View Full Version : The XB4R build begins...

07-15-2012, 06:16 PM
So here is the blast that we will be using the cases from:

and the XB frame(swingarm not pictured):

The blast being stripped down:

Test fitting the swing arm:

Thanks to Bossanova for the wheels and squidbuellie for many of the other parts, aaron914 for the primary cover and a backup ecm. I will be putting the new primary cover on today, and then srat tearing the motor down when I get all the parts in.

I will update the further along I get.

07-15-2012, 10:16 PM
good luck!! cant wait to see what it will look like when its done!! btw, why is it a xb4r? the blast is a 500 so shouldnt it be a xb5r lol? :D

07-15-2012, 10:24 PM
A blast is actually 492, it is an xb9 engine with just on cylinder. The bore and stroke are the exact same. And xb9 is 984cc and is called a 9 so I figure xb4 was fitting. Although this blast engine is not being left stock as the only thing that will be used is the engine cases. I can't wait to get it done. Hopefully within a moth it will be done.

07-15-2012, 11:13 PM
Definitely keeping an eye on this build.

07-15-2012, 11:14 PM
First thought that came to me when I saw the title was inline 4 in a buell. XB4R

07-15-2012, 11:20 PM
XB4.5RR :D [up]

07-15-2012, 11:24 PM
Cool. Looking forward to seeing the finished product.

07-15-2012, 11:30 PM
So far I have the primary cover on, swing arm on, once I have all engine parts that will go on. I ordered new fittings for the oil line so I can hook them up. If I can find an xb9 piston to use, I will be putting a big bore kit in this bad boy. From what I can tell so far, this bike will be lighter than a stock blast and have more power even without the big bore kit. This blast engine is easy to pick up on my own.

07-15-2012, 11:34 PM
You gonna give the piston back after your done with it?? :D props for the build[up]

07-15-2012, 11:52 PM
Haha, I meant if I can't find a piston I will do a big bore. Lol the only way to buy a new piston is to buy a cylinder and piston together which is about $230 plus the gaskets and rings or a big bore kit with everything for like $350.

07-15-2012, 11:57 PM
Squidbuellie didn't have one? Check with buellster parts over on the right side of the page. He carries used parts.

07-16-2012, 12:04 AM
No, but he is checking to see if he can find one. Buellsterparts didn't have any that I saw. They said unless the motor is bad they don't part it out

07-16-2012, 02:14 AM
Dude ,that is bad ass! Can't wait to see her done

07-16-2012, 02:35 AM
That is gonna look pretty cool. Good luck with the build!

07-16-2012, 02:40 AM
I have always wonder why more blast guys don't do this. Looking forward to seeing this build.


07-16-2012, 02:57 AM
That bike you pictured has the 515cc big bore and is carb. If I end up doing a big bore I will get the 1050cc kit for the xb9 but either way mine will be efi and I will be putting an O2 in the header so it should be a breeze to tune.

07-16-2012, 03:11 AM
Been there, done that. The efi is real easy to tune. A stock 9 map is a real good starting point.

07-16-2012, 05:17 AM
Loose1 I remember seeing your bike at homecoming a few years back!, it's by far the coolest blast I've seen in person do far!

07-16-2012, 07:44 PM
Looks like I'm ordering a new piston and rings, found them from a dealer for $100 together

07-16-2012, 11:42 PM
That bike you pictured has the 515cc big bore and is carb. If I end up doing a big bore I will get the 1050cc kit for the xb9...

You do realize that a Blast 515 kit is half of the XB9 1050 kit, right?

Look them up, both are a 3-9/16" bore.

07-17-2012, 12:53 AM
Huh, weird. 515 + 515 = 1030 so how does a 1030 kit equal a 1050? Also, an xb12 has the same bore as an xb9 but there is an obvious difference in the engine displacement. I'm just trying to understand how it's possible for different cc kits to be the same. Also the blast kit is made for the blast head which is different than the xb head which is what I'm using. The xb9 piston is done shaped, higher compression than the blast but the blast has the same bore and stroke as the xb9 but uses a flat piston which is where is loses compression but keeps the cc and also it is exactly half the cc displacement of the xb9

07-17-2012, 01:19 AM
The stroke is longer on the 12 than the 9 and blast. You have to use bore and stroke to figure out your displacement.

07-17-2012, 01:23 AM
Yes, I understand that exactly. That's why a 12 has more power using the same cylinder and heads as an xb9. Because it uses a longer stroke and a flat piston to keep compression high. I'm not confused by that, I'm confused about how a blast 515cc is the same as half an xb9 1050cc which is 525cc

07-17-2012, 02:58 AM
Its in the naming. An XB9 is closer to 1000cc than it is 900cc (984cc, but you know that); they're just rounding the cc's (incorrectly, I might add).

I know XB's have a different head design than the Blast, I'm using an XB9 top-end in my Blast.

I was merely pointing out that between the two kits, the displacement of each cylinder is the same.

Stock bore is 3.5" (88.9mm)
515/1050 kit is 3.5625 (90.49mm)
Stroke is 3.125" (79.37 mm)

Displacement (doing the math (pi*(bore/2)^2*stroke)/1000)
Stock Blast 492.663cc
Stock XB9 985.326cc
515 Blast 510.443cc
1050 XB9 1020.886cc

There's the real displacements of the engines.

Going for half of a 1050 kit would be the way to go, IF you already have an XB front head; and IF the shop is willing to sell half a kit.

FWIW - The shape of the piston/head have no bearing on the displacement of the engine/cylinder, only on compression ratio. Displacement is determined solely on bore and stroke, as in the above examples and calculations.

Because it uses a longer stroke and a flat piston to keep compression high
It uses a dished piston to keep compression DOWN, not high. If the 12 used the same piston as the 9, it would have an ~12:1 compression ratio. Buell gave it a dished piston to counteract the longer stroke to keep the compression ratio at a more reasonable and reliable 10:1.

Going by Harley's retarded rounding rules, the Blast should be a 400, not a 500...or the XB9 should be an XB10.

07-17-2012, 12:22 PM
Ok this is some real engineering, I'm all over this like white on rice. More balls than most! Go for it. I realize were not talking uncharted territory here but this would make a hellified Bonneville bike! If this is lighter than a stock Blast this will be a crap ton of fun to ride.

07-17-2012, 02:46 PM
It's essentially an engine swap on an XB9, most of the mounts already line up. A little fab is needed, but it's certainly not some amazing feat of mechanical engineering. The most difficult part will be getting the ECU to work properly without the rear cylinder, which is electrical. If you want Blast engineering, that's elsewhere.

Not talkin' down on the swap, if I had the parts I'd do it in a heartbeat. Also a huge fan of the color choice, the only XB-R colors that should've ever been offered, imo.

Do you have an XB-R front end, or using the Blast?

07-17-2012, 03:12 PM
Xbr front, doing a tail swap to an s though. So far problems are the trans shaft have different teeth than the xb pulley, and there is no idler pulley mounts, no kickstand mounts, primary cover isn't exactly a direct fit. But that's just what I have so far. FedEx just called me, squidbuellies parts just arrived at my house

07-17-2012, 03:33 PM
What are you doing with the XBR tail?

07-17-2012, 03:38 PM
I'm swapping with a guy, but his only transportation is his bike so I have to wait till he can do the swap. Supposed to be around beginning of August I guess

07-22-2012, 07:26 PM
For an update, still waiting on a few engine parts and just realized that I didn't order the gaskets for the cylinder and such. I tried a test fit for the frame and front end which healped me find out that I need new steering head bearings and a new front axle because it's bent. The rear shock isn't attached so the rear looks low because of that. I have the fittings needed to make my own oil lines to work with the '07 swing arm. Also attached new fittings for the oil cooler.


07-22-2012, 07:38 PM
lookin sweet, I may look into something like this instead of rebuilding my 9.

07-22-2012, 07:48 PM
Unless you have a way of getting parts really really cheap, it's really cheaper to buy another bike. But later plans for this bike (way on down the road) is a turbo that would fit perfect where the other cylinder would be and a big bore 600cc kit. and I've been looking into building a water cooling setup for it.

07-22-2012, 07:59 PM
I have a working blast and an xb9 that is down because of transmission issues. seems like it'd be something I could get done on a nice saturday as long as fitting the swing arm doesn't take too long.

07-22-2012, 08:18 PM
Swing arm bolts right up. For the oil lines you will either need to buy the fittings to attach them or make some like I am doing. You will also need To swap the xb top end and cams to the blast. I would put a big bore on that bad boy too.

07-22-2012, 09:19 PM
Good to know, I'd probably try out the swap before going to a big bore though.

07-22-2012, 09:29 PM
I'm curious to see how far this bike will go before the fuel light comes on. The blast was getting 76mpg and my 9 would get almost 70 on the same ride as the blast. Now that "blast" will have a much larger gas tank.

07-23-2012, 01:55 AM
jeebus, 76mpg! I get 55 on a good day. That must have been one fine tuned blast or lean as heck =)

07-23-2012, 02:18 AM
I don't think the people we bought it from had it jetted for the exhaust, but I'm not sure. I know that when I pulled the heads off the exhaust valve was white, and I mean white.

But I also had another blast with a Vance and Hines and was jetted and I got 70mpg in the city

07-23-2012, 06:28 PM
You dont have to change the head to fit the engine into the XB frame. If you can't find the XB head, only slight modification of the front isolator mount is required.

Cams have no effect on the transplant between the two frames.

07-23-2012, 07:10 PM
I personally wouldn't want to modify ANY engine to frame mounts. Each weld creates another possible weak link. IMO as far as just putting the engine into the frame, no I guess cams arent necessary, but why would you want to go from an xb9 to a straight up blast motor anyways?

07-23-2012, 07:17 PM
because my xb9 is stuck in 2nd gear lol

07-23-2012, 07:30 PM
You don't have to weld anything, it's slightly elongating the holes where the mount mounts to the head.

It's the only way to get the XB head to mount in a Blast frame. So far, no one that has done the swap has had any issues with their modified mounts.

08-05-2012, 02:59 AM
well, still waiting for a few parts and waiting on a lighting tail swap. I put the plastics and everything on to see what it would look like. I sat on the bike and man, this thing is light. I know there is about 20-30 lbs of stuff still not on the bike but even after all of that it will still be really light.


08-05-2012, 03:55 AM
Looks cool, always thought the S tail would look better also - This would be XBBlast #7 that I know of, yeah - you think more would be made. There is a 20lb loss of weight just in switching frames and swing-arm and sub-frames, not counting lighter exhaust, no need for oil cooler, 1 less cyl./piston/head, etc. - 16 front and back would be formula, but no one does that because then front end customization comes in and starts to equal the price of the stock XB set up - I may do that - I have all the parts, just trying to find the time.

08-05-2012, 03:58 AM
Wolfe - that can be fixed - without splitting cases - just almost - lol

08-05-2012, 04:12 AM
i'm back, and it looks like ill be giving you a call tomorrow....
im curious to see what your going to do for the rear head motor mount.

08-05-2012, 03:31 PM
Skip it?

08-05-2012, 05:02 PM
I mounted it, just as if the rear cylinder isn't there do its bolted through the the rear mount to the throttle body mount. I will take a picture to show it.

08-11-2012, 04:49 AM
Quick - call an ambulance - the thread is dying! - pics?

08-11-2012, 01:47 PM
Sorry, I am just waiting for parts now, I haven't done anything with the bike in almost a week.



09-05-2012, 12:00 AM
Okay, it's been awhile guys. A small update right now. Bike is wired, went to start engine fuel pump made a crazy noise, bike turned over, made a loud bang and I smelled something burning. I found the the problem is in the wiring harness. Sometimes the pump will come on, if not you can wiggle the pumps wires at the harness an it will work till you try to crank it... Ugh... No time to pull the harness and find the problem...

09-05-2012, 12:14 AM
Did you change out the blast cam timing cup for a xb one?

09-05-2012, 03:56 PM
I hate to be "that guy", but why? This looks like a ton of work to build a bike way slower than even an XB.. which is already somewhat sluggish compared to normal standards nowdays.

It IS ****in' cool, but what do you have in mind? Max MPG?

09-05-2012, 04:37 PM
I changed out to an xb cup and cam sensor.

And in response to fireinxb: this bike will have more power than a standar blast, look better, weight less, handle better and can easily be upgraded to a big bore and or turbo of I wanted. It's not that I don't have an xb already but this is nicer than a blast.

09-09-2012, 07:12 AM
Blast doesn't need an oil cooler - especially with a half quart extra capacity - a waste of weight - ditch it - lol

09-26-2012, 03:04 PM
any progress on this?

09-26-2012, 03:15 PM
put the turbo right where the other cylinder would have been. Looks cool Man!! I always wonder how much fab/modification it would take to put a blast motor into an xb chassis. It seems for the most part it bolts right up! I dig it!

09-26-2012, 05:13 PM
I'm still tracking down a wiring harness short. The pump will sometimes come on if you wiggle the wires. I'm about to just buy yet another harness.

This reminds me of the Ducati a guy turned from a v-twin to a single an put the turbo where the back cylinder was an it made more power that before with 2 cylinders.

10-10-2012, 07:52 AM
So did you put your blast engine into the xb9 or did you fit the headlight on your blast? Because I would really want to know if it is possible to fit a headlights fairing from an firebolt, lighteningbolt, or just somethin better looking. And if it is would like to know how to do it

10-10-2012, 08:12 AM
Very cool build, I just skimmed through this thread.

Gotta ask though.....if you're going to build a xb chassis why not use the big engine and get more power? 1 cylinder can't weigh THAT much can it?

JMO without really doing a lot of research on this...

10-10-2012, 09:55 AM
I hope you put an 1125 in an xb chasis for your next project.

10-10-2012, 09:56 AM
We had a blast and wanted to do something different. I can tell you, yes one cylinder less makes a huge diff. I've sat on this bike and it's light. A huge difference from my xb9.

10-10-2012, 10:03 AM
I want to see the final hp/weight ratio. Maybe you could be close to ninja 250 weight! It would make an interesting track day machine. Sometimes, less power is better.

I'd like to see a video of this passing up liter bikes in the corners....

10-10-2012, 10:05 AM
What kind of hp and torque does the blast make? I'd assume roughly half what the xb's make, right? JW if saving the weight of one cylinder which I'd guess is less than 50 lb is worth ~45hp?

Cool either way, and if it's what you want it's all good, JW for my own curiosity...

10-10-2012, 12:30 PM
The blast actually only makes 35hp, but the blast has the same bore and stroke as the 9 and has a lower compression piston. So essentially I would expect the bike to have about 40-45hp and about the same in torque and weigh about 50lbs less than a 9. But we shall see once this bike is done. I'm just going to order another wiring harness and screw messing with the one I got.

10-10-2012, 05:35 PM
My blast weighs 385 wet. I haven't had it on dyno yet, I'm waiting to install a xb head and piston with maybe some aftermarket cams.

10-10-2012, 05:41 PM
I hope you put an 1125 in an xb chasis for your next project.

@ANGRYGNOME.....that's my dream bike, power and short wheel base for handling, I'd imagine it would probably almost be to short for that rotax....

10-11-2012, 06:37 PM
email me more detailed steps if you can because i am very interested in doing the same thing. but would like a parts list and instructions if you can ind time. thank you. juanm_valles@yahoo.com

02-12-2013, 02:01 PM
Any updates on the bike?
You mentioned some extra work for the primary cover " primary cover isn't exactly a direct fit", can you let me know what you had to modify on the primary cover.
I want to make my own rear sets for my Blast and was thinking of using the XB primary cover.

02-12-2013, 07:14 PM
I've got to get the bike to a shop to do a few things for me. As for the primary cover, the shift shaft hole has to be changed out to fit, I believe I used parts from the blast to make it fit, one bolt is missing compared to the blast vs xb so you can either bypass it or have material added to the case and tapped to fit the bolt.

02-12-2013, 08:25 PM
.that's my dream bike, power and short wheel base for handling, I'd imagine it would probably almost be to short for that rotax....

Yerp... That sucker is a big 'un.
My dream bike would be an XB1125SXcr with the 1125R front fairing. With only an open pipe for an exhaust. Ha! I wonder if it's even possible to fit the damn thing inside the frame.

This build looks like it will be LOADS of fun to ride as well. I wanna see it done! With track footage!

02-13-2013, 05:03 PM
My Rat Blastard weighed in at 340lbs wet. Factory spec is 360lbs dry, plus ~21lbs of fluids to make it "wet" (17.5lbs gasoline + 3.68lbs oil). That means I've eliminated ~41lbs from the bike; although I've gained about 10-15lbs myself since the process started.

It's getting fuel injected soon to go with the XB head/piston/cams. Dyno will be shortly thereafter.

Waiting to see what this project weighs.

12-28-2016, 05:21 PM
Since this thread died, here's my progress:

Custom axle is being turned and will have it road-going by February.

Engine is EFI and runs fine (been EFI for a couple years now). Front end and electronics are all squared away. Just need to add a couple heim joints, foot controls and rear axle. Already put on a new drive pulley and have a belt fitted, just haven't taken new photo.

12-28-2016, 10:44 PM
It's cool that your still after it !

12-28-2016, 10:54 PM
have you had it dyno'd?

12-29-2016, 06:14 AM
Nice, looks like too much fun.

12-31-2016, 04:43 AM
have you had it dyno'd?

Nope. Kept procrastinating, then the nearest dyno closed shop. I've since moved and am close to some other Buell guys with a dyno and FAST Buells, so I'll be taking it there once it's ready. They're eager and waiting for me to finish, want me to go LSR with them.

This is their Blast:
Somewhere close to 80hp, if he hasn't topped it yet.

and their S2:
1250 with turbo and nitrous

They're pushing me to boost it, but I need to get it road-worthy as it sits, then I'll sort out the turbo and head for the salt.