carb orings

[tc862011]

i have already done the new intake boots and orings at the beginning of this year, will be ordering the carb orings in a couple days, just a simple question here. the bike runs great right now, and if i remember right the oring were in pretty bad shape. but the bike runs excellent, what does the orings change. will they really change my mpgs, will i see more or better performance. i have been reading about the orings, just wanted a more direct answer on what i should see as a change when i put them on.

[GateKeeper]

if the bike runs great !

why are you changing anything ?

most of the time, guys are changing things because the bike is not running as best as it could

why fix what is not broken ?

just curious


as for mpgs,,,,,,I couldn't tell ya, I never looked at that when riding a motorcycle...

.

[tc862011]

thats the only reason why i am looking at it because of mpgs i a getting about 15 mpg less then last year, last year i was getting about 45 - 50, and this year its less more in the 35 range, i live in the higher rpms this year since i am used to the bike and ridding now, more just a curiosity thought if the orings would help with this

[spyug]

the bike runs great right now, and if i remember right the oring were in pretty bad shape. but the bike runs excellent,

This is kind of a contradictory statement or at least requires a bit more description. How bad were the rings, split, cracked, shrunk? What is the definition of "excellent"?

In my experience and that of many of us, if the o-rings are bad, the carbs are not going to work right and it will not run anywhere near excellent.

The bike may run , idle and accelerate but the mere fact that your gas mileage has dropped off dramatically tells you something is going on. Now if you haven't drilled out or changed the jets it must be at least partially down to your heavier throttle hand but I would also suspect the carbs are in need of a cleaning and rebuild with the new o-rings.

For the low cost involved and especially if they have not been replaced in a while I'd suggest they might be part of the solution to your issues at least. Sooner or later you are going to have to do them as they surely will break down and she'll no longer run excellent.

Good luck and let us know how it turns out.

Spyug

[Steve]

I would worry more about adjusting the valves than refurbing the carbs.

But, since you asked: changing the o-rings might not help your mileage any, but it depends on why your mileage is down. Usually, we will suggest changing the o-rings to guys (and gals) who have just gotten a bike and want to get it running, or are having problems. Refreshing (refurbing, rebuilding) the carbs will give you a known starting point and will eliminate one unknown from the puzzle that is "what's wrong with my bike?". At the very least, replacing all the o-rings will give you a chance to inspect the insides of the carbs to verify that they are in good shape, and to verify float height and jetting. If you don't mind taking the carbs out of your bike, it's only about $15 for the o-rings, $20-25 for a can of Berryman's and several days to wait for the parts to soak. You will also need access to a carb sync tool when you are done. Due to the strength of the US Dollar against the British Pound, the most-recommended sync tool is just over $100 right now, which is a pretty good deal.

.

[7981GS]

It is my belief that these are the most important O-rings to change on your carbs.
These are from a CV type carb but they are similar to yours.



If they are not sealing, fuel flows around them.

Eric

[tc862011]

what are those, i have never seen anything close to like those on my bike, and the orings where worn, not split or cracked but you could tell they were old.and when i say excellent, she pulls hard through each gear, no missing or dead spots in the carbs. it just goes and goes great

[tc862011]

steve why do you mention the valves. if they were out of specs wouldnt it cause hard starting or a missing engine, i ask cause i have never had an issue with valves so i dont know the symptoms

[7981GS]

what are those, i have never seen anything close to like those on my bike, and the orings where worn, not split or cracked but you could tell they were old.and when i say excellent, she pulls hard through each gear, no missing or dead spots in the carbs. it just goes and goes great

Number 15 here that goes on number 14:

http://www.boulevardsuzuki.com/fiche_section_detail.asp?section=92943&category=Motorcycles&make=SUZUKI&year=1977&fveh=2106

So, you haven't actually rebuild your carbs yet at all, right?

Eric

[Nessism]

steve why do you mention the valves. if they were out of specs wouldnt it cause hard starting or a missing engine, i ask cause i have never had an issue with valves so i dont know the symptoms

I can't believe how few people understand the concept of "basic maintenance". The idea is to do some minor work to prevent major damage/repairs.

The valves must be adjusted otherwise they will burn and damage the cylinder head. Adjusting the valves should not wait until running problems are experienced as that is TOO LATE and the valves will be damaged already.

As for carb O-rings, I advocate changing them even if the bike is running decently. The O-rings get hard and brittle after 30 years and should be refreshed if you value a reliable bike.

The early bikes (like the 1978 GS550) use VM carbs, and the '80+ year bikes have BS/CV carbs. You need to get the appropriate O-ring kit for your particular bike. Eric's photo shows parts from some BS carbs which are not present in VM carbs.

[gearhead13]

You never had the float valves out?
IMO they are the most important o-rings to change.

[Nessism]

You never had the float valves out?
IMO they are the most important o-rings to change.

Yea but tc862011's bike has VM carbs which don't have O-rings on the float needles.

[hjfisk]

1- Doing the o-rings will probably not increase fuel mileage.
2- Adjusting the valves may help, but more so to preserve the motor, and help keep compression up, Because when the valves on these are out of spec they tighten up not loosen as people get the miss consumption of, meaning holding your valves open.
3- You say you are getting more use to riding and running higher revs, well higher revs require more fuel, Depending on how high and how long you are running that way is probably where your fuel mileage is going.
I have a 1000 and I can ride all day 2-up with luggage, and get 45-48 miles to the gallon, or I can go solo ride hard all day and get 32-35 miles to the gallon. It all depends on how much you twist that right hand

[Steve]

steve why do you mention the valves. if they were out of specs wouldnt it cause hard starting or a missing engine, i ask cause i have never had an issue with valves so i dont know the symptoms

Valves can go loose or tight. Either way, efficiency is compromised and mileage will suffer.

If valve go tight, which is the usual case with our bikes, the engine will be harder to start, especially when cold.

If the valves are loose, the cylinders simply won't be able to breathe as much air as necessary, so power will be down. You will have to add more throttle to make enough power, which will suck more gas.

I will also second a thorough cleaning of the carbs and replacing ALL the o-rings. You say you did not recognize the parts that 7981GS showed. Those are the float valves. All the gas that is supposed to be used by the carbs is supposed to go through the middle of those brass pieces. If the o-rings are bad, gas can also go around the outsides, and will not be controlled by the float. That will raise the fuel level in the bowl, making the carb run richer, resulting in ... let's hear it now ... 'lower mileage'.

.

[Nessism]

Those are the float valves. All the gas that is supposed to be used by the carbs is supposed to go through the middle of those brass pieces. If the o-rings are bad, gas can also go around the outsides, and will not be controlled by the float. That will raise the fuel level in the bowl, making the carb run richer, resulting in ... let's hear it now ... 'lower mileage'.

.

Yes, Steve is correct, but the bike in question doesn't have those O-rings.