Most vulnerable/"perishable" rubber/soft parts?

[Mongrel]

There are a ton of rubber bits on these bikes. And, as I'm sure many of you with older (80's) K's know, those flexible bits won't last forever.

I want to proactively do a check/buy/replace on the more vulnerable bits as lot of rubber is cracking or torn on my bike. I've got to replace all or most of the tank and fairing grommets, the boots for the clutch cable, pick up a spare crankcase vent tube and maybe a few other parts.

What I'm wondering is, what rubber bits tend to be more vulnerable on this bike? I'd like to do a general check and order replacements for anything that looks like it's either getting too soft or too dry. Any suggestions? Good replacements to have on hand?

[richarddacat]

From my little bit of knowledge my 1st priorities would be fuel lines, vacuum hoses and if you're not running SS brake lines that would be the fixes I would concentrate on.

[Inge K.]

Rubbers above and under throttle body (2V), o-rings at bottom flange (4V).

[Scott_]

Sounds like you have it all covered, basically any rubber bits should be replaced by now. I'm planning on renewing all the rubber stuff on my '97 this fall.

For those with newer bikes with the para-lever drive line, there are the rubber boots at the transmission and final drive connections that will start to stiffen up.

Oh, don't forget about the rubbers for the valve/crank cover bolts as it is their "elasticity" that is what maintains the tension for the covers against the gaskets. Be sure you have a good torque wrench for those bolts as they do bottom out and will break/strip threads if they are over tightened.

I think about the only ones that we can't seem to be able to buy individually are the curved/molded tubes that connect the top of the tb's to the air box.

[Grim]

I just went though my 1100 a couple weeks ago.  Pretty well just resign yourself to replacing the throttle body boots/bushings, ORings if a 4v, fuel lines and crank case vent hose. Once I pulled my throttle body every one of those parts was bad. Repeat in 15 or so years.
There is a rubber molded vacuum manifold that joins the throttle bodies together mine had cracks but I used some decent hard drying gasket gunk to seal it up. It's $70+ part. I've seen somebody use some T's and regular vacuum line to make one fore about $10-15.

[tg4360]

I've replaced every bit of rubber I can get at except for the intake boots top and bottom on the TBs.

Almost everything I've replace had at least started to crack.

I think the ones that will give you the most trouble and should be top on the list are the manifold vacuum taps and the "z" crank case vent hose.

TG

[gladstone]

And don't forget the handlebar mounts and the exhaust mount behind the centre-stand. Both made a big difference to the level of vibration (in a good way!).

I also swapped over the footrest rubbers as the front side on each had badly worn - like having new footrests for free. Unfortunately the unworn rears don't fit the front.

Cheers

[orforester]

And the water hoses, and how about the seals?  30 years old, guess they are cracked, transmission seals and the rear engine seal.  Did all of those this past winter on my 85, and they were hard and cracked.  Bike only had 30,000 miles, but time and heat takes a toll on rubber parts.

[Mongrel]

Urgh! The Crankcase/engine head bolt washers were definitely on the list at some point but had fallen off, so thanks for reminding me. Mine look fine, but it'd be bad news for sure if I need to crack the thing with no replacements on hand, so I want to have those ready.

My water hoses are alright, though they'll probably need to be replaced in a few more years (just a little soft, not cracking). My throttle bodies are thankfully fine (I should have mentioned I checked those, because obviously they'd be at the top of any list!). My fuel lines also look good. I think they were replaced already at some point, but I've got to give them a more careful inspection.

How do you switch the footrests over? I was thinking of doing just that and getting some extra wear out of mine. I guess slipping them on is easy, but it seemed like the things wouldn't come off without damage.

Almost certainly needs new head/crackcase gaskets and engine seals all 'round too. But one project at a time.

[gladstone]

Twist and pull on the footrest, give a squirt of silicon lubricant under the rubber if stuck.

Cheers

[Chaos]

Coolant hoses seem to last forever.  Mine are original from 1986 and doing fine.

[Mongrel]

Twist and pull on the footrest, give a squirt of silicon lubricant under the rubber if stuck.

Cheers

Huh. Might as well give it a try - thanks!

[richarddacat]

Twist and pull on the footrest, give a squirt of silicon lubricant under the rubber if stuck.

Cheers

Might also try a blast of compressed air like you would with a handlebar grip.