart for TM28 flat slide. I'm running too rich at 1/4 to 3/4 throttle and need to come down a few jet sizes.

  Here is a link to all of the needle jets for the TM28. They are arranged from leanest at the top (O0), to richest at the bottom (P8)
  
  http://www.nichecycle.com/ncs/categories/carburetor/mikuni-parts-by-category/jettting-tuning/needle-jets/vm30-175-175-series-needle-jet-by-mikuni.html.

  Answer by: Web Support (Admin) on Feb 27, 2019 3:27:00 PM

• Greetings from New Zealand...I already have a set of three TM28 (VM28-418). Can you recommend a baseline jet kit for a 1972 Kawasaki H1B 500 triple two stroke? cost? If not, any recommendations as to who might know? thanks, Martin

  At this time (01/10/17), we do not have any jetting information for the H1. We had planned to create a carburetor kit for them, but the manifold design has set us back. If we run across any information, we will update you.
  
  Out of curiosity, what type of manifolds do you plan on using with the 28mm Mikunis?

  Answer by: Web Support (Admin) on Jan 10, 2017 11:00:00 AM

• I bought the VM28-418 carb. for a 1980's Honda fl-250 2-cycle odyssey . It starts and runs and the spark plug is tan. But at higher RPM's it misses is this caused by the main jet being to small ? Do you know what jet comes in this carb. ? Do you sale different size ? Any ideas ? Thanks Brad

  We don't have enough experience with the FL250 to make any real suggestions as far as size specific, but you should probably try going up on the main jet. That carb uses the VM4/042 series, which can be found at this link: http://www.nichecycle.com/ncs/categories/carburetor/mikuni-parts-by-category/jettting-tuning/main-jets/vm4-042-vm4-042-main-jet-by-mikuni.html
  
  You might want to try something like 200, 210, 220 and see what those do for you.

  Answer by: Web Support (Admin) on Jul 21, 2017 1:50:00 PM