Sputtering at Mid range

[Guest]

Have a '77 750 that I did a top end rebuild on this past winter. I'm running straight pipes and pods on it. It idles like a dream and does well in the higher RPMs but if I'm running about half throttle it sputters. I can't tell if it's rich or lean or what my mains are. I'd have to guess PO put in at least 107.5 or 110 for the pods. I put on the straight pipes. I raised the needles two notches while troubleshooting earlier which proved to be a different problem. Any guesses on what it could be? I'm about ready to take it to the shop because all I want to do is ride instead of working on it...

[Big T]

You need to do plug chops and find out whether it's rich or lean

I'm thinking you're still too lean at 110 mains, 117.5 or 120 should be more in the ball park

[azr]

Why can't you tell if it's lean or rich?? Pull the plugs. Why aren't you exactly sure what is in the carbs? You have to be for what you're trying to do. Pull the carbs.

[phydeauxmutt]

Good luck taking it to a shop. Most shops have a "ten year rule" where anything older than ten years old doesn't get through the door.

Add in the fact that a shop is under scrutiny to keep things somewhat legal, your straight pipes and pods won't be looked on very favorably.

They are also not looked on favorably by several of us on the forum, but that's another discussion that I won't get into here.

[tkent02]

I'd have to guess PO put in at least 107.5 or 110 for the pods.

I've seen POs put in jets 10 sizes too big and also 10 sizes too small. On the same engine. Take it apart and look, it only takes about ten minutes.
Thinking any PO did something right is ludicrous. They don't go there.

[GSCafe]

Geez, if you have that old of bike, you need to find a shop that will do their best for you. Mine is willing to comb ebay or otherwise to find my parts. The dealer won't look at my bike but damn, a real shop can tune carbs whatever you bring. Some folks don't like pipes and pods but....pffft. You are in for an education if you do it yourself, and I can see you don't want that. $250 is what the shop I use charges to carb tune with dyno, just for your reference.

[R3lease1t]

Why can't you tell if it's lean or rich?? Pull the plugs. Why aren't you exactly sure what is in the carbs? You have to be for what you're trying to do. Pull the carbs.

I have pulled the carbs and tried to read the numbers on the jets but can't tell what they are.

[R3lease1t]

You need to do plug chops and find out whether it's rich or lean

I'm thinking you're still too lean at 110 mains, 117.5 or 120 should be more in the ball park

I tried 117.5 with centered needles and it seemed too rich. Then again that was when I was having timing issues. I could try putting them back in and seeing if that changes anything.

[R3lease1t]

Good luck taking it to a shop. Most shops have a "ten year rule" where anything older than ten years old doesn't get through the door.

Add in the fact that a shop is under scrutiny to keep things somewhat legal, your straight pipes and pods won't be looked on very favorably.

They are also not looked on favorably by several of us on the forum, but that's another discussion that I won't get into here.

The local college has a motorcycle tech program that takes in bike from the community and all you have to do is pay for parts. The problem is normally there is a waiting list and they take forever to get the bike back to you.

And yes, I am aware of how a lot of people on the forum feel about anything but stock. I agree, best not to discuss.

[alke46]

PM sent.......

[Big T]

I have pulled the carbs and tried to read the numbers on the jets but can't tell what they are.

Get a magnifying glass and confirm what you have in there
Harbor Freight has some

[Big T]

I tried 117.5 with centered needles and it seemed too rich. Then again that was when I was having timing issues. I could try putting them back in and seeing if that changes anything.

Instead of taking a willy nilly approach, confirm your jet sizes and read your plugs

[R3lease1t]

I put in the 117.5 jets and it helped considerably. I think once I sync it, it will be running like a dream. Thanks for the help

[chef1366]

Ride where it bogs and add choke. If it picks up you're lean and if it bogs down you're rich.