Flywheel F & R Marks and Top Dead Centre Locating – GT250R
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Rebuilding GT250R & getting anxious.
1. Flywheel (F) & (R) MARKS, are they ALWAYS the Front & Rear location? Is it possible to upset the F & R actual location? (i assumed F&R marks would indicate top-dead-centre, but when i moved anti-clockwise from F to R, the front cylinder was NOT at it’s lowest point, it was rising. Now im anxious about putting the top end back on & firing it up.
2. Top Dead Centre (compression phase), how to find it for Front & Rear Cylinders?
3.Torque for 4x main head bolts … there’s probably some thing else i need to know. If you know what that is, please type it below.
(Photos show the Flywheel MARK when the FRONT PISTON is at it’s LOWEST point, (i thought the flywheel mark should be R right about there??)
-----LaserBeam---->
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F – marking would mean the engine is ready to check the valve clearances at the top front, however since you already have the engine apart, you can spin it to see its lowest point , then mark the flywheel to say “PLF” (Piston Low Front) and rear PLR , Korea should have done it at factory, but when i rebuild engines i don’t need the flywheel to know if the piston is up or down since i’ve already removed the heads 😉
4x bolts = around 20ft lbs and use a little bit of loctite-medium strength. (not the hard strength)
// Meditation doesn't mean you have to sit still....
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Thank you, Marcel. The F and R do represent Top Dead Centre of the compression phase.
20ft lbs is about 27Newton Metres? My wrench is only Metric.
I put 2 new pistons & rings on & today i put the cylinders on those. Cam-chain of the FRONT cylinder has fallen off & turns freely.
How do i get the Cam Timing Chain back on?
Can i do it without removing the flywheel? (I have the stator cover off).
I’ve seen a guy flick it back on by giving it slack but i couldn’t manage it.
I’m dark about it – i tried so hard to keep the buggers in place.
-----LaserBeam---->
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Sadly , you will have to get the flywheel off , because the chain may end up hooking on to 8 teeth and 2 are missing! – you will end up stripping the crank teeth as soon as compression hits!
So it is safer to get the rotor off. Same with the clutch side!
To keep cam chains from falling, have a bungee cord pull the chain and hook the other end of bungee to ceiling of your garage
// Meditation doesn't mean you have to sit still....
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So it is safer to get the rotor off
I’ve got an Endoscope Camera to see if the timing-chain is on the teeth correctly too. Small ones are very cheap & plug into phone or laptop’s USB Ports. They have a bendy wire so you can get it in behind the flywheel, etc. If there’s a kink, send the magnet tool in again. It’s a good, fast fix. Saved me time searching for a Suzuki puller (?) for the 250 & money. I’m anxious to ride.
-----LaserBeam---->
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Sadly, you will have to get the flywheel off. Quote
That’d be best but i couldn’t accept that.
I replaced the loose Cam timing-chain with a bit of magic instead. 😎 From the FRONT of the ENGINE, i slid a Telescopic Magnet Tool beneath the UNDERSIDE of the TOP part of the Timing-Chain then pushed it in & lifted it up. I also got some slack on the LOWER part of the timing-chain by pushing that in a bit with a 2nd Magnet Tool from the LEFT SIDE of motor. Then I pushed the top & lower parts of the chain TOWARDS the engine from the LEFT & carefully take up the slack on the lower part of the chain.
Took me 5minutes. The hardest bit is getting your head between the front wheel & the front cylinder so you can see the teeth that your aiming your chain at. I’m fully stoked; hope this helps somone. (The risk of links kinking, by counting the pins & comparing to the other cylinders chain).
-----LaserBeam---->
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Nice investment in to the endoscope, we use them sometimes…
Endoscope Cams are really handy. Some are cheaper than chips. I used my cheap USB endoscope for this job. Plugs into a phone; uses an APP or slots into your laptop with software. The camera is about 4-5mm wide & perched on bendable-wire. LED lights, around the camera, which you can turn up, down & off.
Sadly my little endoscope couldn’t get a view of the cam chain, where kinks would be. Bugger. Anyway, i ROTATED the crank slowly with my fingers on the chain to feel for the kink. No kinks-very relieved.ENDOSCOPE CAMERAS: https://wonderfulengineering.com/10-best-wireless-endoscope-cameras/
-----LaserBeam---->
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