air to fuel mixture weird...stock jetting?

[Draddy]

Hey guys,

I just bought a project bike...pretty excited about it. I come from the land of cars, and looking forward to working on a bike.

I'm not sure where to start with this issue. the PO (previous owner) said he just had the carbs cleaned at a reputable bike shop (no way to confirm) and that it was good to go...he told me the only reason it doesn't run for long periods of time is that he put too large of jets in it, and it needs to go down one size.


What kind of Carburetor is this?

The PO put cones on it, so I know it's getting much more air than stock, so the jet's should be larger than OEM. Just for kicks and giggles, I bought what jetsrus.com told me are the stock jets, but they do not fit (diameter is much too large, it won't fit in the spot the jet is supposed to go in). Current jets are 190, should I go down to 180, or more like 130?

If this isn't the stock carb, what carb is this, and where can I get main jets for it?

some symptoms that leads me to think it's loading up with fuel and killing itself.

1. Initial start: starts better when cold without choke, usually choke prevents it from starting.
2. if it doesn't start immediately on the first button push...it will not start for 24-48 hours. (the engine just turns and turns)
3. if it does start, it sounds great for the first 5 minutes, but as it warms up, it starts choking up...eventually becoming so burdened that the engine dies and will not re-crank.
4. it's great to drive initially, but again, once it's been on for 5-10 minutes, it start bogging down.
5. it backfires.

Right now, I actually can't get it to turn on at all...( the video of it running was from sunday...so it hasn't been long)


Here are some pictures of it, the carb, and a video of it running during that first 10 minute video...towards the end it starts sounding bogged...ignore the awful exhaust.


The bike:

The carb with cones:

the air intake without cone:

The new jets that don't fit in the jet hole:

Video of it running:

http://www.youtube.com/watch?v=_kfeo6athWs




and for reference, where I come from, my project car:

thanks!

 

[Nessism]

Order a Dynojet kit to save time and frustration.

 

[BassCliff]

Greetings and Salutations!!

Greetings and Salutations!!

Hi Mr. Draddy,

The Dynojet kit suggestion will save you a lot of trial and error. There's still some fiddling to do though. Those pods look like the cheap EMGO knock-offs. They can work OK but you would do better to get some K&N or APE pod filters. Those tires look really old. Here's a click for you: How old are my tires?

And now, the rest of the story. Let me dump a TON if information on you and share some GS lovin'.

I just stopped by to welcome you to the forum in my own, special way.

If there's anything you'd like to know about the Suzuki GS model bikes, and most others actually, you've come to the right place. There's a lot of knowledge and experience here in the community. Come on in and let me say "HOoooowwwDY!"....

Here is your very own magical, mystical, mythical, mind-expanding "mega-welcome". Please take notice of the "Top 10 Common Issues", "Top 15 Tips For GS Happiness", the Carb Cleanup Series, and the Stator Papers. All of these tasks must be addressed in order to have a safe, reliable machine. Now let me roll out the welcome mat for you...

Please click here for your mega-welcome, chock full of tips, suggestions, links to vendors, and other information. Then feel free to visit my little BikeCliff website where I've been collecting the wisdom of this generous community. Don't forget, we like pictures! Not you, your bike!

Thanks for joining us. Keep us informed.

Thank you for your indulgence,

BassCliff

 

[Draddy]

Order a Dynojet kit to save time and frustration.

Thanks Nessism, was definitely thinking that...but was worried that this carb is different than stock, and wouldn't fit?

Hi Mr. Draddy,

The Dynojet kit suggestion will save you a lot of trial and error. There's still some fiddling to do though. Those pods look like the cheap EMGO knock-offs. They can work OK but you would do better to get some K&N or APE pod filters. Those tires look really old. Here's a click for you: How old are my tires?

And now, the rest of the story. Let me dump a TON if information on you and share some GS lovin'.

**tone of awesomeness deleted**

Thanks Basscliff, that information is definitely appreciated. i've also read through the "top 20 newbie mistakes" which have been incredibly helpful.

 

[Dave8338]

What size bike are we dealing with?????

 

[Draddy]

Great question...completely forgot to say 1980 GS850 (driveshaft)

 

[Dave8338]

Stock jets are 115's. 135.5-137.5 is where you want to be.

190's are WAYYYYY too large.

Also...make sure that the intake o-rings have been changed out. Only way to know is pull the black boots that connect the carbs to the head.

 

[Steve]

Those 190s are the PILOT AIR JETS that go into the holes in the intake throat at about the 8 o'clock position. You can see them in your third picture.

The jets that you received are the MAIN JETS, they live in the bottom of the float bowl. Remove the carbs from the bike, remove the float bowls, you will see the MAIN JETS staring right at you when you remove the bowls. Use the largest screwdriver that fits the slot, for best results.

And, like Dave8338 said, you need jets considerably larger than the stock 115s. Not sure you would need to go all the way to 135, but I have not jetted for pods and a pipe on an 850.

Best suggestion came from Nessism, "get a Dynojet kit". Besides having the proper main jets, they include a different needle that is not available anywhere else. That needle will make life a LOT easier.

.

 

[Draddy]

Those 190s are the PILOT AIR JETS that go into the holes in the intake throat at about the 8 o'clock position. You can see them in your third picture.

The jets that you received are the MAIN JETS, they live in the bottom of the float bowl. Remove the carbs from the bike, remove the float bowls, you will see the MAIN JETS staring right at you when you remove the bowls. Use the largest screwdriver that fits the slot, for best results.

And, like Dave8338 said, you need jets considerably larger than the stock 115s. Not sure you would need to go all the way to 135, but I have not jetted for pods and a pipe on an 850.

Best suggestion came from Nessism, "get a Dynojet kit". Besides having the proper main jets, they include a different needle that is not available anywhere else. That needle will make life a LOT easier.


.

That's really helpful, thanks steve. So then do you think it's the pilot jets, or the main jets I need to replace? he pointed to the pilot jets when he initially told me what was wrong. This is why I ordered 180 main jets. it list 180 as the stock size (or at least that's my interpretation).


How is this process? I have been warned by everyone I know who rides these bikes that the carbs are awful to work on...primarily because there are 4.

If I take them off...is it pretty straight forward to put them back on?

Again I'm coming from the car world...working on fj40s and the like...I'm not used to syncing 4 carbs together.

 

[cowboyup3371]

People are telling you that only because they don't know anything about them and are scared. Most folks are nowadays. You'll do fine - just follow the advice given here and ask questions if you don't understand. These folks know more than you could imagine.

Welcome, nice bike.

 

[Steve]

That's really helpful, thanks steve. So then do you think it's the pilot jets, or the main jets I need to replace? he pointed to the pilot jets when he initially told me what was wrong. This is why I ordered 180 main jets. it list 180 as the stock size (or at least that's my interpretation).


How is this process? I have been warned by everyone I know who rides these bikes that the carbs are awful to work on...primarily because there are 4.

If I take them off...is it pretty straight forward to put them back on?

Again I'm coming from the car world...working on fj40s and the like...I'm not used to syncing 4 carbs together.

These carbs are so easy to work on, it's pitiful, really. The only thing is that whatever you do, you have to do it FOUR times.

You might want to consider installing the 180 PILOT AIR JETS for your situation. Installling the slightly smaller air jet will richen up your pilot mixture, which will be further controlled by the IDLE MIXTURE ADJUSTMENT SCREW at the other side of the carb.

The real thing you want to check is your MAIN JET SIZE. As mentioned earlier, you will need to drop the float bowl to see what you have in there now. Stock is 115, but with your pods and pipe, you will need something from 130 and up, we don't really know. (The jets you received are the physical size of the MAIN JETS, but the hole (and the number) is WAY too big.) It depends a lot on how well your bike is working. The Dynojet kit will get you VERY close on the first time, and gets you that new needle that will make all the difference.

.

 

[Draddy]

Put my order in for dyno...thanks.

I avoided it at first because it was pretty expensive, however I've already wasted 80 bucks...so might as well buy the real thing this time than waste more money.

 

[tkent02]

Before you waste even more money, you might want to read up a little bit on how these carburetors work.

 

[Draddy]

Before you waste even more money, you might want to read up a little bit on how these carburetors work.

are they much different than a vehicle carburetor?

 

[Dave8338]

are they much different than a vehicle carburetor?

Yes. They are vacuum slide carbs. Engine condition ie. compression and vacuum leaks throw the numbers ALL out of wack. Not too worry...we'll keep your budget as low as possible. Plug chops will dial the bike in, where it needs to be. As others have mentioned, these carbs are really simple however, there are four of them and they all need to be set exactly to each related cylinder. In other words, if you have 160 psi on three of the four holes and 145 on the fourth, that lower numbered cylinder will have to be tuned for its' "situation". No bigggie...

I should also mention: You must also check the valve lash. These engines use a bucket and shim system and they TIGHTEN as they wear, not loosen as do most engines. If they are not in the .03-.08mm range...you are out of speck and this will throw off your carb tune. (just finished this less than four days ago)

Throw the DJ kits in and see what happens...

You may nail it on the first shot. It happens.

I can't stress enough...you need to pull the carb to head boots and have a look. It is one of the most overlooked points in the air/fuel mix and is "usually", the first place that you need to start.

This is what you are likely to see:

For all that have told you that the CV carbs are "really hard" to work on, what they are really saying is that they have NO CLUE, and neither does their "mechanic". DO NOT bring that bike to a shop to get it set right, not only will you waste your money, the 20-something "mechanic" that you are paying to work on it, (if you can even find a shop that will agree to do it) has more smarts in texting than he/she does, about carbs.

I like carbs...REALLY like carbs!

We'll get you running perfect, or YOU are not trying!

Sleep well, you are in very good hands...

 

[Draddy]

Dave you rock. Thanks! Looking forward to working on this bike.

I did call a shop for a quote, they wanted 7 hours to clean the carbs, then another 3 to tune...no parts. Pretty crazy prices I must say to tune up a 31 year old bike. My M3 is not that expensive to maintain.

 

[Draddy]

Does anyone have a picture of what/where the side lift hole is? installing the dynojet.

 

[Steve]

Does anyone have a picture of what/where the side lift hole is? installing the dynojet.

Very simple, actually, no picture needed.

Look on the end of the slide where the needle sticks out. There is another hole beside the needle. That's the "lift hole".

.

 

[Draddy]

Very simple, actually, no picture needed.

Look on the end of the slide where the needle sticks out. There is another hole beside the needle. That's the "lift hole".

.

that the screw is in currently? it's got a bracket holding the needle channel? (the dradle looking thing?)

I feel like if I drill into it, I'll mess up the screw functionality.

 

[Steve]

No, you are looking on the inside. Read my comment again.

Look on the end of the slide where the needle sticks out.

.