RD engine into CR125 (Update;listen to that pipe!)

[billy]

I think I'll abandon the 125 racer project (at least for now, maybe I'll do more on that one later) and build myself an offroad RD. I like the CR, it's a blast to ride, but the CR engine is just not durable enough for me. It's great fun but let's be honest, it's a piston chewing b**tard.
And on top opf that, the whole engine is WAY worn out. There's basically NOTHING else then the spark plug worth saving from the CR engine. Every goddamn part inside it is crap.

So out goes the CR engine, and in goes the RD engine.

The CR frame had 15 mm swinger pivot, the frame was also 20 mm wider than RD, so two 10 mm plates with a 12 mm hole in each, and then some welding and it's spot on.











I decided to use the swinger I was going to build for the racer RD, I'll just add an extra shock mount and use it as a conventional swinger (the triangle thingy is good for extra stability, but I won't use the upper shock mount, though it'll stay there as I might use the swinger on an RD later).

Anyway, here's the first weld on swinger, (well, except for the little ones at the rear of each tube) I'm very pleased as the welding machine is rather hard to deal with, and I havn't been welding since God knows when:



This gives you an idea of how it'll look once done:



Hey hoe...

[Norbo]

You seem to have a good handle on things and your welding is excelent

[rich]

I was going to say the same, 10/10 for ingenuity

[billy]

Thank you guys, warming words.

I've come this far with the swinger, it looks pretty good, HOWEVER! I had a slight warping issue when welding. The swinger is not perfectly straight so the swinger pivot doesn't go in without a bit of force, so I'll have to straighten it up and then make a proper jig for it as I do the final stuff. I can't say I Didn't expect a bit of warping, (it pretty much always happens when mig welding bigger stuff) but I was hoping the build would go more smooth than this.

Oh well, I'll see what I can do about it, it shouldn't be very hard to straighten it as I havn't yet added the two tubes that closes up the triangle shape of the swinger.



EDIT: I just fixed it, it wasn't very complicated, I was lucky enough to be able to use the CR frame as a "bending tool". ;D

[snowbound]

Is that supposed to be a sub box its stood on?

[lovelydog]

Jun 15, 2012 22:02:15 GMT 1 snowbound said:

Is that supposed to be a sub box its stood on?

I reckon it's a wooden sandblaster. ;D

[billy]

Jun 15, 2012 22:02:15 GMT 1 snowbound said:

Is that supposed to be a sub box its stood on?

Haha it's actually a speaker box I built for the basement. I didn't want to have my better speakers down there because of the moisture so I had to build something.
Come to think about it, I never finished the speaker, neither did I take the better speakers up to my room.

Btw I havn't done jack s*it to the bike anymore, (I've added the upper shock mount though) the work takes too damn much energy out of me so I'm pretty much just working, eating and sleeping. ;D

[billy]

Bit of an update, it's rolling! Still alot left to do though. The swingarm is not actually done yet, I just welded it so it works allright for farting around carefully, but I will weld the rest someday for extra strength. Reason I didn't weld it all was that I'm welding outside, and even the slightest wind will tit the welding up, so I'll just leave it for now.



What a skinny tire eh! ;D The rim will be replaced (I just put that rim on to get a rolling chassis) and I'll use a real mx style tire. Possibly something like the DT 125 and similar bikes use.







A problem I encountered is that the suspension at the back is too sloppy. I knew I should have kept the lower shock mount further away from the swingarm mount, why didn't I listen to my goddamn intuition?
Oh well, I'll see if I can drill a new shock pin hole in a more reasonable location.

[billy]

I have successfully drilled new shock pin holes so now the rear suspension should be a tad better now (although I'm sure it's not as stiff as I wanted it to be, but it'll work).

Other than that I've started on the engine mounts, I got one of the two front mounts welded on, cut some old engine mounts off, stared at the build etc.

I've also made my mind up about the radiator dilemma I wrote about in another thread, I'll use both CR rads as one CR rad is smaller than the RD rad. The bike will probably be a b**tard to warm up but I'd rather have that "problem" than a blow up from lack of cooling.
Also, someone on another forum insinuated that this bike will probably not be driven as fast as an RD and therefore may need a bigger radiator, and he's right. I never thought about that. I'll most likely just fart around at a general speed of approx 45 km/h or so, (sometimes much slower because of really tough terrain) which makes a bigger radiator necessary as the wind against the rad isn't very strong at those low speeds.

[billy]

All mounts finished, phew! Making engine mounts is not as easy peasy as one might think.

[billy]

I've started fiddling the pipe together.

This is an Mk1 pipe with the internals at the expansion chamber taken out, (yes they do actually have some sort of silencer stuff inside the ex-chamber!) and obviously I will rebuild the rear and add another silencer.
The original silencer broken, bits rattleing around inside and I just couldn't be arsed to fix it. I don't even want the original Mk1 silencer as it is butt ugly as hell with it's cigarr shape.

I wanted to use an RD350 YPVS header as it was longer than the Mk1 header, it would have meant I could have got the expansion chamber sitting in a much better looking angle, but I encountered some problems with it and ended up using the Mk1 header instead.

[billy]

The pipe is done! Well, except for the rear mount that I havn't got in place yet.

[billy]

I put the pipe on the RD just to see what it sounded like, it's freaking awesome! The camera sound quality doesn't quite do it justice though.