Flywheel removal

[SBvision]

Hi,

Just acquired an '82 550 and a later 400 (registered here in New Zealand in 1989, but i suspect they were made about 1987 at latest) for spares.

550 has horrendous clunking from starter clutch. I need to remove flywheel to get to it but am not sure which direction the bolt undoes. Seems as tight as and do not want to sheer it off!

[Night Vision]

hi, welcome to the forum

the flywheel bolt loosens to the left, counterclockwise.

it helps if you wedge a lead wheel weight in the gears to keep the engine from turning over when you go to loosen the bolt.

one big tip when pulling the flywheel, dont thread the flywheel puller bolts in too far. it'll bend the metal on the back of the stater clutch.

[SBvision]

Briliant.
Must say I'm greatly appreciative of the forum...not too many other jap bikes get such dedicated fans.

[Coil Coyle]

SB,

     And, after the puller center bolt is tight, a smooth swing with a big hammer right against the puller bolt head is required. Like you are trying to drive the crankshaft out the other side of the engine.

      Shock and awe....the flywheel pops right off the crankshaft taper.

$00.02

coil

[h2olawyer]

If you are fortunate enough to have a pneumatic impact gun, no hammer blows are necessary.  Used with the puller, mine came off quite easily with that method.   ;D

H₂O

[MotorPlow]

Don't forget to thread some type of bolt back into the crankshaft before putting the puller on. Otherwise, the center shaft of the puller could damage the threading in the crank.

[Night Vision]

Don't forget to thread some type of bolt back into the crankshaft before putting the puller on. Otherwise, the center shaft of the puller could damage the threading in the crank.

ooo, good reminder

[SBvision]

Thanks guys.

Have done exchange with starter clutch from 400. 550 one had a cracked housing. Started the beast up and there was still a generous emission of clunking from top end. Some back story here: Bought the bike not going. The previous carer (I use the word advisedly) had tried to start it "had it firing" then burnt out two solenoids.
Having turned it over by hand, it was obvious all was not as it should be. Setting the cams in the right place made it feel a whole lot better... then had to rebuild starter, starter clutch etc.
Short version is: the top end has sustained some damage.
Next step put 400 engine into 550 as temporary. Have done so and it's a nice runner.

Today's question: Does anyone know what valve sizes, bore and stroke 400 version of Vision runs?
I'm wondering if Mr Yamaha took a lazy option and de-bored and de-stroked 550 to make a 400. That would mean he could use original heads without too much alteration for squish area. Would just need a couple of links shorter camchains.
The fact the exhaust system is interchangeable and the carb manifolds likewise sort of points in that direction.
But before I haul the 400 heads off and try them on the 550, (with potential for two motors in bits instead of one runner and one in bits) I'd like a second opinion (or two).

Ps Summer almost here in NZ, want to get on the road (preferably with 552cc instead of 398cc).

[XZv2]

Hello, SBVision,
The 400 has a different bore and stroke (73 x 47,6 mm) than the 550 (80 x 55 mm). On my webside (xz550.nl) is a topic XZ400 that gives these and other basic data.
The valves of the 400 are smaller (in 27 mm, ex 23 mm) than those of the 550 (in 31 mm, ex 26 mm), the camshafts are lower.
The flywheel of the 400 is lighter than that of the 550, but it fits. Would be interesting to use it in a 550 and see what the effect is.
XZv2
 

[SBvision]

Thanks for that. The 550 would obviously wheeze like an asthmatic on dope with 400 heads. Planning to run 400 flywheel when I resurrect the larger engine.