Description
This kit includes a customized Mikuni HSR 42mm Carburetor, where for less under gas tank interference when using the OEM Honda or a Clarke gas tanks, we have re-manufactured this carb, lowering and moving the throttle cable connection to the left-hand side of the carb. There is still the requirement to heat and depress these tanks but nothing to the extreme shown in the other 650R kit picture library.
The carb comes fitted with an anodized aluminium outlet sleeve to enlarge the carb to match your 49mm engine rubber flange and 63mm air-box adapter sleeve to match the other end and mimic your OEM carbs length. The kit also comes with throttle cables and a 1/4 turn quick action throttle which must be lubed before fitment and a short choke cable with universal mounting bracket. The carb has some Honda specific adjustments made and is pre-jetted for your engine. A specially made size 30 pump nozzle is fitted as the accelerator pump circuit on the TM42’s will not work properly on Honda’s without it. For this Mikuni carburetor to operate correctly the motorcycles air box must be opened up to allow more air flow in. Using a hole saw, a 45mm diameter hole will be sufficient for a Suzuki DR650 but some Hondas require way more. The best process is to keep opening up the air-box until no more improvement is noticed and you will be surprised at the difference.
The Mikuni TM42-6 HSR flows 17CFM more than our TM40-6 and incorporates many upgraded features such as a roller-bearing slide. All this when compared to you stock carb means going even faster has never been so easy, say goodbye to hard starting, hesitations and flat spots.
Climate, altitude and fuel density from different octane fuels all have varying effects on final fine tuning as does cam, exhaust and cylinder head porting etc. For this reason, we have included what we have found to be a range of jets to allow you to tune to most variables. International buyers please advise us of your fuel octane rating so we can make any applicable changes. Australian fuel is 91, 95 and 98 octane rated.
Important information regarding your gas tank clearance: For fitment with most other aftermarket large capacity tanks being the Acerbis 22 litre tank or Safari & also with the IMS tank which just clears, use the other listed TM42 XR650R kit with the RH side throttle cable attachment which is the cheaper option. If looking at that kit you will see the drastic tank mods required for using the OEM or Clarke tanks. some minor mods may still be required with this carb but nothing to the extent if using the other. TANK MODIFICATION FOR OEM HONDA AND CLARKE: A competent person can easily heat and depress the contact area to allow carb clearance on this tank. After thorough removal of all fuel from inside the tank, slowly heat an extended area using a heat gun. Allow plenty of time for the heat to absorb right through the Polyethylene. If the heated area gets shiny or wet in appearance this indicates the surface is melting and you do not have full heat penetration. Shield the petcock when heating close to that area. Once it starts to become soft around 140 degrees C, carefully depress and hold in place the area using a bezel or similar object. The polyethylene material will not lose any of its strength or integrity once cooled back down as long as you allow for an even spread without excessive thinning. If at all concerned we highly recommend having this professionally done or otherwise buy an aftermarket tank. The improvement in performance far outweighs any inconvenience.
Fine tuning is generally related to cam or sometimes exhaust system with the XR where the supplied setup is in most cases perfect but if you don’t get that instant “WOW I’ve got myself a crazy wheel standing machine” feeling, it will only usually relate to main jet size and or needle clip position setting. If at all confused or in need of guidance, we offer our customers business hours phone support for any carb we sell. The TM42 for big Jap singles are now our most popular selling kits worldwide and our knowledge base for tuning to different engine configurations of all brands is extensive.
You will instantly experience way better throttle response, improved smooth acceleration, increased horsepower and torque. Plus the bonus of better fuel economy. Dyno tests show improvements of up to and over 25% when fitted to OEM carburetored engines. To fully appreciate the potential this carburetor has you must fully read and follow the provided fitment and tuning sheets.
To clarify some commonly asked questions about this carb in regards to a comparision with the 40mm:
In the late 80’s Mikuni American released the HS40 (TM40-6) as an amazing new carburetor for the Harley Davidson market, literally knocking all its competitors out of the park. We were at the San Jose Custom Chrome Show when it was released and become part of that buzz as Australian Mikuni distributor. This slide type fuel metering device basically made the competitors butterfly type carbs seem like lawn sprinklers.
With the huge increase in Harley Davidson sales this became a very lucrative market. Recognizing the potential of this market and being aware of the efforts of competitors to try and grab back their share of it made Mikuni realize the necessity of replacing the 40 with a carburetor to be the be all and end all of all carburettors. The target was to deliver unrivaled peak performance combined with smoother throttle operation and lighter throttle pull by replacing the metal on metal slide action with a slide running on roller bearings. Also a larger fuel bowl capacity was provided but most of all, superior venturi design and fuel atomization resulting in more precise mixture ratios to not only increased horsepower and torque but also to enable the fitment of a larger carb to smaller capacity engines without losing valuable bottom end power, where in fact instead gaining more. In 1994 the HSR42 was born and just like you will if you fit one to your bike, all we could say was WOW. Instant throttle response delivering 25% more horsepower and torque over the stock CV carb before even putting on a real high flow air-cleaner. As the badge says 20 years later” Still the best performance carburetor on the planet”.
Unfortunately, the TM42 only had limited sales in the Japanese single market due to it only appealing to the custom fitter as there had never been a cable set or air-box adapter available off the shelf. With the slowing of the Harley market due to fuel injection on new bikes, here in Australia, Mikunioz realized the opportunity to offer Mikuni’s best Carburetor to the big Jap single market and in late 2015 we released a range of ready to roar direct fit up kits with correct jetting and a few trick mods to make them work better than anything before on big Jap Thumpers.
The fuel consumption is way less but when comparing with the stock carbs, it all depends on how having a lot more power and torque effects your riding habits. If you can manage to back off and just have your bike perform at its present level you’ll be surprised by the fuel economy, but of course when the same amount of throttle twist becomes front wheel lifting, breaking traction action, well it’s hard to not want to go and play. If you have more horses in the paddock and you want them all to perform, you have to feed them more hay!
You will enjoy this new carb but do be sure to hold on tight on your first test ride as she may try to spit you off if you nail it to hard.
All international buyers are responsible for the payment of their domestic customs duties and taxes charged on imported goods. The duty free threshold and duty/taxes payable rates differ from one country to another and we strongly advise you check your liability before ordering if unsure. Please check your tracking on all international shipments within 7 days to follow their progress and determine if it is being held by your local customs dept. or on their behalf by the Postal Service, who you will need to make contact with using the provided tracking number.
Please Note: Other than exact replacement OEM carburetors, all Mikuni Aftermarket Carburetors and Tuning Components are sold “As Is” for Off Road / Racing Use Only and are not intended or approved for use on vehicles operated on Public Roads or in locations where applicable engine tampering and anti-pollution laws apply.
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