32hp Crossfire 250R Build - Ninja 250R Swap

[T@BD]

Hey guys, wanted to share my latest build. I started writing about this back in July, figured now is a good time to get caught up!

Original post: Mon Jul 31, 2017 8:13 pm

I've been looking forward to packing a Ninja 250R engine into a Tomberlin Crossfire 150R frame for a few years. Getting time for another project is always a problem, but last week I pulled the trigger on a bunch of 250R parts, and I'm (im)patiently waiting for everything to come in.

Some of the goodies have already arrived, set next to our intended victim.



More coming!

[T@BD]

While I have the frame apart, I'd like to update the looks of the CF150R.

The original CF150R:
I grabbed a picture off of Google Images that was perfect for trying different modifications in Photoshop. I believe the original source of this image comes from this video.




Making the CF150R's look a bit more modern:



This gets close to the look I'm shooting for, without needing to invest much time in fabrication. The work will involve cutting out a 12" section of the top roll bars, and relocating the mounting points on the rear frame to match. I'm debating whether or not to bring in the top of the roll bars in 4" on each side for an angled look when viewed from the front/rear. We'll see.

[T@BD]

Swap parts list














Not seen:

• Ninja 250R Ignition Switch with Keys
• Stock Ninja 250R Handlebar Grip
• Stock Ninja 250R Clutch Lever
• Stock Ninja 250R Exhaust Gaskets
• Stock Ninja 250R PAIR Valve

[T@BD]

[T@BD]

I'm happy with this for the moment. I won't weld the cage until all four tires are mounted and get a good look at how it all looks together.

[T@BD]

Tires: 25" on 12" rims

[T@BD]

Figuring out Long Travel Suspension - Part 1: Front Bulkhead

The stock suspension on the 150R is comfortable, but not very capable over rougher terrain in my opinion. Suspension travel at the wheels is about half of what I want for this build.

The stock control arms use unsymmetrical pivot points, with heim joints to compensate for the misalignment. I can see the reasoning behind this design. It's an inexpensive and easily manufacturable way to put the front tires where they need to be, while giving extra foot room, with decent travel.

I'm not worried about making more of these, or getting costs down. So I'm free to overcome some of the stock limitations and make this a true long travel system.

Design Parameters:

• Target pivot range: 45°
• Target vertical travel: Between 12" to 16" (Stock around 6")
• Maximum overall width: 57"
• Ground clearance: 12" with 225lb driver at 15° rest angle

I own my own private riding properties, so I'm not worried about trail regulations on width. But, I want to be able to trailer the buggy, so I need to keep total width below 57" maximum.


Mocking it up
Keep in mind that everything in this post is "mock up". I'm working out the dimensions and geometries first, and will come back later to make final reinforcements, bushings, and hardware.




Modular Bulkhead:

I'm a big fan of modular design. I want to avoid welding to the frame as much as possible, mostly for convenience and ease of mocking things up and making changes later. Let's work out a bulkhead design that can be easily removed and upgraded later if need be.



Didn't take long. This is just one plate of 4 that will make the bulkhead, but for now will work well to confirm dimensions.

The stock control arm pivot points are 10" top and 12" bottom, and spaced 4.5" vertically. We'll use the existing control arm pivot points as our mounts for the bulkhead, and relocate the new A-Arm much closer to the center. 4" horizontally, and maintain the stock 4.5" vertical.

The purpose of moving the pivot points closer to the center is to allow us to make the A-Arms as long as possible. Longer A-Arms result in more travel at the wheel for every degree of pivot.

Cutting it on the CNC plasma looked like this:




Cooked up in 1 minute and 14 seconds.



The mounting turned out as expected. The bulkhead plate bolts right into place, no welding.




18" A-Arms:

After a little math, I decided I wanted to try 18" A-Arm length. A-Arms on 150's are usually less than 13".





The mock A-Arm was made from American 1.5" cold rolled DOM tube with 0.120" wall thickness. It's some heavy stuff. I plan to do the same for the final A-Arms.

I turned down an insert from 1.125" round as a bung the temporary heim joint. This is just to mock up, as I'm not a fan of heims and don't want to use them on this build. I'm going to replace the heim joint with something more robust in the next update.

For now, I just want to see how I like the 18" A-Arms.

Testing:

• 15° Angle | 12" Ground Clearance | 58" Width
• 25° Angle | 16" Ground Clearance | 54" Width
• 35° Angle | 18" Ground Clearance | 52" Width

So it turned out that the 18" A-arm length is just a little too long. But I'm going to keep it. I figured out a way to cheat the width by making a suspension lock at 25° (54"). Just lock it and load it into the trailer like normal.

Front suspension part 2 update coming next.

[T@BD]

Long Travel Suspension - Part 2: Theory

I'm moving forward with the 18" A-Arms. Across a range of 45°, we're looking at 13.3" of vertical travel at the tire. This assumes that the shock travel is 2.85". I believe it's actually over 3", but I haven't confirmed that yet. These dimensions are still all tentative.

I'm not using ball joints or heim joints on this build. More on that later.

Let's draw it up!

Angles and travel drawing



Front View Drawing



Top-down Drawing



Animating it - Full range

1. Fully compressed ...-7.5° with 6.88" ground clearance

2. Normal resting angle ...15.0° with 13" ground clearance

3. Fully extended ...37.5° with 20.2" ground clearance

[T@BD]

Ok, enough theory, let's make some A-Arms!







Bushing Carriers
The oversized bushing carriers are huge. 2" outer diameter, and 1.25" inner diameter.

Back to the lathe:


Carriers in their slots:



Since the tubing is 1.5" and the bushing carriers are 2", I needed to correct for the difference in height when laid on the fixture. Conveniently, the fixture plate itself is cut from quarter inch (0.25"). Instead of using spacers to raise the tubing, I included slots with mating corners for each carrier. This lowers the carriers to the correct height, and has the added benefit of locating the carriers more true and precise than using a series of clamps.



A little flair.







Before welding, I'll turn down a couple of end-caps on the lathe for the exposed tube ends.

Then come the polyurethane bushings for each carrier.

[T@BD]

Finally set aside a little time to weld the first A-Arm.

[BuggyMaster]

Wow man! Super nice! Crossfire is one of our favorite Buggies!

[T@BD]

Thanks! It's getting there piece by piece, more coming shortly!

[T@BD]

Building shackle joints (No ball joints or heim joints on this one)

For this build I want to go with a stronger setup than what ball joints or heims can provide. This massive shackle-style "joint" replaces the traditional ball joint at the end of the A-Arms, allowing articulation of the A-Arms, and pivot of the spindle.



More drawing



More cutting

[fan4chevy]

I will be keeping up on your thread. Pretty awesome. I have a larger Roketa and two silver Guong's that look like a cross between hammerhead and trailmaster.

I just know I need more power than the gy6 but reverse has been a real concern with engine swapping.

[BEEFKING69]

Awesome work and love the drawings etc. Not a fan of the rear bars being moved but i believe it would grow on me. 25-12s on the front just look way outa place on a small frame to me but i can see the benefits of them i just like the look of 10 front 12 rear i guess. Id like to increase the travel on my CF400r maybe a few more inches but i dont think i need as much as your doing although it would be awesome to have.

Love the Knuckle.....Could you build a set that would work on normal 150r a-arms? If so id be intrested ina pair as ive got to replace all of my balljoints sooner than later

[jmansracerocket]

Some nice stuff there travis. I like those wheels. See some more buggies in the background waiting for mods also.

[EVILWS6]

Wow this Crossfire is going to awesome. Will be following this thread now.

[T@BD]

Originally Posted by BEEFKING69

Check this out. https://www.youtube.com/watch?v=4_62fcas6rk

Originally Posted by fan4chevy

I have seen this ninja 250 video before and it is so fast and sounds awesome. I have seen others as well with 250 ninja. They put out so much power compared to putting in a larger cc engine of another type.

I think it is the best way to go as long as shifting is not an issue.

I had Jeremy's 250R videos on auto-repeat for over a month before pulling the trigger on this swap. I have a 2012 Ninja 250R, but didn't want to use it as a donor. I feel that it's about the perfect power output for a 150 class frame.

The 250R is great for flying around flat terrain, but compared to the CVT in the GY6 I think there will be limitations going up hills. I'm fine with this though, different builds for different riding locations. Each best at its intended purpose. You can see in a few of Jeremy's videos that he stalls out one particular hills a couple times. Although, I'm sure it's a good sized hill. It's hard to tell in video/pictures.

Jeremy used a 1988-2007 250R engine, which as more peak HP, but less mid-range torque. I decided on the 08+ engine for that torque.

[T@BD]

Just realized that I've been holding on to some pics since August. Have been tied up coding some overdue webstore improvements for the last few months. Eager to get back to this build. Next up will be the spindles.

The bolts at the ends of A-Arms are 1/2" diameter. Vertical bolts on the knuckles is 5/8" Grade 8.

[tkeagle]

very nice

[scjeep4.7HO]

Wow those are done very nicely. Real attention to detail.