Another ex500 swap into a pregen ninja 250

[Mauricemonge]

Hey all, I killed my ninja 250 sidecar last week after a 3000 mile trip to Colorado from San Francisco (added lots of miles going to national parks).

Anyway, I started my ex500 swap today. I struggled with how exactly to mount it in, it’s offset to the right side of the bike to make the chain line work. Because of this the carbs don’t line up well.

I luckily had another ex250 frame that I ripped every tube out of the head tube (while thrashing on my sidecar..) I measured the offset of where the sprocket was from a point on the frame, then with the bare frame, did the same with the 500 engine. I found that the lower left engine mount on the frame gave me the right chainline with the corresponding mount on the engine, but only when I removed the rubber insert.

I tried to just use that mount, but it made the engine too low (I’m slammed) and when I started measuring things closer, it really did have to have that insert in there to line up properly.

I spent a lot of time just looking at things. But I did eventually pull the trigger and weld the upper rear motor mount in - only to realize it was crooked!! I panicked, but when I put the motor back in to see how bad it was, I realized that mount has a ton of play in it, and it let me align it a bit.

I then made the front mounts. I figured I’d make them symmetrical, and they’d put the engine back in a straighter position. They did kinda, but since the engine is offset, I had to space them out using washers and nuts of larger size. It worked though.

My chain is now too short by about 6 links., I went and separated the chain, and rode it back and forth to see my chainline and to also see if the teeth were binding or grabbing. It actually looks spot on somehow.

I ordered a 41 tooth rear sprocket to go with the 15, and 4 extra chain links (was at 45 tooth while testing)

I wrapped up without actually get much done. I ordered an ex500 cooling system, my 250 was struggling because my fender blocks a lot of wind when lowered 4”+. And I’ll be using a “modified” ex250 exhaust. I plan to route them 2-1 like I had with the 250 engine, and use the same gsxr1000 can I had before.


I’ll post pictures if I can figure it out. I also plan to make a YouTube video

[Mauricemonge]

Link to original page on YouTube.


First three are just before killing my 250 engine. 1. Bonneville salt flats. 2-3 Manitou springs Colorado.
963BB6A8-995C-4873-8804-DC2873B24ABD by balletdude2000, on Flickr

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037640E1-9C6B-4F4B-9679-380EDA64B608 by balletdude2000, on Flickr

84082551-394E-4F4E-AC01-3C52E61A3AEF by balletdude2000, on Flickr

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BA8DCC46-111B-4F09-934B-74D9EC170020 by balletdude2000, on Flickr

[DannoXYZ]

I replaced the lower rubber bushings with solid mounts from FOG. It made lining things up easier since there's no play.

[jcgss77]

This is definitely an awesome thread, thank you @Mauricemonge. Can't wait to see where this goes!

[Mauricemonge]

After trying my best for some time, I realized that the ex250 pipes just won’t work with the 500 engine. I was hoping to somehow make them fit, but I broke down, drove almost 4 hours round trip, and bought some 500 headers. I will be doing a 2-1 and making the back half of my exhaust the same as the 250.

I haven’t welded in my last set of motor mounts for fear that my chain line isn’t perfect. I got the chain, but not the smaller sprocket yet, so I haven’t seen how it spins at speed.

If I had to do this over again, I’d make the very front mounts, then pivot the engine off that to make the rear mounts square. It would also allow me to space out the chain little by little. I think my motor is slightly crooked, but it seems to roll the chain well enough to not matter.


One day I’ll figure out pictures and post some.

[DannoXYZ]

Make your exhaust exit out left side so you have a stop for centrestand.

Also calculate larger size of tubing needed after 2-1 merge. Use a true merge collector.

[Mauricemonge]

Originally Posted by DannoXYZ

Make your exhaust exit out left side so you have a stop for centrestand.

Also calculate larger size of tubing needed after 2-1 merge. Use a true merge collector.

I bought a 2-1 connector from a company called cone engineering. Unfortunately I bought it for the 250, so instead of these pipes sliding in, they sit flush against them. I already welded up the 2-1 part, and just need to connect it to the rest of my exhaust. It’s a 1.75”, I didn’t do the math, but just looking at it makes me feel like it’s enough flow. The back half of the exhaust is from my gsxr 1000 that got stolen, so I feel like it’ll flow enough.

My 250 exhaust came out of the left side, the crosses over to the right. I’ll make this the same.

I wish I could post a picture, my sidecar setup doesn’t need a center stand, I use a shortened kickstand with a block of wood underneath to prop up my back wheel for chain lube or removal.

[Mauricemonge]

I finished the exhaust today, and only managed to blow through the tubing a few times.
I hooked up the new chain and sprocket, and it seemed to spin fine, so I welded up the last of the motor mounts. The throttle and clutch cables all work with the 500. The alternator plug plugs in too.

My main project now will be the cooling system. I pushed the engine so far forward that I don’t have room to mount the radiator with the fan attached. I may buy an aftermarket slim fan, or consider running it without one (not needed as much living in San Francisco).

Tomorrow I’ll try to tackle the cooling system mounting, and then work on splicing in the ignition box and mounting the coils. I may have this thing on the road tomorrow!

[DannoXYZ]

darn good progress!!!

[Mauricemonge]

Aaaaaand I’m done-ish.

Just did a first start, at first I thought the exhaust was burning out a bunch of stuff, then I thought the rings were bad (it was a race motor, it came with another rebuilt race motor). I checked my idle screws, and they were turned out just over 5 turns. I brought them back to 2.5 and it smoked less. I have an AEM wideband, but I killed it last week, and it’s like pulling teeth to buy just the gauge from them, I’ll go with another brand next time.

The radiator mounted up okay, but I had to mount it super high, and without a fan. Mounted the overflow bottle (a flask) and the thermostat and radiator cap in an awkward position, but it’ll work.

Electrical was quick and easy, but I still need to trim up some wires. I’ll probably drive it down the block in an hour when I’m done cleaning up the tornado of a mess I made in my garage.


I promised a video, and maybe a bunch of pictures, so I’ll get working on that tomorrow

[DannoXYZ]

Woohoo!!!

[Mauricemonge]

Originally Posted by DannoXYZ

Woohoo!!!

Thanks! I drove it down the block, I might drop the front sprocket from a 15 to a 14 since the sidecar with passenger(s) in San Francisco can require lower gearing.

I’m really stoked to try this out on the road. My carbs are leaking fuel so I’ll need a bowl gasket set. And my front end needs to come up at least an inch, maybe 2. I’m also making some passenger pegs from a set of Ducati monster passenger pegs someone gave me, so I can have someone on the back and on the side.

My work has been slow, so I might be able to slap a video together at work tomorrow. And eventually I’ll learn how to post pictures.

[DannoXYZ]

Let's see some photos of this sidecar!!!

Are you using airbox with EX500 carbs or pod-filtres? If you end up with intake-resonance issues and stumbling in mid-range, really helps to install 6" long intake-runners between carbs and pod-filtres.

Do you have gen-1 or gen-2 EX500 engine? Best to not rev either one over 10K.

[Mauricemonge]

I’m running pod filters on Ltd454 carbs. I never opened them up to check the jetting, after driving it today, I’m pretty sure I’m lean. I’m now afraid to open them up since they’re slowly dripping fuel. I’m waiting for my carb kit to come in before I destroy whatever gasket is left in there.

I totally have a mid throttle stumble, it’s not always a mid rpm issue, but it’s definitely there. I was thinking it’s just a lean condition, but the pod filters make sense. I’ll go through the carbs, and throw fuel at it until I can make it as happy as possible. I’ve got a new AFR gauge coming in, so I cam see exactly what’s going on and where, and see if I can’t jet my way into it being happy.

Aside from the stumble, I’m a little over geared for city riding, but the torque is good, and past the stumble area it runs like a mofo! Totally rips!!

This is a gen 1 engine. I’ll take it easy on the revving until my AFR gauge comes in. It makes so much more torque, I don’t need to rev it. I have stalled it a couple times, but I think it’s the gearing trying to go uphill. Clutch feels heavy, might not be stock.

Okay, I finally posted some pictures! See post 2 for pics.
I still want to make a YouTube video. I’m thinking of doing a quick overview for those with a short attention span, then go into me talking for 15 minutes rambling on to the camera trying to figure things out.


Lastly, does anyone know why this site is down like 80% of the time? I can’t load the website most of the time

[DannoXYZ]

Gen-1 engine has fragile bottom-end and alternator. No need to redline it, power drops off after 8K anyway.

Awesome photos, that sidecar is so cute!!

Never have problem accessing this site. Maybe something to do with your ISP?

[Mauricemonge]

Originally Posted by DannoXYZ

Gen-1 engine has fragile bottom-end and alternator. No need to redline it, power drops off after 8K anyway.

Awesome photos, that sidecar is so cute!!

Never have problem accessing this site. Maybe something to do with your ISP?

Thanks! The sidecar is rad. I slept inside of it while driving back and forth to Colorado, except when I got close to vegas it was so hot I had to sleep on top of the motorcycle, leaning over the gas tank. I’ve been rocking this thing for a little over 3 years with a 250 engine.

So no turbo with this bottom end? Bummer lol. I’ll keep an eye on my powerband. I never got above 35-40ish yesterday. I was more feeling out the jetting and making sure things didn’t fall apart. I’ll try a freeway run after I go through the carbs, or when I get impatient waiting for parts. But good to know 10k is about the redline

No idea about my isp, I’m bad with technology. I’m only using my phone, and I’ve tried using a different browser. It just says the server won’t connect. Oh well.

[Mauricemonge]

Carb update:

I opened them up when I found out they use the same gasket as the 250. Someone they didn’t leak last night, and the gasket actually looks decent. It’s got a 40 pilot, and a 145 main. Looks like some jetting was done for the pod filters and whatever exhaust was on the 454. I’m now confident I won’t melt yet another piston, and I’m going to take it for a 100 mile round trip to San Jose and back.

When I get my O2 sensor gauge I’ll start messing around with jetting, pod filter spacers, etc.


Post trip update. When I put my pod filter that fell out back on, it ran much better hahaha. It’s actually not bad overall. I think I won’t touch anything until I get that gauge. My top end power seems to be a little lacking, but the torque is amazing. I also like that I can cruise at 6000rpm, and the offset engine gives me weight over towards the sidecar a little.

[Mauricemonge]

As promised, I made a video of the whole swap (see second post). Unfortunately, it doesn’t want to play directly off the forum site. But the link works.

It’s a bit long and I talk too much. But there’s some mild doughnut action in the first minute.

I also loaded a few more pictures

[Alex]

Originally Posted by Mauricemonge

As promised, I made a video of the whole swap (see second post). Unfortunately, it doesn’t want to play directly off the forum site. But the link works.

Youtube link edited; pic links cleaned up. To have it show you need to put only the youtube video ID in between the youtube tags, not the whole URL. On the pics you double-embedded IMG tags, I just removed the outer ones.

Link to original page on YouTube.

[Mauricemonge]

Originally Posted by Alex

Youtube link edited; pic links cleaned up. To have it show you need to put only the youtube video ID in between the youtube tags, not the whole URL. On the pics you double-embedded IMG tags, I just removed the outer ones.

Link to original page on YouTube.

Awesome! Thanks for your help. I’m bad with technology a lot of the time.

[Mauricemonge]

Originally Posted by DannoXYZ

Let's see some photos of this sidecar!!!

Are you using airbox with EX500 carbs or pod-filtres? If you end up with intake-resonance issues and stumbling in mid-range, really helps to install 6" long intake-runners between carbs and pod-filtres.

Do you have gen-1 or gen-2 EX500 engine? Best to not rev either one over 10K.

I finally got an AFR gauge back on it. I pulled fuel from the idle, and my moderate stumble got even worse. I think whoever had the carb tinkered with ran the idle rich to compensate for it. My wide open throttle is a hair leaner than I want it to be, even with these 145 main jets (130 is apparently stock).

I ordered some tubes as you said. I might also run a 2-1 large pod filter like I did with the 250 (k&n RC-3510 is what I’m thinking). The similar one I had on the 250 did a good job of evening out airflow.

Aside from the lean stumble, this thing rips.

I did have an electrical issue, while cranking it struggled greatly, and seemed like it dropped voltage. I pulled the cover off and some of my magnets had self destructed, grounding out my stator. I have a freshly rebuilt 500 race engine that I swapped parts with.

I’ll take the sidecar to the drag strip when I get the tuning stuff worked out.

[Mauricemonge]

Oh boy, I’ve been down a 2 day adventure trying to tune with pod filters.

DannoXYZ I installed 6” of runner tube between the pod filters, but I don’t think it helped much. I’m still running them anyway, they probably help overall. I may take them off to see if there’s a difference.

Not to bore with the details of how I found the compromise of making it work. But I was struggling with a 1/3 throttle lean out around 5-6,500 rpm. It would lean out to 16.5 and get choppy.

I ended up using my ex250 needles with two shims underneath.
The carbs are from an LTD454 so the slides and spring are apparently different. The slide had already been drilled out to 3mm.
I used a 140 main jet, 40 pilot, 1.5 turns for the idle screw.

Seems to run great! A slight lean out (14.5 AFR) around 4000-5000 rpm between 1/3-1/2 throttle, but it corrects itself quickly. It backfires on deceleration a bit though, I blew up my muffler a week ago because of backfires. But I jb welded it back together.

Drag racing this Wednesday!

[DannoXYZ]

Originally Posted by Mauricemonge

Oh boy, I’ve been down a 2 day adventure trying to tune with pod filters.

DannoXYZ I installed 6” of runner tube between the pod filters, but I don’t think it helped much. I’m still running them anyway, they probably help overall. I may take them off to see if there’s a difference.

Not to bore with the details of how I found the compromise of making it work. But I was struggling with a 1/3 throttle lean out around 5-6,500 rpm. It would lean out to 16.5 and get choppy.

I ended up using my ex250 needles with two shims underneath.
The carbs are from an LTD454 so the slides and spring are apparently different. The slide had already been drilled out to 3mm.
I used a 140 main jet, 40 pilot, 1.5 turns for the idle screw.

Seems to run great! A slight lean out (14.5 AFR) around 4000-5000 rpm between 1/3-1/2 throttle, but it corrects itself quickly. It backfires on deceleration a bit though, I blew up my muffler a week ago because of backfires. But I jb welded it back together.

Drag racing this Wednesday!

Awesome progress!!! Add 1/2" crossover tube connecting 2 intake runners about 1/2-way.

[Mauricemonge]

Originally Posted by DannoXYZ

Awesome progress!!! Add 1/2" crossover tube connecting 2 intake runners about 1/2-way.

That would totally be the way to go! I almost bought a k&n 2-1 filter rc3510 to put at the end. I ran a similar one on the 250 and it was really helpful with tuning since it gives kind of a little plenum to even out some pulses.

I sadly haven’t welded aluminum before. But I bet I could jb weld a crossover tube.

My AFR’s aren’t perfect, but it’ll work. Here’s what they are.
Idle 14.0+/-
Coasting (low, med, and higher rpm) 12.5ish AFR
Accelerating low 11.8-12.2
Accelerating medium 12.5-13.2
Accelerating high rpm WOT 13.2 (richer at lower rpm WOT)

The only lean I have is between 4-5000 rpm and 1/3-1/2 throttle. It’s not for long, and it only leans out to about 14.5 afr.

I actually can’t believe the ex250 needle worked so well. It’s so different from the 454 needle that was in there. I had bought an ex500 carb kit, and the needle that it came with was shorter and had some taper to it, but still very different than the 250

[DannoXYZ]

Personally I would lean out low-throttle/low-end for more power and speed. AFR of 14.5:1 at 33-50% throttle is OK. On turbo engines, I prefer it around there for hottest mixtures to spool up turbo quicker. On NA engines, @ 75-100% WOT, I like 13.5:1 where max-power is made.

You can braze aluminium together easily with lower-temp soldering rods. Works pretty well and just as good as welding for something like this: https://alumiweld.com/

Trick is to mark the joint with black soot 1st. Run torche with no oxygen for smoky flame and coat joint with it. Then turn on oxygen and when all soot burns off, joint is at proper temp. Then apply brazing rod.

Actually, make it a 1" crossover pipe. EX500 engine has 360-degree crank vs. 180-degree on 250.

[Mauricemonge]

Originally Posted by DannoXYZ

14.5:1 at 1/3-1/2 throttle is OK. On turbo engines, I prefer it around for hot mixtures to spool up turbo quicker. On NA engines, @ 75-100% WOT, I like 13.5:1 where max-power is made.

Okay sweet! Good to know.
The lean only happen for about a second when I tip into that throttle and rpm area. I forced it there by bogging the engine over geared and it lasted about 2 seconds before correcting. I’ll leave it as is for a bit, but I could also experiment down the road

[DannoXYZ]

Yeah, that's where acceleration-pump feature comes in. On EFI systems, I usually give +15% when TPS-velocity is higher. +20% when velocity highest. Some systems have 4 levels of accel-pump with programmable duration. Haven't really needed that fine of control really, little squirt's fine for momentary action. Not even sure it makes much difference, but a little ping & here and there can get customers panties in twist...

[InvisiBill]

For whatever it's worth, I ran into a lean spot around 6-7k when I put slipons on my EX500. It would actually sputter like I was running out of gas, even though it seemed fine elsewhere in the range and before the exhaust change.

I assumed that was just the leanest spot in the stock setup, and my change had leaned it out enough that it became noticeable. I switched to adjustable Factory Pro needles using the second slot, and it seemed to be a great fix.

One of the forum oldtimers stated that a lean spot there was indicative of the valves needing to be adjusted. However, I had never heard that mentioned previously, in many years of hanging out there, even though he made it sound like common knowledge. This doesn't seem too likely in your case, but it might be worth checking.

[Mauricemonge]

Originally Posted by InvisiBill

For whatever it's worth, I ran into a lean spot around 6-7k when I put slipons on my EX500. It would actually sputter like I was running out of gas, even though it seemed fine elsewhere in the range and before the exhaust change.

I assumed that was just the leanest spot in the stock setup, and my change had leaned it out enough that it became noticeable. I switched to adjustable Factory Pro needles using the second slot, and it seemed to be a great fix.

One of the forum oldtimers stated that a lean spot there was indicative of the valves needing to be adjusted. However, I had never heard that mentioned previously, in many years of hanging out there, even though he made it sound like common knowledge. This doesn't seem too likely in your case, but it might be worth checking.

Someone recommended factory pro needles on the 500 forum too. I never checked my valve adjustment. It feels like it runs great with the ninja 250 needles, I may just leave it as is for now.

I do have a misfire at idle, but I’m pretty it’s one of my coils since it followed it when I swapped them yesterday. They’ve got over 100k miles on them so it might be time for a replacement set

[ducatiman]

"Someone recommended factory pro needles on the 500 forum too."

now who could that have been, eh?

[Mauricemonge]

Originally Posted by ducatiman

"Someone recommended factory pro needles on the 500 forum too."

now who could that have been, eh?

Lmao! I didn’t see your signature until now hahaha.

I took it to the track yesterday, but didn’t realize there was no drag racing because someone had rented out the track. I did however hit about 101mph on the way back. Runs great through all the rpm when warmed up. I feel like there could be a bit more top end, but it could just be the drag on the sidecar.

[Singh2jz]

MAURICE!!!!!! It’s me!!!

Love that you posted the build here!! Deserves more exposure!