OzVMX Forum
Marque Remarks => CZ => Topic started by: Husabergpete on December 01, 2023, 10:39:58 am
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Hi Gents,
Had the 1973 380 going with new Vape Ignition. Brilliant.
New issue is oil leak behind the dry clutch.
Question - what are the sizes and or id numbers for the seal (and type maybe) and oring/s ???? Possible 50 x 65 x 8 mm but not sure if single or double lip, or spring etc if it matters.
Question - size of the Oring on the kick starter shaft ?
Question - I want to paint a steel tank in the original '73 Blue colour. Any idea what the colour code is or close to it?
Many thanks once again
Pete
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I use a viton seal for the clutch, deals with heat better than the normal nitrile seals. Can't remember the size at the moment but know like all the seals & o-rings they are available from most bearing or seal suppliers
I feel that where the leak generally comes from is not the seal but the o-ring on the back of the clutch hub, the step that the o-ring sits on is larger than the o-ring thickness so all the sealing work has to happen on the outside diameter. I modified my sidepiper clutch by having the step ground down to 1.9mm & a new thicker washer made to keep the stack height the same, basic idea was to sandwich the o-ring, so far it's worked perfectly
I have a look in my parts book on Wednesday for the sizes if you want
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Thanks Tony. You are a champion.
Much appreciated.
I am in touch with my local bearing supplier and will change it to Viton etc.
Might look at that mod as well.
Kind regards
Pete
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Clutch seal is 50x65x8 The seal I have sitting here has 2 lips, 1 at each side
O-ring for clutch hub is 26x2
O-ring for primary gear that seals the clutch basket is 35x4
O-ring for kickstart shaft that sits inside the cover is 20x2
Hope that helps
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Thanks so much Tony. Got a couple of them yesterday and the rest on order.
Had another win yesterday. Got hold of an original 1974 parts book. Will do electronic copy soon for who ever needs it. Super helpfull book
Cheers
Pete
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Yeah I have the 74 parts book as well, the 73 manual from bear motorsports has the parts book in the back as well so it's well worth getting, also have their sidepiper manual
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Hi ya Tony,
Now the clutch seems fixed I got it hot and found the jetting was a little lean.
Not sure if you have a favoured mix of jets - looks like a newish 36mm Mikuni
I just took it apart again so I'll document what is in it.
Main 280
Nozzle Jet 159 Q 5
Needle 6F5
Clip was in the middle - as of yesterday dropped the clip one down - richer and it went a lot better
Pilot - 25
Slide 2.5
Air Screw was at 1 and Half
Im going to do some searching now.
For future reference the Clutch Seals and Bearings are as follows
The 2 needle bearing inside the clutch are K 25 x 30 x 13 ( C3's )
Item 26 is an ORing 43 x 35 mm
Item 8 is an ORing 26mm ID and 2mm diameter/thick
The Kickstarter seal is an ORing 24 x 20mm
And the main seal that goes in the clutch cover is 50 x 65 x 8 double lip with a spring - I used the normal black one because the Viton was only single lip I could get and wouldn't have worked.
Cheers Pete
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Jetting seems close to what I used when my bike was still piston port except I ran a 45 pilot jet, can strip down the carb & confirm tomorrow
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Hi Tony, Just back from overseas and see your last post about checking the jetting in your bike.
I noted you were using a 45 Pilot. Mine improved a lot from the 25 pilot in it to the 37.5 (which I had at home). Just about to order a bunch of extra pilots and a few mains from Hadrick now.
I also got hold of an original 1974 owners parts list from Adrian's dad. I have made a PDF copy and a paper copy. Let me know if you could use the PDF.
Kind regards
Pete
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JET SPECS TAKEN FROM SPREADSHEET PROVIDED IN THIS THREAD
CZ 125 MX -72 VM 32 200 35 Q6 5FJ9 - 3.0
CZ 250 MX -66 VM 32 240 35 Q6 6FJ6 - 3.0
CZ 250 MX -66 VM 34 230 35 Q8 6FJ6 - 3.0
CZ 250 MX -71 VM 34 210 35 Q5 6DP5 -
CZ 250 MX -72 VM 34 240 40 Q8 6FJ6 - 3.0
CZ 250 MX VM 34 210 35 Q5 6DP5 -
CZ 250 MX VM 36 260 35 Q5 6FJ6 - 1.5
CZ 250-380 MX VM 34 300 40 Q6 6FJ6 - 2.5
CZ 250-380 MX VM 34 310 45 P8 6DH3 -
CZ 360 MX -67 VM 34 250 35 Q6 6DP5 -
CZ 360 MX -67 VM 34 230 45 Q6 6F5 - 2.
CZ 360 MX -67 VM 34 240 40 Q8 6FJ6 - 2.5
CZ 380 MX TM 36 290 45 Q6 6FP17 -
CZ 400 MX VM 34 230 30 Q5 6DP5 -
CZ 400 MX VM 36 280 25 Q5 6FJ6 - 2.5
CZ 380 MX VM 36 350 45 Q8 6FJ6 - 1.5
CZ 380 MX VM 34 320 45 P8 6DH3 -
CZ 380 MX -66 VM 34 260 35 P0 6DH3 - 2.5
CZ 380 MX -69 VM 34 320 45 P8 6DH3 - 2.5 O. Persson
CZ 380 MX -71 VM 34 230 30 Q5 6DP5 - 2.0 AMS Racing USA
CZ 380 MX -72 VM 36 290 45 Q5 6FJ6 - 2.0 R.L Dengler
CZ 380 MX -72 VM 36 270 45 Q6 6DH2 3.5 Pete Maly specs
CZ 380 MX Reed Valve VM 36 430 45 Q8 6DH3 - 2.5 C.M.
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27..01.24 jetting changed which improved it a lot.
Original 25 pilot changed to the 37.5 and now a 45. Great improvement.
After that it was still prone to increased revs by itself just above quarter throttle.
So left the Q5 in and replaced the 6F5 needle with a 6FJ6 (both middle clip) No more self over rev.
Ridden around street, hot, but will need to get a track day to maybe increase the Main from the 280. See how we go.
Cheers
Pete
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Improved again.
50 pilot and 300 main and then raised the needle one step by dropping the clip one grove down from the middle groove....
Cheers
Pete
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Great work making progress
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cheers Pete