Derestricting my TZR 250 3XV RS

[Martin77]

The squishband is a larger diameter in the head than the bore, and the angle means the further the squish starts from the bore, the larger the clearance. This is to allow the head to be mounted a little off centre (same spec as oem Yamaha). If you fit little pegs to locate the head to the cylinder you can be more precise.. a la TZ. 

Also the edge of the squish in the head would have a little radius, so measuring the depth can be quite hard and not always representative of what the squish will be when fitted.

Personally, I would always go with the measured squish clearance, which sounds ideal now.

[SouthCoastRich]

Thanks Martin!

So both sides came out the same. 0.85-0.9mm. The cylinders had the little metal guides for the studs so that was good and should mean all well there.

Bit the bullet and cracked open those really expensive head gaskets - correct side down and very carefully centralised on the barrel before dropping the heads on. New head gaskets and some fishing hooks of solder poked through the plug hole and it's 0.9mm per side. Just about perfect for my aims.

PS - when reinstalling barrels, it's easy to forget this cable stay. 

[SouthCoastRich]

Next step is checking for leaks. So I have the kit from Ron, and made up some high pressure push fit (don't laugh, the kit off the bike held 6psi overnight without any drop).

I think I've got the exhaust clamps the wrong way around though as it won't take any pressure. Spray bottle of fairy required!

[SouthCoastRich]

Major leaks around the manifolds/reed cages. I'll pop these both off and threebond as per ybk's rebuild thread.

(oh and I did forget the oil feed pipes  blanked off with some heat shrink)

[ybk]

Very nice progress Those manifolds are a headache, so many sealing surfaces..

Also forgot to seal the oil feeds once, was very confusing for a while 

[thump566]

Good to spot the leaks now before it goes back into the chassis or worse when you finally fire it up 

[SouthCoastRich]

Very nice progress Those manifolds are a headache, so many sealing surfaces..

Also forgot to seal the oil feeds once, was very confusing for a while 

Thanks Karel. I'm sealing up with 1215 now, how long should I give this to cure before another leak down test?

Good to spot the leaks now before it goes back into the chassis or worse when you finally fire it up 

Agreed! I specifically wanted to see the crankcase repair was holding so the gearbox is still out too. However, intake leaks are far worse than the other side of the reed block. This is an insightful video from my pal from Norway https://www.youtube.com/watch?v=wtJdWwrnp68

[SouthCoastRich]

While waiting for the threebond to set on the reed blocks, I did a few housekeeping things.

One was to reset my right footrest to the right orientation (it was folding straight up instead of backwards at 45 degrees). I thought that the Allen bolt would be tough and seized, but no... it was finger tight (just like the right hand engine bolt). So good in two ways, now I have the peg right and secondly it won't fall off with the rear brake. Ahem.

Back on the derestriction (getting back to the topic of the thread!) I've gone up on the main jets. All jetting was stock 3XV8 so now the upper has gone from 200 to 220 and the lower from 270 to 290. That should be a good start for tuning as it should be starting rich.

[SouthCoastRich]

Turns out I was using 1138, not 1215. 

Got a few leaks around the reed/manfold. Taken these off again and cleaned up with acetone. I guess 1215 should be better as it has higher pressure resistance according to the chart. https://threebond.com/wp-content/uploads/Products-Guide_ver6-LOCAL.pdf

Maybe I didn't leave it long enough to cure? About 30 hours @ 15 C and 40% humidity, but I think 1215 is the way to go.

Anyway, the initial results were good on one side, got it up to 6psi then it pinged the leak down tester input off the inlet manifold with a big POP and it just missed my head 

[SouthCoastRich]

Couple of updates. First the Suzuki Bandit gear linkage boots work well enough for the PV boots. The shape is round on the seal rather than flat, but I can live with it.

Second. The TB1215 has arrived! After speaking with Karel the following plan is now at stage 1...

• Apply 1215 to surfaces and lightly torque
• After 12 hours or so, fully torque to spec
• After 24 hours, leak test

[SouthCoastRich]

Success on the Threebond TB1215 reed/intake sealant

The only leaks are from the test kit, which may have been 3d printed(?) as the inlet stub seems porous and would benefit from an epoxy seal/paint.

However, leak test is done and all good, I'll leave any further improvement to Ron and I'm cooking on!

[SouthCoastRich]

Engine back in the frame! Carbs back on, clutch cable back on, fuel and clutch routed properly. Next up is to look up the torque settings for the engine bolts and prime and refit the oil pipes.

Then a big torque up of the crank primary bolt. (Balance & Crank gear dots are aligned)

[SouthCoastRich]

I did see a curious thing on the case under the water pump side. Looks like a pressed ball bearing. Maybe for manufacture?

Should there be some sort of cover for this? (See second pic for an odd rubber bit on the top of the engine)

[Warwick]

Good progress  .

Both of those blanking bungs are as they should be so nothing to worry about there. 

[SouthCoastRich]

Good progress  .

Both of those blanking bungs are as they should be so nothing to worry about there. 

Cool - off the worry list! Thanks!

Next off the worry list (well nearly all of them) are the jobs I really hate - high torque bolts 

Crank bolt, thanks to soft aluminium jammer - was actually really easy.

Flywheel was a real pain until I found a helpful feature in the TZR frame that snugly accepts a 15mm socket! (I thought I'd do this rather than ask because I'm sure it's a bodge way of doing things)

Rear sprocket will be a breeze too because that's just a piece of wood between the wheel and the swing arms.

Dreading the clutch though