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Discussion Starter #22
Ok guys sorry its once again taken so long for any updates but I have just about got everything moved into my new garage and have started back on this project again....but I can already tell every step forward is going to be 2 steps back. Last night I removed the stroker engine and was able to get a couple pics of the 125 engine next to the ninja 300 engine. From the pics it does not appear that much bigger, however once placed under the bike you can see just how much work and modifications to the frame this will require. Also don't forget I still need to stuff a radiator up front as well as some sort of air intake in the op rear of the engine. I was hoping to use the stock airbox from the ninja but I don't think this will be possible at all. I will be lucky just to fit some filters in there, and hope it does not affect low end torque too much.

My next step from here will be to remove all the wiring and tank and start fabricating and welding up a jig to this table to hold the front stem and the rear of the frame in place. This will allow me to start cutting away at the upper tube and re-design one around the new engine. The Ninja frame was very weak on top because it used the engine itself to triangulate the frame for strength. The Z does not have any engine mounts on the head so the upper tube in the frame had to hold everything rigid. Another thing you can see from the pic is the 300 engine is tilted more upright than the z engine was. I have a line on the side of the engine case that should be level once installed.
 

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You should have went with a KTM 300 two stroke engine😀
Think big. CR500 motor.

Well maybe not. Touch the throttle a little bit and the bike flies out from under you, leaving you sitting on your *** and saying WTF. :D

I recall the Grom CRF450 conversion a while back. Maybe you can get some ideas from that. He put the radiator under the rear fender. I think you're off to a better start with the 300 motor. It's dimensions seem more appropriate.
 

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Discussion Starter #25
I put a ninja 600 motor in a go cart many years ago. It was the most dangerous thing I ever drove. I sure did learn a lot about suspension systems, or maybe I learned a lot of ways they should not be built. A buddy of mine gave it too much gas and it flipped up on the rear tires then crashed into another friends truck. I ended up having to rebuild it again, which solved a lot of the original problems I had. I ended up selling it.

The project was a lot of work, but looking back it was the first project where I learned why a high rpm race engine was a terrible idea in a off road buggy despite gearing it very low. The same can be said for putting a tractor engine in a race car.

I believe the 300 engine will be a good all around engine for the type of riding I plan to do with this bike. Tonight I am picking up the 300 frame from my buddies shop and taking it home to start deciding where and how I will mod the z frame. The biggest problem I have that the Honda 300 guys don't run into is the dual throttle bodies. I can lower them slightly by rotating the offset rubber adapters 180degrees, but there is no way to turn them out of the frame like the grom guys do on their swaps. This requires me to remove the center frame tube and possible use the ninja upper frame. Even with that I still have the fuel pump on the bottom of the tank right in the way. I may have to use a remote fuel pump, and build a custom sending unit for a modified fuel tank. My head hurts just thinking about that. I also am going to have to lower the rear swing arm, and I am still not sure I have the space to fit the factory radiator mount in front. I may end up using the ninja rear suspension and pushing it aft an inch or two.

My biggest goal is to keep all the fairing attachments in the same spot, as well as maintain the same angle on the head tube and try not to change the suspension, but no matter what some is going to be changed, and depending on how low the engine sits it may have to be raised a few inches.

Has anyone else seen or heard of a Kawasaki swap being done?
 

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Discussion Starter #27
Hey everyone just a quick update. I have been working on this for about the past week or so. I would say I am 80% done with the frame. I ended up using the 300 suspension because I wanted to use the factory air box from the ninja. I have cut the swing arm down but its still going to stretch my wheel base 4.5 inches. Anyways, I have been taking short videos along the way, I just need to get some time to put them all together then upload it. So far I am very happy with everything. I'll keep everyone posted who is following this build. Ive attached just a couple pics from the beginning but like I said I have a lot of videos to come.
 

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Wow you're either crazy or a genius. I would love to do this but you really need to have skills for this project.
Can't wait for the build videos. I'm impressed and wish I had them skills.
 

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I'm following this project very closely, but with the amount of frame modification needed, wouldn't it have been easier to slap the Z forks, wheels and bodywork on the 300?
 

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Exactly! Why the fascination with the 300? Grom people as well??? A Kawasaki KDX 175 or 200 engines are dirt cheap, have lighting coils, WAY lighter and smaller AND make more power!!
 

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Discussion Starter #32
I'm following this project very closely, but with the amount of frame modification needed, wouldn't it have been easier to slap the Z forks, wheels and bodywork on the 300?

I guess you could put the wheels on the 300, but the body is a lot different as far as size shape and attachment points. I lost about 1/3 of my videos when my pos phone crashed but I will try to get some videos posted soon. My goal was to keep the ride height and look of the Z. I am done with the frame but want to finish the tank for final fitting before I send the frame off to be coated.
 

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Discussion Starter #33
Here are a couple pics from last week. It was a lot of work to get to this point. As you can see I was able to use the factory airbox. All body panels still attach where they did on the factory frame. It's not shown in these pics but I got the passenger foot pegs welded on last night, so the screw in the end of the body attaches there now. I am going to start working on the swing arm next. I'm still waiting for a dented ninja gas take to arrive (I sold the good one) so I can cut out the bottom to use the fuel pump flange and the hump that goes over the ABS controller. Overall I still think it looks like a Z for the most part. Of course anyone who knows what they are looking at will be able to tell its different, but the avg driver on the road will think its still just a little pit bike.
 

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Discussion Starter #36
Here is a pic of the ninja tank just set on top of the bike to give everyone an idea of just how much smaller this bike is than the 300. The tank looks huge on top.

The other pic is the rear swing arm in place. I spent a couple days cutting off the tabs that hold the fender, chain guard and brake lines. I ended up cutting about 3 inches or so off the end of the swing arm and cutting new slots for the rear axle bolt. I also had to make a new tab which you can't see and weld it on the inside for the rear brake caliper mount.
 

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Discussion Starter #38
Hey guys, I haven't been on here much lately but I have pour hour and hours on this project. I will try and get some pics up soon, but I have finished some huge obstacles. One was the gas tank. I don't know if I have mentioned it before but I am putting ABS on this swap as well, however you will be able to disable it with the flip of a switch if you want. Because of this I had to mount the ABS controller under the tank. Not that the tank fit after the frame mods anyway, but this made it much more difficult. I basically had to cut the bottom half of the tank off, and start over from scratch with sheet metal. I also had to do the vent and drain hoses that run inside the tank itself. The other parts I have been working on were adapters to mount the rear ninja 300 brake disk on the Z rims. (ill be using two rear ninja 300 disks for the front and rear Z) This took a lot of time designing on cad and milling the part out on the CNC. I have a proto type for the rear cut out of 6061 but we will cut the final one from 7075. Still working on the front. The last thing has been just trying to get the wire harness routed. There is absolutely no room for anything at this point. Trying to get the ECU and the ABS computer a home was like playing tetris for hours. Also welding all the little brackets to hold the relays and fuse boxes and etc. Anyways, ill try and get some pics posted soon. I am hoping to have it all stripped back down and get the frame and rear swing arm off to powder coat by Monday.
 

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After going big bore, stroker, race head, etc. on my Z125, I sold my Z and built this “Mini Monster” with a stock ZS190cc 20hp motor. This bike is amazing. Way faster than my modded Z - 85-90mph top speed on GPS, monster torque - wheelies in the first 3 gears, 5 speed transmission, and more reliable than a modified Z125 motor. I wish I woulda have known of this motor sooner. This is truly a great in town bike and a great freeway cruiser. Check out the ZS190 swap shop page on Facebook! Many Grom owners doing this motor swap.
 
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