CB250 RS - Project "Phoenix"

paddyshepherd

Active Member
Picked up the wheels the other day and tyres arrived yesterday as well.

The wheels look absolutely fantastic. I have now decided that for now, I'll run them tubed. Purely because I started to clean them for applying tape, but to remove the 30 odd years of crud from the inside, I'd probably knock myself out with fumes first.

Tyres should be mounted up tomorrow so I can order my shocks Saturday. Then when my new Yoke set arrives I'll finally have a rolling chassis again. About time!

 

paddyshepherd

Active Member
Well, tyres are on and I think the aspect ratios and widths are bang on.
Unfortunately, the back is still going to foul the back end of the bike with 350mm shocks. So I'm going to have to relocate the battery tray. However, I do now worry that even with the battery tray relocated, my planned bodywork may have to change, as I think this would also foul.

The really annoying thing is, that if the axle was run at the back of it's adjustment slot, it's way clear. It's only when my chain will be new and the wheel will be right forward that it's gonna catch. It's looking like I may have to run a hollow seat unit, which I didn't really want to do.

If you look in this pic, on full compression the tyre would actually go between the top frame rails slightly:

 

540Nova

Been Around the Block
Re: CB250 RS - Project "Phoenix"

You could install Progressive travel limiters onto your shocks.

Sent from my SM-G955U using Tapatalk
 

paddyshepherd

Active Member
Re: CB250 RS - Project "Phoenix"

540Nova said:
You could install Progressive travel limiters onto your shocks.

Sent from my SM-G955U using Tapatalk
I'll consider that, if I can't make it work otherwise. I'd like to keep the travel as is as it's already just 80mm. Thank you for the suggestion though as they're something I wouldn't have thought of!

Pete12 said:
Bloody hell, nice wheels Paddy..
Thanks Pete... I do think they look pretty well!


Been doing some design work back and forth with my machinist. This is currently the plan for the new top yoke. The profiled front allows for my speedometer to sit partially recessed into the yoke, meaning it'll look like it's supposed to be there rather than just an afterthought. Should get that the end of this week hopefully and can then build the chassis back up. One of these days the frame will go for paint... but I want to make sure I've got brackets for everything in place and all welding done first. I essentially plan on doing a dry build, then strip it all back down again for paint and finishing.


 

paddyshepherd

Active Member
Finally! Some progress worth sharing.

So!
My billet top yoke arrived yesterday, along with a new bearing kit for the headstock, since the other set had been on and off a few times and the bearings were looking worse for wear. The top yoke looks absolutely beautiful:



So of course today I simply couldn't wait to get it fitted. I started to reassemble the front end and didn't take many pictures. but the end result looks great. I have unfortunately had to drop the forks through the yoke by 20mm - this is because with the shorter stem, I'm actually struggling to hit the lower clamp point of the forks, and half of the bottom yoke wouldn't have been clamping anywhere! I may end up mounting the clipons above the yoke to hide this a bit, but I've never been a fan of the bar-above-yoke look. I also borrowed some shocks from a mate at work, they're cheap crap but they're adjustable length, so perfect for me to use for mocking up. I'll get some more photos tomorrow but in this pic they're actually 370mm long and the top line of the bike looks nice and flat. I did try 350 but it looked too low at the back. I may however shorten the forks and run the 350mm shock to bring the swingarm angle back down. To gain a bit of perspective, I threw the engine cases, barrel and head loosely back together and dropped the engine into the frame.



I'm still not sure on that tank. I no longer think it looks in proportion - but that could be because there's a part of me telling myself the bike is now too high for it's length... might just look worse due to the lack of tail unit, though. I also think the tank looks too low compared to the top yoke now. I feel the yoke should be either flush with, or just below the top of the tank, at the moment it's significantly higher.



However, if there's one thing I do now love about the bike, it's this cockpit:

 

cb360j

Been Around the Block
That's pretty rad! I've drawn up a couple designs of my own. How did you take all of your dimensions for your modeling? Or did you base it slightly off the old top yolk?
 

paddyshepherd

Active Member
cb360j said:
That's pretty rad! I've drawn up a couple designs of my own. How did you take all of your dimensions for your modeling? Or did you base it slightly off the old top yolk?
Thanks dude. Unfortunately I can't take credit for the yoke or the design of it. My machinist took all the measurements for it, based on the KTM standard top yoke, crossed with the Honda one. He then produced the model from that. He sent that through to me and I modified it to suit the speedometer. He then finalised it and added some holes for a bracket for the speedometer and machined it from that.

If you're going to measure it all out for modelling, I would check each measurement at least 3 times. Initially start with the fork leg position compared to the stem. Use a standard yoke and measure that, making sure you get the centre of each hole. Then just mould your design around those! 8)
 

LMCol

New Member
That thing's going to be a ton of fun to ride. I think the tank would look a lot better with an inch or two added to the swinging arm.

I don't suppose your machinist need a new friend does he?
 

teazer

Over 1,000 Posts
DTT BOTM WINNER
That is starting to look wicked. I like the tank, but now I see those wheels, I am tempted to thick supermoto with high bars which of course don't work with that sexy top triple clamp....... That's the problem with projects, as they start to come together, you start to see other possible outcomes.

Pegs look a bit to far back to be able to take your weight. Think of a horse race jockey with legs underneath him so he can use his legs as suspension. That's more or less what you should be aiming for but less extreme of course.
 

paddyshepherd

Active Member
LMCol said:
That thing's going to be a ton of fun to ride. I think the tank would look a lot better with an inch or two added to the swinging arm.

I don't suppose your machinist need a new friend does he?
I hope so mate. I tend to agree there as well - I did look to try and find an alloy swingarm I could use, but the frame is that narrow that it's proving nigh on impossible! I may keep an eye out for a different tank still. It's difficult to tell as I think the fact it's just one slab of solid black paint. But at the same time I don't want to paint it only to find I still don't like it! I quite like the CB360 tanks, so I may consider one of those, but I imagine difficult to find.

Unfortunately my machinist has currently had to stop taking on work. He does them as cash in hand type jobs on his lunch breaks at work, but they've done a rotation and he's no longer on the mill for a while now!
 

paddyshepherd

Active Member
teazer said:
That is starting to look wicked. I like the tank, but now I see those wheels, I am tempted to thick supermoto with high bars which of course don't work with that sexy top triple clamp....... That's the problem with projects, as they start to come together, you start to see other possible outcomes.

Pegs look a bit to far back to be able to take your weight. Think of a horse race jockey with legs underneath him so he can use his legs as suspension. That's more or less what you should be aiming for but less extreme of course.
Thanks Teazer. Yeah, I can totally see your logic as it did cross my mind too!
Yeah, the pegs are going to be moved forward an inch or two, I just haven't got round to it.

I sat on a triton at a local show and noted how comfy the position was. The bloke said to me "as a rule of thumb, sit your arse over your shock mounts and have your heels in line below". At present, it's probably like, my ankle bone below, so they do need to shift a bit.
 

LMCol

New Member
paddyshepherd said:
I did look to try and find an alloy swingarm I could use, but the frame is that narrow that it's proving nigh on impossible!
Get 'er welded!
 

teazer

Over 1,000 Posts
DTT BOTM WINNER
Your Triton friend is almost right. On a Manx, the back of your posterior is just in front of the shock mount, but the pegs are under the front edge of the seat.





Here's a Dave Camier (DCM) SR500 race bike for inspiration.
 

paddyshepherd

Active Member
So this project had been put on hold for quite a while due to uni work and building my campervan.
However this weekend I got a spare couple of hours and didn't have anything to do on the van, so I dug the bike out and did a few odd jobs.

I installed my new Gilles GP Light 2 clip-ons, which I bought to replace the previously purchased ones, which I decided were too bulky looking. I then fitted my custom ordered Hagon shocks which arrived a while ago. They look bang on.

Then I finally looked at the foot peg mountings, I decided that since I had a spare set I would butcher these ones and see if I can improve the location of the footpegs. I took them off and flipped them over. Handily, there was a pressing in the casting which looks like it was originally designed to have a captive nut in it, approx 60mm forward of where they were currently sat. I decided I would use that as a first try, since I could drill as many holes as I wanted in these ones then make it right for the good set. However, no need, because first try seems perfect up to now. I drilled the holes, tested, and then lopped the excess metal off. They still require some tidying up and smoothing, but that will come when I have more time. I intended rounding them completely as you will see by the marker pen on the modified one, but I've taken it in line with one of the stiffening ribs from the casting, whether it'll stay that way long term or not I don't know.

Modifications to the said mounts:




and the pegs back on the bike, along with the new clip ons and the hagons. I still think the forks need to be another colour, either back to silver or possibly a copper colour, depending if I stick with my colour scheme plan.




I don't know if it's the shorter footrest mounts, the slimmer shocks, the fact I've moved the wheel backwards in the adjuster or a combination of all 3, but I think the proportions of the bike look much better now. I hope you lot agree but let me know!
 

paddyshepherd

Active Member
So with me now graduated from Uni and with my campervan nearing completion, I've finally dug the bike out from under all the crap I've collected over the past few months and ordered some parts. My engine has gone off to my tuner/engineer for some serious work so I'm once again left with a rolling chassis. I'm determined to get this finished in time for next summer. So this week, I've made CAD drawings of the stock wiring diagram, then used that to make a simplified diagram for the bike, probably using a Motogadget M.Unit. Whilst on such a simple bike the M-unit doesn't really make the wiring massively simpler, it does bring a lot of extra functionality and reliability.

I also ordered some Lucas Tri-bar headlights a while ago, to use one on the bike. However when they arrived I decided to offer them up to my car.... and needless to say they never came back off. So I ordered another set yesterday, along with a headlight bowl, indicators and headlight brackets. All of which arrived today so I had a play fitting:



The headlight does need to sit lower, although unfortunately I need to send the brackets back in exchange for bigger clamps, as the taper on these forks starts mooch sooner than I remembered. Nevermind. I like the indicators though, tiny little units but extremely bright. The bike is also finally sitting independently as well, after refitting the side stand. This is going to need work as the new gear shift arm currently fouls it, and some of the threads are stripped on the frame too where the stand mounts, so I'll have to helicoil those.

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I am tempted to go for a shallower headlight bowl (they had two options, this is the "standard" one) as I think it may be too big. But I'd like to see it better positioned first.
 

paddyshepherd

Active Member
Well thankfully, my engineer hadn't yet done anything on my engine... as I've just managed to seal a deal on an imported FT500... CB-500-RS hybrid incoming.......
 

paddyshepherd

Active Member
So I've been away at Stafford Classic Motorcycle show this weekend.
I picked up a new Motogadget M-unit at a nice price and a bargain Rickman style seat (£25 and brand new in primer). I then picked up the FT500 on the way home.

Here's the FT. It's missing a lot but the engine looks fairly good. No carb or starter motor so we couldn't try and run it. Turned over by hand and compression felt good. I'll be rebuilding it anyway to add kickstart and decompression, and get rid of the starter. I might do some tuning work on this one but it'll be much less than I wanted to do to the 250. Maybe use the 250 cam as it's a better tune (so I've been told), a 540cc bore and 10.5:1 compression, and a bit of port work. Add in a good carb and exhaust and it should go nicely! Getting it into the van proved difficult (we were in a campervan with a garage underneath the double bed, meaning it's only as long as the width of a double bed. So we had to drop the front end out then lift it in, which proved difficult with limited tools and I put my back out in the process). So we stayed away another night (what a shame!) and then drove back today. Once home I pulled the engine out quite easily, a californian import is much nicer to work on than a british bike, as nothing's rusted! It took me 45 minutes compared to 3 and a half hours on my 250 engine...




Then here's the Rickman seat. It goes nicely with the 400/4 tank. I'll be shortening the seat base to get the proportions right, and make some adjustments to the fit. But as a quick throw on I'm happy with it. It is a little too wide for the 250 frame, but it fits the tank really well, so I'll leave it stock width for now. However due to the taper on it I might change my mind on that and end up cutting a piece out of the middle after I've shortened it. We'll see. It's starting to look like a bike again, but we've got a lot more to do.

 

Pete12

Been Around the Block
This will be a trick bike with a 500 in it now Paddy. Looking forward to the updates and glad to see you're back.
 

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