ATCr125x

[Dirtcrasher]

I have 75% or more of the parts to put a Blaster motor in an 86/87 chassis. I'd also like to run a TRX450 swinger with linkage suspension. I have an 05 shorter swinger 450 setup...

When I had a Blaster for my "EX", A FMF pipe, lid off and jetting really woke it up.

Simple air cooled reliable motor as well and a short kicker.

I guess it's all in what you have laying around, lol.

[onformula1]

I have 75% or more of the parts to put a Blaster motor in an 86/87 chassis. I'd also like to run a TRX450 swinger with linkage suspension. I have an 05 shorter swinger 450 setup...

When I had a Blaster for my "EX", A FMF pipe, lid off and jetting really woke it up.

Simple air cooled reliable motor as well and a short kicker.

I guess it's all in what you have laying around, lol.

I have said for a few years that would be a great build, I would use a 240cc kit and build it for torque, it's not much of a pin the tach motor.

The toughest part will be the pipe, I would look into using a Kawasaki KDX200 pipe with a few mods.

[Jmoozy27]

Neat project, I've thought of building something like this for my son to ride. This setup would be pretty good for a racer, one that stays up in the rpm all the time. 125's don't make good power until they are really revving. How much do you expect the final product to weigh? 125 motocross bikes are extremely light and only have a single skinny rear tire to turn which allows them to spin and stay revved. Are you concerned of the fact that it will undoubtedly be more difficult to ride on trails than a 250 2 stroke or any 4 stroke, or are you strictly a racer? Looking good so far.

I'm not a racer per say, but I do enjoy going fast and I understand the mechanics behind doing so. This one will be built for speed, and performance. No trails, I may try my hand at a local series, we will just have to see. I expect good results with the proposed suspension, gearing, jetting, mixture, etc.

[freewheeler]

I think you would be surprised at how much power they make a lower revs, look up Jimmy lewis or Paul Edmondson and a few others, they had great careers waxing 2 stroke 250's and 4 strokes in tight woods, enduros and GP's. With the modern design and power valve they make a nice spread of power, now if you are going flat out against a good running 250 you will need to be between 11,000-12,500 RPM to be competitive.

With a killer set-up you should be able to get to 250lbs., probably more like 260lbs. with out going nuts.

Yes but dirt bikes have a skinny rear tire that can be easily spun and kept in the revs. Champions have a tendency to win no matter what they are riding. A cr125 weighs about 190 pounds. Even at 260, hoping to stay in the power anjd have fun, make it useable and fast on a trail with 2 fat rear tires locked together with a 125cc engine pushing them will require the rider to to be extremely skilled. If it was intended to be an all out go-fast ride then I'm wondering why such a small cc engine was used. A 250 2 stroke engine is not much heavier at all and realistically is going to be a boatload faster in the same chassis. There are riders that can beat 250r's on a flat rack riding a 200x so flat out speed isnt everything but a four stroke has useable power down low thats why they can hang. A 125 three wheeler will get ran outta town by any good running 250 theres no doubt but a very cool project for a class racer if thats the plan

[onformula1]

Yes but dirt bikes have a skinny rear tire that can be easily spun and kept in the revs. Champions have a tendency to win no matter what they are riding. A cr125 weighs about 190 pounds. Even at 260, hoping to stay in the power anjd have fun, make it useable and fast on a trail with 2 fat rear tires locked together with a 125cc engine pushing them will require the rider to to be extremely skilled. If it was intended to be an all out go-fast ride then I'm wondering why such a small cc engine was used. A 250 2 stroke engine is not much heavier at all and realistically is going to be a boatload faster in the same chassis. There are riders that can beat 250r's on a flat rack riding a 200x so flat out speed isnt everything but a four stroke has useable power down low thats why they can hang. A 125 three wheeler will get ran outta town by any good running 250 theres no doubt but a very cool project for a class racer if thats the plan

So you think a CR125 MX bike has less traction that a CR125 trike? On a MX track or pretty much anywhere? I disagree

This trike or any trike like it will use a 16" or 18" tire 8.5-9.5" wide, compared to a 25" tall modern computer designed and very aggressive MX tire that digs down deep and finds the best traction available.

Take a 250r and a CR125 to the dunes with stock tires, you will find out the 250r goes nowhere pretty quick and has major traction problems, the MX bike will climb anything in sight and has more traction.

The CR250r doesn't fit very well in this chassis, aside from the vibration issues, a 1985-86 250r chassis would be better.

So, from what you wrote the CR125 trike will not hang with a 250r?

Again, I think you are forgetting many things such as-

Weight
Horsepower
The modern design of the engine
RPM
Spread of power
Power valve
No counter balancer
Much less inertia
A transmission with much less drag

Interesting they use a larger carb. stock vs. stock

I am not saying this trike will be faster than a 250r, but it deserves not to be underestimated, your quote- "A 125 three wheeler will get ran outta town by any good running 250" is not correct, I have seen it myself have you?

Also, take a look at- Oscar Mayers sons quad in the quad section YZ85- 90cc kit and it destroys the same rear tires the 450 pro's use on their quads.

[Jmoozy27]

Yes but dirt bikes have a skinny rear tire that can be easily spun and kept in the revs. Champions have a tendency to win no matter what they are riding. A cr125 weighs about 190 pounds. Even at 260, hoping to stay in the power anjd have fun, make it useable and fast on a trail with 2 fat rear tires locked together with a 125cc engine pushing them will require the rider to to be extremely skilled. If it was intended to be an all out go-fast ride then I'm wondering why such a small cc engine was used. A 250 2 stroke engine is not much heavier at all and realistically is going to be a boatload faster in the same chassis. There are riders that can beat 250r's on a flat rack riding a 200x so flat out speed isnt everything but a four stroke has useable power down low thats why they can hang. A 125 three wheeler will get ran outta town by any good running 250 theres no doubt but a very cool project for a class racer if thats the plan

Freewheeler, thanks for your opinion. I agree that this will be a challenge. I'm not one to waste my time with something that won't perform. I think at this point neither you or I have anything to base our opinions on, because neither of us have completed a similar build. To answer your question, the motor was chosen after much research by myself and a few other 3ww members. I had a lot to choose from for this project, I have an 250cc sitting on the bench right now that I could have used. But it's not time for that. This is the build I chose, and until it's complete, no one, unless that person has built one, knows what it's gonna do once completed. Your comments are welcome, but please keep the fortune telling to a minimum.

PS: If I go to TF 2016, I'll bring this one along and you can judge it's integrity then...

[hawaiirider]

sweet build, id love to ride that trike!

[oldskool83]

Some of us just built bikes with left overs and do not care what anyone really thinks or says lol. These documented smaller 2 stroke swaps can help to inspire people who have a mix of stuff that may not have much money into anything and just want something that can be run all over. Light small trikes are fun. I like tacos also.

[Jmoozy27]

Some of us just built bikes with left overs and do not care what anyone really thinks or says lol. These documented smaller 2 stroke swaps can help to inspire people who have a mix of stuff that may not have much money into anything and just want something that can be run all over. Light small trikes are fun. I like tacos also.

Tacos rock, and I have a lot of parts!!! Too bad I'm like Johnny Cash at a caddy plant, all different years... My builds are all mutants!!!!

[Ol Deuce]

the small cc 2stroke conversions are a blast ! lower gears and RPMs up they are fun !!

[video]https://youtu.be/TZEtQDPKM3c[/video
//www.youtube.com/watch?v=TZEtQDPKM3c

[hawaiirider]

the small cc 2stroke conversions are a blast ! Lower gears and rpms up they are fun !!:bounce:bounce:bounce:d

https://youtu.be/tzetqdpkm3c

https://youtu.be/tzetqdpkm3c

awesome bike man, like wow!!!!

[Jmoozy27]

the small cc 2stroke conversions are a blast ! lower gears and RPMs up they are fun !!

[video]https://youtu.be/TZEtQDPKM3c[/video
//www.youtube.com/watch?v=TZEtQDPKM3c

Randy, I may have said this before, if mine looks half as good as your then that's a win in my book!!!

[86125m]

yes jmoozy your builds are mutants but your builds are more like the teenage mutant ninja turtles just awesome. Ive seen pictures of your other projects and your work is great. I love the superx you built.

[oldskool83]

Keep building. I just had a friend tell me one day I will stop messing with this old crap and buy a 450R quad....problem is I road a 06 trx450r and liked nothing about it. I like my timeless classics because people like to hate when you have an arsenal of toys in the garage plus the "WTF" is that bike?

That's when you get the pleasure of telling that person to lick your satchel.......and grab a spoon

[86125m]

Yep the day I stop messing with old crap is going to be the day I die and hopefully I'll be on one of my old machines and go out in a blaze of glory. I'll probably say something like "hay y'all watch this" before I go as well