BD125-8 ZS190 swap and EFI conversion
 

Just another 190 swap into a Vader/Baodiao grom copy, except this time I will hopefully have it converted to EFI as well.

I already have the 190 engine, new exhaust, and a Microsquirt ECU. I am still waiting for EFI-supporting hardware such as throttle body, fuel pump, injector, etc from here (kit 4), as well as a wideband o2 sensor and controller from amazon.

The parts from the Chinese seller also included another ECU, but this one is supposedly not compatible with the software that is used to tune the microsquirt, and will only work with the software that the seller gives you with the parts. Also, it states on the Chinese seller's product description, that wideband 02 sensors are not supported, however the option to use either a narrowband or a wideband is still selectable in the software.

If it turns out that the software truly doesn't support wideband, I'll just skip right over using the Chinese ECU and software and use the genuine microsquirt and tunerstudio. I'm sure I could eventually get a decent tune on an engine with just a narrowband sensor for ECU feedback, I've seen a few videos of people with this same kit or one very like it get an engine running and rideable; but this is my very first foray into EFI conversion and tuning, so I want the experience to be as good (easy) as I can make it so I won't have a sour taste left in my mouth from a bad first experience with tuning.

I already have 90% of the bike taken apart and will probably drop the engine sometime between tomorrow and Wednesday. Trying to drop an engine, even one this small, without an platform jack is... painful. I'll probably end up using a combination of trolley jacks, jack stands, and rope to drop the 125 and lift the 190.

Unless something unexpected happens, I probably won't document the engine swap part too heavily as it's quite straight-forward; take stuff off of your bike until you can remove the engine, disconnect anything that is connected between the engine and the frame or wiring harness, remove front sprocket, remove the right rear set to get access to a bolt, remove engine mount bolts (that's where I am right now), drop (hopefully not literally) the engine, new engine install is reverse of removal. I think there is one or two wires that I have to move/swap, if you were going to stay carbureted, you'd be 95% done.

I'm not good at wrapping up ideas, thoughts, and posts.

I'm going to be doing this swap as well except I will be staying with a carb setup. There is a member on here that went EFI with the zs190 but he hasn't been active for over a yr. I don't know anything about the efi but keep me informed with how the swap went. I won't be doing anything until it warms up some in a couple months.

With some juggling of engine support bolts, trolley jacks, and a hammer I managed to get the 125 engine out. Looking at the 125 and the 190 side-by-side I'd guess the 190 is... about 20% bigger externally; the longer stroke, 6-plate clutch, 5th gear, and overall increased beefiness are probably the reasons why.

I drilled out the 190 mounts and the mounting tabs on the bike to 3/8 in. If I, or anyone else wanted to, they might be able to drill out the mounts even larger if it turns out that this engine shears bolts as well. Although if you look at the location of the crankcase breather nipple and the angle it goes into the case, it seems to be very close to the top mounting hole.

I'm hearing a creak from around the swing arm pivot when moving the bike, so I figure this is the best time to check that out and make sure nothing is broken or about to break around there.

I tested the microsquirt as much as you can with only power and a serial connection - some readings fluctuated a bit since their input pins were left floating, everything I looked at and tested seemed to work.

I got an update from the seller on aliexpress - the order has now shipped and should be at my door in 5-8 days with a refund in it doesn't show up in 21 days. When it arrives I get the arduous task of wiring the 190 into the 125's wiring harness and combining the harnesses from the microsquirt and the aliexpress seller.
I think I'm going to keep all of the EFI-related wiring in its own separate loom and harness - if for some reason the EFI doesn't work out It'll be much easier to just disconnect the EFI harness and remove it than taking apart the entire wiring harness to take out just the EFI-related wires.

The exhaust I bought does seem to fit the 190, but it is very close to the starter motor, and I'm worried about all the heat that will be going into it. Exhaust wrapping may be in my future.

Apologies for the lack of pictures and video; a build thread without pictures is quite lackluster, but I am doing all of this in my bedroom and I'm afraid if I take a picture, I'll have a prescription bottle or a butt plug in the background. Not to mention I don't have a very high standard for household cleanliness.

" I am doing all of this in my bedroom"
So how is your wife enjoying that?

I just might have to make room in my house for this project but it certainly won't be in the bedroom.

You mean my right hand? She's having a blast finally getting to hold on to tools bigger than a golf pencil. In all seriousness, no wife, no GF, no significant other (unless you count cats); I'm just working from home while living with a family member. I'm too conditioned to the single life at this point that unless something INCREDIBLE happens, I'll be single for the foreseeable future.

Honestly, there isn't much in my room in the way of furniture, there's just lots of crap in lots of piles on the furniture and in shelves. Screw it, here's a crappy distorted panorama from the perspective of my computer chair. Go ahead, blast me for being messy.

Another small update on the aliexpress order - it should arrive Wednesday.

Lol, that looks great compared to the current state of my craft room ,and dont even get me started on my mechanicing space simply known as "the shed" .

Right there with ya. I wish I had that much room to work on the bike in the house.

Had to buy a longer 3/8 drill bit to really get the mounting holes on the 190 bored out properly; new hardware was slightly larger. You really want the bolts to easily slide through the mounting points on the frame and on the engine, when you're lifting a heavy engine into place, all of the weight and any slight misalignment will make pushing the bolt through incredibly difficult.


Last night I was doing some probing with a multimeter on the 190 engine and made a discovery - the trigger coil for the CDI (not the spark plug coil) has one lead grounded to the engine case. That just won't work when I switch to EFI, everything else that is returning power through the engine ground (sensors, pumps, heaters, relays, switches) will add interference to the trigger signal.


I took off the stator cover to get a good look at the trigger coil and the stator itself.


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Oh look a token gesture of lubrication!
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There is only one ground wire coming out of the engine, but there are two green wires going into the wire covering. Me thinks the wires are soldered together somewhere inside the black wire covering.


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As I thought! Now, If I (or anyone else) wanted to run a carb and a CDI instead of going EFI, I wouldn't need to do this. The stock CDI (at least on my 125 that just came out of the bike) can still get a good signal with the ground going through the engine. I am going for EFI, so I am going to unsolder the green wire coming from the stator at the point that it is soldered to the green wire coming from the trigger coil, leaving the green wire from the trigger coil connected to the green wire going through the black wire covering. I still wanted to have a wire coming out of the engine connected to the green wire coming from the stator, so I got a spare piece of wire,soldered it to the green stator wire and ran the wire through the black wire covering. Now, there is no continuity between the engine case and either lead coming from the trigger coil.

The 190 stator is sized and wired very similar to a 139qmb engine. This is a good thing... kinda. I have a 50ish cc scooter that I have installed a trail tech regulator/rectifier on. I had to modify the wiring on the stator only a little bit (I think I moved one wire from one solder point to another and disconnect another) to get it to work and now the scooter has a great charging and lighting system.

The 190 stator being sized similar to a 50cc one is slightly worrying. I'm honestly wondering if I'll have enough juice to run a fuel pump, (maybe) o2 sensor heater, a headlight/taillight, and charge the battery.

I put the stator back into the engine and everything still fits as it should with an extra wire.

Since I still don't have an engine in the bike, I took this chance to clean and lube the steering head bearings since it will be easier to get and keep the bike supported without the majority of the weight it usually has.


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I don't know enough about grease to know what kind of grease was on the bearings or if it was bad, worse, or abysmal. At least the ball bearings were caged. I cleaned the bearings and races and re-packed them with some waterproof marine grease.

I noticed a little bit of rust pitting on one of the struts.


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Uh Oh. Hopefully this won't get too much worse too fast, but this is from china...

I might leave the fork tubes out for a few days - depends if I can find a local B&M that sells shock oil. I want to try that "$15 fork mod", however, I have heard that our bikes (the Chinese ones, as opposed to the grom) are missing something or something is different inside the tubes that prevents us from doing said mod. I at least want to replace the oil that is in the tubes now.

That's all for tonight.

That token gesture of lubrication was about as much grease as Dan's Hawk had on his steering bearings.

After a few blood sacrifices, bruises, and many cramps, I got the 190 into the bike frame. The top mounting tabs on the frame and the mounting... tube on the engine fit perfectly, however...


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The rear mounting points didn't line up perfectly - the welds on one side on the frame were hitting the mounting points on the engine, so I ground that down as well as right in the middle of the rear mounting points on the engine, right where the two case halves meet (not shown in pics). The frame and the engine still didn't line up quite perfectly, but enough that a hammer would persuade it into place.

I didn't want to go out to the hardware store today - old man winter dropped a slushy mess 'round my parts over midnight, so I used washers instead of buying a spacer. I used this same method when I replaced the engine bolts on the 125 and both bolts stayed right in place.


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One minor mod that is mandatory when swapping in a 190 is grinding, bending, or otherwise removing the rear brake return spring and mounting tab on the rear brake pedal arm. I just bent the top part of it off with pliers, but I still need to grind off a little bit more.


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The clutch cable is a bit close to the engine mounting bolt, but I think it'll be fine.

The stock intake manifold for the 190 looks as if it was designed to have an injector in it. If you drill a hole in the center of the larger semi-circle, it will be pointed exactly at the intake valve and the smaller semi-circle on the flat could be drilled and tapped for a bolt to hold the injector in place.


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I'm not sure if I'll try putting the injector directly in the intake manifold, I sincerely doubt I could drill perfectly perpendicular to a small flat spot like that. There is (at least) one metal-working shop in town that I could ask to drill a hole as-perpendicular-as-possible, but they mainly do welding and sheet metal work. I may ask them to weld in the o2 sensor bung instead of going to a muffler shop, it just seems like I would get a better quality weld going to a sheet metal specialist.


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The stock mounting location for the spark coil isn't going to work, nor is the piece of metal it is bolted to. The 190 came with another spark coil with a different mounting scheme so I'm not too worried about that. I probably won't even use either of the spark coils that I have now in favor of a logic coil also called a smart coil. All I have to do with one of those is send it a logic-level high to start charging the coil and a logic-low signal to release the spark.

The weather delayed the aliexpress package until tomorrow.

I have a question for those who are reading this thread - what method of posting pictures do you prefer? IMG tags like I have been doing? attachments? text links? It seems like using IMG tags with large pics makes it difficult to read my posts.

I wonder if this will work with this engine?
https://www.steadygarage.com/store/c...sr-razkull-125

Thanks for asking. When you say IMG tags, are they from another site that is hosting them? If so, I'd recommend uploading directly to the forum from your device.

I'm uploading and hosting my pics on tinypic. If I upload the pics directly to the forum (I'm assuming you mean attachments to a post), won't that cost you a lot of bandwidth to serve them?

Uploading to the forum is encouraged by the Admin. Here's how we do it: http://www.chinariders.net/showthread.php?t=14422