Seems like this question is slowly becoming more popular, usually online shops stock what you need, or big wholesalers like CMPO and eBay. However some things are just not readily available from these sources, such as valve heads, some particular engine big bore kits, EFI conversions and so on…
With China, the best place to source seems to be TaoBao, the Chinese equivalent of eBay. The problem is, communication, then many sellers won’t sell beyond china, due to not being able to sort out the delivery nor the tax at their end, this does create a problem. The good news is, you get companies that are agents and you tell them the item and they order it on your behalf, they take a very small merchant fee and money for the item. Order it to themselves, sort out shipping to you and invoice you for the final shipping costs. I use TaoBaoNow as my agents, they have been brilliant, if I asked for extra packaging they did, they even showed me pictures to double check everything in my EFI conversion kit was present, plus it still works out cheaper for many items to be obtained through China than many online stores and they do have a bigger variety.
The last problem with TaoBao is, sometimes its difficult to find what you are looking for, and translating tools don’t seem to word things correctly, so here’s a small list to some of the parts I have ordered to help you see what you are searching for and how things are phrased. Some sellers will also offer small extras in the description for a few Yuan more, ie better piston rings, ceramic coated piston etc.. So bare that in mind.
These parts may or may not be any longer available and are merely a reference, but you can try. My future upgrades yet to come are a 200/250 valve head and the EFI conversion followed by a new downpipe.
I thought since upgrades are now happening more and more and I keep getting more and more emails regarding melted pistons, I decided maybe its time to keep things a little more safe and try and provide the engine with some more additional cooling and try and increase the oils lifespan.
Started looking at kits all over the place, the cheapest option was continuously heatsink type coolers, the same you would find on a circuit board or resistor, which is merely air cooled. I wanted something more, a real fin system. So off to eBay it was. Started looking around and managed to find a tiny fin cooler around 80mm by 120mm. This was a small kit designed for mini-moto bikes with a 50cc capacity, but it was more than adequate for the job.
From rebuilding parts of the engine and looking at countless manuals, I notices the system does a small compressor that pumps the oil, this merely produces enough pressure of around 4~6psi, nothing great as even the CB (OHC) engines still seem to heavily rely on splash lubrication more than anything it seems from having various parts if the engine apart and running.
The trouble with the cooler is where do you put it, placing it too high on the frame means the pump has to work hard and no guarantee the oil will reach that high so the lowest point is advised, also long runs mean once it starts pumping oil it will deprive the sump of oil as well which is not something you really want to do.
Basically the stock system runs the oil through a paper filter or a strainer and just after that is a small return hole, with the engine off, I cleaned up the return hole and filled the return in, then I bought two banjo bolts, one which goes on the cap that holds the strainer/paper filter. This becomes the oil supply to the cooler.
Looking at the system closely the return after the filter is merely back to the sump, so with the oil drain plug off I had a feel and basically drilled into the cast aluminium sump, roughly between the filter and sump bolt, again threaded things and put the second banjo bolt in as the return from the oil cooler to the sump. Basically all you are doing is mimicking the stock system but blocking the original system so all oil is forced to the cooler. Word of warning be careful where you drill in the sump, I turned the engine over and felt around with a screwdriver and some bent wire before I took to drilling and again don’t drill between sections of the vertical sump, as the engine is typically at the bottom end sandwiched together vertically than horizontally.
Once the feeds are done, I bolted the cooler to the lowest engine mounting frame, added more oil to the system around 500~800ml more (trial and error sadly), linked the pipes up and ran the engine. The cooler works superbly and you can just feel oil pumping through on idle, so its doing its job and since bikes never sit in traffic, a fan is not required. I was lazy in terms of lack of photos but here is a rough result.
The brilliant thing is small coolers are easy to source and not expensive at all, piping and banjo bolts come in a variety of sizes to accommodate the cooler you manage to source easily, just remember keep things short and low. In the end I had to bent the radiator on its bracket by 90 degrees to accommodate the downpipe as I forgot to account for it.
Thought I’d do another cosmetic mod, nothing too special, just fairing mirrors, the stock ones are a pain too fix into place and sometimes flop back on you at speed, I’ve torn them off twice having fun. On the second time round they have finally revised them to have a locking nut on the stud, making it much more secure and easier to fix into a position you like. But i hated the fact when you turn the bars, it would turn the mirrors some what of a slight inconvenience, so I opted for a fairing mounted ones, best place to get these are ebay once again, however what I found is most sellers refer them to as “universal mirrors” opposed to fairing mirrors. Plenty of different styles out there.
They are pretty easy to fix on, just a case of drilling a hole or two, and mounting them on with the brackets and bolts supplied, don’t think a tutorial is really needed for this, but here’s the end result… It does look like an elf or yoda though!
Continuing on from the initial install, you should have the piston in the barrel awaiting to go back on and hopefully you’ve either opted to bore out the stock rod or create a spacers for the stock wrist pin to accommodate the new piston.
Now this is done I mentioned the CB150 kit has the issue of valve clearances, this is another one of them problems you can tackle in two ways:
1) Gasket stacking, you require 3 head gaskets stacked which are easily obtainable of ebay for a CB150, this will give you the clearance you require or 2) Make a custom bottom end gasket and use a single or two head gaskets depending on the thickness of the bottom gasket. Not an easy route at all to take!
I personally hate the idea of stacking more than two gaskets, but it does work as effectively. I decided to opt for a custom built bottom end gasket and stack one or two head gaskets to clear the valves, the material I opted for is copper, its a brilliant material for making gaskets and is very durable, its actually now making a return in the automotive industry fast due to how reliable copper gaskets are. My flaw was I anticipated about 3mm of thickness was required, but 3mm copper was beyond cheap in comparison to 2mm, so I ended up buying a small sheet of 2mm copper and fabricated a gasket.
What I did was use the bottom gasket that came with the kit, placed it on the piece of copper, sprayed over and created a template, next was to cut the template and place it on the engine.
You can also see my rod bored out to accommodate the bigger wrist pin. Now its a case as any Haynes manual would put it, refitting it the reverse of removal. Slide the barrely back onto the stud bolts, leave it lifted up to you can carefully place it onto the rod and insert the wrist pin and clips in, once that is secured, tape the barrel down so it sits at the bottom and on the remainder of the engine like so.
Now its a case of putting the runner in and gasket, sadly 2mm of copper wasn’t enough so I still had to stack two head gaskets together. This in itself caused another issue altogether, with all the added height the stock cam/timing chain becomes to short, it can be forced on and I did attempt it only for the chain to snap after a WOT test. What needs to be done is two extra links to be added in to lengthen the chain.
This continuous onslaught requires further modification, as you can only lengthen the cam chain in multiple links of two, two becomes a tad to much and the stock tensioner isn’t sufficient, so this has to be lengthened, I was admittedly lazy for this, I could of welded a bolt of a plate onto the tensioner to lengthen it so it applies more tension to get rid of the slack, but instead I just used metal putty.
This now allowed the chain to be tensioned accordingly to the new requirement, the only issue from this… Yeah, yeah, I know each step so far has required another modification just to set things right! Anyway, back to the topic, because the chain is longer and the tension is greater setting timing becomes slightly more difficult from my earlier post. As when you apply the tensioner in, it pushes the crank and cam lightly out of alignment, so you need to mark things up and try moving the chain a tooth or two off mark, so when the tensioner engages it will align things perfectly, otherwise timing will be completely off!
With all this done and the engine re-assembled in reverse order you can now finally rest, enjoy a beer, or simply… cry.
But while all this was going on and if you fancied doing some porting, you can, I ported my inlet a tad like any bored man with a dremmel, what I did discover was there was nothing to work with on the exhaust port, just only the inlet.
Now the verdict, the engine did start up straight away once I placed it back in the bike, the valves were off, but that’s for me to do another day, the big bore adds additional torque and nothing more, so for all this effort, was it worth it? Well I’d say not really, but you may well disagree. I did help someone else do this install and gave him two extra links of a new cam/timing chain to finish his build as he encountered identical issues along the way regarding the valves, his verdict was yep it pulls more, definitely has more torque and that’s it! However the cams opened things up a tad for me further which is definitely a worthwhile mod for me, as its merely a swap job, non off this modifying to the gaskets, rod, lengthening the chain, modifying tensioner… So should you ever end up with a melted piston and you are doing a rebuild I’d say don’t worry about the big bore kit, its seriously a headache, but definitely swap the cams for more lift!
From dealing with the engine, I managed to get into a few issues where I was forced to reset timing, but to find any information regarding the timing was proving to be beyond difficult. Seems like it’s some sort of deep secret, for whatever strange reason it may well be. The timing requires for the engine to be on or off the bike depending on the intent and oil to be drained so you can turn the crank over with a 14mm socket in anticlockwise direction and the inspection cap off to the crank and cams.
Its not exactly the most labelled up engine in the world, the cams are under a preload so they will typically be shut just before either the inlet or exhaust valve is about to open, grab a pair of grips and try and turn either the crank or the cams (cams only if chain is off) and see where it is on the cycle. If anything turn it over till its just about to open the inlet valves, this is the start of the 4-stroke cycle. The cam sprocket has two lines, these two lines must be pointing to 3 & 6 o’clock and with the crank turned over you will find two markings, you are interested in the line with the letter F to line up with the notch in the inspection hole. Now with the cam at 3 & 6 o’clock and the crank at F, you have officially setup the engine at TDC. Turn it over again by hand to make sure you’ve not offset by 180 degrees, what you will find is just as you turn over from F the inlet should open, in which case you have set things correctly.
Not the greatest pictures in the world but they give you the idea of how things should be and make sure to look out for the F, as I have no idea why TDC is labelled F or what F stands for, frogs??? Who knows. Hope this helps you should you ever need it.
My speedo failed not far from my house and all it was, was the return spring (the spring coil that pulls the needle back) had broken off the crimp. So this was a golden opportunity to look for something else in MPH rather than KMH.
I opted to what seemed like the closest bike in terms of the gauges, this being a CBR125 04-08 variation and ordered some gauges, but not a complete cluster for reasons I will explain. The CBR is water cooled and I imagine much more sophisticated, as well as having a temperature gauge which doesn’t exist on the XTR-S, which means different wiring and plugs, plus single units are cheaper. I took the tacho off and decided to replace all bulbs with 3D LED bulbs in a T10 size, its an easy procedure, but it will require testing, as the LED may be sitting back to front then it will not light, all you have to do is pop it out and rotate it 180 degrees.
Then it was time to replace the speedo, a Honda CBR 04-08 is a direct swap, and the new trip meter is also in MPH unlike the stock one. In the UK, you don’t have to declare the new mileage from a tacho change, but if you do sell the bike you must legally tell the new owner you changed the gauges before the sale. But I do advise you do check the law for your country and region as it maybe different.
I also decided to tear off all the sealant around the unit when the cover is off, due to it being worn, I replaced it with draft excluder tape you would typically use on doors and window and it has been doing the job fine. The next part was the rev gauge as the whole tacho now looks a bit out of place, the CBR125 04-08 is a very similar unit, but completely different and will not work as a direct swap, so i merely took the foil and needle off and transferred it with the following end result.
A much neater unit and a lot better for the UK roads or in any country with MPH being present as a main speed. The Honda CBR125 04-08 MPH gauge new was only £25, whilst the rev counter was £12 second hand as it was merely for the foil, overall a £37 cost to repair and neaten the unit, which is cheaper than a new cluster for the Lexmoto or a complete CBR125 cluster.
Since everything is here in theory and the barrel is sprayed its all go!
Removing the engine is a fairly straight procedure especially when the engine of a single cylinder isn’t to heavy and can be lifted by yourself with some effort. You start by:
Removing fuel tank
Remove carb
Remove side panels
Drain oil
Unlink the clutch, chain and gear lever
This should leave you with the engine exposed, now its a case of getting some spanners ready, 10mm, 12mm, 13mm, 14mm and 16mm. The smaller bolts are at the front end and easily undone. However at the back of the engine sit two colossal bolts and nuts at 14mm and 16mm, even with a big torque wrench I struggled to no end and ended up sheering one nut. In the end I had to borrow my neighbours van and take it to my friends garage to borrow his pneumatic gun to undo the bolts with an aid of the smaller socket and some heat for the sheered one. It seems the Chinese have only two torque settings unlike the torque settings listed in an earlier post. Which are tight and very tight!
Once bolts are undone, gently push them out and support the engine, the engine will then come out. Take it to your allocated area of work.
For the big bore kit you want to have the official marking tool to mark things up, or as mechanics call it “tipex”, I know many mechanics that use this for marking up timings, in and on and engine without any problems, and I use it as well. Now what you want to do is remove cam cover at the top of the engine along with the two inspection caps at the bottom end (they look like they can easily be undone with a coin rather than a screw driver). Turn the engine over with a 14mm socket anticlockwise and mark things up to anything and everything timing wise.
Once done, you have 4 head bolts at the top (12mm from memory) followed by another bolt just below the cam sprocket with a phillips head (10mm), undo them. The next step is removing the starter motor and undo the tensioner with allen keys (the starter motor gets in the way). The next step involves you holding the bottom end with a spanner (where you turn the engine over) and undoing the two bolts of the timing sprocket off the cams. Once undone take the sprocket out slowly and gently and slip the chain off and keep it tensioned, the last thing you want to do is drop the chain and unset the timings completely! Heed this warning! – However should you loose timings I will explain in the second part to this install!
Now you can take the valve head off and the barrel off slowly whilst keeping the chain tensioned! Once off, support the chain as not to loose timing, you will end up with something like this.
Undo the two clips around the piston and push the wrist pin out, the piston will then just come off, now this is where problems start with the CB150 kits.
My CB150 kit came with everything required, the ceramic coated piston, barrel etc… but there’s some issues, the wrist pin on the CB150 kit (156cc) is bigger, you have two options:
Use the stock pin and make spacers (very good idea) OR
Bore the stock rod to around 15mm at the top end
The only problem with the second option is if it’s a good idea to begin with, as I’m not sure if boring out will make the rod to weak and no longer durable long term, but I’m going to guinea pig it and give people feedback providing its successful or not. Boring out the rod is extremely slow and requires some tools, I used a drill press and a 15mm blacksmith drill bit, not cheap and boring (-literally boring as in boredom) as it takes a lot of time with continuous oil lubrication to aid cutting and cooling.
Once done you can use a piston compressor and lightly tap in the new piston into the bigger barrel for assembly, whilst the valve head is off you can easily adjust clearances as well. But this is merely the start of the install as there’s another issue which I will discuss in part 2. The issue being the new piston sits considerably higher around nearly 3mm, meaning it will and does hit the valves, but this will be discussed in part 2!
On top of this………. I decided I wanted to also throw in a 163FML camshaft which has 1mm more lift, however getting the cams out is a very difficult task. The top of the engine isn’t very user friendly, no rocker cover. So instead the camshafts are hydraulically pressed in, which causes many issues as you can’t get anything in like a hub puller in, due to the lack of room, alternatively wedging a screw driver does not exert enough force for it to come out either. Sadly I do not know anyone with a reversed hydraulic press nor have I ever seen one, as usually presses are used on wheel bearings, press old one out one side, followed by pressing a new one in.
So what do you do??? Well my honest answer is, no idea? However my friend decided to come out with a daft, yet brilliant idea that did work for your entertainment, I do strongly advise against it though, but enjoy.
Started to spray the barrel in preparation for the rebuild, not exactly amazing progress, but at least you know I’m on my way. I’ve also stocked up on oil resistant tubing (6mm) and M8 banjo bolts (6mm) for the oil cooler. There’s also plans to fix a 12v socket later on for a satnav so I can finally start doing some mileage.
The other good news is I have started playing with the clocks and will be doing a write up on them as the odometer gauge is a direct replica of the original CBR125 04-08 unit. Whereas the rev counter side is slightly different and not interchangeable but the foils are! Its handy for the UK market as people are tired of seeing KMH and squinting to see the MPH readings. Anyway here’s the barrel in progress.
Finally it looks like the 156cc barrel arrived with a ceramic coated piston, managed to source a 1mm extra lift cam off the 163FML engine and the oil cooler I got from the USA.
Next step will be firstly to repaint the barrel, it however won’t be going on straight away as I’m extremely busy at the moment, but when I do get round I’m hoping my research paid off and it all fits. I’m also finishing another project off at the moment, I built a small bit of decking and a shed in my garden as a workshop a while back, I have finally got round to starting to finally wire up electrics to it with heating so I can work away in the dark and cold once it comes around, here’s the shed I have built whilst going somewhat off topic. Planning to fit a small mill and a 3-axis CAM down the line, work never ends sadly.
My XTR-S Project 