Yamaha XTZ125, good news

[Symon260z]

Modrod,

I decided not to fit this oil cooler kit as I thought that the oil pipes could easily get caught up in branches or rocks when off road, I use Motul 7100 and so far I have had no indication of overheated oil.

BTW I have done a few mods to my XTZ, the main ones are :-

BBR 150cc kit with performance Camshaft
Protork Exhaust
Mikuni TM24
Programable Ingtech CDI, set up by yours trully
YZ250 46 mm forks, YZ 250 front wheel and brakes.
TTR125 Aluminum swing arm, shocker and pro link

I am running Kenda 778 tyres front and rear.

It has turned into a really nice bike, of course it is short on power but next summer I am planning to do a 194cc, 4 valve conversion using aftermarket parts for a Yamaha Zuma. That should get wake up the old girl.

[modron]

BTW, does this small "Yamaha" engine has some other filter element than this steel mash in the... oil pan, some oil spinner or something similar?

Theres nothing really.
On Taobao there are kits to mount oil cooler like the one above and external oil filter connected to one of the hoses that goes to the radiator. Would have to figure out where to put that filter cos i recon it would rattle a lot hahah

Symon, PM on its way

[Symon260z]

Actually I don't see a great problem about not having a removable oil filter, just change the oil often.

[Zorge]

...It has turned into a really nice bike, of course it is short on power but next summer I am planning to do a 194cc, 4 valve conversion using aftermarket parts for a Yamaha Zuma....

Oh man, it would be interesting thing to see, not just the final result, but even whole process. Symon, don't hesitate to share with the folks here how you managed to made this conversion.

About oil filtering element: I would be expected to see at least oil spinner because it is cheap to implement this thing. Even older engine designs than this "Yamaha's", such are "Honda's" horizontals, CBs and CGs have oil spinners who really picks up fine dirt that freely passes through the steel mash in front of the oil pump.

[Symon260z]

Zorge.

Actually there is not that much to tell about the conversion, it is all quite straightforward.
I did all the engine stuff at the same time. The BBR 150cc kit and cam is an off the shelf item sold for the Yamaha TTR125, same engine as the XTZ. So just dismantle and refit with no dramas. The Protork exhaust system can from Brazil, a neighbour of mine exports Chinese bikes to Brazil and he knows the owner of Protork, so I got a on off, looks like standard, exhaust system which is considerably better than stock. There were a couple of issues fitting ( maybe the Brazilian XTZs are a bit different to the Chinese ones ) anyway nothing that a bit of cutting, welding and repainting couldn’t solve. I also was able to swop the original carb that was useless at making power with a Mikuni TM24. It bolted right up except I needed a new throttle cable ( from a TTR125 ) and a sneaky mod to make the front of the carb slightly larger in diameter to fit like a glove in the inlet manifold. I bought a few different jets and after a bit of trial and error I have got it dialled in nicely.
Then came the cheapest engine mod, lighten the flywheel. The original is just so heavy. Not sure how much it weighs now but the motor revs up a lot easier.
I thought the Yamaha CDI was holding back the bike, so a programmable CDi and a bit more of trial and error made a big difference.
Must be ok as the original motor struggled up to 80 kph and now it flies straight up to the rev limit which gives about 105 kph. It could easily be geared for more speed but I prefer to have a bit more acceleration off road.
Probably the worst thing about the XTZ when I bought was the original suspension and tyres. Tyres are an easy fix, I started with Kenda K270 and now I am using Kenda K778s. Both of which I highly recommend and have the advantage of being so cheap on Taobao. A really good mate of mine that travels regularly to Australia sourced a complete front end from a 2003 YZ250. It was in near pristine condition, I learned how to rebuild the forks from a Youtube video and fitted new bushes and seals. To get the YZ triple tree on to the XTZ was not as straight forward, I had to get the centre shaft machined to the same size as the XTZ so that I could reuse the XTZ bearings. I made a mess of the fork oils, firstly I used an oil that was far too thick and I didn´t read the workshop manual about setting the oil height. Anyway that got fixed with some Torco RSF Light oils and a bit more reading, but the front was still too stiff. A pair of 0.37 Eibach springs sported that out, the front end is now excellent. I used the YZ250 from wheel which is about half the weight of the XTZ one and of course the YZ brakes with some EBC pads. At the same time I fitted a set of EBC rear shoes from a TTR125 and the rear now stops well.
I sourced from Ebay a brand new rear swingarm, shocker and pro link of a TTR125 which apart from being a lot lighter that the original soaks up the bumps as well as the front. Of course it wasn’t a straight fit, I had to make and weld some brackets for the prolink to mount to the frame and as the TTR125 uses a 16” rear wheel I had to get the swingarm extended by about 2,5 cm
For the winter I will be using the XTZ as is, it is now a fun off road bike with enough power to actually climb hills and to get out of its own way. The suspension and brakes are really nice.
It seems that there is always something else to be done with this bike, I am ok with that as I enjoy getting my hands dirty and working stuff out. At the moment I need to source a Speedo drive and cable from a Yamaha WR450 to get the original speedo working again and I really should take her down to a rolling road to see if my trial and error set up is ok.
Over the summer ( when it is too hot to ride down here ) I will probably do the Yamaha Zuma cylinder and head conversion. It basically all bolts up except for a couple of hacks. I nice build to do on the kitchen table when the misses is away. I’ll need a bigger card, maybe a Mikuni TM 28 or 30 and then a bit of trial and error to get it running right. Like that it would be a pretty decent fun off road bike.

[Zorge]

Actually there is not that much to tell about the conversion, it is all quite straightforward.

Gosh, as I'm getting older, those bolt-on conversions and tool-shed-level mods, start to look so good.

Over the summer ( when it is too hot to ride down here ) I will probably do the Yamaha Zuma cylinder and head conversion. It basically all bolts up except for a couple of hacks.

That is the point! As people use to say - the devil is in the detail!

I hope that you will treat us with some report about those hacks.

[Symon260z]

Zorge,

Nowadays these conversions are quite easy as there is so much information available on the internet, i t's just a case of sifting through. This is my favourite thread http://planetminis.com/forums/bigger...ike-build.html

I am lucky that most of the XTZ is the same as a TTR125 and that there are so many aftermarket products available, E bay is a great source.

The biggest problem i have found is when you have to get others here in China to do something for me, just this morning I went down to the local machine shop to get a simple spacer made up. We spent more than 30 minutes trying to explain to them what I wanted only for the guy to say come back tomorrow. I told him it will take 10 minutes and that he should let me use the lathe. In the end I just told the machinist what to do and 10 minutes and 40 rmb later I had my spacers. I must give thanks for my every patient wife for helping me out.

I have been surprises by the amount of products that I have bought that don't fit, the last one was a BBR Cradle / Sumpguard, I had to cut and then get it rewelded. Wasted a whole morning ! And then some products have been 5 minute fits and work so much better than I expected, one of those was an AMS high out put coil.

I used to tinker around with cars when i was back in Europe, I only realised how much I missed it when I started to do stuff on my XTZ.

[Zorge]

Ha-ha-ha...! This your "spacers case" reminded me how much time took my attempt to make some... thingy which would help me to fit carb with flange type connector on a intake manifold intended for a carb with clamp type connector. Took me two weeks to organize foray on a machine shop guy, and after that, another week to find welder at home. Few more of my "projects", and I will be tempted to buy some Chinese lil' desktop lathe and mill.

Nevertheless, don't be shy to tell us how you fitted 4V head on your bike.

[Symon260z]

Zorge,

Sure, I'll let you all know how the 4V / Zuma engine conversion goes, I plan to start ordering parts after the CNY. I presume that I will have everything by the summer when I don't really want to ride my bike as it is far too hot for anything more serious than riding down to the beach for a late evening swim.

For the next 3 - 4 I just want to ride and enjoy after spending too much time fiddling with the XTZ, I do plan to get a lot of riding done during the CNY. How about a road trip to the other end of Guangdong ( to my wife's howm town ) and while the rest of the mob are playing Mahzhong or eating something that looks like it came from Kronos I'll get out and explore some of the small country roads and tracks I have seen on previous trips to the area.

[Zorge]

Symon, while we are waiting for this 4V conversion, if it isn't to much trouble for you, can you share with us some of your thoughts and impressions about this programmable CDI you bought?