Carb boots/joints

[RBFD415]

I did a search of the forum on this topic and had several answers/posts-come up- none of which seemed conclusive. I have the bike running, actually not bad, but the old familiar idle surge reemerged. Did the WD-40 spray test on the front boot and could see clear indication of a vacuum leak (bubbling of the WD-40, only in reverse, I'm sure some of you have seen this before). I purchased a new rear boot a couple of years ago and was told both boots were no longer available- I got the last rear one, or so the dealer told me(?)

Searching other bike sites on the web, there was a resolution to the issue by using an extra large piece of electrical shrink wrapping material. The shrink wrap when heated seals the boot completely. I looked for a piece big enough at 2 places today without any luck. I'll try a few more Tuesday. I have no doubt shrink wrap this large is made.

My current question for you guys was the prior forum discussion seemed clear that there where gaskets between the boot and the cylinder head. I'm guessing if the boots are no longer available than I can't hold out much hope for the gaskets?! Considering what a major trouble point a leak in this area is- sealing it effectively is very, very high on the priority list! Any thoughts? Continue searching for gaskets, make gaskets or use a form a gasket type tube product (RTV)? I also realize the boots are not actually called boots by Yamaha, but are referred to as "joints".

[QBS]

Early in Forum History there were posts that sang of the virtues of Liquid Electrical Tape. The concept is to coat the outside of the "boot" being sure to fill in all the cracks.  I've never done this, but may give it go in the future.  Perhaps others can shed more light on the process.

[The Prophet of Doom]

I found the liquid electrical tape to be pretty useless, and ended up buying a pair of the K&L replicas off ebay


If self fusing silicone tape (aka SOS tape, Zap tape) had existed back then I'd have  given it a go.  It's pretty awesome stuff - nice and stretchy and can seal a mains pressure water leak so it should be good for carb vacuum.  It's safe up to 260C

[fret not]

One problem with silicone is that fuel tends to destroy it.  I read "not for use near fuel" dealer's comment concerning the high temp silicone radiator hoses.  RTV silicone will definitely turn to goo if exposed to fuel. 

"O" rings make good seals for joints like this, but you need to make the groove to hold them in place.  Heat transfer from the head is an issue most carbs do better without, so an insulating gasket or non metallic spacer would probably be a good idea.

[The Prophet of Doom]

Not all RTVs are made equal.  There are plenty that are fuel resistant - but yes, many that aren't.  You have to read the labels.

The packet on my silicone tape says: Chemical Solvent Resistant to fuels, oils, solvents, salt water, road salt, UV Rays

[fret not]

Thanks for the correction.  That stuff sounds up to the task.  Is it marketed by a well known brand?

[The Prophet of Doom]

Lots of people make it.  I don't know what brands you have in USA but 3M, Rustoleum, Holdfast for starters.  Like RTV though there could be differences so read the packet and check the online tech sheets. There's a military spec for it out there somewhere.

[RBFD415]

There is a gasket! I'm between 2 Yamaha dealers- one to the south and another north of me. Yesterday I went to the south one (Stumpys Yamaha)- folks there are very helpful and understand old bikes. Through some searching he came up with a part number and it turned out he HAD JUST ONE in stock- see attached picture. Cost- $13.00! Its a ridged gasket with a odd raised portion that goes around the intake pathway. It looks suspiciously like some kind of applied liquid gasket material applied to the ridged portion. The gasket fits both front and rear intakes- I tried it.

So where I'm at now is I pulled off both boots and examined the surfaces. It's been a while but I think I used an RTV type sealer prior as there is material left on the matting surfaces. I'll check my local auto parts place- but I think most common "make your own gasket" type material comes in rolls and is more akin to soft cardboard than the ridged type gasket from Yamaha.

The parts guy used to own a Vision and he suggested sealing the boot itself by coating it with RTV sealer on the exterior. I still have not given up on finding a large enough piece of shrink wrap.

Search continues!

[turbosteve84]

Stumpy's in Neptune! Yeah, the old dealers have parts collecting dust on shelves that rarely show up when parts guys search the national parts network. Another good source in NJ is FW Speer Yamaha in Passaic. Been in business forever and I've found a few "obsolete" there over the years.

Go with those K&L aftermarket boots on eBay before they're all gone. Excellent quality.

Bikes & Breakfast this Sunday at the 9W Market in Palisades, NY. Show up on your Vision and that will be two of us with odd tastes in motorcycles.

Steve

[RBFD415]

Steve- thanks for the invite- but I'm working Sunday! Besides which, I doubt the bike will be running by the weekend- at least in a form to attempt that ride from down here at least!

Are you in NJ too?

[turbosteve84]

Yeah, I'm in Englewood up in Bergen County. All the good riding here is north up through Rockland County and beyond.

What about you?

[RBFD415]

Been a while since I updated- I got the tape to wrap the boot. I gave up on the shrink tube after going to an electrical supply house- a large one in my area- largest size shrink tube fit on the boot- up to about half way. Plus the cost was like $50.00 for way more of it than I needed! So- I used the tape (Miracle Wrap) self-fusing silicone, which was impressive, however there was a major drawback- the tape worked so well it tighten up the boot to the point where it was too tight for the carb! I ended up cutting it off and instead using it to just wrap the it partially. I also sealed the area around the 2 ports where the tubes join with the soft material- which seemed logical points for a leak. End result Monday the bike fired up and runs. Took on the first ride in some time. Runs much better. It is still experiencing some surging in the revs- but nothing like prior.

However- and of course- with the Vision, there's always a however involved- I noticed that after running for around 20 minutes and fully heating up the bike started really acting up! It stalled on one ride twice and I barely made it back to the driveway! I have a really strong suspicion its electrical related. I searched the site for some clues on this but found nothing related? My suspicion is traced to noticing a tremendous amount heat generated in the MAIN circuit feed. Its the last remaining circuit I have not gone through and replaced as of yet. My plan for now is to cut out that circuit and solder it together with clean fresh material- new fuse holder. Do we have a clue on the gauge of the MAIN circuit wire in that part of the harness?

A bigger point is- how many carb issues are really intermingled with electrical issues? As these bikes age the electrical contacts are not fairing well. Any suggestions or comments are always welcome! Like I said I did search the forum but found nothing specific to what I mentioned?

[fret not]

If your wiring gets hot it has too much resistance.  Something wrong there I think.  Clean and grease all the connections with dielectric grease for a start.  On such old wires I would look for any nicks or rubbed areas in the insulation.  A nick or rub through can allow moisture into the wire which can cause corrosion and lots of resistance.  It can be hard to see sometimes.

[jefferson]

Make sure all your grounds are good and clean. If you can check how much voltage is on the ground at the ecu with the bike running and revving. If you see much voltage there it would be good to run a wire from there straight to the battery. Just splice it into the wire that is there.

[Rikugun]

I noticed that after running for around 20 minutes and fully heating up the bike started really acting up! It stalled on one ride twice and I barely made it back to the driveway! I have a really strong suspicion its electrical related.

My first Vision acted like that. It turned out to be multiple vacuum leaks including the YICs and intake boots. This improved things but on very hot days the symptoms persisted. Eventually I replaced the throttle shaft seals which cured the problem completely.

You might try taking a spark tester with you on a ride so you can test your electrical theory. If you still have the glass fuse it's connections are likely poor and the cause of the heat. I don't think replacing the wires are needed, just the fuse and holder.

[RBFD415]

Here's my up date, its been a while, busy summer at work! I've been reviewing the boards here (repeatedly!), especially the carb topics. I dug back into my carbs and found:

The enrichment circuit- the front carb had some how become disconnected. That tiny screw fell out, most likely vibrated lose? I don't know? Found a replacement 5 mm cap screw at the big box store. Fixed!

Rear carb accelerator nozzle. The orifice was clogged despite the complete and repeated cleanings. Cleared it with a brass wire from a cheap wire brush. Fixed!

Float levels. From reading the boards here I found that the replacement needle valves are taller than factory Yamaha. I adjusted the float level. as I read, as posted, that adjusting the floats is a less than an exact process. Did my best. Sure I'll be revisiting this.

Bike starts fine now minus starting fluid! Seemed to idle fine. Took for a brief ride and was overjoyed to not have to push it back home! Still has a lack of power going up a hill. Midrange was smooth! Most amazing- the surging idle seems to have disappeared?

Work continues. I'm either too optimistic or stubborn to give up! Any input always welcome!

[injuhneer]

Has anyone tried the re-molded carb boots?

https://www.ebay.com/itm/Inlet-Manifold-Set-for-Yamaha-Xz-550S-55-S-550-1982-1984/173931051145?hash=item287f193889:g:aecAAOSw0Rdc~9fn

Apparently the hard parts are used as investment for new molding. The vendor asks for old leaking cores to be sent.

[The Prophet of Doom]

Has anyone tried the re-molded carb boots?

https://www.ebay.com/itm/Inlet-Manifold-Set-for-Yamaha-Xz-550S-55-S-550-1982-1984/173931051145?hash=item287f193889:g:aecAAOSw0Rdc~9fn

Apparently the hard parts are used as investment for new molding. The vendor asks for old leaking cores to be sent.

I've not tried it, but a most excellent idea, and a new one for RoV I think - I need four and buying them is pretty spendy.
The hardest thing might be deciding on which materials to use - there are such a lot of them available.  Sitting on the heads they have to be able to withstand considerable temperatures once cured. 
Given that the lifespan of boots is about 10 years, cracking this nut would make you a RoV hero.  I'll watch your experimentation with extreme interest.

[injuhneer]

Has anyone tried the re-molded carb boots?

https://www.ebay.com/itm/Inlet-Manifold-Set-for-Yamaha-Xz-550S-55-S-550-1982-1984/173931051145?hash=item287f193889:g:aecAAOSw0Rdc~9fn

Apparently the hard parts are used as investment for new molding. The vendor asks for old leaking cores to be sent.

I've not tried it, but a most excellent idea, and a new one for RoV I think - I need four and buying them is pretty spendy.
The hardest thing might be deciding on which materials to use - there are such a lot of them available.  Sitting on the heads they have to be able to withstand considerable temperatures once cured. 
Given that the lifespan of boots is about 10 years, cracking this nut would make you a RoV hero.  I'll watch your experimentation with extreme interest.

It appears someone is already doing it. This vendor is recycling the hard components (flange) to investment mold new boots/mounts. Probably EPDM material.

I am also looking at machining an aluminum adapter that bolts to the head then allows us to use a more common straight mount or even a short section of hose/tube.

[The Prophet of Doom]

Someone is already doing it, yes,  but to be really valuable it would good to have detailed pictures, materials used etc so we can do it ourselves without that expensive learning curve.  I'd rather make my own than just buy a set on ebay.