[MWatts9728]

I building a 03 Americia I bought after the previus owner disassembled it for some chroming, and crash repairs. I just fired it up for the first time yesturday. I opened and cleaned the carbs before installing them onto the bike months ago. But now months later I have started it for the first time and is missing badly on the left cylinder. I'm as sure as I can be the carbs are the source of the problem. So I'm going to remove them and rework them again. But know that I know that these pipes are loud!!! And they diffinatly are not TOR's from the factory like my speedmaster has on it. These things are twice that loud.
There is deffinatly going to be some jetting required. I was wondering if anybody can give me a baseline on how I should setup these carbs to accomidate these pipes. I'd preffer to just go get me some Kiegn main jets, and maybe a needle. Rather than buying a whole jet kit. And what would make a good baseline for the idle air mixture screw.
I would greatly appreciate any advice here. I'm ultimatly out to get this bike running perfectly. After all its for my brother not for me. I fix things he just gives them to me to fix. So Id preffer to be conservative when choicing what jets to use.

 

[B02S4]

OK, you have a 790/270 with presumably unbaffled pipes. Any mods on the intake side? If I may ask, why are you sure it's the carb, as opposed to a plug, coil, CDI, or pickup?

 

[MWatts9728]

As far as the intake side its all stock. As far as if it has baffles or not I believe it does have some baffles but I can find out for sure in the morning. Upon visual inspection for the spark plugs the appear to have good spark. And I can't rule out electronics issues yet.
I suspect the carbs because the previous owner is a freind of mine and the bike ran good before he took it apart. I tore the carbs down today. The spring loaded plungers on both float valves were stuck. Wich could have possibly caused it I guess. But I believe the more likly cause was somthing fouling the pilot jet, but the whole is some dang small its hard to know for sure it lookd like somthing was there, but its clean now. Other than that I found a piece of somthing fouling the a main jet. Wow it all got in there is beyond me but I may have been some depris in the tank and painting it. I forgot to run clean fuel through the picock and clean it before connecting it to the carbs.

 

[B02S4]

Need to confirm if any baffles are still in, & need to know your elevation where you normally run.

Stock airbox, & the snorkle is still in, correct?

Did the previous owner ever have the vacuum carbs off?

 

[MWatts9728]

The bike does not have baffles. The carbs where removed when I got the bike. The motor was wrapped in plastic the carbs were not. And The bike will spend 90% of its life between sealeavel and 2000ft.. My home is about 700ft above sea level.
I finished cleaning the carbs today and fired the bike up again. It starts nicely and runs good. But the left side carb is still flooding. The float valve doesn't seem to be working. I've adjusted the float and double checked my work but the fuel level countinues to rise when I check it with a piece of tubing. I'm going to remove the bowl again and make sure the area where the float valve seats is good and clean. Other than that. My best guess is the float valve. It looked good and the spring loaded plunger operates freely. But maybe the rubber has point has dryed out and gotten hard or somthing.
As far as jetting the bike to match these pipes. We just decided we don't like these pipes they are too loud for our taste. Sorry I ran you through this for nothing. But myself and my brother preffer a more baffled exhuast note. But for now the bike has 122 mains, 48 pilot jets, 3 turns out on the Idle air mixture screws and what appears to be the stock needle.

 

[B02S4]

OK, now we're getting somewhere...are you going to replace the pipes? If so, with what?

Once you get the float valve squared away that should improve things. The pilot jets appear too large, though.

Are the needles shimmed at all?

Respond on the pipes first though, as that will definitely impact the main jet recommendation.

 

[MWatts9728]

Im installing the factory original silencers of off my speedmaster for now. I agree the 122 main are probably larger than what I want. But They keep the bike running so that I can continue Testing things and making progress. As for the needle it is not shimmed up at all. I am working up another parts order But it looks like I'll be ready to place it in the next couple days. Thanks for your help and your patience.

 

[B02S4]

OK, if you are going to run stock pipes with the stock airbox with a paper filter then I would suggest 118 main jets, 42 pilot jets, stock needles, & 1 shim.

 

[MWatts9728]

You say I should use "stock needles, & 1 shim". What should I use as a shim? I assume a washer would would work; Yes? And is there any general thickness that I am aiming for?

 

[B02S4]

You say I should use "stock needles, & 1 shim". What should I use as a shim? I assume a washer would would work; Yes? And is there any general thickness that I am aiming for?

Yes, it is a tiny washer that goes under the head of the slide needle. PM me your address and I'll send you two.

 

[MWatts9728]

You don't have to do that. But thatnks for the offer. I just got done placing that long awaited parts order. I really hope this is the last one. It seems like evertime I order parts its $300.oo. But once the bike is streetable I'm giving it to my little brother. And it is a perfect bike but the headlight bowl is tweaked out. I straightened and made it functional again but its not beautiful. But that is somthing I hope to pick up on ebay somtime soon.