CB250RS café racer project

**xwhatsit** · 6th May 2009, 22:57

Originally Posted by NordieBoy

Nothing. Nothing at all

You'd need to sleeve it though? That's an 82mm bore... What piston is that?

**tychver** · 8th May 2009, 22:55

http://www.trademe.co.nz/Trade-Me-Mo...-217304017.htm

Does that look like a PD70A rebuild kit to you?!

Maybe we should ask if he can do a few more. I need two, you probably need the same again eh?

**xwhatsit** · 9th May 2009, 00:07

Originally Posted by tychver

http://www.trademe.co.nz/Trade-Me-Mo...-217304017.htm

Does that look like a PD70A rebuild kit to you?!

Maybe we should ask if he can do a few more. I need two, you probably need the same again eh?

Looks about right, I bought a XR250R kit from the same seller (Nikau) and the main jet was a different sort (hex head, long) but apart from that everything was all right. The needle may have a different taper, and the main jet is possibly different -- then again the guy let me choose the main jet so tell him you want a #122. On the other hand, the CB250RS is jetted slightly lean because it has a pumper carb, so it can run lean when cruising but there's extra fuel chucked in for acceleration when you turn the throttle. Or so the manual says. The XL250S had the same PD70 carb but no pumper, so it might've been a bit richer despite the tamer cam and port sizes.

**tychver** · 9th May 2009, 20:24

What do you use to pull the spark plug?

I haven't got a spark plug socket to fit, and my long 12mm socket has walls to thick and won't fit between the plug and the head

**xwhatsit** · 10th May 2009, 00:08

Originally Posted by tychver

What do you use to pull the spark plug?

I haven't got a spark plug socket to fit, and my long 12mm socket has walls to thick and won't fit between the plug and the head

I went to the Honda dealer on Barry's Point Rd and asked him for a spark plug socket to fit a NGK `D' plug... he gave me one of those lightweight pressed aluminium tools with a little L-shaped rod to fit through the top to rotate. Only cost a few dollars.

**tychver** · 20th May 2009, 10:31

I got the plug out. Running massively rich. Completely sooted up.

New plug is much easier to start and runs a lot better.

---

You're definitely going to need a bigger carb than the PD70 with the 335cc engine. The standard carb was well sized by honda and is right at its limit at 26hp:

I'm tossing up between a VM34 and a VM36.

**NordieBoy** · 20th May 2009, 15:28

Find an old 79-81 XR500 carb and you're away laughing.

**skidMark** · 20th May 2009, 15:30

Sounds like you boys are in search of Moar powar.

**xwhatsit** · 20th May 2009, 17:38

Originally Posted by NordieBoy

Find an old 79-81 XR500 carb and you're away laughing.

Yup -- that's what Mr Original XR336 reckoned, didn't he. Dunno what they are though -- CV or slide (pumper or not...?).

EDIT: It's a slide type, with no pumper. Looks like the XL250S carb, just bigger. Dunno what size. Don't see how going too high is going to help, as the intake port is only 31-32mm anyway.

Originally Posted by skidMark

Sounds like you boys are in search of Moar powar.

Don't need too much, I'd just like the `thumper' feel. CB250RS feels like a tiny Jap twin, you have to scream it everywhere. A nice thumper I can short shift up to sit at 100kph comfortably... should've bought a GB500 but this is more fun.

**Ixion** · 20th May 2009, 18:03

Originally Posted by tychver

I got the plug out. Running massively rich. Completely sooted up.

New plug is much easier to start and runs a lot better.

---

You're definitely going to need a bigger carb than the PD70 with the 335cc engine. The standard carb was well sized by honda and is right at its limit at 26hp:

I'm tossing up between a VM34 and a VM36.

two standard carbs on a common manifold.

**xwhatsit** · 20th May 2009, 18:22

Originally Posted by Ixion

two standard carbs on a common manifold.

Ha. Like you want that headache. Didn't you own an SRX250 once?

**mylittletony** · 21st May 2009, 07:54

OK, as promised but very late due to mix of hangovers, rain (working in the back garden) and only getting a 45min lunch break to knock up parts at work, here are some photos of my street tracker attempt. New parts:

Enduro style rear mudguard
Enduro rear light
Home made (you can tell) battery box
Mini gel battery
4.5" bottom mount headlight

Modified parts:

Cut down seat base padded using foam box material from work, re trimmed in material previously used

Still to be done: Fit battery and wire up, wire up mini indicators, paint and mount new mini chrome instruments, tidy front wiring. Oh and paint the tank - not much then!!

I also included a before shot and one with my 6'2" 17 stone housemate on for scale!!

http://i245.photobucket.com/albums/g...d/CIMG1588.jpg
http://i245.photobucket.com/albums/g...Halfway001.jpg
http://i245.photobucket.com/albums/g...Halfway003.jpg
http://i245.photobucket.com/albums/g...Halfway006.jpg
http://i245.photobucket.com/albums/g...Halfway009.jpg

**tychver** · 21st May 2009, 10:53

Originally Posted by Ixion

two standard carbs on a common manifold.

Can't be bothered with making a manifold and linkages. Plus the VM34/36 isn't that much more expensive once you factor in the cost of reconditioning two carbs, linkage and hours setting it up right.