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Messages - tony27

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General Discussion / Re: physical
« on: August 13, 2018, 05:37:09 PM »
But who rolls & smokes their bacon rather than eat it?

CZ / Re: 360 sidepipe pistons
« on: July 25, 2018, 07:02:56 PM »
Got the motor apart & the bore looks good so the piston or rings at minimum I need are 80.91mm for a 81mm bore. Piston appears to be a Kolbenschmidt

Tech Talk / Re: Unlocking a motor
« on: July 18, 2018, 07:01:58 PM »
Motor freed up amazingly easily, only had the kero/brake fluid mix in the cylinder for a couple of days.
After washing the motor with degreaser & the water blaster I loosened off the head & cylinder base nuts, top of the piston was fairly clean & the head has no signs of damage at all. Out of curiousity I tapped the top of the piston with a dead blow hammer (no room to swing it) & thought I saw movement so I kept going.

This is what I found. Piston is in good condition but fitted backwards, somehow the rings hadn't snagged the exhaust ports

Bore within spec & only in need of a hone but new rings may not be available

Wanted / Re: 1974 CR250M crankcases
« on: July 17, 2018, 07:22:18 PM »
There are kits available that have a spacer under the barrel, 1 of the guys here in NZ bought 1 after having the crankpin break from memory

CZ / Re: CZ Aftermarket Head. Period Item?
« on: July 14, 2018, 06:35:50 PM »
I managed to score 1 last month out of the states, came up for $80us so I grabbed it before I even had the sidepipe in my possession. Quite a bit heavier than the original head but will definitely give the bike a bit of period trickness

Tech Talk / Re: Yamaha pipe slip on flange shortening?
« on: July 03, 2018, 06:02:59 AM »
Had the same problem with the DG pipe on my 465, I made the spacer but discovered that the end of the port wasn't square to the pipe so even then it wasn't sealed properly
I did a whole heap of measuring & found that the start of the pipe was smaller than the inside of the port so I made a new flange that fitted the cylinder properly & cut the end of the pipe off. In effect I made the parallel section of the exhaust port longer

Yamaha / Re: YZ125G stator winding resistance.
« on: June 27, 2018, 08:00:56 AM »
Think a few people are using imgur now, may have the spelling wrong

Tech Talk / Re: Unlocking a motor
« on: June 25, 2018, 02:25:28 PM »
Was found in Auckland I think but has a south island history, sounds like Paul Doecke knows who raced it back when Paul won the New Zealand title in 69 or 70

Tech Talk / Re: Unlocking a motor
« on: June 24, 2018, 06:13:11 PM »
Steve Gallichan picked it up amongst a package of 4 bikes & parts, he kept the Maicos & gave me first option on this 1 as he already has a 360 sidepipe that he's restored. Needs to get a twinpipe now so he has all the stages of CZ evolution
Going to take a far amount of time & money to get it race ready but I never thought I'd get my hands on 1

Already have the correct shape front guard & a JOK radial head coming for it, the biggest expense will probably be the getting the forks rechromed.
May have to see what parts I can come back from the CZ worlds with next year depending on how far along the rebuild is at the time

Tech Talk / Re: Unlocking a motor
« on: June 23, 2018, 03:22:28 PM »
That sounds gentler than beating on the end of a lump of wood

CZ / 360 sidepipe pistons
« on: June 23, 2018, 02:36:00 PM »
Are pistons available for 360s? I know OTZ has rings in 80, 80.25, 80.5 & 80.75 but don't show 360 pistons
Any possible sources that people can suggest?
Not sure what size bore the bike I have coming is but if possible I would prefer to keep it as a 360 rather than open it out to 380 when I rebuild the engine

Tech Talk / Unlocking a motor
« on: June 23, 2018, 02:28:35 PM »
I have a CZ sidepipe coming which I've been told is locked up, has been sitting a long time so I don't know exactly how bad but knowing CZ bearings I assume rings stuck to the cylinder is the most likely reason
What is the best product to soak the cylinder in to slowly work on freeing things up?
Once the cylinder is free I'll be replacing every bearing in the motor, depending on condition of the bore I may get away with rings for a 360 which are available unlike I suspect pistons

Tech Talk / Re: Metal Filler
« on: June 22, 2018, 06:48:11 PM »
Used JB Weld to blank off the oil pump holes on my TY250, being liquid it flowed where needed & shaped really well once it was set.

Twinshock Trials / Re: Longterm TY250C
« on: June 18, 2018, 10:16:11 AM »
Have only ever ridden it without the weight so I can't say what it was like with the heavier flywheel. It's quite a nice motor, almost feels modern. I'm still running the standard carb but the airbox has been altered & I have a v-force reed block for a yz85 fitted
Biggest set up issues I've had so far is no freeplay in the clutch & needing to be quite deliberate in changing gears. I may also need to find a richer needle as I ended up on the lowest position
The full majesty forks work well, didn't get to try them on big rocks but I couldn't fault them on roots & the medium sized rocks in a river bed that we had in a few sections

Twinshock Trials / Longterm TY250C
« on: June 17, 2018, 07:00:35 PM »
Finally got my 250C back in a ridable state. We worked out it had been about 5 years since I'd ridden it last when the main bearings & rings were that worn that the motor could be turned over by hand by gripping the end of the crankshaft with the flywheel off

While the motor got a full rebuild with the cylinder being bored to 1st oversize I made a few changes both to looks of the motor & had the swingarm extended with shedworks axle plates
The axle plates extend the swingarm by 38mm or so which puts a bit more weight to the front. As it turns out even with the lengthened swingarm the wheelbase is standard which confirmed that the steering head angle had been modified, the welds are far better than normal & the front down tube are completely smooth. We stood the bike in front of a Beta Techno & the fork angle is the same which makes sense as the Techno was the current bike when the mods would have been done
The original shock mounts were deleted & a gusset fitted to help strengthen the tubes above the repositioned mounts that were done before it's last ride
I fitted a DT250C head that Ian Cameron supplied me for looks, I race a 73 CZ & owned a YZ465H when I built the motor so radial heads are my preference. The combustion chamber is meant to measure the same. There was minor grinding of a couple of fins to clear the exhaust & I cut about 10mm from the rear to match it to the cylinder
An electrexworld ignition is fitted now with the band removed from the flywheel, I had to put marks on the flywheel & stator plate for timing while the head was off. Unfortunately we didn't get a chance to strobe the timing as per the fitting instructions & had to run it set at the middle of the slots but it seems to work well

I'll see what other detail photos I have & try to put them up at some stage

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