Puzzled.

[MaxMidnight]

Centre bolt is part # 90105-12374-00 and using the following


Tells us it is an M12.

 

[Limeyrider]

Hey MaxMidnight ... that is a handy reference guide ! .... thank you for posting.

 

[putin]

A question .... what is the diameter of the centre bolt ?....I will be making from scratch and not using a " donor " puller.

Just buy a round puller from Amazon. More than enough.

 

[Limeyrider]

Hey putin .... thanks for the idea .... will check it out

 

[keith eacott]

I screw the retaining bolt out only a couple of threads then use the puller pressing on the retainer bolt. When the clutch hub releases it can not fly across the room.

 

[Limeyrider]

Hey Keith ... sounds like a good tip ... I'm not quite at that point yet, but will bear that in mind ... don't fancy a face full of flywheel !.

 

[MaxMidnight]

Attached is all you need for the job.

 

[Limeyrider]

Hey MaxMidnight .... brilliant !!.... excellent tutorial. The boys at the Yamaha factory could learn from that.
Thank you for taking the time.

 

[Limeyrider]

My apologies to all who contributed to my " Puzzled " posting for the long delay. I was trying to nail down the lost ignition sparks, going through various testing with the help of Sean, suddenly, the motor would not turn ... yep ! ... the starter motor clutch had failed ... many thanks to Sean for pointing me in the right direction ... and for supplying the repair parts. I fitted the new clutch, all SEEMED well, the motor turned on the button, but then stopped turning on the button. I was praying that the clutch was ok. The clutch is fine .... I removed the flywheel and clutch gearing, and, using a wrench on the crankshaft bolt I can turn the engine only 300 degrees ???.... it comes to a dead stop in either direction .... clockwise and counter clockwise ???. I am about to begin checking valve timing. The engine is still in the frame so may be a bit tricky to get the timing sorted properly. May have to remove the engine from the frame anyway.

 

[Fire-medic]

Dare I say it, a dropped valve? Pull the plugs, use a cellphone fiber optic probe to visualize the combustion chambers as you rotate the engine.

 

[02GF74]

This is going from bad to worse.

To summarise.
Engine wouldn't turn over as the starter cable was not connected to the starter solenoid.

Once that was fixed, engine turned over but would not fire, testing the coil, leads and plugs pointed to a failed ignition unit.

During these tests, engine stopped turning over due to broken starter clutch.

After the starter clutch was fixed, has the engine turned over OK then stopped or never turned over?

Either something is interfering with a piston dropped valve as FM says or maybe the starter clutch?
If the cam chain skipped, then valves would interfere with all 4 pistons so if my maths is correct, you'd be able to turn the engine less than 180 degrees.

BTW you can buy a cheap endoscope with built in LED that connects to a mobile phone via USB , this would allow a look see through the speak plug holes.

 

[Limeyrider]

Bad to worse just about sums it all up ... after I replaced the starter clutch the engine turned over on the button, I did not keep the motor turning over as the side cover was not in place and the gear train was not secured. The next day, I tried to turn the engine over and the starter motor operated, but the engine did not fully turn over. I can rotate the engine CW and CCW by hand for a total of approx 300 dgrees ...there is a definite " thump " as the engine stops, I don't hit hard ... I am used to using a piston stop on my old bikes for setting TDC, so I recognise the sound and feel. Fibre optic endescope ??.... as said " bad to worse " !!.... anybody want to buy a Yamaha VMax paperweight ???.

 

[Fire-medic]

you can buy a cheap endoscope with built in LED that connects to a mobile phone via USB , this would allow a look see through the speak plug holes.

What's the difference between a gastric endoscope and a rectal endoscope?



Taste.

 

[02GF74]

I'm not convinced something has dropped in a cylinder. Valves are immensely strong, If they are to fail, I'd would expect that to be at high rpm, not when cranking..... but we shall see.

I would suggest having another look at the work you did on the starter clutch, perhaps removing it to see if engine turns over. .

This is the scope, less than $10. On ebay.

 

[Limeyrider]

Hey 02GF74 .... I have removed the starter clutch and flywheel, I re installed the crank shaft bolt with a spacer, still cannot turn the engine over a full 360 degrees. Thanks for the link for the 'scope. I don't know what would cause a valve to drop ... at less than 1 rpm., I will be removing the engine from the frame to get a good look at the valve operating mechanism.

 

[02GF74]

Other possibility is for a spark plugs to fall apart, or something dropped in via carbs through the inlet. You're not missing an air box screw or similar?

I know space is tight but can the cam covers be removed with the engine in place?

I'm sure it will be worth it when fixed...... in 2024.

 

[Limeyrider]

I have the carbs closed off with pieces of rag. I used a semi flexible magnet to probe down the plug holes .... hopefully nothing made from brass / stainless / aluminium found it's way in !.
I will only find out if the cam covers can be removed in situ by attempting ... I'll do that before taking the engine out. I'm not sure what I will see with the cam covers off ??..... camshaft / shim buckets ?.... will a dropped valve be apparent ?. My bikes have pushrod OHV engines.

 

[02GF74]

Good point about the followers. I've not been under the cover, will need to check the manual to figure out if a broken valve will show up any differently.

Not sure but if the valve head and stem is inside the cylinder, then nothing is holding the spring in place so the follower will be up against the cam lobe = no clearance?

 

[Fire-medic]

Years ago I had a Yamaha Special II SOHC 650cc parallel twin. It was given to me, "it doesn't run." I got it running, but a tremendous clatter. I pulled the valve cover to see that somehow a keeper was spit-out, the valve was hitting the piston crown. I replaced the keeper and the engine seemed to run OK. I sold it soon after, "runs, needs work." I owned three KZ1000's at the time, and really had no interest in it. It was a 1 owner bike. The buyer sent it to the U.K.

02GF74 said, "...the follower will be up against the cam lobe = no clearance?"

The 'follower' is the valve stem acting on the cam lobe. OHV's have rocker arm followers on top of the pushrods and usually hydraulic followers acting on the cam, usually close to the crankshaft. Some engines have a 'high cam' design using very-short pushrods which aids in higher rpm's achieved, because the pushrods are shorter, lighter, and stiffer. OPEL used that design in the late 1960's (advertised as 'cam-in-head,' but definitely not overhead cam!), and Moto Parilla used a high-cam design (but still an O.H.V.) for motorcycles in the 1950's and '60's.

Parillas, as they were often called, shortening the name, were often considered to be among the most elegant-appearing bikes of the post WWII era, though by the 1970's they were out of the motorcycle business. For four-strokes, they had decent performance too. A Moto Parilla is a rare sight in the USA.

 

[Limeyrider]

A bit / lot off subject .....my own " high cam " engine ... 1957 Velocette Venom.