Viton-B Vacuum Cap Premature Failure?

[Jetflyer]

I was surprised to discover the source of my deceleration popping. It came from the air leaks on my vacuum caps that had ALREADY cracked and split.

Within 6 months, all six of the highly touted Viton-B vacuum caps had cracked and split. Although there is no specific life expectancy on such items, I thought the failure was premature.

If you installed these Viton-B caps recently, pull and inspect them closely.

[Patrick]

Thats too bad.But, as highly touted as viton is, I haven't been impressed.

I replace the intake nipples with cap screws and just reinstall them when I want to check the carburetors. But, using a short length of good quality vacuum line with a nice cap screw stuck in one end then pushed over the nipples will last just about forever  and really isn't too noticeable. I've never had good luck with any vacuum cap no matter what the material.

[pancho]

The OEM ones seem to be made from a material that lasts for awhile, and at $1.52 each at Partzilla, a decent deal when making a parts order.

http://www.partzilla.com/parts/search/Honda/Motorcycle/1997/GL1500C+AC/CYLINDER+HEAD/parts.html

[BobB]

I never cared for the made-up caps supplied by Redeye.  I turned to the caps that are sold by BigBF at Inzanes. 

[Jetflyer]

I too replaced my caps with the ones by BigBF.

[Daniel Meyer]

The valk has an aggressive cam and that gives a significant intake pulse...it's hard on vacuum lines and caps.

[BradValk48237]

I also put a set of the Redeys on last year after I desmoggered it...

2 of them were crack when BF did my Sync at Inzane....

I don't think they were defective, probably just from me putting them on with pliers after I got them later..... they are thin

replaced with BF.. no pop, no leaks.....

I actually got good milage on the way home to Michigan.... at 85+ most of the way!

B

[BonS]

What are these BigBF vacuum caps of which you speak? I've been to his website without any luck - but I sometimes have trouble finding milk in the fridge.

[BobB]

What are these BigBF vacuum caps of which you speak? I've been to his website without any luck - but I sometimes have trouble finding milk in the fridge.

They are a one piece molded cap that simply slips over the nipple.  I do not see them on his website either and they are certanily not in the fridge.  I would e-mail him at 98valk@bigbf.com and inquire.

[98valk]

some consider hypalon caps the best for engines, jegs and others sell them.
the site also list the properties of other materials including viton which is excellent, your viton caps should not be failing looking at the specs, unless its a blend of materials.  every material has its pros and cons. also remember to look for sunlight exposure resistance, some materials are very poor.

http://www.timcorubber.com/rubber-materials/hypalon.htm

http://www.timcorubber.com/rubber-materials/viton.htm

looks great except very poor sunlight exposure
http://www.timcorubber.com/rubber-materials/nitrile.htm 

[BigBF]

Yup I thought Viton tube is good but kind of way too thin. I carefully pry it off for carb sync and it got ripped and some were already ripped before too...  I recommend all caps should replace new caps whenever removed in future...

I use the caps I find work pretty good and then some cap blew out so I start to use tie strap and no problem so far.  When need to remove, use small long cutter plier to cut tie strap off. Sometimes cap get harden then replace new cap and sometimes still soft so I guess it depend on weather and fuel.

[BigBF]

What are these BigBF vacuum caps of which you speak? I've been to his website without any luck - but I sometimes have trouble finding milk in the fridge.

They are a one piece molded cap that simply slips over the nipple.  I do not see them on his website either and they are certanily not in the fridge.  I would e-mail him at 98valk@bigbf.com and inquire.

I will add that on my web site when I get back home in Aug... Thanks for the idea.

[98valk]

what size are the caps, 1/16", 1/8" etc. I just used some I had left over form other projects, but would like to have some more just in case.

[YoungPUP]

I got tired of looking for and wasting my money on caps that wouldn't last a season. I ended up pulling the nipples out of the intake runners and replacing them with socket head allen screws.  No problems after that.  As for the Vacuum line for the petcock I used a piece of silicone tubing left over from some project from some time  .

[Jetflyer]

I like the permanent solution of using socket head Allen screws.

It would be nice to say goodbye to the nipples on the desmoged dragon. Has anyone else removed the dragon's nipples?

[Jetflyer]

Doctor Daniel Meyer... may we have your second opinion?

[Patrick]

I like the permanent solution of using socket head Allen screws.

It would be nice to say goodbye to the nipples on the desmoged dragon. Has anyone else removed the dragon's nipples?

Looks like just 2.  But, it doesn't make much difference cuz it works well.

[BigBF]

I like the permanent solution of using socket head Allen screws.

It would be nice to say goodbye to the nipples on the desmoged dragon. Has anyone else removed the dragon's nipples?

I remember back in 2006 at Frisco Inzane one of Valk had remove and put bolt with gasket washer on all intake manifold tubes. When he came to me for carb sync. I discover it does not have fitting for me to connect hose on fitting. I asked him do you have the fitting for it? He said he could not find it where he put it and he thought I would have it I said no I don't have it. I told him see if you can borrow 6 intake manifold tubes from someone's bike and he asked several and most of them said no.... We end up no carb sync for his bike. I don't know if this was good idea or not???

[YoungPUP]

I know where my dragons nipples are. I keep all my carb bits in a dyno jet parts box (think small tiny tackle box.)

[Patrick]

Well, you do have to keep and know/remember where those little nipple critters are. A carb sync isn't something that needs to be performed very often, but, those nipples are kinda required aren't they.

[doubletee]

Thats too bad.But, as highly touted as viton is, I haven't been impressed.

I replace the intake nipples with cap screws and just reinstall them when I want to check the carburetors. But, using a short length of good quality vacuum line with a nice cap screw stuck in one end then pushed over the nipples will last just about forever  and really isn't too noticeable. I've never had good luck with any vacuum cap no matter what the material.

Any chance of you posting a picture of those cap screws in place? I'm struggling to understand where/how/etc.

[Patrick]

Thats too bad.But, as highly touted as viton is, I haven't been impressed.

I replace the intake nipples with cap screws and just reinstall them when I want to check the carburetors. But, using a short length of good quality vacuum line with a nice cap screw stuck in one end then pushed over the nipples will last just about forever  and really isn't too noticeable. I've never had good luck with any vacuum cap no matter what the material.

Any chance of you posting a picture of those cap screws in place? I'm struggling to understand where/how/etc.

Post a pic ?  As computer illiterate as I am !  Ahhahaahaha.

But, its simple. The nipples just screw in. I forget the thread size, its been a dozen years, but the threads are deep enough that they won't leak. Once the screws are started by hand a long ball hex driver from the opposite side works fine. Or you could remove the runners and install the screws. I add a dab of never-seize just for good measure.
These are not needed, but, there is no worry about vacuum leaks.

[Daniel Meyer]

Doctor Daniel Meyer... may we have your second opinion?

Not much to say that hasn't been said already.

The Valk has an aggressive cam and a significant backpulse on the intakes...hence the complicated scavenging airbox...tends to be hard on vacuum lines/caps.

Buy big, thick, heavy ones. Replace them at intervals. Replace the vacuum lines at intervals too. Don't bother with viton, silicone, expensivadupe, suckerstan, pockettoofullofcash, or any other fancy material. Regular vacuum line works just fine. All last about the same.

[Brian]

Yep, the Viton caps are too thin and crap. I went back to auto store type heavy vacuum hose with a screw in the end. Not using any wimpy clamps either and have never had one fall off.