CZ 125 to 350 project

[Jason Potts]

finally managed to get a bit done on this.

for those that do or don't remember it from this years Exeter,(2017) it looked like this at the finish. I didn't pick up any awards with it but I did get a finishers certificate which was my goal. it was my first ever LDT and I completed it on my standard CZ 125 road bike with road tyres fitted. I had a ruck of fun and I made some new friends too.



since then I've stripped it to the bare frame, made new engine mounts to accept a Jawa 350 engine and fitted a 21" front wheel. I've also gone for NATO green paint. I've chopped the rack and moved it forward, I've cut the seat shorter but this is not shown. I've lifted the handle bars a tad and added new rear foot peg hangers. these will be fitted with some homemade bear trap pegs for the offroady bits. I fitted MZ250 rear shocks too which are 2" longer than the CZ ones. These give the bike a nice lift at the rear to match that gained by the new front wheel. I'll post some more pics as and when it moves on a bit more.





 

[Jason Potts]

unfortunately I missed the Exeter this year    after all the posts and so much looking forward to Simms etc but my wife became ill and I had to stay home and look after her and the kids. I was gutted but she's now slowly on the mend so hopefully that will give me a little free time to slip in the shed for a bit..

With the trailer project finished and out of the way I can get back onto one of the many bike projects. the most complete of the lot is my old CZ and Rick's suggested i try and get this done for the lands end. something new to look forward too. 

just dug it out and made some space and this is how it looks today. before stashing it away i painted everything army green to stop some of the bare metal frame from going rusty so i'll either stick with this paint or not. its not my favourite colour i'll be honest.

still some work to do on the rolling frame. going to fit a bash plate, got to make up some exhausts and rebuild the engine. plus wiring, controls cables and a bunch of other stuff to make it work. 

not so sure about the front mudguard. might go back to a hi-level one.



just to compare this picture was taken in the Hotel garage at the end of the 2017 Exeter. 

[Paul K]

The project is looking good .  The bike has a balanced posture front and back; the fork rake looks right for a trials bike.

Personally, I’ve always preferred a low front mudguard; it keeps more crap off the front of the cylinder block and doesn’t restrict air flow to the cylinder head (my theory).  You can purchase a low trials front mudguard up from someone like feked.com for about £20.

I can’t tell from the photos if you have folding footrests, but I’d fit a set of those if it were mine.  I picked a pair up from Pride and Clarke (internet only now) for about £24 and they were good quality.  You might be able to weld the mounts onto the existing bar.

Be great to see it on the Lands End .

[Paul Wheatley (Wheaters)]

Jason, Shame about the Exeter; hope your wife recovers quickly. The CZ looks great, very purposeful in that colour.

I still regret selling my 1977 CZ 988.2 Enduro 250 - it was a very unusual bike, not like any other I've seen. It had frame number 009 and engine number 140 so in retrospect I think it might have been something even more special than I realised at the time. The Czech chap who bought it sent a driver from Prague to collect it so at least it's gone home!

It's still shown on this page although I sold it years ago!

http://www.jawaczownersclub.co.uk/photo_gallery1.htm

[rick howell]

Jase that is looking bl**dy superb! I love the military green - just like the MZ's that the East German's had; very business-like.

And a tidy workshop to boot, not like my midden!

[Jason Potts]

Thanks for the comments guys. I have a new aluminium front trials mudguard so I'll have a go at fitting that. Sounds right what you are saying Paul, also Rick has just swapped to a low level one on his SP370. Seems to be the way forward.

Both the front and the rear footrests fold up. I cut off the pillion footrest hangers because they were too far back. I welded on some stubby mounts which are just behind the swingarm spindle. Next job is to fit this bash plate I bought off eBay. It came off a Yamaha and offering it up looks like it will fit just fine. I'll post a picture of that when it's done.

By the way that CZ enduro looks awesome. Wish I could afford one of those. 

[Jason Potts]

UPDATE....

front mudguard fitted also bash plate on too.

wheels are off to the powder coaters tomorrow and im working on exhaust routing concepts.

i'll be having a go at the seat this weekend too.

pushing on to try and get it ready for the lands end. 

[Paul K]

It's looking good.  Particularly like the fitment of the front mudguard; a neat job.

Does the top run of the chain clear the pivot tube of the swinging arm, or do you need to fit a chain slider of some sort?

The exhaust pipe run is nice and out of the way; so far .  What sort of silencer is going on?  Doesn't seem to be much room for an expansion chamber, which is what I thought two-strokes benefited most from. But, that's a science of its' own .

[Jason Potts]

Hey Paul, yes the chain just about clears as it stands. I guess when I'm sat on it its going to compress the suspension and give me a bit more clearance. Might still look at putting some kind of rubber guide on there as well though.

Without going into a massive essay these engines don't need expansion chamber exhaust systems. They could run on a straight pipe. I'm looking to fit a mid pipe silencer and an end can as well. Need to keep the dB,s down for those early morning rides through QQ villages. 

I'll post more pictures when I make some progress on that. I bought some new seat foam today and a set of new bar grips.

[Jason Potts]

Here's a question.

If I can prove that the frame I'm using is pre 1970 by design as the CZ125 model first went into production in 1969. And the engine, all be it in 6volt form, was launched in 1968. Can I claim that this bike is class A compliant?

 

[Jason Potts]

.  Does it comply with that? Can you tell from the frame number?

No, other than the engine and frame have remained unaltered since they went into production which predates 1970. Rather like the Enfield Bullets.

[Stephen Bailey]

On some bikes you cannot tell by the frame number I.e. Velocettes….. They used the first frame that they picked up from the stores and bunged an engine in it... Meaning that it was possible that a frame at the back got used much much later than its manufactured date.
The later swing arm frames being used for different models as well as were some of the crankcases.

[Jason Potts]

I'm guessing that the reason the club allows  Enfield bullets in class A is that the base design of the engine and frame predates 1970. I have a 1967 bullet and there is no discernible difference between that and one built in the 1990's.

You can say the same for my CZ. Apart from a styling Change to the shape of the petrol tank it is exactly the same bike that was launched in 1969.

The 350 engine I'm fitting was launched into production in 1968.

[Jason Potts]

Yeh I know exactly what the regs say but I'm of the opinion that if the design of the engine and frame was designed pre 1970 and is unchanged, irrespective of when it was made, it should be class A compliant. This president has in fact already been set with the Enfield bullet.

Hasn't it ?

[Paul K]

The SSR are always under review; witness the recent change to allow all bike classes to use class C tyres.  Bike tyres will be looked at again in the future.

Put your case for the CZ to the Competition Secretary, Dick Peachey (contact details in Triple).  The SSR are a topic on the agenda for the next Executive Committee meeting on 9 February 2019.