Xv125 Modifications Anglais

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Foreword:

This guide presents some ways to get a more powerful XV125 (and XV250). There is certainly

other different ways to explore and things to do that can enhance your motorbike as well, but

this guide simply introduces everything I made on my XV125 (model 4RF). It does not pretend

to be the best method, but a tough one which works well.

Everything costs a lot, especially parts for motorbikes and some people could say it is better to

buy a bigger bike with that money. Why not ? But if I buy bigger, I would surely want to make

it better too and I will not save any penny.

Concerning the 180cm3 bore kit, some people could also say to swap the engine with a XV250.

This method will work at 100% and would be easy to realize here in Japan, as one can buy used

and relatively cheap engines on the net auctions. But in this case, I would not have any pleasure

enhancing my XV125 with all existing parts for her and I would rather buy a Virago 250.

I would like to say at last that even I spent a lot of money on my XV125, I had as all bikers a lot

of fun searching around possible mods, parts and informations. And I can now share all this

knowledge with people who love their Viragos. I will keep my Virago all its lifetime (that I

expect to be long…) and the investment is worth it, as well as the result: while being a nice

cruiser and a nice ride for everyday, my top speed is 130 Km/h.

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1) TCI unit:

For XV250 owners: the XV250 is not restricted at this level.

If your TCI is not a TNDF45, then you should get one. Prices are different from countries to

countries, so the best thing to do is to ask your local dealer or search on the net.

The virago 125 has 3 types of TCI units (4 if we include the one on the XV125 model produced

in Japan). These types are:

� TNDF43 (5AJ-82305-00) = top speed restricted to 93 Km/h

� TNDF44 (5AJ-82305-10) = top speed restricted to 80 Km/h

� TNDF45 (5AJ-82305-20) = not restricted. The top speed is 107 Km/h and the RPM rises up

to 10500 rpm. You should consider this point if you want to install a tachometer.

� TNDF24 (4RF-82305-00) = top speed restricted to 93 Km/h. This model was sold with the

Japanese XV125. It has a non working stand connector, as the bike has no stand relay.

When you replace this TCI unit with the above mentioned models, you have to short the

connectors.

Remember to keep your original sprockets ratio (13/47) to achieve these top speeds.

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For more details about the XV125/XV250 TCI unit, have a look at the picture below.

If you want to go further with your TCI, you can check the following link:

http://www.ignitech.cz/english/aindex.htm

This Czech company site proposes replacement TCI units – SPARKER TCI - for different bikes

(including XV125 and XV250 for about 120 Euros). I did not try because I am happy with my

TNDF45 unit, but XV250 owners should give it a try.

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2) Air intake:

As everybody knows, the XV125 and XV250 have their intake located in the right pod.

You can mod the XV125 air intake by cutting the rubber restricting the air inlet inside the pod

(see the picture). But in order to have a clean job done, the best thing is to simply replace the

XV125 right pod by a XV250 one.

The second thing to do is to modify the pod by cutting it as on the picture to allow the air flow

enter more easily. (Mod also recommended for XV250 owners.)

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3) Air filter:

For XV250 owners: this mod is recommended.

To have a better air-gasoline mixture, replace the air filter itself. The best one (no need to

modify something) is a GREEN FILTER, model MY0576. I found the cheapest one (36,68

Euros) on this French company website:

http://www.pieces-auto-moto.com/categorysmoto.aspx?cat1=filtration&cat2=filtres-air-moto-ac

cessoires&cat3=yamaha

You can see what does this filter look like on the picture below.

I first used a K&N filter (model RC-2450) which gave me the same results, but I had to modify

the connections to get it fitted.

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4) Carburetor:

Once your air intake is modified, you have to rejet the carburetor. As rejetting is a pain in the

a..e, the best solution for the XV125 is to get a kit from this French company:

http://www.up-power.eu/125_Virago-shop_list-38.html

They have a carb modification kit for 79 Euros. This kit contains:

� A complete notice explaining how to modify the air box (see Air intake section) and the

carb, with the parts included in the kit.

� Parts included: 1 shim for the jet needle, 1 spring, 1 main jet, 1 idle jet and 1 front sprocket

(12T)

The result is perfect (see the chart below), but if your TCI unit is not a TNDF45, it is wise not to

install the 12T sprocket included in their kit; your first gear will be too short and therefore

unusable.

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Note also that Unlimited Power has a 170cm3 solution for the XV125, but personally it is not so

convenient. 180cm3 bore kit is the ultimate choice for me.

This carburetor mod is not suitable for the XV250 and Dynojet has also no reference

available. You can however check this Japanese company website for a so-called BAKUDAN

KIT. The one for the XV250 is the BAKUDAN KIT STAGE 2 (reference 000111-0382), and

consists of a special jet needle and main jet. It costs 10,800 Yen (see picture):

Left: BAKUDAN Kit stage 2 – Right: standard main jet and needle

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http://www.kenso-bakudan.co.jp/parts/bakudan/stage2/index.html

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5) Exhaust:

(Also recommended for XV250 owners.)

There is a lot of stories about restricted XV125 exhaust systems. European XV125 exhaust is

also a bit different from the XV250 one. My Japanese Virago (model 4RF) had the same

exhaust as her big sister XV250.

A lot of people are drilling their pipes but this just gives a deeper sound and has no impact on

the overall performance. I do not want to speculate if this way is good or bad but the simplest

(but not the cheapest…) solution to get more rumble and power is to change the complete

exhaust line.

However, if you went for the carburetor mod proposed by Unlimited Power (see carburetor mod

section), than you might encounter a slight power loss which will be totally compensated if you

install a 180cm3 bore kit.

Here are the most famous exhaust solutions for XV125 and XV250:

� Laser exhaust (Holland):

http://www.laserexhausts.com/

Unfortunately, they stopped the production of the XV125/XV250 line. You may still find some

on the net or at some dealers’ if you are lucky.

� BSM exhaust (Germany):

http://www.bsm-exhausts.com/

You can still find exhausts for XV125/XV250.

� Leo Vince (Italy):

http://www.leovince.com/it

They still have their Silvertail K02 exhausts.

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� Marving (Italy):

http://www.marving.com/faces/home.jsp?lingua=ENG

The one I have fitted on my XV125.

Choosing between these replacement exhaust systems is just a matter of taste, as the only

difference is the design. Performance remains the same. You can also remove or drill the inner

part of these exhausts to get a deeper sound.

Here is a link to a British company selling Marving exhaust systems (I bought mine on an

Italian web shop because of the attractive price, but this shop does not exist anymore).

http://www.wemoto.com/bikes/Yamaha/XV_125_Virago/97-00/

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6) Cams:

Upgrading cams is normally better when your cubic capacity has changed. But some bikes, like

the XV125 and XV250 can support better cams.

The XV125 and the XV250 have the same set of cams:

Front: 2UJ-12171-00 Rear: 2UJ-12181-00

(First models of XV250 had a different set of cams: 3DM-12171-00 for the front and

3DM-12181-00 for the rear. The power with these cams was 13 kW at 7000 rpm while it is 16

kW at 8000 rpm with the new set. If your Virago 250 specs are 13 kW, then you can go for an

upgrade – see with your Yamaha dealer to order your cam set).

The Japanese model of the XV125 (4RF) has a different set of cams too (maybe the same as old

XV250 ?). When I replaced my cams with the “standard” set, the power increased dramatically.

The cam replacement was also an occasion to change the cam timing chains (from DID) by a

better model from the same company (reference 25H110). These chains were found on this

British company web site:

http://www.patternparts.net/?i=18486

If you want to enhance your cams, you can always ask a specialist to do the job for you. Here is

a link to a French company specializing in cams:

http://www.techniprofil.com/

Their site has changed and prices are not indicated any more, but I think cam mod for XV125

was around 300 Euros for two cams. Of course, you surely have such a specialist in your own

countries.

As for the TT-R 125 cam replacement trick (from BBR Motorsports), I do not know if this

information is a hoax. The only place I saw something about it was just on the Viragotech forum

and I do not want to try it personally.

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7) 180cm3 bore kit:

As written before, the French company Unlimited Power has a 170cm3 bore kit for the XV125.

Why do less when you can have more, such as 180cm3 ?

The cheapest place to get a complete and new 180cm3 kit from BIHR is this French company

selling miscellaneous motorcycle parts:

http://www.blue-oil-france.com/

The kit reference is 054015 and here is a picture of it:

Its price is 545 Euros, but always remember to ask for a VAT deduction when you live outside

the EEC. All the stuff I bought in Europe cost me less than the original price, even with the

postal fees to Japan included…

There is also this solution for 265 Euros from BIHR if you prefer to modify your own

cylinders:

http://www.bihr.eu/productdetails.aspx?sku=154002&cat=AHW&typ=Bihr&st=Vehicle&v=19

427&vt=2&vtm=63&vcy=125&vy=1996&vn=XV125+VIRAGO

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8) Sprockets:


When you reached to this point, it is advisable to change your sprockets. For me, the best

compromise is 14/45 (original is 13/47) for the XV125, but feel free to do else.

XV250 ratio should be different. Check the VIRAGOTECH forum for more information.

My sprockets are:

� Front: AFAM, model 21308-14

� Rear: AFAM, model 12505-45

I also replaced the original DID chain by a better model (DID 520VM silver).

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9) Crank case vent:


I have decided to get a crank case filter in order not to mix fresh air arriving to the carburetor

with oil vapors from engine. The filter I got is a K&N filter, model 62-2470. Just remember to

close the hole in the cradle where the tube coming from the crank was leading to.

10) Ignition coils:

(Also recommended for the XV250.)

It is not easy to find power ignition coils for XV125 and XV250, and the standard ones are

pretty crap. There is however a Japanese company selling miscellaneous coils and ignition

systems for different bikes. The model fitting the Virago 125 and 250 is the 1PX2 and costs

35,700 Yens.

Here is the link to this company, called AS UOTANI:

http://www.asuotani.com/pckid.html�

Really no regrets: immediate engine start, better torque, etc

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11) Spark plug power cables:


When changing your coils, it is a good idea to change your plug cable to get a better spark. I

have opted for NGK Power Cables. Combined to the ignition coils, the result is very good.

Here is a link to the Japanese NGK page, presenting these cables (different colors and shapes).

There should also be one in your own countries or nearest ones.

If you chose the thickest ones, you will have to make them a bit thinner in order to get them

fitted in the AS UOTANI power coils, but this job is really simple.

http://www.ngk-sparkplugs.jp/products/cordcable/bike_cable/index.html�

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12) Spark plugs:


And of course, with this better ignition system, spark plugs should be replaced.

The standard XV125/250 plugs are NGK CR6HSA or Nippon Denso U20FSR-U. A good

alternative is the NGK Iridium IX, model CR6HIX or if you can get it, the DAYTONA

Maxfire, model 61485, made in collaboration with NGK.

Here is the link to the DAYTONA company:

http://daytona-mc.jp/sp/maxfire/feature/index.html

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13) Earthing:


Earthing your bike will give you a better torque and a more stable spark, etc. I did not want to

add wires around my cylinders, so I chose a solution called in Japan “condenser tuning”. It

consists of a metal tube full on condensers which you have to connect to the battery and… voila.

The most popular one is a so called “Hot Inazuma”:

You can find them in Japan on the net (auctions) and if you want to build your own one, you

can even get plans on the net.

Xv125 Modifications Anglais

Documents

180cm3 bore

air intake

tci unit

xv250 owners

top speed

parts included

air filter

air