CB key question..... need answer.

[Chipstien]

I have 5 mil keystock in both steel and stainless steel. Which should I use?

PS. I believe the stainless is harder. ?

Thanks.

[Satch0922]

use the stainless

[thumper245]

I agree with satch the stainless is harder.

[Chipstien]

Would the stainless cause damage to the crank?

[grayracer513]

If this is something that's likely to loosen, you might want to make sure that the key will get beat up first, and not hammer the crank to death. See what others know about using harder than stock keys in this application. As much as it sounds like they get to rattling, it would make me a little nervous.

[tool]

Would the stainless cause damage to the crank?

i always used the stock yamaha key, and replaced it a few times but not as much as i should have. i had to replace the crank because of a broken keyway.

i think the key is supposed to be soft and get all marred up when worn, instead of the crank giving, the key will. maybe the key is supposed to be softer. its only a dollar and it takes like an hour or two to change.

[Dirty_Sanchez]

Chip, am a Loctite factory Rep and have an 04 YZ450F.

The key should always be softer than the base metal. If something goes awry in your engine which forces it to come to a screeching halt, the Key should give before anything else.

The only purpose of the key is to hold something in place at a certain place on a shaft usually to trigger some sort of an event (ie, the spark) at a particular time in relation to the crank position.

Keys do wallow the keyway on a shaft because when the spark hits, an explosion happens, which accelerates the crank, which tries to pull along the clutch and flywheel just a nanosecond later. Well, remember Newton saying that an object at rest stays at rest....you remember the rest don't you. Anyway, in an internal combustion engine or in any other piece of machinery that has a high frequency of startups and shutdowns each day or each second, Key wallowing is a problem. The crank accelerates but the clutch and flywheel want to stay put, but the key becomes loaded, and taps on one side of the keyslot...and guess what, after a million of these tiny taps, we now have ourselves a wallowed keyway.

The fix for this is to put a machinery adhesive like Quick Metal 660 in the keyway, slap the key in the keyway on the crank and a little smear around the shaft and put everything back together. If you're wondering how to pull everything apart once we glue it together, just use your regular 2 jaw, 3 jaw, or flywheel puller.

By taking this proactive approach-which unitizes the crank to the clutch or flywheel you'll have a one piece crank-everything is unitized and will not come apart until you want it to. This way, when the spark hits, everything accelerates at the same time..Newton dosen't have anything further to say. No more changing sheared keyways, or dead bike 40 miles from nowhere due to a sheared key. You'll have a much stronger assembly-if you know how to recognize and address all the potential modes of engine failure during an engine build.

And by the way, I just put my bike up to rest, draining her tank and carb, for 3 to 4 months while I'm down for my 2nd ACL reconstructive surgery this Friday. I haven't even run 3 tanks through her yet. You think I'm a bit bummed right now?

Take Care and don't plant your foot too hard in the turns,

Chip down in Baton Rouge

[Satch0922]

i always used the stock yamaha key, and replaced it a few times but not as much as i should have. i had to replace the crank because of a broken keyway.

i think the key is supposed to be soft and get all marred up when worn, instead of the crank giving, the key will. maybe the key is supposed to be softer. its only a dollar and it takes like an hour or two to change.

Here is an example of using the "soft" key and it ruined the crank. There goes that theory.

The 01 and laterYZFs used a spline gear to mate the counterbalancer to the crank. The counterbalancer would not "blow up" and cause damage to the crank. The counter balancer has to be able to come off of the crank so you can service the engine (split the cases and change bearings etc.). The newer (01-05) bikes use a spline gear....let me tell you ...there is no safety net with a spline gear. The counterbalance is on the crank and it is not going anywhere......sort of like using a stainless steel key.....there is an idea.

Best thing to do is get an 01 or newer crank and counterbalancer....but I realize that is cost prohibitive.

[Bryan47]

I found a 02' crank on e-bay that was in good shape, for $50 bucks...might try looking on e-bay for some parts. Just my .02 cents. ?