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I got mine yesterday, have to say the quality is TOP NOTCH.
Let's hope the bearings are up to the task. Time will tell.

What do you use as a guide for setting cam chain tension?

The sound method does not work for me.

I just make sure there is some slack in the chain in cam chain tunnel near the guide wheel, but not enough slack to contact the wall with max finger pressure.

P.S.: Joined the KTM 390 forum btw. Considering the 390 or 890 as next bike.

390 wet weight about 390lbs (ironic!) 42 hp
890 wet weight 405 LBS 111hp

I wish the 390 weighed less!

My Grom wet weighs 209 Lbs with around 20Hp
 

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...

I have a Yuminashi manual CCT on mine, it uses the stock spring and push rod (has a hard Yuminashi button on it too). I tighten it until I hear/feel the slop go away completely, then back it out about a quarter turn and lock it down. Really don't think it can get too tight with the stock spring in there & the Yumi adjuster is only adding a bit more pressure to it, but if you have the other type that eliminates the spring and stock push rod, I can see that easily being over tightened.
Good pics and explanation of the differences between Yuminashi and Gromfatherz type chain tensioning rod, in this thread:

 

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… The reason I hated it is because I spent HOURS picking shavings off of it before I would even think of installing it. It is magnetic and ends up covered in metal dust and shavings. When it arrived it looked like they might have shook it real hard to knock some of the metal off before mailing it to me. That was clean enough, ship it.
That is pretty outrageous. I may order one and give it a try. Air compressor to blow off the debris?

 

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Going to make sure the bolt holding the wheel has some thread lock on it before install.

Things that worry me.... A bearing failure, while unlikely, can be catastrophic.

The bushing approach eliminates that issue at the cost of a drop more friction.
 

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That's unfortunate, but just for added perspective, mine arrived perfect and I haven't heard any complaints from the multitude of members in my group who've bought one. I've had JC ports heads for me also, and they've been great as well.

You'll get faster revs out of your motor with a lightened flywheel, but the reason for me purchasing one was to help avoid shearing the woodruff key in my crank, which happens on motors that make power.
Received the JC lightened flywheel today, so hope to get the new speed shop tensioner installed this week with new flywheel.

It came very clean. No complaints.

Will report back!
 

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Installed the speed shop unit.

The Takegawa unit that came out actually seems perfect. No significant wear. I like the beefiness of the Takegawa arm and the weep hole for lubrication of the bushing at the pivot.

The speed shop unit has the advantage of ball bearing metal wheels, if in fact that will increase reliability. Time will tell.

I set tension of the cam chain using the manual tensioner till finger tight and then backed of 1/4 turn. Chain is snug. Finger tight is actually misleading. I gently turn in the adjuster until I feel slack taken out, not until max finger strength, certainly not max wrist strength. Then, I back out 1/4 turn. I confirm that the chain has slack but is snug enough not to jump the sprocket.

"WHAT PART OF "FINGER TIGHT" DO SOME PEOPLE NOT UNDERSTAND?

The object is to take only the slack out of the cam chains, not put any tension on them. It is worse yet if you start to bog the engine at idle. That is damaging tight. The goal here isn't just to have everything silent, it is to know when you have proper cam drive adjustment. It can be silent, but be way too tight.

Fact is it would be better to have a tiny bit of play than too tight. Finger tightening is plenty adequate in every case I've encountered including tens of thousands of miles on my own bikes. I don't care who's manual tensioner you are running, finger tight is finger tight and is adequate to do what is necessary. Any thing more just promotes premature wear or possible head damage. You wouldn't overtighten your drive chain, why would you do it on your cam drive chain?

I have had a few people who bought tensioner kits from me have noise issues when they overtighten the adjusters. Once I get them to readjust them to finger tight the noise may go away or they found it was coming from another source. With around 400 tensioners around the world, I have yet to have anyone have any problems when adjusting them finger tight. The only issues are when they don't follow instructions.

Take this in the spirit it is meant - to open some riders' eyes to the correct adjustment to keep their bikes running. Nothing more and nothing less."



Started up and runs fine. Full test to follow.

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Good stuff! How much weight was shaved off that flywheel? Notice a quicker rev from it? I noticed immediately the difference in how quick mine revved from the Takegawa light weight spinner.
.6 pounds lighter.

Did not take the bike out for a proper ride yet, so no observations to report on performance. Will ride today or tomorrow, I hope!
 

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Good stuff! How much weight was shaved off that flywheel? Notice a quicker rev from it? I noticed immediately the difference in how quick mine revved from the Takegawa light weight spinner.
First ride. 70 miles of hard twisty fun.

Subtle but definitely feel the reduced (25% reduced) mass on the crank mostly when downshifting. The RPMs drop faster. Not as noticeable when getting on the gas.

Makes riding in traffic more difficult as the throttle has to be managed a bit more carefully.

Recommended if you ride mostly WOT.

No idea if the cam guide wheels do anything for performance :)

Part of today's test ride.

 

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Lightweight flywheel has other effects on the bike as well.

The flywheel acts like a gyro, as do the wheels. They all rotate in the same direction, so the combined gyroscopic stability of all three forces affect handling.

Carbon wheels and a light flywheel with spinner delete is one maneuverable Grom!

Read this. Fascinating stuff:

 
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