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Topics - stump magnet

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CZ / side pipe crank
« on: April 02, 2013, 02:49:59 AM »
hi, my right hand side main bearing diameter on the 360 crank has worn to such a degree that the crank hops about in the main bearing and destroys the crankseal and then sucks in air and pinks, loctite used to work but now no longer, have tried a repair sleeve that lasted a little while but again no longer, could the crank half be remachined and sleaved back to the right diameter or is there another method i.e. spray welding and re grind or is it best to just replace it all and does anyone have a new crank?
would prefere the repair method but have no idea of cost any advice would be much appreciated

CZ / avgas?
« on: March 04, 2013, 07:43:00 AM »
want to run it in my cz's, should I run it neat or mix with pump fuel? any jetting changes? any advice would be great guys

CZ / sloppy gear lever
« on: October 01, 2012, 06:05:09 AM »
i have a bit of up and down movement at the gear lever (not worn splines) on the side pipe making it difficult to upshift without bashing my knee into my chin because i have to lift my foot so high! where might the wear be within the shifting mechanism? has been like this for ages its just not as crisp as my other cz's would it be posible to see anything with the cover removed?

CZ / jikov cd float height aaaarrrrrrr!!!
« on: September 24, 2012, 08:31:53 AM »
help cant find any info on setting the float height on a jikov cd carb as fitted to the latter 513 bikes have checked cz madness manuals and the info i desire aint there HELP!

CZ / rear brake pedal travel
« on: August 06, 2012, 06:08:45 AM »
hi all, i would like to reduce the travel of the rear brake pedal so that i dont have to press it down so far to get the same braking effort, the reason i ask is i have to run the rear brake quite tight on the adjuster to get the short travel on the pedal i like and so it heats up and starts to bind (so i have to run it slack for me) but if i had more slack in the adjustment but still a short pedal travel then the brake would not bind so my question is what do i have to do to the pedal or the brake arm? do i lengthen or shorten the pedals pivot or the arms? i have a longer curved rear brake arm at my disposal but have not tried it, it must all be a question of leverage ratio's i supose? the bike is a 360 sidepipe, cheers

CZ / new sidepiper rod
« on: December 10, 2011, 10:59:50 PM »
anyone tried the rod kits that are available from that guy in poland? have bought one and it seems absolutly identical to the original but at half the price, just want to make sure there ok before i fit one

CZ / weird running
« on: September 05, 2011, 06:49:23 AM »
right try to solve this one chaps, the 250 twinport is running a gerrard copping electronic ignition, dellorto carb and gmc pipes and up till three meetings ago ran perfect then at the next meeting it would start to cut out when flat out in 3rd and then 4th gear just at the top of the rev range as though the kill button was being pressed or fuel starvation. stripped carb checked float height etc all fine, plug was a bit lean as very hot day so upped the jetting still no joy, maybe crankshaft seal leaking so replaced that and checked and replaced base gasket and any other obvious air leaks seems to rev out perfect on the stand and when flat out in 1st then into 2nd gear but as soon as you click into 3rd and approach the top of the rev range it just goes buurrrrrrrr so grab 4th and same again pulls hard till top of rev range and buurrrrrrrr.
so any ideas PLEASE? thinking maybe the coil is breaking down at prolonged revs but not sure as have no experience of coils doing this (is it posible for the coil to play up in the two higher gears only?) pretty much covered every thing i can think of other than a crankcase air leak that i cant find though would have thought the bike would run on and generally run crap regardless of gear or revs as have had plenty of experience of air leaks over the years.
please some one give me a clue as im totaly stumped and pulling me hair (wots left) out cheers

CZ / twinport kickstart shaft
« on: August 31, 2011, 05:58:18 AM »
a freind has just broke his twinport 250's kickstart shaft, is it posible to fit one from a later model? they look very similar apart from the return spring, could it be modified to work? cheers all.

CZ / femsatronic dual spark ignition
« on: August 15, 2011, 05:56:36 AM »
my 360 sidepiper has a femsa dual spark electronic ignition and it just died today, what is more likely to fail? the cdi box or both coils as the same time!
it packed up at the last meeting and i remade the connections and low and behold the sparks came back but this morning started bike up for practice and it ran for a minute or two then died and thats it ive checked all wires and conectors but still nothing could it be a duff joint within the sealed cdi box as i find it hard to belive that both coils can go together i would think one would still spark but somthing inside could be ratling about giving intermitent spark.
what alternative systems that cater for twin plugs are available? and are there any femsa replacements about?
could i open up the box and have a look?

CZ / twinport on dellorto problems
« on: May 30, 2011, 06:15:20 PM »
right over here i can run a dellorto carb on the twinport 250 but am having various starting problems, it would start from cold on choke and when warm would start ok ish but occasionaly would not go at all. plug removed and bone dry so a little fuel poured in the plug hole and away she goes. decided to fit next size up pilot jet at the recommendation of dellorto uk and now it gasses up when starting hot i.e. you have to hold the throttle wide open with the fuel off till it clears which can take ages, what causes this? is it the starting circuit or the float height or is the float needle and seat suspect (its the only thing i havnt checked yet) its a new carb a 34mm phbe and ive stripped it and checked it numerous times its driving me mad!! could it be anything to do with the slide? its a #40 which im told is rich any help out there please thanks

CZ / 360 max over bore?
« on: May 17, 2011, 08:33:51 AM »
my side pipe decided to eat its left hand side wrist pin circlip yesterday after running fine for nearly two years! the bore has some good scores and grooves so a rebore is required the current piston is 82mm dia which  is 380 first size how big can i go? cz stuff quote up to + 2mm for the 380 but dont know if theres enough meat in the liner on the 360 any one else had a rebore anywhere near this size? (though might get away with 3rd oversize one groove is quite deep)

CZ / twinport gearbox shims/clearance
« on: January 18, 2011, 09:47:46 AM »
can anyone advise on the clearance i should look for between the gear and shaft on the end of the two shafts in the gearbox?
have just fitted a modified single port gearbox into my twinport and have fitted the original thrust washers and have a clearance of around 0.3-0.35mm at the moment, still in dry build so can add shims if need be although the clearance seems ok considering everything will heat up when running what do you guys rekon?

CZ / mikuni twinport specs
« on: January 07, 2011, 05:20:21 AM »
can anyone tell me the size and type of mikuni to run on a 250 twinport plus the jetting specs please cheers.

CZ / twinport fork springs
« on: December 14, 2010, 11:56:55 PM »
my fork springs are sacked out any idea what the standard length should be? these are progresive wound springs with 3.8mm dia wire, are the progresive ones standard? i would like to replace with the same if possible cheers

CZ / 360 chain tension
« on: November 08, 2010, 11:47:24 PM »
finished my last race of the day yesterday and noticed the chain had gone as tight as a tight thing! any ideas? the bike is a 360 sidepipe 

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