Carb bowl drain bolt size/thread - CV carbs - and where to get?

[Andrew Vanis]

Carb bowl drain bolt size/thread - CV carbs - and where to get?

I want to get extra carb bolts to:

1 - make bowl float gauges

2 - get them in thumb screws or weld on lever/thumbscrew or weld on valves to make draining the bolts easier. I don't ride much and I'm tired of cleaning carbs so to help prevent carb gumming I plan on draining when I don't know when I'll ride next.

 

[Steve]

Presuming you are asking about the DRAIN bolts, they are M6 x 0.5 thread. Length is probably about 10mm.

Not riding much? As in ... once or twice a year? A couple of years between rides? How much worse can it be than those of us that deal with a little bit of snow every winter? I just use Sta-Bil to treat the gas before laying up for the winter. I double the dose, run the bike around the block to get the treated gas through all the circuits in the carbs, change the oil and filter, put the bike to bed. Four or five months later, will make sure the battery is up, turn the petcock to PRIme, turn the key ON, apply the proper amount of "choke" and push the button. I have never had that fail. Not sure how many years you can keep the bike in storage this way, but I have never drained the carbs (intentionally) for storage.

.

 

[solarae]

I would ad that filling with ethanol free gas before storing really helps.

 

[Andrew Vanis]

And where are good places to get some?

Good suggestions as always Steve. using your approach, I'd be ALWAYS running with Stabil. Sometimes it is weeks or months between rides.

My Hypothesis is that vs. the once-annual put it away process that it is the RECURRING evap that causes the varnish buildup. I live in a hot environment so that might hasten the evaparations even faster.

I plan to try draining after rides when I don't know when the next one will be and run the bike dry before putting it away on the stand.

 

[solarae]

Ethanol free gas is availble at my local lawnmower shop and also at an independant fuel dealer in my area. I realise it's different all over the country but might ask at a small engine place. It can be pricey but for just a couple of gallons, it's worth it.

 

[Burque73]

And where are good places to get some?

Good suggestions as always Steve. using your approach, I'd be ALWAYS running with Stabil. Sometimes it is weeks or months between rides.

My Hypothesis is that vs. the once-annual put it away process that it is the RECURRING evap that causes the varnish buildup. I live in a hot environment so that might hasten the evaparations even faster.

I plan to try draining after rides when I don't know when the next one will be and run the bike dry before putting it away on the stand.

There's an unmanned station south of Candelaria, between University and Carlisle called Brewer. They have 86 octane ethanol free.

 

[Steve]

They have 86 octane ethanol free.

And, ... before anyone jumps on you for using 86 octane, they need to be aware that at your altitude (roughly 5000 feet), 86 octane has all the same properties of 87 octane that is closer to sea level.

.

 

[Burque73]

And, ... before anyone jumps on you for using 86 octane, they need to be aware that at your altitude (roughly 5000 feet), 86 octane has all the same properties of 87 octane that is closer to sea level.

.

Thanks for mentioning that Steve, and for putting my mind at ease. Just kidding, ignorance is bliss, LOL!

I did find another place with 91 octane ethanol free (fourth street North of Osuna) and have not noticed a difference in how the engine runs between the two. At over $4 per gallon for the 91, which Andy may choose for his 750, the $3.59 was a bit easier to swing. Plus it happens to be much closer to my house.

 

[850 Combat]

I drain mine all the time. I've been thinking about two things: switching to allen screw, and cutting a slot in the tip to allow it to drain without pulling the bolt all of the way out in order to drain. My bikes are spread out over three states, and I sometimes don't even see them in a year or so. For me draining is better than Stabil. Second best is pulling off the vacuum line and plugging it. Then, you can start and run the engine until it dies. You can even empty out the choke that way.

 

[Nessism]

I keep marine sta-bil in my tank (and garage gas can) and the fuel keeps wonderfully. Never an issue even with gas that's several months old. I'm sold.

 

[Guest]

I just use Sta-Bil to treat the gas before laying up for the winter. I double the dose, run the bike around the block to get the treated gas through all the circuits in the carbs, change the oil and filter, put the bike to bed. Four or five months later, will make sure the battery is up, turn the petcock to PRIme, turn the key ON, apply the proper amount of "choke" and push the button. I have never had that fail.

This is my routine as well and it works fine in snowy Alberta where my bikes will sit for a good 5-6 months if we have a bad winter.

And where are good places to get some?

https://www.pure-gas.org/

Have a look and see what is in your area.

using your approach, I'd be ALWAYS running with Stabil.

There is nothing wrong with that aside from the cost of using stabilizer non-stop. Considering your riding schedule that shouldn't be prohibitive, though. There is also nothing wrong with draining the float bowls as well and I would suggest using a stabilizer even if you are draining the bowls.

Never an issue even with gas that's several months old. I'm sold.

There seems to be a vast range of fuel performance across North America. I see references like this to several month old gas being considered very old and then the fuel can for my weedwacker has fuel in it that is probably 5 years old and it still starts and runs just fine on that. It is a 2 stroke and the premix oil does have a stabilizer in it, but there is still a huge difference between a few months versus a few years old.


Mark

 

[Andrew Vanis]

https://www.pure-gas.org/

Have a look and see what is in your area.

My question of where to get them is asking about the bolts, not the gas.

**** Has someone found a source for these bolts other than Suzuki?

I'm considering re-tapping the bowl to a readily available thread. Anyone got 4 spare ones I could experiment on?

I might even set up a manifold drain system with one valve and a pigtail that I can drain the gas into a container rather than having it stink up the garage for what seems for ever.

 

[Agemax]

I might even set up a manifold drain system with one valve and a pigtail that I can drain the gas into a container rather than having it stink up the garage for what seems for ever.

like this you mean? These are only overflow though, not drain. I made a few of these, years ago, sold quite a few on eb@y as well!

 

[Agemax]

I also made these as well, they were good sellers!

https://www.thegsresources.com/_for...rain-and-fuel-height-level-adapter&highlight=

 

[Andrew Vanis]

like this you mean? These are only overflow though, not drain. I made a few of these, years ago, sold quite a few on eb@y as well!
View attachment 55587

Yes, something like that!

Ideally I'd do it with modifying the drain bolts IF I COULD FIND ANY and re tapping the bowls for brass nipples readily available woudl be choice 2. I'd sure like some to modify without kiling mine. Anyone have any extra extra bowls?

 

[Guest]

My question of where to get them is asking about the bolts, not the gas.

**** Has someone found a source for these bolts other than Suzuki?

Did you try Sudco for Mikuni parts? Why is a Suzuki dealer not a reasonable place to order them from? Are they a discontinued part?


Mark

 

[Nessism]

Why not just modify the screws you have now if the goal is to create a "fast drain" feature? The factory screws are special in that they have an integrated washer shape underhead and it's unlikely to find an off the shelf screw that's a perfect match. If you are just looking to make some level gauges, just about any screw with the right thread shape will work. Drill out the center of the screw and JB Weld on some steel tubing. Put an O-ring on the screw and run them in hand tight and they won't leak. I've made just such gauges before and they work perfectly.

BTW, the sealing washers for those screws are unique. They are not O-rings. Robert Barr includes O-rings which are okay, but the proper sealing washers are superior for that application.

 

[Fjbj40]

I just picked up 4 of the drain bolts from a used parts place. Drilled #30 holes as it was a snug fit for #2(1/8") copper tubing and made my fuel height tooling. Worked great, helped me fix my carb issues. Even though my floats were set to spec, the fuel height was not where it was supposed to be, it was to low. This caused a lean idle mixture that could not be tuned out with the pilot screws.

As has been stated, you will have a hard time finding the screws just anywhere. I paid $10 for the 4.

The bolts are around $6 each from Suzuki.