Thumper Club Forum
Club House => Chatter => Topic started by: Propellor on July 09, 2015, 10:29:52 PM
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Thinking of grafting an xbr engine into an rs frame.
Should I see a psychiatrist?
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Nope, but anyone buying a new R1 or big beemer for £15 grand plus, probably should! There is loads of members on here seem to have achieved same successfully :)
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Nope, but anyone buying a new R1 or big beemer for £15 grand plus, probably should........ :)
;D ;D ;D
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500cc into RS250 has been done several times and is supposed to make a great bike - I believe Steve H had one. I haven't seen one with an XBR engine, it's usually done with an FT or XL engine rather than an XBR. I'm not sure where/how you would site the oil tank - the XBR has a dry sump - but it's probably do-able.
I've seen an XBR in a Brit single rolling chassis - Matchless or AJS? - and that looked pretty cool.
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I think if it could be done it would make a great bike.I've thought about it a lot but don't have the mechanical nous to do it myself unfortunately.Another problem could be getting it insured as we know only too well insurers don't like modified bikes.When i am out on my RS i often think :if only this had an XBR engine and when i am on my XBR i often think : if only this had the (lack of ) weight of the RS!
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I don't think that the XBR engine will bolt in like the XL/FT engine.
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I don't think that the XBR engine will bolt in like the XL/FT engine.
Well, yes and no!
Got the rs injun out and popped an empty xbr injun in. The frame needed tickling literally only 1mm off the area where cylinder head touches on a seam weld on the frame.
The "yes" bit: the rear engine bolts line up perfectly. In she goes, easy as you like. Sprocket alignment good. Not worrying about the front mounts as I expect to remake these anyway. Besides I have ideas regarding stiffening the frame. This is looking good, but then......
The "no" bit: stepping back to get the bigger picture the cylinder looks too upright. Not the same angle as in the xbr. First thoughts are that you could go with it like that but it doesn't look "right" and I think I'd like to get the engine laying at the same orientation as it does in the xbr for practical reasons too. Don't want to risk any lubrication issues. So, that means some reworking of one or both of the rear mounting plates. Ok, so be it. In for a penny......
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We have the thecno oligy. (I think) :) ;) ;) :o
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I think if it could be done it would make a great bike.....
..........if only this had an XBR engine and when i am on my XBR i often think : if only this had the (lack of ) weight of the RS!
Here's the rub. The RS frame is clearly very light. Skimpy! But looking at the robustness of the bottom end of the RS engine it seems fair to conclude that they made this a semi stressed member, contributing to the frame stiffness. So, would one risk simply dropping an xbr engine in there without putting some metal around it? Personally I wouldn't risk it. The frame rigidity might be compromised and you might risk cracking the engine case?
So, for me, the solution is to add framework between the front and rear of the engine. This adds weight. Maybe I can remove weight elsewhere to compensate a little? We'll see.
But then you look at the forks and think mmm, bit flimsy for the higher speeds and I'm looking for an ace handling bike anyway. Then the brakes.... Etc. next thing you know, you end up with a bike the same weight as the xbr!
Don't get me wrong, I'm going ahead with this regardless. But you see my point? Tbh, I'm really looking forward to getting stuck in.
Still not decided fully, but this bike may be for track use only.
My train of thought is to go more modern with the running gear. Better strength to weight ratio and lower unsprung mass. But we'll have to see how things pan out. I have other projects running at the same time!
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At the risk of repeating myself, before you get too far into it, where are you gonna' stick the oil? You need a resepticle for around 2 ltr (1600ml refill). I don't know the RS frame, but could you convert the top tube into an oil tank?
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At the risk of repeating myself, before you get too far into it, where are you gonna' stick the oil? You need a resepticle for around 2 ltr (1600ml refill). I don't know the RS frame, but could you convert the top tube into an oil tank?
I'd casually brushed aside the worry of what to do with the oil. ;D
There is enough space under the seat for an ally or stainless tank. The oil in frame idea is good, but probably a step too far for me at this stage. You'd be getting into out and out frame building. Something I'd love to try, but not yet. So it'll be a tank under the seat. I'm lucky that I can now get to look at an ikuzawa on a regular basis, so hopefully I can glean information from that.
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I'm lucky that I can now get to look at an ikuzawa on a regular basis, so hopefully I can glean information from that.
Not GC's Ikky per chance? ( may well be there's only 3 in the country!!).
The Ikuzawa used the engine as a stressed member with no lower frame rails and that Mr 'arris knows a thing or three about frame making!
As for uprating the frame/forks, the Rs500 seems to work well with the standard rolling gear with the FT/XL engine and I wouldn't have thought the XBR lump would be much different weight wise.
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I'm lucky that I can now get to look at an ikuzawa on a regular basis, so hopefully I can glean information from that.
Not GC's Ikky per chance? ( may well be there's only 3 in the country!!).
The Ikuzawa used the engine as a stressed member with no lower frame rails and that Mr 'arris knows a thing or three about frame making!
As for uprating the frame/forks, the Rs500 seems to work well with the standard rolling gear with the FT/XL engine and I wouldn't have thought the XBR lump would be much different weight wise.
Yes. GC's ikky. My brother bought it last year.
Yes, I was looking briefly at the fact that Harris didn't use the lower front hole. But as to the extent to which the Harris frame relies on the engine to assist in rigidity, that's another thing. I have a pretty firm idea of the way I'm going to add to the frame. I'll post up photos once I get going.
Running gear. Well you have ask why the xbr ended up the weight and size it did. True, to an extent it is to build a bike the physical size people expect, I suppose, but also because a faster and heavier bike needs forks and wheels of a, certain size to properly fulfil the role.
The main attraction to what I want to do is just to stretch my abilities a bit and have some fun both building and riding the thing.
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Running gear. Well you have ask why the xbr ended up the weight and size it did. True, to an extent it is to build a bike the physical size people expect, I suppose, but also because a faster and heavier bike needs forks and wheels of a, certain size to properly fulfil the role.
The main attraction to what I want to do is just to stretch my abilities a bit and have some fun both building and riding the thing.
There's about 20kgs diference between them - 136kg for the RS against 157kg for the XBR. Some of that will be the 2nd silencer on the XBR and oil tank & plumbing so not that much really. I suppose part of it was that the RS was around when we still had the 250cc learner laws so may be it was made on the slim side so that once you passed your test and got the 500 it felt like a 'big bike'.
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The Ikuzawa used the engine as a stressed member with no lower frame rails
So did Tigcraft, Hagon, Spondon and many others
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The Ikuzawa used the engine as a stressed member with no lower frame rails
So did Tigcraft, Hagon, Spondon and many others
With the engine removed, the standard RS frame would be as stiff as these others?
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......There's about 20kgs diference between them - 136kg for the RS against 157kg for the XBR. Some of that will be the 2nd silencer on the XBR and oil tank & plumbing so not that much really. I suppose part of it was that the RS was around when we still had the 250cc learner laws so may be it was made on the slim side so that once you passed your test and got the 500 it felt like a 'big bike'.
Very true. It was also out at time when the two stroke ruled in terms of power to weight. So maybe Honda did everything they could to reduce weight on a budget.
20 kg difference is a lot. If I ended up adding 10kg to the RS standard weight I'd be pretty happy I think.
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Had an opportunity to spend an hour on looking at the fit of the injun.
Removed the top rear engine mount bolt. Kept the bottom rear engine bolt in place. Pivoted the engine forwards until the cylinder fins were about 10mm off the down tube. The angle of the cylinder is not quite the same as in the xbr frame, but almost. This looks very reasonable as a solution. It means the top rear mount plate needs re fashioning.
The bonus is that the top mount lug on the head now misses the frame by a mile.
Made a few cardboard templates for some ideas I have for strengthening the frame.
Feeling good about it. Will be a long haul, but hopefully will yield something radically different.
Ps. Note to self. Remember to allow for an oil tank!
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The Ikuzawa used the engine as a stressed member with no lower frame rails
So did Tigcraft, Hagon, Spondon and many others
With the engine removed, the standard RS frame would be as stiff as these others?
Difficult to say, they are very different designs but with the engine in they will all be much stiffer.
My engine was tilted slightly further forward without any issues, if you tilt it too far then you may have problems with insufficient oil in the 'buckets' for the cam.
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If anyone could explain how one gets photos direct from i pad onto here I could show progress.
Cheers chaps.
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Here here, it wud certainly make life easier for the techno logically challenged among us (me in other words) cheers
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Ps. Trust me when I say you,ll want to see the photo,s of the mock up. It,ll be an "interesting" looking bike when it,s done
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What to do with the buckshee rs motor?
Thinking of making a full ally frame. Mono shock.
Thinking of selling beemer to fund it.
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What to do with the buckshee rs motor?
Thinking of making a full ally frame. Mono shock.
Thinking of selling beemer to fund it.
You want to look at some of the alloy beam framed 125 race reps, - the Cagiva Mito 125 was popular for fitting an SRX600 engine in - great frame and brakes, light weight with a big thumpy engine!. You might be able to pick up a rough blown motor example fairly cheap.
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What to do with the buckshee rs motor?
Thinking of making a full ally frame. Mono shock.
Thinking of selling beemer to fund it.
You want to look at some of the alloy beam framed 125 race reps, - the Cagiva Mito 125 was popular for fitting an SRX600 engine in - great frame and brakes, light weight with a big thumpy engine!. You might be able to pick up a rough blown motor example fairly cheap.
Cheers Steve. I'll check that out. Even if I go with making the frame I'm still looking for running gear from something light.
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How about this Prop!
(https://lh3.googleusercontent.com/-T0f6V3ggv24/VcthRy86mwI/AAAAAAAAAiI/LjcIQhpKZKA/s640-Ic42/IMG_20150812_0002.jpg)
XBR engine in RGV rolling chassis!! Nice!!
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Yes tis indeedy Steve, not so sure about the very 90's colour scheme tho. What were people on back then?? Oh yeah aceeed was,nt it. Thanks for posting it tho, shows what ya can do with a bit of imagination eh. Take note PROP. ;) ;) ;)
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It's the business ain't it. Lovely thing.
My own personal style is less plastic, in fact no plastic! But the idea of an xbr injun in a ally frame and decent running gear really appeals. Thanks for posting that .
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that is nice. It reminds me of a Spondon chassised XBR that I guy called Brett Randel used to race in the early 90s - he swore that it wasn't actually pink.
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Wow a spondon framed XBR, now that I would love to see. I was lucky enough to be in the right place at the right time last year when graham was selling his Harris framed ikuzawa which in itself is a thing of beauty but I,ve always had this thing about spondon and then later the martek frames. Just love em. Crying shame both companies no longer trade. (As far as I,m aware) don't suppose you have any photos of the spondon?? Cheers Michael
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Edit.
Links deleted.
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Aaaarrrrrr what is this twin stuff I see before me?? It,s the work of the devil I tell thee. Thy engines overflowath with pots. Banished I say, banished. Nothing on the links anyway, just the opening page of the aaaarrrrr gpz, there I said it, forum
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Oops.
They were pictures of my mock up xbr/rs. I can get photos (of any file size) onto that site, direct from i pad no problem.
Thought I'd found a way, but scuppered. The photos have disappeared. Best laid plans. Doh!
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Haven't we been through this about a year ago, the XBR engine is a pain in the arse to fit into an RS frame, and it looks odd, but that last bit is just my opinion. the FT/XL500 engine is a much easier conversion. The reason I did mine was because at first glance it looks like a tricked up RS250 but when you're still on the back wheel in third it kind of gives the game away. There's a couple of videos on youtube now of RS500s including my own
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Haven't we been through this about a year ago, the XBR engine is a pain in the ******* to fit into an RS frame, and it looks odd, but that last bit is just my opinion. the FT/XL500 engine is a much easier conversion. The reason I did mine was because at first glance it looks like a tricked up RS250 but when you're still on the back wheel in third it kind of gives the game away. There's a couple of videos on youtube now of RS500s including my own
I'm not attempting it because it's easy. The opposite tbh, I'm enjoying the challenge. It's early stages yet, but the mock up looks pretty cool as far as I'm concerned. It did look a bit odd when I first dropped it in, using the two rear mounts. But with these mounts aligned the cylinder was too upright and looked slightly odd, as you say. So I disregarded the top rear mount and tipped the engine forward until it looked right. Ill be able to spend an hour or two more on it tomorrow night. I'm well buzzed up about the challenge.