Carb Rebuild Complete - Dies on throttle

[oohsam]

Hi Guys,
I did a full carb teardown and rebuild on my GS1100 ('83).
I followed Nessims rebuild to the letter.

The only thing I did different was buy 4 carb rebuild kits from Z1 and replace all the internals with new parts instead of cleaning my old parts (lots of damage done to the jets from PO).

The kits came with 2 of every jet, I'll get the numbers that I put in later as I'm not home.

The bike started right up and the hanging idle issue seems to have gone. I didnt need choke or anything to start up, took a few cranks and off she went.

I did a bench sync, but not a vacum sync yet (waiting for my synchroniser to come in).
Idle screws turned at 2.5 turns...
When I put the bike in gear and throttle, the bike dies.

Now I know that it still needs a proper sync, but is this common for the bike to do this without the vacum sync, or is it possible I jetted too big/small. Is this an indication of running rich or lean?

Just some assistance would be great as I'm not sure what to tackle first.
Is it possible that the carbs did not get a good clean, and will need to be re-dipped ?

I am running pods but not the K&N pods, also a 4 to 1 exhaust.

 

[BassCliff]

Hi,

I am running pods but not the K&N pods.

Congratulations on a successful clean and rebuild of your carbs. You've made a good start. Did you also replace all of the internal O-rings using the kit from cycleorings.com?

Perhaps you should search the forums a little and find out how most people feel about the cheap EMGO pod filters. Most don't like them and say they never run right. I suggest reading this thread: Top 10 Newbie Mistakes.

Did these "carb kits" come with stock sized jets? Pod filters require larger jets because of the increased air flow. Sometimes the mains have to go up 4 to 6 sizes, maybe up one size on the pilot jet. Normally you have to shim the needle to richen up the midrange. It sounds like it's time for you to research tuning and jetting your carbs for a modified intake (exhaust too?). You'll find articles on my little website that may help.


Thank you for your indulgence,

BassCliff

 

[oohsam]

Hi basscliffe
Yes I did lots of reading about the filters I have some on order but.they r 2 months away! !

Yes the kits came with stock size jets.

 

[BassCliff]

Hi,

Drat. That's a long time to wait. I edited my post to try and offer some guidelines. It sounds like the stock jetting is way too lean now that you have pod filters installed.



Thank you for your indulgence,

BassCliff

 

[Nessism]

You are going to have to rejet those carbs to match the pods. Dynojet makes plug and play jet kits so that might be your best bet. Some people rejet on their own, but the stock needles are not the proper shape for pods so it's a real compromise if you choose to run them.

 

[oohsam]

Ah ok,
I had the bike running fine through all 6 gears with the 'old' jets and the current pods....

I'll look into the dynojet ones.
I can always put the stock airbox back on to have a starting point...With the stock airbox and stock jets, should the bike die on throttle?

 

[Nessism]

I can always put the stock airbox back on to have a starting point...With the stock airbox and stock jets, should the bike die on throttle?

Stock jets + stock airbox + stock exhaust = known good configuration

So no, the bike should not die on throttle (goes without saying).

 

[Big T]

You should check first to see if your needles are adjustable before getting a DJ kits, since you're in Australia, your carbs are probably different from the US "nonadjustable" versions

 

[BassCliff]

Hi,

You should check first to see if your needles are adjustable before getting a DJ kits, since you're in Australia, your carbs are probably different from the US "nonadjustable" versions

Yes! Good call. I'm glad you caught this. The DJ kits do have a special taper on their needles. But if you have adjustable needles, maybe you can make it work without spending the extra money. Although the DJ kit does make tuning your carbs a lot easier, some have had success without.


Thank you for your indulgence,

BassCliff

 

[oohsam]

Thanks guys,
I got home and pulled off the float bowls to see what jets I put in vs the standard.

I took out the jets and made all the jets as per standard specification.
Once I did this I took it back out to the bike (with my emgo cheapy pods) and fired up the bike. Took a while to start but it started and idled very smoothly. Took the bike out for a spin, and it rode fine.
When I pulled up i could hear the idle slowly dropping and about to die. I revved it a little to keep the bike running, but it died eventually.

I adjusted the large idle adjuster to put the idles up a little, and put it back in the garage, when i got to the garage the idle hung at about 3500 rpm. I killed the bike and then turned down the idle adjuster all the way and started the bike up.

The idle was not eratic, but it was much higher than previous (around 2k rpm).

Shut it off and called it a night.
Would these symptoms be due to

1. Not having done a vacum sync yet
2. having cheap emgos (varying air flow)
3. Not adjusting the idle screws on the carbs yet (2.5 turns still)
4. All of the above

Cheers.

 

[hampshirehog]

4
............

 

[hampshirehog]

Sorry about the 1 digit reply - couldn't resist it. The Emgo pods are the main culprit - unless you change your jets / needle position it'll never run right with them fitted. Indeed, some will say it will never run right with Emgos

 

[oohsam]

hhahaha nah all good! was quite funny. LoL.

So I shouldn't even bother trying to vacum sync it now until the pod filters arrive?..

Not too sure at what stage I play with the idle screws, before or after vacum sync?
I've read every carb rebuild thread on GS resources....

Oh this carb rebuild has taken more effort than the entire rebuild! tiring!!!

 

[Guest]

Hey mate, here's what my very limited jetting/carb work has shown me so far with my 450...

Unlike the US carbs, my mixture screws were already exposed to adjustment and my needles are adjustable.

After thinking I had the pilots worked out to be far too lean, I went four sizes up and then after the shake down run and a proper warm up I discovered that was far too large and went back to two sizes up.

When heading to get the rego sorted, I discovered I had set my idle way too high because previously I hadn't really warmed the engine up enough, so I had to pull over to wind it back from the 3 - 4000RPM it was idling at

Then, after a bit more fiddling, I decided the mismatched header lengths were causing my left carb to be richer than the right carb, so I ordered another pilot jet so I'm running one size up on the left and two sizes up on the right.

Then I got my Morgan Carbtune for Christmas and I sync'd the carbs... now I'm back to square one with the jetting because I get lots of popping on decel that I never got before which means I reckon it's all running too rich now...

Moral of the story... I reckon do a proper sync first then play with your jetting, and make sure it's nice and hot and warmed up properly before trying anything

PS: Sorry for the lengthy post, just want you to see the run around you can cause yourself by not doing it the right way...

 

[cr480]

I would synch the carbs with the pods in place first,don't take too long though your bike will be running pretty lean and its better safe than sorry. As far as finding the right jets I have found it helpful to got the Dynojet site and look up the kit they sell for your bike, there will be a pdf file that has the install directions, not real useful for you but they always show a parts list. This parts list shows the jet sizes for different stages within the kit. Take the jet size for the stage your configuration requires. Go to the bike shop and buy a set of jets in that size + a set in the next size up. The jets are really cheap and you will save allot of money over buying a kit. remember the kits are nice but there are no plug and play jet kits, everysetup is different and the kit is only going to get you close anyway. I have found that 1 size up over what thier kit supplies almost always nails it. You will benefit from all the research they have put into thier kit and mecifilly not have to keep pulling your carbs to change jets. I have had good luck with the low cost pod filters and in some configurations have found real power gains using them. The directions will also give you a good starting point for your mixture screws. Install the jets, warm up the bike then adjust the screws slowly in 1/4 turn increments in iether direction evenly across the carbs, you are looking for the idle rpm to go up while doing this if it goes down you have gone too far or in the wrong direction. Highest idle speed for each carb adjustment. Once this is done, recheck your synch and enjoy the ride! Needle hieghts may come into play here but do these things first, more times than not the bike will run fine and have great throttle response. if it doesn't have a look at the needles and try going up 1 notch if they are adjustable. To double check the jetting on a seemingly good running set up - warm up machine , take off in first gear and nail it wide open, hold wide open and shut off the bike, pull plugs and inspect, Bone white= Lean ashen gray - light brown = good jetting Sooty black = too rich I hope this helps make it a little easier for you, every bike and configuration can produce different challenges but this should get you damn close! Good luck:lol:

 

[oohsam]

Thanks guys, that is some amazing information right there. Exactly what I was after.
CR480 - Top info there mate. I'll do just that..

Pete...where did you get your jets from? Looking for an Aussie supplier.

Cheers

 

[oohsam]

Oh one more thing, is it common to replace all 3 jets ? ( Main Jet, Pilot Jet, Air jet) ?
Or is normally just the Main Jet ?

also, how does one convert the numbers from dynojet to the minkuni numbers?
Example

Stage 3 kit comes with :

4 Main Jet DJ114
4 Main Jet DJ118
4 Main Jet DJ165
4 Main Jet DJ170
4 Fuel Needle DNO405
4 Adjusting Washer DW0001
4 E-clips DE0001
4 Main Air Jets DCO301
1 Slide Drill DD #7/64
1 Plug Drill DD #5/32
1 Screw DS000

Do I need all those??

Thanks for help.

 

[koolaid_kid]

With just pods you will use the smaller mains and all the other parts. You can probably adjust the factory Pilot Jets to suit. If you need them you have to buy them from a dealer or Z1Enterprises (my choice). They are around $2 each.

 

[oohsam]

Ok I'm still confused.

The Stage 3 Kit comes with stage 1 components too...thats why there are 2 small jets and 2 large jets.

So I'm running pods and an exhaust, so I'm assuming I'll need to change the Main jets from what I currently have (stock 115) to 122.5, which is 3 sizes up ? (surely 170 is too large?)

I'm currently running a #40 pilot jet (i also have a #45 that came with my rebuild kit) does that need to be changed too?

With the air jet, does that need to be changed at all ?

I'm way out of my depth here guys, have no idea what needs to go up/down in order to compensate pods and exhaust.
So many threads where so many people have tried different things, but there has been nothing conclusive or rock solid with a "winning" solution!

 

[cowboyup3371]

Ok I'm still confused.

I'm way out of my depth here guys, have no idea what needs to go up/down in order to compensate pods and exhaust.
So many threads where so many people have tried different things, but there has been nothing conclusive or rock solid with a "winning" solution!

I still have the stock setup on my bike so I can't answer how to fix yours. However, this last statement of yours is why so many people on here tell everyone else to start with a stock set up first to ensure the bike runs correctly. THEN, and only then, should anyone start to change things from there as there just isn't a right answer. You have to adjust things based on your bike, what you intend to do, and it takes a whole lot of testing to get it right.

Good luck. I hope you can figure it out without having too many headaches.