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Discussion Starter #1
Guys I’m going to rebuild my z and I already have a 143cc kit with larger valve head and mid size cam. I have the larger 26mm thrott body and a pvc. I was thinking of going to the 173cc and add the striker crank to make it I think194cc. Any thoughts or issues you can see? I want to go as larger as I can with out making her ureliable
 

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I have had a high compression 125, 143, 155, 165 and now a 165 with a stroker crank, the 177 is we’re it’s at, i did have a piston come part once but it has took a beating since the rebuild, I rode a stock bike today, a Vader boom with a zs190 and my bike, I would take the 177 over all them. The 194 like to blow headgaskets because the studs are so close together
 

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Discussion Starter #4
Sounds like I need to look at the 177. That needs the case bored right?
 

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How much does a Z125pro + big bore + fuel management + exhaust + intake cost?

I just don't get the urge to increase the displacement for all the money spent, and still end up with less power than a 250 at the same or greater cost. The only benefit is the little 12 inch wheels. Yes it is still the cheaper insurance from the "125cc" on the label, but if you get into trouble and the insurance finds out, they are very likely to pull your coverage.

All that said, I have "big bored" one of my bikes. My Buell XB9R needed new cylinders and pistons because of damage from the previous bonehead owner. The cost to go with a bolt on kit was only about $100 more than stock. An extra $100 made sense to gain a little more performance and fix the problems.
 

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With the new Steady Garage EFI kit, I'd be tempted to try the ZS190 route. From what I understand that kit allows you to use all the factory wiring... When that goes kaboom, you still have the factory motor to go back to... or sell the factory motor to offset the cost of the kit.
 

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Discussion Starter #7
How much does a Z125pro + big bore + fuel management + exhaust + intake cost?

I just don't get the urge to increase the displacement for all the money spent, and still end up with less power than a 250 at the same or greater cost. The only benefit is the little 12 inch wheels. Yes it is still the cheaper insurance from the "125cc" on the label, but if you get into trouble and the insurance finds out, they are very likely to pull your coverage.

All that said, I have "big bored" one of my bikes. My Buell XB9R needed new cylinders and pistons because of damage from the previous bonehead owner. The cost to go with a bolt on kit was only about $100 more than stock. An extra $100 made sense to gain a little more performance and fix the problems.
It's all about fun I don't care about the money. I have more in mods then I paid for the bike new. I just enjoy modding bikes. I have plenty of big bikes this little one is just for fun.
 

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Discussion Starter #8
With the new Steady Garage EFI kit, I'd be tempted to try the ZS190 route. From what I understand that kit allows you to use all the factory wiring... When that goes kaboom, you still have the factory motor to go back to... or sell the factory motor to offset the cost of the kit.
I don't know much about that. I might need to take a peek.
 

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Not finding an EFI kit, but I did find a 212cc engine:


Any of these come with a 4 valve head?
 

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@Greg_E From what I understand, the ZS190 motor is a 2v head. There is a Daytona 190 with a 4v head and apparently the heads are interchangeable. ZS190 bottom end with a Daytona 4v 212cc jug and head are popular upgrades on the Grom/clones.

Here is the link to the Steady Kit:

I don't know anyone who has used this kit yet, so there is some speculation on it's completeness... but if you don't have to replace the Z125 harness with a Grom clone harness, that's huge.
 

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OK, I was thinking it was a stand alone EFI system that could be added, not to use the stock z125 system. A good (and affordable) EFI system that I could adapt to my KAYO would be nice, the carb can be a pain some days... Pull the seat, drain the fuel, pull the bowl, change the jets, hope you got it right, etc. I should probably find a used z125 system and couple an Aracer ECU with it.
 

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Discussion Starter #12
I’m lean towards the 177 kit. I already have the V2 head, cams and throttle body so really just need to get the cylinder and piston and do a kick *** porting job and figure out how to bore the case and I’m in business. Well and add my auto tuner. Lol
 

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Best way to bore the case is with a big milling machine. After that I'd probably build something that bolts to the studs, but this could be really ugly. I've seen people use die grinders and sanding drums, but you'd want to be real careful that you don't get a tight or loose spot because it might cause the cylinder skirt to crack.

A router with a bearing guide and guide plate might work pretty well. The hole in the guide plate might be easier to get precise. Bolt the guide down with flush fitting bolt heads. If I were doing this, this might be how I approach the issue. How big is the hole in the case?
 

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I have a video on my YouTube how to bore the case at home, the zs 190 motor has potential, my bike don’t start pulling the other bike with it on it till 10,000+ rpm in third gear, then it’s a train wreck, the zs feels choked up above 9,500, I am sure a large throttle body, port job and efi the zs would be a fast little motor,



I used to think modding the bikes are dumb, till I started, my bike started out running 13.10’s @46-47 in the 1/8 to now we been [email protected], between the clutch upgrades, gearing it down, levers, rear sets, my bike feels more like a big bike then a mini
 

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Discussion Starter #15
Best way to bore the case is with a big milling machine. After that I'd probably build something that bolts to the studs, but this could be really ugly. I've seen people use die grinders and sanding drums, but you'd want to be real careful that you don't get a tight or loose spot because it might cause the cylinder skirt to crack.

A router with a bearing guide and guide plate might work pretty well. The hole in the guide plate might be easier to get precise. Bolt the guide down with flush fitting bolt heads. If I were doing this, this might be how I approach the issue. How big is the hole in the case?
not really sure. I also so the guy on You tube using a sanding drum. It didn’t look that bad. It looks likee you need to go out about a 1/16” to maybe a 1/8”. A milling machine would be best but not sure how you would secure it on the table. I think the drum would be the easiest way.
 

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If you had a mill big enough, some large angle plates would probably be best. If you strip it all the way down, then there should be a few places where you can clamp the block to an angle plate. But that's a lot of disassembly to get there. I think milling out a guide plate that bolts to the cylinder studs and using a router with a guide bearing might be a good way for people to accurately perform this step at home. Still need to pull everything out of the way to get the tool clear of everything. Not sure if you could swing a similar cutting tool in a die grinder, but that might be an alternative. Something like this bit Amana Tool 45364 Carbide Tipped Down Shear Face Plunge Template 3/4 D x 2 Inch CH x 1/2 SHK w/ Upper Ball Bearing Router Bit so the bearing can ride on the template and should give you accurate cutting with a hand held router (or maybe table mounted).

And I get modding things when there is a good reason, like racing. Racing is nothing more than fun and throwing money onto the pavement. But so many buyers get one of these and need MORE POWER for riding on the street and then spend more money that buying a decent 250 or 300. A far better bike for the road would be a wr250 with street tires if you want a fairly upright bike, Ninja 250 is really good for a sport style and the R3 is really nice. But don't shy away from a used Buell XB9 or XB12 if you want a big bike, much different than an inline 4 and I find it suits me nicely if I want "real" power on the road. They are super cheap in the $3000 range for a good used one.

Only reason I bought my z125 was for the track, hasn't worked out so well since I bought it. The Z was supposed to be the stock endurance machine because I couldn't build what I really wanted out of a TTR125, and the TTR would have cost a lot more money. Same goes for the KAYO, it was a track bike (no lights, etc.), and the KAYO has had all manner of mods that keep it to 125cc. High compression piston, cam, carb. and manifold, gears, rearsets, rearset mods, seat, tires, front fork lowers, fork oil and spring spacer, rear shock oil, race fuel for the high compression... Hope I can get back on the track next season with both of these. I have thought about a Honda water cooled 150 swap in the KAYO, they "bolt right in", but that would put it into a different class, and the bigger dogs run in that class and it would really be "out classed" by the 285cc air cooled machines.

I'm also thinking that I might ditch the KAYO and go full performance on the Z125 (or buy a second Z), depends on what happens with the racing near me. Right now the only real racing is 8 hours away at NJMP, the 3 hour away thing fell apart. But I should be able to practice at my local kart track which is 20 minutes away. That might make it worth going 8 hours every once in a while, but certainly not very often. Penguin Racing also normally offers one or two track days for small bore machines in New Hampshire or Vermont, expensive but would be a fun trip. Those got cancelled this year but should be back next year.
 

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Discussion Starter #17
If you had a mill big enough, some large angle plates would probably be best. If you strip it all the way down, then there should be a few places where you can clamp the block to an angle plate. But that's a lot of disassembly to get there. I think milling out a guide plate that bolts to the cylinder studs and using a router with a guide bearing might be a good way for people to accurately perform this step at home. Still need to pull everything out of the way to get the tool clear of everything. Not sure if you could swing a similar cutting tool in a die grinder, but that might be an alternative. Something like this bit Amana Tool 45364 Carbide Tipped Down Shear Face Plunge Template 3/4 D x 2 Inch CH x 1/2 SHK w/ Upper Ball Bearing Router Bit so the bearing can ride on the template and should give you accurate cutting with a hand held router (or maybe table mounted).

And I get modding things when there is a good reason, like racing. Racing is nothing more than fun and throwing money onto the pavement. But so many buyers get one of these and need MORE POWER for riding on the street and then spend more money that buying a decent 250 or 300. A far better bike for the road would be a wr250 with street tires if you want a fairly upright bike, Ninja 250 is really good for a sport style and the R3 is really nice. But don't shy away from a used Buell XB9 or XB12 if you want a big bike, much different than an inline 4 and I find it suits me nicely if I want "real" power on the road. They are super cheap in the $3000 range for a good used one.

Only reason I bought my z125 was for the track, hasn't worked out so well since I bought it. The Z was supposed to be the stock endurance machine because I couldn't build what I really wanted out of a TTR125, and the TTR would have cost a lot more money. Same goes for the KAYO, it was a track bike (no lights, etc.), and the KAYO has had all manner of mods that keep it to 125cc. High compression piston, cam, carb. and manifold, gears, rearsets, rearset mods, seat, tires, front fork lowers, fork oil and spring spacer, rear shock oil, race fuel for the high compression... Hope I can get back on the track next season with both of these. I have thought about a Honda water cooled 150 swap in the KAYO, they "bolt right in", but that would put it into a different class, and the bigger dogs run in that class and it would really be "out classed" by the 285cc air cooled machines.

I'm also thinking that I might ditch the KAYO and go full performance on the Z125 (or buy a second Z), depends on what happens with the racing near me. Right now the only real racing is 8 hours away at NJMP, the 3 hour away thing fell apart. But I should be able to practice at my local kart track which is 20 minutes away. That might make it worth going 8 hours every once in a while, but certainly not very often. Penguin Racing also normally offers one or two track days for small bore machines in New Hampshire or Vermont, expensive but would be a fun trip. Those got cancelled this year but should be back next year.
Yes me too I bought the Z for a pit bike while racing and to bring to the go kart track and have fun. I have about 1800 miles on her and about 200 might be on the street and I don’t even think it’s that much. Lol I’ve already done about everything you can do to it. Ss brake lines, bars, Ohlins suspension, power commander, Yoshimura pipe, 143cc head, cam, v2 head, 28mm throttle body,short air intake, slicks,quick shifter, rear sets but I took them off because I liked the stock ones better. Double sinter pad and sprockets. Im sure there’s more but can’t remember lol

but it’s so much fun I can’t help it. I have no plans to sell her and figure it’s a long winter so screw it! I’m going to go 177cc and BST rims with some extensive head porting and an auto tune and I’m done .lol
 

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I still feel mounting a 125cc 2stroke (kx125 engine) would be the best bang for buck. Small, simple, and I'd bet you could twist the swingarm with that. Maybe a little off topic (sorry OP) but if we're talking about double or triple the horsepower I'd say mount brackets are much easier than trying to give the runt some roid rage.

Either that or a scary amount of nitrous. One or the other will be happening to the Z this winter. :ROFLMAO:
 

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Discussion Starter #19
I still feel mounting a 125cc 2stroke (kx125 engine) would be the best bang for buck. Small, simple, and I'd bet you could twist the swingarm with that. Maybe a little off topic (sorry OP) but if we're talking about double or triple the horsepower I'd say mount brackets are much easier than trying to give the runt some roid rage.

Either that or a scary amount of nitrous. One or the other will be happening to the Z this winter. :ROFLMAO:
haha love the NOS part! The two stroke idea is cool but I do like the fuel injection.
 
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