Hi all. In looking into adjusting my oil pump setting, I took off the OEM air box and noticed the rubber on the air box tubes (part # 17253-KV3-831) was curled up in places (see pic). First question, why would this happen? Second, more important question, does this mean a) replace it before riding again or risk very bad outcomes, b) okay to use for now but work on getting a replacement ASAP, or c) not ideal but really not likely to hurt anything significant?
Thanks for any advice.
-Jim
_________________
-Jim
'93 MC21

Are you talking about the crinkles I have highlighted with my picture?

If so I can't see why these should pose a problem, as long as the rubbers seal properly inside the airbox and seal onto the carbs, that's all they have to do.
Inspect them for any cracking or splits, they need to be airtight really.

That (crinkled) outside lip is just there to create a channel to secure the jubilee clip in if I am not mistaken. It may reshape if you removed the rubber tract from the airbox and plopped it into hot water but then in the process you would break the seal of the rubber tract to the airbox...which would not be good.

I have seen this before and I think it occurs when somebody over tightens the jubilee clips which in turn forces the rubber to slightly twist off the carb bell mouth and disconnect. If left they deform in the way you have seen.

I would have thought that when properly refitted the crinkles would pretty much straighten out, the jubilee clips just need a gentle nip up, no need to hang on the screwdriver, just looking to make it airtight and secure. Try and refit, if good, then leave them as is 👍

Thank you again, Max. Those are indeed the wrinkly culprits and I am no doubt the wrinkly culprit (I really am too old to be riding this bike, as my son often reminds me!) who overtightened the screws to cause it! I really do have a tendency to overtighten (as well as overthink) things - it gets me into a lot of trouble! I'll refit with a gentler hand and see how it goes. Thank you.
-Jim
_________________
-Jim
'93 MC21

Hi Jim,

I used to have the same tendency, my default torque setting used to be "Landrover tight"
I purchased a 3/8" torque wrench (much lighter settings than the 1/2") and started to use that for every little job, (you can develop some easy base settings for say 4mm,5mm & 6mm threads). You start to recalibrate to the new lighter HRC touch.

Also worth having a think, how tight would you put the lid on a jam jar to keep the air out and keep the jam secure inside?...maybe then a 1/2 more of a turn because of the vibrations from the bike...and that in my opinion is roughly your carb rubbers tight enough! Just a nip'n'tweak.

Hi Max,
Yeah, I have a good 1/2" torque wrench but as you say it is not often of use for lighter settings (and tighter spaces). Maybe a 3/8" would be a worthwhile addition - I do love having the right tools for a job. I like your jam jar metric - I'll try to keep that in mind when I'm putting it back together! thanks again.
Jim
_________________
-Jim
'93 MC21

Jim wrote:Thank you again, Max. Those are indeed the wrinkly culprits and I am no doubt the wrinkly culprit (I really am too old to be riding this bike, as my son often reminds me!) who overtightened the screws to cause it! I really do have a tendency to overtighten (as well as overthink) things - it gets me into a lot of trouble! I'll refit with a gentler hand and see how it goes. Thank you.
-Jim

Hi Jim, your never too old to be riding an NSR, don't let your age stop you, iam well past the sell by date where I should have stopped, it's probably one of the pleasures that keeps all us old farts going.
_________________
Proud Father of , 05 ktm 400exc supermoto 2018 honda crf rx supermoto

Thanks. Pretty sure I have you and most everyone else on this board in years, but we won't go there. But I do agree with you in spirit, which is the reason I keep doing it, even if my knees and wrists beg to differ!
-Jim
_________________
-Jim
'93 MC21

Replacement rubbers are available from Japan.
_________________
Why do things simply when you can complicate them

Thanks Rob. I was about to order some from Rising Sun Cycles in the States and then remembered I had a takeoff, modified OEM airbox somewhere in the garage. After much burrowing and cursing my lack of organization, I found it and was able to scavenge some decent-condition inlets and get them installed on my current airbox - surprisingly easy to do, even for me! 😙

For future reference, is there a way to order directly from Japan? Thanks.
Jim
_________________
-Jim
'93 MC21

I normally use jauce.com
_________________
Why do things simply when you can complicate them

Very helpful, thanks!
-Jim
_________________
-Jim
'93 MC21