Carb holders

[NorCoaster]

I've noticed that all four of my carb holder boots are cracked and are now slightly leaking fuel. How important is it for me to replace them? Already read the FAQ on the subject, but it doesn't say anything about what one should do if they are leaking...I have a 300mi ride coming up on Saturday and while I know I'm losing a couple mpg(and possibly running a little lean as a result), I want to know if it will significantly affect anything that could result in a catastrophic failure.

[DiverRay]

If you are leaking fuel, you have more than carb holder problems!
There should be NO FUEL in liquid form going through the holder, as it should be a fuel/air mix. I would start with the float height and seat "O" rings to find the problem with the carbs.
As far as the holders, they DO get old and crack, so yes, order a new set online. Cost is usually less than $100 delivered, and it's about a 2 hour job to replace them.

[NorCoaster]

Sorry, should've clarified that it's not liquid(so far as I can tell). All I can see from outward appearances is that the vapor is leaking...there's a slight residue on the outside of two of the four(when not running). Also, I dropped the air cleaner to clean it a few days ago and the filter was damp with fuel. Any thoughts? I can't, for the life of me, think of why that would happen.

[rover]

carb holders

The leaking fuel on the filter is from the float valves leaking. You MUST repair the leak(s), or the fuel will run into the crankcase and contaminate the oil. Put a CLEAN stick or rod into the oil thru the filler HOLE and smell it. If it smells like gasoline, CHANGE YOUR OIL!!!!!! If you still have the vacuum controlled shut off (octopus), repair or replace it. This somewhat troublesome device is famous for leaking. It is supposed to shut off the fuel supply when the vacuum to it stops. Anyway, your float valves in the carb(s) ARE leaking. There is an o ring under them, should be replaced with nitrile rings, along with replacing or cleaning the float valves. The carb mounts are double walled, and can be repaired with liquid rubber. While the engine is idling, put an unlit propane torch near the boots, if the engine speed changes, they are leaking. Mine are original, cracked, but do not leak. Good luck.

[NorCoaster]

Alright. Have located all parts needed between bikebandit.com and mikesxs.net. Would that octopus be the diaphragm assembly that connects to the lines coming off the petcocks?

[rover]

octopus

Yes, that is the vacuum controlled fuel shut-off, but if your needle valves in the carb were holding, there would still be no fuel getting thru. The specials have this, and the standards have vacuum operated petcocks. I don't know why Yamaha put such a complicated device on the specials. If the air filter has gasoline on it, then the next place the fuel can go is in the crankcase oil supply. Be sure you check that, cause it will greatly reduce the lubricating properties of the oil. And that could be the death of an engine. Good luck.

[TopCatGr58]

Hey guy,

Okay, there's a Harbor Freight store on 5115 Burning Tree Road in your town/city, and you can get a nice pack/assortment of Nitrile Orings for just a few bucks....will come in handy down the road. You will find a size that will fit your float valve seat in that kit....just use some WD-40 to put it IN, it will be snug..but you want it to be able to slide IN and not get crimped/cut!

While you have the float seat out, get some Q-tips and carb cleaner, and then later brass/metal polish, clean the seat and then polish it a bit so that the VITON tipped float needles will make a better seal. WHile you have the carbs off/apart, ensure that the floats move easily on the pins, not hanging/binding. You can make your own gaskets from cereal box or other thing type cardboard. Be careful with the float pins.

For now, remove the OCTY and just put it aside. Cap off the front nipple of the petcocks. Plumb the fuel line from the rear nipple, to an inline filter, and then to the carb pair across the bike/from the petcock. Just remember to turn OFF the petocks when parking for extended time/overnight. Also verify that the petcocks work...turn OFF when in OFF position. If the petcock is leaking...you can emergency repair the valve by getting a large neoprene/nitrile fender washer...1/8" thick, use the old one as guide to cut out shape of new one, then use a standard single hole puncher...or leather punch if you have one, to make 4 outer holes. You don't need the 5th inner hole because that is only for the Prime and is not needed with the Octy removed. The O-ring kit won't have the very thin one needed to fit around the actual Valve edge, but hopefully it'll still be in good condition. The wavy washer can get flattened and loose it's tension. Apply some grease around the valve. IF the wavy washer isn't strong enough, I actually used one of the O-rings in the kit INSTEAD of the washer to provide pressure for the valve seal, just apply plenty of grease on O-ring and valve where it will contact the outer mounting plate.

While carbs off, REMOVE the intake boot from the head. Check out the INSIDES, as stated they are double walled, and usually the inner layer is still intact, the outer can be cracked but won't really cause any performance issues as long as the inner layer in good. You can use Liquid rubber or rubber sealing tape just to help make it look more aesthetically appealing! Check the mounting surface...they often get hard/crack/crumble where they contact the head..you can use Yamabond or similar, UltraBlack gasket maker, to help making a better seal with the engine when reinstalling to head.

And as stated, fuel on air filter and inlet boot=carb leaking which can flow all the way into the head/past valves, piston, rings and into the crankcase! Check for fuel, but if in doubt change oil/filter, lest risking burning bearings and engine due to contaminated oil!

[NorCoaster]

I believe I already owe you guys a few beers when we meet for a ride/rally. We'll be up to a keg by the end of winter at this rate! Haha

Will definitely be picking up that o-ring kit from Harbor Freight tomorrow.

As for the intake boots...I've found a full set of them that are supposedly made by the original supplier to Yamaha for only $82 on eBay(http://www.ebay.com/itm/NEW-YAMAHA-7...-/201423702196)...am 100% sure that they're leaking so I might as well pull the trigger on them.

So, you're basically saying that bypassing the octy will work just as well for the time being? I've done all sorts of bypasses before(electrical, hydraulic, fuel, etc) so that should go really quickly.

Now, the wavy washer...I'm thinking it's possible to put the waviness back in as long as the metal isn't worn out too much?

But, ugh, yet another malady popped up today. Charging/starting issues. Battery will take a charge, tested as good, and WILL start the bike, but won't hold it. Didn't have the time to pull out the multimeter to see what's going on, but am pretty sure it's the voltage regulator after reading a few posts on here.

[Prothec]

So, you're basically saying that bypassing the octy will work just as well for the time being? I've done all sorts of bypasses before(electrical, hydraulic, fuel, etc) so that should go really quickly.

A lot of us have eliminated the octy to simplify fuel line routing. It's surprising just much fuel line you need to plumb the fuel system appropriately for the octy. As TC says, it's important to make sure you shut OFF the petcocks when you park the bike. It's a hard habit to start, but a good habit to have whether you have the octy in place or not.

If you want the extra insurance against overflowing carbs, consider putting it back after you get everything else working.

[natemoen]

Hey guy,

Okay, there's a Harbor Freight store on 5115 Burning Tree Road in your town/city, and you can get a nice pack/assortment of Nitrile Orings for just a few bucks....will come in handy down the road.

Don't use nitrile o-rings for the needle seats. Get the Viton o-ring set and use those. Nitrile is not rated for extended contact with ethanol.

[NorCoaster]

As TC says, it's important to make sure you shut OFF the petcocks when you park the bike. It's a hard habit to start, but a good habit to have whether you have the octy in place or not.

I've already made turning the petcocks off a habit just because I'm kinda ocd about stuff like that so I may just keep the octy off for good.

Don't use nitrile o-rings for the needle seats. Get the Viton o-ring set and use those. Nitrile is not rated for extended contact with ethanol

Thanks for that tip...had no clue. 90% of the fuel I use is non-oxy anyway, but I'll get both sets regardless.

[Prisoner6]

I've already made turning the petcocks off a habit just because I'm kinda ocd about stuff like that ...

Me, too ...

Mine get turned OFF after every ride ... it's just an extra layer of protection ... assuming, of course, that your petcocks are functioning properly!

Oh, and by the way ... WELCOME to the Forums!

[NorCoaster]

$11 for a 180-pc Viton o-ring set at Harbor Freight?! Yup. Done

[NorCoaster]

So, that inline filter. Should I get a specific style? I see 40 and 60 micron styles for 1/4" line and I'm gonna lean towards the 40 because the less particulates the better, right?

[BowlingSS]

So, that inline filter. Should I get a specific style? I see 40 and 60 micron styles for 1/4" line and I'm gonna lean towards the 40 because the less particulates the better, right?

Make sure they are the small ones. I bought a couple of large ones and had problems with the routing.

Welcome.
Bill