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Valve adjustment locknut coming loose

L

LeFrog

Joined Mar 2005
3K Posts | 3+
Mesa, AZ
The locknut I found the other day was not the one that came loose last year and wrecked the bike. It is actually the new one that I put in replacement. Same exact valve (intake left).

I already talked to Berger about this and he thinks the thread on the adjustment screw might have become stretched from over torquing.

I don't remember over torquing myself, because I only used a flat and short wrench, plus there is not a lot of space to get a good grip.

He thinks I should get a new factory screw but I wonder if I could just loctite until I get the new screw.

What type of loctite or thread lock do you recommend? It needs to hold the nut in place but not be too strong so that I can unscrew the nut when I need to readjust.

Thanks in advance!
 
you're safe to re-fit, tighten and go for a ride. but you should put the new tappet/locknut on order.

regards

Taffy
 
Well, I added a little bit of loctite on top to make sure it stays put. I wish those covers were transparent, though...
 
wouldn't risk it myself. narrowly avoided damage myself when one came off mine, also, wasn't your exploded valve cover caused by the lock nut coming off and being picked up by the cam chain?

could also be coming off because you've under torqued it. that was a mistake i made when i rebuilt my rocker arms.
 
I did make sure I had it torqued properly and no it does not seem the thread is damaged. I torqued it good again and added loctite to make sure it is not coming off.
 
Alrighty, I tried tonight with the current parts and the bike started fine considering I opened the covers and drained the carburetor. It restarted easily as well, one kick at first, then became harder and harder until it simply would not even idle.

So I opened the inspection cover and found that the whole adjustment screw had rotated and that there now was a gap of about 5 mm, which would explain the not running so great.

Well... A new adjustment screw is in order. Can anybody think of anything else?
 
i think you have either overtorqued the locknut and damaged the screw or the rocker threads (or both). i would pull the screw and look at it critically with a magnifying glass and run a new nut up and down to see if it binds indicating a bad screw (but i've always said even a bad screw is a good screw :lol: ). if it appears to be good, try a new screw in the rocker to check for binding, indicating a bad rocker. bueno suerte.
 
I actually never really over torqued the locknut, I have always been careful. It may just be the age of the bike.

Can the thread in the rocker be fixed if it is indeed the issue or should I get a new rocker in this case?

Darn it will never end.
 
Can the thread in the rocker be fixed if it is indeed the issue or should I get a new rocker in this case?
Click to expand...
i would change the rocker.
sometimes, nic, its just wear and tear, rather than overtorqueing. but unless you have a keen sense of torque in all the tools you use, its not hard to apply too much. (especially when guys like you are telling us how easily these nuts come loose)
 
Well I have my eyes on a rocker cover on eBay, nobody bids on it or else...!
 
Be aware that the one on Ebay is from a 2000 400 with the crappy rollers, you would be better to buy the later rocker with the new type of roller.
Also the exhaust rocker from the 400 is different to the other models as the valve spacing is different.
 
Nick,

You can buy an acceptable torque wrench for less than the cost of 2 adjustment screws and nuts.

Then none of this will happen again to your bike.

Regards,
Joe
 
Well, I did look for good torque wrenches but the ones that are accurate for low torque are hard to come by. I tried Ace and multiple Autozone types of stores and never found anything.

And I'd like to insist: I did not over torque the nut, since the only wrench I use is a tiny 10mm flat wrench (see my gallery). I never use a ratchet for that job.
 
To close the thread Joe referenced - I ended up getting the 3/8" KD one from Sears and it did a fine job.

I never should given away my old one when I got the new style internal one... :)

Cheers

Mark
 
Well... I've always been under the impression that torque wrenches with a wide range are not accurate in the low range, meaning that if you set it on 10 lbs, it can click out at 7, 12 or even 20. I had a bad such experience on a KTM years ago and then was told on ktmtalk to look for something specifically designed for the lower range torque.

I have a beam type as well as the regular ratchet type and I guess I can trust them for around 30NM (20+ lb-ft) but for that type of job, I am not so sure.

The previous explosion indeed happen because the nut was not tight enough. This time I tried to tighten well, just what it needed, and the same exact nut is coming off, which seems to indicate the thread is toast.
 

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