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1999 Shadow 750 ACE VT750CD3
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@BobberTurtle91 comments over people messing up perfectly good bikes were not aimed at you and your recently acquired bike. It is something we see too regularly and if you spend some time around around here you will realize that @Chuck_Michigan nailed it perfectly. Just watch you'll see. And yes we get sidetracked from forum threads. (-;

I've heard all kinds of explanations for running the rear cylinder richer, from making the rear cylinder run cooler, to Honda only did it originally for emissions, to forget it make them both the same.
I have found and I've played with the carbs on my 750 ACE more than most normal people, is for whatever reason the rear spark plugs look like the front ones with that much main jet off set.
Stock the bike pre-Bean box would have had 105 front and 110 rear main jets. With my slightly differently Bean box modded 750 ACE I ended up running 132 Keihin main jets on the front carb and 135 Keihin mains on the rear with Dynojet slide needles and #40 slow jets, but I was also running a stock exhaust and an aftermarket ICM box.

The slow jet is a different design than the main jets and feeds the low speed mixture circuit that's adjusted by the screw and also handles the transition to throttle opening/closing.
Grab the Service Manual from here: Manuals
Take a look in the Fuel System section and the location of stuff will be explained.
 

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Discussion Starter #25
CSRoad ok I see what you mean. does those pictures look like the right Kind? I have seen a bunch of different ones.
 

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1999 Shadow 750 ACE VT750CD3
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Careful buying jets on Amazon. There is some real crap offered through there and eBay.
The ones with the Kstar logo next to the number will likely be real Keihin jets since it is their logo.
I have also have had good luck with EBC (the brake people) jets.
If I get stuck for a jet size (pre-covid) I will go bother them at the local dealership, the parts department still has trays of them and unless it is a weekend are happy to look.
The Keihin mains will have a part number starting with 99101-393 and then the jet size. They are commonly called 393 "round" main jets.
The slow jets have numbers like N424-21 and then the size, these are specific to this family of Keihin carbs.
 

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Kinda nice to be on a active forum and I appreciate the advice I can’t really tell if “chuck Michigan” is making fun of me for whatever reason. The only thing I done was quite the bike down with baffled and it started running different so I needed to tune it a little and was having a time dialing it it.
BobberTurtle91, truly I am not making fun of you personally. I actually feel bad that you're having these problems which are preventing you from enjoying the bike while you try to get it working right again. It's just that I have seen this so so so many times that I want to get ahold of all people new to riding and beg them to spend a couple of seasons just riding for the sheer pleasure of riding before they start all the mods to make it louder or faster.

I guess I am using humor to express my exasperation because I can guarantee that there are many thousands of people who never got to enjoy their new to them bikes after saving up their hard earned money for one. So they wind up sitting in someones shed or behind the garage after the owner finally realizes he just doesn't have the time or the money anymore to keep trying to get it back to how it should be running after he messed it up big time with certain mods.

Nope, not making fun of you at all.
 

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Discussion Starter #29
Small update started the bike up and drove around. I feel I got it the best at what the jets are but I still feel rich but not in a danger zone, the bike idles and does not die. Sounds healthy but I’m still gonna re jet just for peace of mind and make sure I’m in the right range for mods.I wish I had an rpm gauge for it so bad so I could know I’m at the right idle. Lol Getting use to hearing the bike more instead of just a blast of exhaust. And as a side not a friend at work bought the EXACT same bike, he didn’t know what mine looked like but he got the same year, color, and everything.
 

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Discussion Starter #30
BobberTurtle91, truly I am not making fun of you personally. I actually feel bad that you're having these problems which are preventing you from enjoying the bike while you try to get it working right again. It's just that I have seen this so so so many times that I want to get ahold of all people new to riding and beg them to spend a couple of seasons just riding for the sheer pleasure of riding before they start all the mods to make it louder or faster.

I guess I am using humor to express my exasperation because I can guarantee that there are many thousands of people who never got to enjoy their new to them bikes after saving up their hard earned money for one. So they wind up sitting in someones shed or behind the garage after the owner finally realizes he just doesn't have the time or the money anymore to keep trying to get it back to how it should be running after he messed it up big time with certain mods.

Nope, not making fun of you at all.
Ok man I couldn’t really tell but I see where your coming from. Being a previous mechanic I hated coming in after someone and trying to make sense of it all and generally is was better to start from ground zero and do it cause you gonna spend that much time just figuring what they did. And being new to motorcycles, in terms of diving in understanding the intricacies, it’s still fun but even though I’ve worked on engines and everything else it’s a different world. Still exciting and am enjoying it but it’s just learning something new. Like a 3-cylinder 2-stroke turbo/supercharged Detroit diesel I use to work on you just gotta learn the machine and figure it out.
 

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1999 Shadow 750 ACE VT750CD3
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Small update started the bike up and drove around. I feel I got it the best at what the jets are but I still feel rich but not in a danger zone, the bike idles and does not die. Sounds healthy but I’m still gonna re jet just for peace of mind and make sure I’m in the right range for mods.I wish I had an rpm gauge for it so bad so I could know I’m at the right idle. Lol Getting use to hearing the bike more instead of just a blast of exhaust. And as a side not a friend at work bought the EXACT same bike, he didn’t know what mine looked like but he got the same year, color, and everything.
Better a little rich than too lean. The spark plugs are a good window on how close you are getting.

There are a few tachs that work fine on these from the $20 inductive digitals and up, I use a Drag Specialties analog mini digital one as it looks presentable on the handle bar and has a white face.
I never thought I needed one beyond the bench, until wasting time and money eventually made the engine spin up quite quickly.

Do you work the same hours and travel in the same direction as the other one?
Let us know if you need to win any match races. (-;
 

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Discussion Starter #32
Alright changed and cleaned the air mixture screws, noticed a backfire at idle. Is that too much fuel? And I also found a potential vacuum leak.
 

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Your backfire is usually because of a lean condition and a vacuum leak will cause that. Not sure of the hoses. May be for carb heaters.
 

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1999 Shadow 750 ACE VT750CD3
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If this is what I'm looking at in the photo and it is a non-California spec. bike, the the two shorter hoses go to the carbs as vents and the longer tube on the right just hangs down open.
This innocuous looking fitment has caused many threads on many forums around the internet, an open hose seems so unHonda and people have tried plugging that hose off or plugging it into something else and those don't turn out well either.
287284
 

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Discussion Starter #38
Hm it goes on both carbs , I was thinking vacuum but maybe not. You are right very in Honda if that’s them.
 

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I tried to get a picture of mine, but I would of had to pull the tank to get a decent shot and I wasn't up to that.
On a regular 49 state 750 ACE other than the air filter and carb boots there are the following coming off the carbs:
Choke cables, larger vent pipes to the secondary air filter off the black elbows, fuel lines that run into the T that goes to the fuel pump and the 2 skinny vent lines that run to a T that has one open free end. That should be it.
 
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