Since I have the site, I get a lot of questions of people, like which exhaust must I use etc... Mostly the questions they ask are already subscribed on the site. ...Therefore, questions asked concerning tuning are no longer responsed to ...
Attention, the tuning is only for racing purpases, not for streetuse.
To avoid that I have to explain 50 times to anyone what it's all about, try to learn first the basics of the twostroke. Buy the book of Bell - twostroke tuning, read the sections cylinder and exhaust on this site, etc...
There are several rules you can follow on the mbx/ns1 80cc cylinder:
1) the first rules are basic rules: which displacement does my cilinder have...?
Your standard Honda MBX or ns1 uses a crank with a stroke of 41,4mm. Placing a longer conrod does NOT change the stroke, keep this in mind
The standard GE3G German Mbx80 cylinder, or GE3F or NS1 cylinder can be bored to several bore dimensions:
The formula to calculate your displacement in CC is described in the formula here below. (boring= bore, slag=stroke, aantal cilinder= number of cyl.)
(3,14/4) x (bore x bore) x stroke
NS1 cylinder= bore 48mm= 0,785x2304x41,4= 74,877 cc
GE3G cylinder= bore 49,50 mm= 0,785x2450,25x41,4= 79,630 cc
GE3G cylinder= bore 51,50mm= 0,785x2652,25x41,4= 86,195 cc
Malossi cylinder mbx= bore 53mm= 0,785x2809x41,4= 91,289 cc
Gilardoni cylinder mbx= bore 54mm= 0,785x2916x41,4= 94,767 cc
Athena cylinder mbx= bore 55mm= 0,785x3025x41,4= 98,309 cc
Autisa cylinder mbx= bore 55mm= 0,785x3025x41,4= 98,309 cc
Bored out standard mbx cylinder= bore 55mm= 0,785x3025x41,4= 98,309 cc
So forget the douchebagstories of a '110/125 kit cylinder', certainly in the Netherlands they say this alot...which is total crap of course.
Now, there are many options available for the STANDARD Honda mbx 80 cylinder in bore sizes
* you can use a 49,50 to 51,50mm standard MBX piston (pen 12). The standard pistons comes in 8th oversize (+2mm)
* you can use a 53-54mm piston of a kawasaki AR80. Keep in mind that one of the pistonringslocks are centered and come together on the
boostport of the cylinder. This has no influence on the reliability or performance of the cylinder (A race Honda RS 125 does also have this)...
it just works...
* use a vertex italkit piston 54mm in size (stille available at Italkit)
* use a polini piston 55mm in size of the brand Polini for the yamaha rd80LC2. Fits without any modyfications and the pistonlocks are in the right
place.
The other option is to use a italkit crank 44mm in stroke and a Italkit derbi 52mm piston. When the 44mm Crank is placed in the engine, the cylinder has to be raised with 3mm to compensate the longer stroke. You can fit a Italkit derbi 52mm piston which is 3mm shorter and so you do not have to raise the cylinder. The piston is a racepiston and comes with one pistonring and is coated.
For 2014 Italkit will produce a new race crank for the mbx/nsr 80 engine with a larger stroke of 44mm. In other words the maximum displacement achieved on the Honda mbx 80 will be= 0,785x3025x44= 104,483cc. I have asked at Italkit for more information, but I guess communication isn't their greatest achievement...Google the site of Italkit and download the PDF catalogue 2014. Italkit will no longer produce the 54mm cylinder, but instead will offer: a 44mm race crank, a race cylinderkit 48mm (to fit the crank) with 44mm crank (=80cc), a standard height 48mm cylinder to go with the standard crank. Pistons will still be available in sizes 48mm and 54mm for the Honda engine specifically.
So this new 44mm crank will open up a whole other spectre of configurations.
My experience is that high tuned setups only work untill a bore of 52mm. The 53-55mm bore options are more for low tuned setups but with lots of torque.
2) Second rule is, what timing does my cylinder have?
The standard German mbx cylinder has a exhausttiming of +- 166°, which is too low. The most other factorycylinders aren't that well timed either.
The easiest way is to tune your own standard mbx cylinder. Once you've tuned the cylinder you can fit the right exhaust.
Good cylindertimings are:
a) 180 °= +-23mm measured from the top of the cilinder to the top of the exhaustport
b) 185°= +-22mm ...
c) 192°= 21mm...
d) 195°= 20mm...
option D has to be used with a innerrotor igntion like HPI or PVL.
3) What exhaust should I use, remembering rule 1 (=bore) and remembering rule 2 (=exhausttiming)
There are several choices available for getting power out of the mbx engine:
Do not forget that a Derbi or AM6 exhaust can made fit to the chassis. A exhaust like a MVT carrera for derbi, or a yasuni R3 or R4 can made fit to the mbx chassis. I have fitted several derbi and AM6 exhausts to the mbx chassis and they all worked well - but most important is that everything must be adapted to each other. It is useless for example to fit a yasuni R4 pipe on a standard bore and timed honda mbx cylinder.
for example: use a Yasuni R4 exhaust for a derbi and widen the holes of the exhaustflange (calculated for timings +- 195° and 90-94cc), use a Italkitcrank 44mm in stroke and tune your cylinder to 192-195° exhausttiming and bore your cylinder to 51,50mm, which makes around 91cc. Use a innerrotor and use a mimimum 30mm carb. Fit a mototassinari vforce3 type reedvalve. This wil take a big deal out of your budget though...
!!!YOU CANNOT TUNE YOUR BIKE WITHOUT INVESTING MINIMUM 600 EURO INTO IT!!!
The cheapest way to get fast is:
* tune your own standard cylinder to 192°= 0 euro
* use a Taiwan standard mbx piston, available in differnent sizes up to +2mm= prices around 20 euro
* innerrotor ignition: cheapest is the HPI with adaptorplate= 220 euro
* a AM6 JAZEN exhaust special 74/80cc= 178 euro with shipping (powerband 9000-13800rpm)
* boyesenreeds nsr 50= 35 euro
* airfilter= 10 euro
* oko ebay carb= 65 euro
* change the cylinderhead to squish 0,8mm and o-ring= 50-60 euro
* mainjet set: 142-160 keihin= 16 euro
* malossi carbflange= 40 euro
= 634 euro
JAZEN, a producer of exhausts, located in Murcia (Spain) produces the cheapest available race exhaust. It's low in price but big in performances...!
The Chassis
For race usage, try to find a honda ns1 chassis. Not one of the lightest, but from my experience you can easily fit several brands of tires of Honda RS125 slicks on them. Several honda nsf100 parts are also interchangeble, like steps
A Honda ns1 drives like a Honda rs 125, but the biggest disadvantage is the weight of course. The NS1-chassis is very stabile in cornering at high speed.
Fit a YSS rear shock of a honda cbr 125, because the standard shock is useless for the racetrack.
Attention, the tuning is only for racing purpases, not for streetuse.
To avoid that I have to explain 50 times to anyone what it's all about, try to learn first the basics of the twostroke. Buy the book of Bell - twostroke tuning, read the sections cylinder and exhaust on this site, etc...
There are several rules you can follow on the mbx/ns1 80cc cylinder:
1) the first rules are basic rules: which displacement does my cilinder have...?
Your standard Honda MBX or ns1 uses a crank with a stroke of 41,4mm. Placing a longer conrod does NOT change the stroke, keep this in mind
The standard GE3G German Mbx80 cylinder, or GE3F or NS1 cylinder can be bored to several bore dimensions:
The formula to calculate your displacement in CC is described in the formula here below. (boring= bore, slag=stroke, aantal cilinder= number of cyl.)
(3,14/4) x (bore x bore) x stroke
NS1 cylinder= bore 48mm= 0,785x2304x41,4= 74,877 cc
GE3G cylinder= bore 49,50 mm= 0,785x2450,25x41,4= 79,630 cc
GE3G cylinder= bore 51,50mm= 0,785x2652,25x41,4= 86,195 cc
Malossi cylinder mbx= bore 53mm= 0,785x2809x41,4= 91,289 cc
Gilardoni cylinder mbx= bore 54mm= 0,785x2916x41,4= 94,767 cc
Athena cylinder mbx= bore 55mm= 0,785x3025x41,4= 98,309 cc
Autisa cylinder mbx= bore 55mm= 0,785x3025x41,4= 98,309 cc
Bored out standard mbx cylinder= bore 55mm= 0,785x3025x41,4= 98,309 cc
So forget the douchebagstories of a '110/125 kit cylinder', certainly in the Netherlands they say this alot...which is total crap of course.
Now, there are many options available for the STANDARD Honda mbx 80 cylinder in bore sizes
* you can use a 49,50 to 51,50mm standard MBX piston (pen 12). The standard pistons comes in 8th oversize (+2mm)
* you can use a 53-54mm piston of a kawasaki AR80. Keep in mind that one of the pistonringslocks are centered and come together on the
boostport of the cylinder. This has no influence on the reliability or performance of the cylinder (A race Honda RS 125 does also have this)...
it just works...
* use a vertex italkit piston 54mm in size (stille available at Italkit)
* use a polini piston 55mm in size of the brand Polini for the yamaha rd80LC2. Fits without any modyfications and the pistonlocks are in the right
place.
The other option is to use a italkit crank 44mm in stroke and a Italkit derbi 52mm piston. When the 44mm Crank is placed in the engine, the cylinder has to be raised with 3mm to compensate the longer stroke. You can fit a Italkit derbi 52mm piston which is 3mm shorter and so you do not have to raise the cylinder. The piston is a racepiston and comes with one pistonring and is coated.
For 2014 Italkit will produce a new race crank for the mbx/nsr 80 engine with a larger stroke of 44mm. In other words the maximum displacement achieved on the Honda mbx 80 will be= 0,785x3025x44= 104,483cc. I have asked at Italkit for more information, but I guess communication isn't their greatest achievement...Google the site of Italkit and download the PDF catalogue 2014. Italkit will no longer produce the 54mm cylinder, but instead will offer: a 44mm race crank, a race cylinderkit 48mm (to fit the crank) with 44mm crank (=80cc), a standard height 48mm cylinder to go with the standard crank. Pistons will still be available in sizes 48mm and 54mm for the Honda engine specifically.
So this new 44mm crank will open up a whole other spectre of configurations.
My experience is that high tuned setups only work untill a bore of 52mm. The 53-55mm bore options are more for low tuned setups but with lots of torque.
2) Second rule is, what timing does my cylinder have?
The standard German mbx cylinder has a exhausttiming of +- 166°, which is too low. The most other factorycylinders aren't that well timed either.
The easiest way is to tune your own standard mbx cylinder. Once you've tuned the cylinder you can fit the right exhaust.
Good cylindertimings are:
a) 180 °= +-23mm measured from the top of the cilinder to the top of the exhaustport
b) 185°= +-22mm ...
c) 192°= 21mm...
d) 195°= 20mm...
option D has to be used with a innerrotor igntion like HPI or PVL.
3) What exhaust should I use, remembering rule 1 (=bore) and remembering rule 2 (=exhausttiming)
There are several choices available for getting power out of the mbx engine:
Do not forget that a Derbi or AM6 exhaust can made fit to the chassis. A exhaust like a MVT carrera for derbi, or a yasuni R3 or R4 can made fit to the mbx chassis. I have fitted several derbi and AM6 exhausts to the mbx chassis and they all worked well - but most important is that everything must be adapted to each other. It is useless for example to fit a yasuni R4 pipe on a standard bore and timed honda mbx cylinder.
for example: use a Yasuni R4 exhaust for a derbi and widen the holes of the exhaustflange (calculated for timings +- 195° and 90-94cc), use a Italkitcrank 44mm in stroke and tune your cylinder to 192-195° exhausttiming and bore your cylinder to 51,50mm, which makes around 91cc. Use a innerrotor and use a mimimum 30mm carb. Fit a mototassinari vforce3 type reedvalve. This wil take a big deal out of your budget though...
!!!YOU CANNOT TUNE YOUR BIKE WITHOUT INVESTING MINIMUM 600 EURO INTO IT!!!
The cheapest way to get fast is:
* tune your own standard cylinder to 192°= 0 euro
* use a Taiwan standard mbx piston, available in differnent sizes up to +2mm= prices around 20 euro
* innerrotor ignition: cheapest is the HPI with adaptorplate= 220 euro
* a AM6 JAZEN exhaust special 74/80cc= 178 euro with shipping (powerband 9000-13800rpm)
* boyesenreeds nsr 50= 35 euro
* airfilter= 10 euro
* oko ebay carb= 65 euro
* change the cylinderhead to squish 0,8mm and o-ring= 50-60 euro
* mainjet set: 142-160 keihin= 16 euro
* malossi carbflange= 40 euro
= 634 euro
JAZEN, a producer of exhausts, located in Murcia (Spain) produces the cheapest available race exhaust. It's low in price but big in performances...!
The Chassis
For race usage, try to find a honda ns1 chassis. Not one of the lightest, but from my experience you can easily fit several brands of tires of Honda RS125 slicks on them. Several honda nsf100 parts are also interchangeble, like steps
A Honda ns1 drives like a Honda rs 125, but the biggest disadvantage is the weight of course. The NS1-chassis is very stabile in cornering at high speed.
Fit a YSS rear shock of a honda cbr 125, because the standard shock is useless for the racetrack.
!!NEW 2014 ITALKIT complete kit available!!
Fellow racers. Italkit has finished their site and what is very nice is the fact that Italkit dedicated a complete page for the honda nsr 80. The complete kit - cylinder with W-shaped exhaust port, 194°-133° timing, boosterports in the intake, nicasil coated and alu casted, vertex 48mm racing piston with single, complete racingcrank 44mm, inlet manifold. Italkit claim to have 24 hp (I pressume on the crank of course). It is very nice of them to put the specs on the site. You should fit a adapted cylinderhead, squish 0,8mm and a good racing pipe minimal 194° in timing.
The cylinder is 48mm in bore, but due to the longer stroke of 44mm, 80cc is obtained. (cfr. the above possibilities with the crank and using a original mbx cylinder...)
Normally the turbokit carr0603 or 0604 for the ns1 is the perfect pipe for this cylinder. Bear in mind that a derbi or am6 race pipe will also do the job.
The cylinder is 48mm in bore, but due to the longer stroke of 44mm, 80cc is obtained. (cfr. the above possibilities with the crank and using a original mbx cylinder...)
Normally the turbokit carr0603 or 0604 for the ns1 is the perfect pipe for this cylinder. Bear in mind that a derbi or am6 race pipe will also do the job.
192°-195° 80cc kits
!!NO MORE AVAILABLE!!
!!!!ABOVE MENTIONED KIT IS NOT FOR SALE ANYMORE!!!!!! - sold out!!!!!
The 3 pictures above gives you a listing of which parts you have to install to turn your mbx/nsr 80 engine into a little racer. Attention, there are many parts which can be replaced by other parts of course. For instance the innerrotor hpi can be replaced by a PVL rotor (you'll have to make a baseplate, the hpi has one...). The malossi reedvalve can be swapped with another brand like topperformances Vforce for am6. The exhaust is a turbokit 0603, also exists in chrome finish. The carb can also be swapped with a 24 - 28mm, but the 30 gives the best power. Go to the cylinder section and tune your cylinder to 192° minimal exhausttiming and your done. The listing comes from the webshop www.josdijkman.nl There are many other shops, mostly in the Netherlands who sometimes can get a part cheaper. Also note that the flange for the carb, brand malossi is standard 26mm wide, so it has to be widened to 30mm with a grindingtool.