YZ125G Build

[alexbrown64]

The G project is taking a turn.
I have decided to make two G's.  Using the older parts from one, to build the other.

The original G will be a show bike.
I have sourced a company to make me a works style alloy tank, and another member on this forum to had paint it in the factory speedblock colours.
I have hopefully sourced a guy in the states to build me an Ohlins shock
I have some 490 43mm forks being delivered which will be Titanium Nitride coated.
I have another airbox thats getting a carbon fibre look treatment.
I have a Preston Petty front fender and genuine Swedish Gunnar Gasser throttle and cable from the US.
Geoff has built me a ripper cone pipe and muffler setup.
I have a DLS dual front brake that i am reconditioning.
I am picking up an H swingarm that will have gussets welded in as per the OW125 works bike.
Rims and hubs to be powdercoated black with new spokes and gold nipples.
DC has sent some transparent side covers and a JT cable saver front plate. Sidecovers will be slotted.

I have a bunch of NOS parts such as sprockets, hardware, etc..

This frees me up to build another G that will be a rider.  I have some H 38mm forks to go on it.  A rebuilt shock, lots of plastics etc.. but need an engine, frame and some knick knacks.

Hope someone can help out with parts..

Cheers,
Alex

[alexbrown64]

DLS front brake delivered.  This will restore nicely.  These brakes were a big improvement over stock and were a great upgrade.  They are pricey these days and are well sort after..



These front forks from a 1982 YZ490 are being delivered.  They were a big upgrade back in the day as they are 43mm compared to the wimpy 36mm original flexy forks.  They will be stripped and rebuilt, as well as having a ti-ni coating added....



The Gunnar Gasser whirlpool throttle was an upgrade back in the day. Yamaha decided to make one that had the cable coming directly out of the housing.  These ones came out at 90*.  Ebay sells a lot of fake one.  These originals can be picked up from Speed and Sport in the US with various options on custom cables.



Preston Petty makes a nice front guard for vintage bikes. The white one goes well on the G...



Broc Glovers factory OW125 in 1980.  It was watercooled like the next years H version bikes.. I will be fitting an H swingarm and adding the extra swingarm brace..



I will also be getting an alloy tank custom made and painted (in white) like the tank above..

Cheers,

[alexbrown64]

Been a while since i posted on the ozvmx.com site.  There is a YZ125G Facebook page that i have been using lately for tips, idea's etc.

Anyway, things have been moving along nicely and i finally, just about, have two G's in pieces.  Still need a few final parts of the puzzle, but i know exactly what i need, cost and how/where to get them.

OK, the G's are being divided into two categories.  One is a rider, and the other is a show bike. Some parts that will be on the rider, will be on the show bike.  We are not building a race bike, but rather a stock, reliable G with a few upgrades.

The show bike will be nothing like original and will use a combination of some nice parts you could get back in the day, in conjunction with modern parts..

So lets get started with the show bike.....

I heard performance was not improved with a DG radial head.  But the cool factor is there from the day, so this bike had to have one.  Located a DG gold radial head for the G in Canada that the owner was willing to part with.



MotoTassinari makes a VForce reed block that fits the G.  Its usually for a Husky 125 but reported to fit and improve performance on the G. Pic below of the VForce reed block for the 1980 G, plus the DG head, and a some very rare parts in the form of a crank and 3R3 clutch.  The clutches on these old girls are all cheese, so pic after this shows the solution.



Robert Fish in the U.S makes billet clutch kits for the G.  Direct fit with instructions and all parts to make it work.



The suspension is taken care of via 43mm YZ465 forks that went to the UK for Ti-Ni treatment.  The rear shock is a new Ohlins unit sourced directly from Sweden by Russel Speak at Dynotime in Perth.. Pic below of tubes together with a nos stock size piston kit for the rider, and part of a full titanium bolt kit for the show bike..





A bunch of parts have been modified, sourced and trialed on the G.  I found that Pivot Pegz make a direct fit Yamaha peg for the G model bikes. No pin or spring mods.. just bolt straight on. They are a beaut Ozzie made peg. HotfootMoto makes intakes.. look great quality.. A mob in Queensland does hydro dipping and my airbox came back with a trick carbon fibre look.  Red64 makes titanium sprocket covers, DC makes chain guides, and EBC for the clutch plates going in the billet basket.



Local fabricator Trevor at TJO welded in some nice gussets on the upraded H swingarm..



And, finally for now, Brendon at BF Customs in Albany WA is in the middle of fabricating a works style alloy tank for the G.  Its coming along nicely... the tunnel, brackets and a few other bits have to be finished off...



There is a heap more to these builds, but i will leave it there for now.  Its all systems go, but will still take a long time.....
 

[YZ250H]

Always love your work Alex.  Well done mate 

Some good tips there.  That clutch basket find is a definite winner.  As you say they are made of cheddar cheese and VERY hard to find in decent condition these days.

[80-85 husky]

good to see you are still dropping in here, i find facebook full of "Ive got one of those"(we are all guilty) and its hard to find good details wheras the older forums while clunky still seem a good source of hard info. the bikes are coming along nicely!

[alexbrown64]

Thanks guys.. yep, i am guilty of "ive got one of those".. but been working hard to get some of those.  Myself and Geoff at GMC worked together to create a fantastic cone pipe for the 125G.  Fits perfect, looks fantastic and is a work of art.

Its some of the little things i like tinkering and experimenting with.  Took me a while to find some decent pegs for the G.  You can use the Stainless Steel PW50 pegs found on Ebay.  I have a set and they are super good quality and others have run them for years.  Do not buy the cheaper cast ones.. absolute junk and a death wish.  However, supporting Aussie companies is a good thing and the Pivot Pegs are a great product and fit straight on and perfect option for VMX racers with stiff and worn ankles.
I also come up with a plan to swap the 1980 steel brake arm for the 1983 alloy brake arm.  Just a bit of mild chamfering of the perch bracket and a few other small mods and it fits perfect.



Another area i have been playing around with is the shifter.  Not much out there, but for the G, the CRF50 shifter fits.  Now these come in all sorts of aftermarket brands and sizes.  BBR makes a 1" longer shifter that fits and is perfect with the bigger pegs.  Gives you a bit more room to get the big gumboots around. They also look great in the titanium colour and have a flexible tip. 



Before i tackle these projects in earnest, the workshop needed a serious refurb.  Not finished yet, but getting there.  Each station i can sand blast, weld buff, sand, paint, rebuild, etc..



On a side note.. i found a few more pics of me at 16 on the G.  It was basically Wide Open Throttle until either i broke or the bike wore out ha ha....





Cheers,

[Viper666]

The build/s look great, well done.

Question you on one thing though

They were a big upgrade back in the day as they are 43mm compared to the wimpy 36mm original flexy forks.

Both my YZ125G's have 38mm forks & they all look original?

So I looked up the seals & it seems you are right & I am losing my mind. 36mm

So now I'm going down the shed to check, again

[tony27]

Are the 2 brake arms the same length? I assume you mean the torque arm that attaches the brakeplate to the frame
On my 465 I fitted a later model alloy arm which had to be shortened, I cut the bearing end off & made a new 1 that took a standard GE12 bearing that was 0.5mm smaller on the outside than the special platinum plated gold bearing Yamaha fitted, means if the new owner ever needs to replace the bearing he can buy it at any bearing retailer
Looking forward to seeing how the bikes progress

[alexbrown64]

Tony, the H swingarm i am using was supposed to be an upgrade over the G.  It is 1" longer.  I got the torque arm with the swingarm so i could measure it.  After some research, i bought a 1984 CR125 torque arm.  Fits perfectly and is the same length as the H arm but looks much better in slotted alloy.
I also got Jimmy Button bend Renthal titanium colour bars.  These have a slight vintage rise and bend, but not the crazy big bars from back then.

Neale, the G came with 36mm forks, but an upgrade these days is to put the 125H 38mm forks on.  I have a set of H forks to put on the rider bike, as i think that is the best size/weight combo.  The show bike gets the 43mm Ti-Ni  forks.



Cheers,

[tony27]

Jimmy Button bars seem to be a popular bend on vintage bikes, ran them on my 465 & still have them on my CZ
Are the bearings for the Honda torque arm still available? Yamaha were really good at using special bearings, normally 0.5mm larger on external diameter

[alexbrown64]

The alloy works style tank for the G is finally finished.  Thanks to Brendon at BF Customs in WA for taking on the task.  I think he forgot how long it takes to build up a tank from scratch. Final product is amazing and will look great on the show bike..







Cheers,