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RC8R engine in my 990smr - am I nuts?

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23K views 40 replies 14 participants last post by  prestige-boy  
#1 ·
I love my 990smr but I do want more power. Don't want a Superduke 1290 and I've had an RC8R and prefer the upright hooligan riding position of my SMR so...

Here's what I was thinking-
1- find a 2010-2011 single spark RC8R engine for sale (that's got to be easier than going with the later dual spark engine, right?)
2- use my 990 fuel injection on the rc8r engine and add a power commander and custom dyno tune (I realize this isn't ideal for performance as the rc8r has larger throttle bodies but with a custom tune and an open Rottweiler air box, I'm hoping I can achieve what the engine needs)
3- use my 990smr exhaust headers as I don't want to run an under-belly exhaust system from the RC8R - I already have aftermarket mufflers in place
4- use my 990smr radiator as I've got a dual fan setup ready to go - the rc8 does use a larger radiator and I believe I've got the physical space for it but I'd rather avoid it if the plumbing is the same or similar between the two engines / radiators
5- use my 990smr dash, ecu, etc - I don't want to start swapping electrics if I can avoid it
6- I assume I'll have to build or buy new upper front engine mounts to hang the engine properly in the frame
7- I assume the rear of the engine will bolt right into my frame and swingarm pivot mount points (assumption comes from I've read of others installing these engines into 950/990 adventures) so I believe the two engines are identically dimensioned at the rear and the chain alignment will be correct as well.
8- I assume I won't have any clearance issues up front as the oil tanks are quite similarly dimensioned in the rc8r engine and my 990smr engine (the 950/990 adv oil tank is quite different up front) and my bike is "open" up front unlike the 950/990 adventures which have limitations for clearance.
9- I assume that the rc8r's oil cooler will not cause any clearance issues as it is in a spot on the right lower front area of the engine that is far enough away from my fuel tank (this is an issue when attempting this on the 950/990 adventure)
10- I have made no assumptions with respect to the exhaust yet - will my exhaust headers bolt onto the rc8r heads? Will my front header clear the front of the engine since it runs underneath the engine like the 1290 Superduke as opposed to the side of the engine on the 950/990 adventures...
11- I assume my fuel injection system will physically bolt onto and in between the Rc8r cylinders
12- I don't know if I'll need to run a different ignition flywheel / sensor magnet pickup, etc.

Assuming I can source a low mileage RC8R engine, I have to believe that this will net more performance than any tuning I can perform on my 990smr engine with bolt on parts and custom tune / ecutune load. You can't replace displacement and the rc8r has some fantastic cylinder heads and camshaft profiles.

Any thoughts on my assumptions? Have I forgotten anything or other considerations?

Any input would be greatly appreciated - I've got all winter long to proceed if this makes sense and if I can locate the right donor engine.

Thanks everyone
 
#3 ·
Street fighter an RC8? Explain please and as for butchering the SMR, if I have to cut or weld anything, I won't proceed.
 
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#4 ·
Its a great idea. I'd be surprised if you end up with an otherwise unmolested SMR that's simply got an 1190 engine in it though. I reckon there might be more modifications required than that and it'll be in for a penny, in for a pound and no going back.
Why would you use the 990 throttles and pipes? Cost? If the engine will fit the throttles ought to fit as well. I doubt you'll get the best from the engine without the correct breathing apparatus.
If you're going to source an engine you might be better to source a 990 frame as well. No reason why it wouldn't work But if you compromise the engineering to fit the budget you'll end up with a compromised result.
Without a lot more research and a lot of measuring I couldn't say but my instinct is that this is a complete one-off build here, not a straight engine swap. Doesn't mean its not worth doing though. I'd love an 1190 SMT. But if you start off with the idea that your original SMR is sacrosanct you may be tying one hand behind your back.

Funnily enough I was in a KTM dealership today getting some bits and I was chatting with one of the sales guys about the GT and saying that I'd be booking a back to back test ride on the GT against the SDR in the spring. I don't buy the idea that the GT is cast in the SMT's mould, its a completely different concept. I was thinking how much fun it would be to have that engine in the SMT and I threw a leg over their demo 1290 SDR and it struck me how close the SDR is to the SMT already. Its a light, uncomplicated hoon bike with a little bit of comfort. And I was thinking if I could afford to start customising a 12 grand bike how easy it would be to SMT-ise an SDR with a small screen and some underseat pipes...
 
#6 ·
So Locul and the other guy on advrider both installed rc8 based engines into their KTM adventures (950/990) which presented all sorts of issues that would not be the case with the SMR:
1- the adventure exhaust is plumbed alongside the right of the engine versus the rc8 engine which plumbs it down and under - this down and under is already the case with my 990smr (notice that KTM located the exhaust under the engine on the 1190 adventure). This down and under plumbing has to be done due to the oil cooler that is integrated into the engine casing on the right side (which prevents the "alongside" method) so I'm hoping that as long as my 990smr headers will bolt onto the rc8 heads, exhaust should not be an issue
2- the centre stand conflict on the 950/990 adventure is a non-issue for me on my 990smr as I don't use a centre stand
3- the issues that Locul had with the clearance of the oil cooler and larger rc8 radiator were related directly to the 950/990 adventure fuel tanks - again, this will not be an issue on the 990smr as it doesn't have the large side mounted fuel tanks that drape over the sides and cover much of the engine
4- Locul experienced a ton of electrical issues relating to the need to rebuild his 950 adventure wiring harness to work with the rc8 ecu and array of sensors - this is largely due to the fact that his bike was carb'd and non-immobilizer based. My 990smr is fuel injected (uses the same idealogy of O2, air temp, etc sensors) as the rc8 and part of why I want to reuse my fuel injection is to avoid having to change wiring and immobilizer systems; just bolt my injection on and custom tune for as ideal of a tune state as possible. This is also the reason why I think my conversion would be more simple using the RC8R single plug engine rather than the later (2012 and up) dual spark engine which also used a different (and heavier) flywheel.
5- the rear section of trellis on the adventure frame that Locul had to cut and modify does not exist on my 990smr - I'm assuming that takes care of that complication
6- engine mounts: Locul chose to cut his front engine mounting tabs and weld on tabs that aligned more closely with the RC8 engine. My approach would be to not cut and weld anything but rather to design and build new mounts that replace my current cast mounts that connect the frame to my current engine.
7- I also saw the trimming that was required to the engine casing where the swingarm bolts on; I assume I'd have to perform the same narrowing to my donor RC8 engine as well but from what I can tell, it's only a few millimetres of reduction, I can get a local machinist to shave that off the casing without too much fuss
8- apparently, the rc8 radiator uses two connections on the upper left side versus my 990 single so I'd either have to devise a 2-1 hose adaptor if I am using the 990smr radiator or change it to the rc8 radiator if room allows - this is one thing that is probably easier to achieve on a conversion on an adventure as their suspension travel and rake take the front wheel further away from the front of the radiator where on my 990smr, there isn't much room. If the rc8 radiator had to be moved forward (toward the front wheel) for clearance due to its extra height, I could potentially run into a radiator/front wheel clearance concern. Then again, I could always look into adding more capacity to my current 990smr radiator but then again, I do plan to use dual fans on my 990smr anyhow.

So (and this is a big so) if I didn't have to modify my 990smr frame and I didn't have to rewire anything and my exhaust works on the rc8 engine, what else would I need to worry about and would you agree based on above that this engine transplant seems to be more simple than what Locul underwent?
 
#10 ·
I've seen that vid on the 950sm rc8 engine conversion - very impressive performance, I just haven't seen any threads anywhere that cover off the details of e conversion itself though I think I did find out somewhere that he's in Germany. As for the RC8 streetfighter thing, it's not for me. I like the rc8 the way it is but I love the upright comfort of my 990smr and its bars/seat/etc.
 
#9 ·
Yes, well two things first:
1- try to validate my assumptions and see if there's anything I've missed
2- find the right donor engine for my transplant (and I do prefer an RC8R 1195 engine vs the RC8 non-R 1190 engine)
 
#12 ·
So I've been speaking with two guys on advrider.com who have done this on their 950 ADVs and one of them had now confirmed two things that disappoint me:
1- the front engine tabs on the 990smr frame (as with the adv frame) must be cut to clear the alternator cover on the rc8r engine; cutting this frame tab is unavoidable
2- one section of the trellis toward the background the rear cylinder will need to be cut and modified to clear the rear cylinder head, both sides will need to be cut if using a dual spark rc8r engine

I don't think I'd proceed if I need to cut my 990 SMR frame - I'm not going to bastardize my bike. Damn!
 
#13 ·
As long as you don't put any form of red bull waste can on it like the above example....

Mate - such a bold thread to stop at cutting off some wee frame tabs. Pussy. There is nothing less stressful except matching the paint codes...

Even my Honda I ended up cutting off steering stops and making new ones, so to balk at frame tabs is so gay!!! Just sayin'

Do IT!!!! We want to see this!! :D Great idea - don't let some frame tabs stop you!!! "Not going to bastardise your bike"? A 1190 transplant no matter what will do that for you sir :)

Great idea, don't stop! :D
 
#14 ·
LOL - so now I'm gay because I don't want to butcher up my frame? I'll keep investigating. Cutting some tabs off may not be a big deal but I want to see what really needs to be done out back with removing and replacing one of the trellis sections - that is more extensive than just cutting tabs.
 
#19 ·
#23 ·
Although the price they're asking for this frame is actually only about $150 less than one brand new from the KTM dealer. Need to find a cheaper frame if that's what's hanging me up the most on this conversion...time to shop for a used one in the UK given how often I'll be there for the coming months. I assume the 990sm, 990smr and 990smt all share the same frame apart from the colour.
 
#20 ·
#21 ·
#22 ·
#25 ·
You cannot buy a frame from KTM unless you trade in the headstock of the old frame. Stops people stealing a bike and fitting a new frame.

That is also the reason why legit used frames are expensive, cheap way to get a bike if you are that way inclined :mad:
 
#26 ·
Been thinking more about this concept of having an extra frame to use to build this up and trying to be honest with myself as to why I feel I need this extra frame. There's a part of me that thought I'd like to be able to put the bike back to stock and so cutting and modifying the original frame worried me. The truth is that unless I decided to sell it, I don't know why I'd ever put it back to original so I don't really need the frame at all. The only value it would have then would be to be able to build it up while continuing to ride my bike. If I can source everything I really need quickly enough, I'll have until April 2016 to build the bike and then use April to debug and tune it. So at this point, I'm waiting to hear back about the actual engine in the link I've provided above and for confirmation from anyone that using my 990 SMR fuel injection bolted into the rc8r engine is the right approach.

I've had a chance to take a closer look at my bike this morning and I can see why I'd have to trim the front engine mounts tabs on the left side and why I would need to modify one of the vertical trellis sections near the rear cylinder on the right side of the bike - both of those areas are going to create conflicts with the RC8R engine. Shit!

And yes Kevin, what you say about KTM's policy for selling replacement frames makes perfect sense, thank you for confirming.
 
#41 ·
alon said:
I've provided above and for confirmation from anyone that using my 990 SMR fuel injection bolted into the rc8r engine is the right approach.
Click to expand...
The single spark 1190 engine was known for poor mixture that's why they moved to the dual spark system on the later models . The extra velocity of the 48mm bodies may help this plus you can always have them bored out to 50mm . I think the 48s will be fine with all the secondary's removed and setup properly
 
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#27 ·
People put RC8 throttle body assemblies onto LC8 motors, so they have to work the other way too.
But the reason they do it is to get more fuel in, so does that mean the LC8 throttle bodies wont be up to the job of getting full power out the RC8?

Also forget about putting the bike back to standard, you will never do it. I have been involved in modifying bikes for decades. All you end up is loads of parts sitting at the back of your garage for ages, then sell the project as is. If you are lucky the parts you took off come back into fashion, if not..... you have lost the opportunity to sell parts from a current model at decent money.

Why not buy a cheap hack, then set to with your bike. It's doable... so do it!
 
#30 ·
If I can run the RC8R fuel injection / throttle bodies using the 990 SMR ECU (with help from a power commander / bazzaz), then I have no issue using it - I just figured that the 990 SMR assembly would be the easiest approach even if it's not entirely ideal for sheer power output.

As for putting the bike back to stock, you're right; I don't know why I'd ever do it. In fact, if I'm not ever going to restore it then I can sell my 990 SMR engine to help fund this project.
 
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#28 ·
Or buy a tatty second 990 cheap as poss as a doner bike. Convert that and if you're happy with the result sell your SMR to cover the cost.
Also what about fitting the 180 bhp race kit while you're at it. If I had an engine on a bench I wouldn't be able to resist blue-printing, balancing, porting, skimming, cam dialling etc. And you know you've got a brand new engine.
 
#31 ·
I've seen one single 990 SMR come up for sale within 500 miles of me in the last three years and I bought it so finding another around here is going to be nearly impossible. As for the race kit, no need - I'm not looking to make a full 180hp but a reliable 150-160 with a good smooth tune would be just fine.
 
#32 ·
Buy one already done? They don't exist. The easiest path would be to buy a used Superduke 1290 but where's the fun in that? For me, it's more about the project and doing it rather than just having the end result - call me a masochist :)
 
#34 ·
Who or what is Wazza and what is being sold, an RC8R engine? If yes, where is Wazza located?
 
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