engine trouble

As mentioned, your problems could be related to several different things (ignition, carbs), but I would definitely have a look inside your carbs to check their jetting and verify proper float level setting right away. There's no telling what the P.O. did, if anything, to tune the carbs for the mods done. For the typical "pods and pipes" type mods you have, some re-jetting is usually required. For most of the carb sets, the increase needed isn't huge, maybe one or two up on the pilots, same for the mains, but your '76-'77 carb set can be an exception to this. It came with the smallest mains (122.5) ever put in the 650. While fine for a totally stock bike, those small mains are quickly outpaced when you start doing mods. Your carb set may require 3 or 4 steps up on the mains, to a size in the low 130's. But, before you get started on jetting changes, you'll want to positively I.D. the year of your carb set. You need to know this because jetting changes are based on the year of the carb set, not the year of the bike, and carb sets are easily swapped on these. The one pic you posted isn't detailed enough to I.D. the carb set 100%. It does appear to be a linked set meaning it could be the original '76-'77 set but it might also be a '78-'79 set. To positively I.D. them, remove one of the pods and look at the intake bell. Both sets would have the oval slot on top but a '78-'79 set will have 4 additional round holes around the edges. A '76-'77 set would only have 2 additional holes .....

3mQOwp3.jpg
 
As mentioned, your problems could be related to several different things (ignition, carbs), but I would definitely have a look inside your carbs to check their jetting and verify proper float level setting right away. There's no telling what the P.O. did, if anything, to tune the carbs for the mods done. For the typical "pods and pipes" type mods you have, some re-jetting is usually required. For most of the carb sets, the increase needed isn't huge, maybe one or two up on the pilots, same for the mains, but your '76-'77 carb set can be an exception to this. It came with the smallest mains (122.5) ever put in the 650. While fine for a totally stock bike, those small mains are quickly outpaced when you start doing mods. Your carb set may require 3 or 4 steps up on the mains, to a size in the low 130's. But, before you get started on jetting changes, you'll want to positively I.D. the year of your carb set. You need to know this because jetting changes are based on the year of the carb set, not the year of the bike, and carb sets are easily swapped on these. The one pic you posted isn't detailed enough to I.D. the carb set 100%. It does appear to be a linked set meaning it could be the original '76-'77 set but it might also be a '78-'79 set. To positively I.D. them, remove one of the pods and look at the intake bell. Both sets would have the oval slot on top but a '78-'79 set will have 4 additional round holes around the edges. A '76-'77 set would only have 2 additional holes .....

3mQOwp3.jpg
Thank you for your in-depth explanation. I definitely have the 77 set with 2 holes, but I have the big brass piece in mine like the 78-79. Does that mean someone changed it, or does it really make a difference?
 
That's the slide. It just happened to be removed from the '77 carb on the left in my pic.
I have one really important question. I am looking at the carb guide you guys created and there is a small discrepancy. The chart says to use BS pilots for my 77, but the fine print on the bottom says use the VM series. I do see a star by two of the boxes, so just wanted to clarify before I buy anything.
 
I would pull out the pilot jet installed currently and see if it is a VM (holes in the side) or non-bleed (no holes in side) then buy a similar one in a larger size.
 
Your '77 carbs take the VM22/210 type pilot jets. You can't buy the "no hole" versions the factory used, I think they had them made special, but the standard style with the holes down the sides work just fine. For your mods, I'd recommend one up on the pilots (to a 27.5) and 3 to 4 up on the mains (to a 130 or 132.5). The larger mains will probably also require you to lean the needle setting a step.

7wbHkpb.jpg


Yes, the asterisk by the pilot jet sizes for the '76-'77 and '78-'79 carb set refer you to the note in the "Misc." column telling you these carb sets use the VM22/210 type pilot jet. It is also mentioned in the notes below the chart.
 
Your '77 carbs take the VM22/210 type pilot jets. You can't buy the "no hole" versions the factory used, I think they had them made special, but the standard style with the holes down the sides work just fine. For your mods, I'd recommend one up on the pilots (to a 27.5) and 3 to 4 up on the mains (to a 130 or 132.5). The larger mains will probably also require you to lean the needle setting a step.

7wbHkpb.jpg


Yes, the asterisk by the pilot jet sizes for the '76-'77 and '78-'79 carb set refer you to the note in the "Misc." column telling you these carb sets use the VM22/210 type pilot jet. It is also mentioned in the notes below the chart.
Thank you again, will get those jets ordered asap, and found a local guy yesterday who works on Yamahas, and he is willing to give me a hand with the carbs, as he knows a lot more than I do.
 
Ok, got the new mains (132.5) and pilots (27.5). Also ordered new rubber carb holders and brass floats, which is my question before changing everything. The carb guide lists 25+- on the floats, but how much does that differ with the change in jets, if any? Definitely hoping to get this thing dialed in and running this week.
 
Jet changes don't affect the float level, it should stay at the same spec.
 
Ok, got mains and pilots changed out, reset needle clip to #2 ring, and new rubber carb boots. Bike fired up with choke on, but cut right off after choke released. Only starts with choke on and tried throttle with choke and just coughed and sucked wind. Any suggestions where to start?
 
Do you still have those pleated style pods on there? If so, I'd take them off and test. Besides causing a turbulent air flow, many of them have another issue. There's a rather large rubber lip inside the flange, a "stop" of sorts so they don't slide on too far. It does that alright but can also block or partially block the air ports around the edge of the intake bell .....

Uvs9R7Y.jpg


I would also check the mix screw setting, making sure they are at least set somewhere "in the ball park", which would be 1.5 turns out for your carb set.
 
Do you still have those pleated style pods on there? If so, I'd take them off and test. Besides causing a turbulent air flow, many of them have another issue. There's a rather large rubber lip inside the flange, a "stop" of sorts so they don't slide on too far. It does that alright but can also block or partially block the air ports around the edge of the intake bell .....

Uvs9R7Y.jpg


I would also check the mix screw setting, making sure they are at least set somewhere "in the ball park", which would be 1.5 turns out for your carb set.
No pleated, using the foam now, but had them off during this trial run. Had mix at 3 turns first, per Norton, who used to work at mikes XS in Tampa and has a history with them. Backed it off to 1 1/2 like you said and still the same. Can slowly increase throttle but after slight rise in rpm, it cuts off. Have no idea what changes those jets are supposed to make, but definitely sounds a bit beefier when running.
 
When you set you reset the needle to 2nd clip was that from the top or bottom? Also did you make sure the carb slide diagrams were lined up and sealed when you put the top back on the carbs? If you use your finger to slide the diaphragm up and then release it then it should drop slow.
 
When you set you reset the needle to 2nd clip was that from the top or bottom? Also did you make sure the carb slide diagrams were lined up and sealed when you put the top back on the carbs? If you use your finger to slide the diaphragm up and then release it then it should drop slow.
Clip was 2nd from top, that was how the diagram showed it, and I made sure the rubber lined up correctly and pushed it down all around, but there is always a chance that it wasn't 100%, and on that note, would it run at all if it was not completely pressed in?. I'm pretty sure it really needs some adjusting after I did so much to it, just need some direction as I am not a bike mechanic. And really appreciate all of you guys willing to help the rooks out.
 

Check out this video and it will help. As for the 2nd clip from the top you leaned out the needle which acts from 1/4 throttle to around 3/4 throttle. Try putting the clip back in the middle and see if it helps a little when you rev it but I can’t be sure it’s your needle. It could also be the air fuel mix screw since you tried 1 1/2 turns try a half turn richer. The trick is to make one change at a time and figure out if it’s running rich or lean and at what throttle position. You need to read the carb help guides in the tech section. Also there is the carb sync as well if you haven’t done that it need to be done and can cause issues too.

And more learning stuff..
https://www.youtube.com/playlist?list=PL4RtmJ8bkFdm6yfhx4eAPKCgJe-zqvPNx
 
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Get clear on this: secondary effects are very strong, especially in older carb designs, and everything affects everything else. The main circuit (which
ain't just the main jet, the needle jet, needle, and slide are also main circuit components) never turns off: even with the throttle fully closed, the main circuit feeds fuel to the engine, which is why the slide has a cutaway and why the throttle plate has a mixture designation stamped on it. Changes in needle position affect the mixture even at idle and in off-idle transition. A change of a single step in needle position can force a compensating change in PJ size, and conversely.
 
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I think my next step would be to verify the fuel levels in the bowls using the clear tube test. I doubt your fuel levels are too high or the carbs would probably be over-flowing and leaking gas, but they could be too low. That could cause symptoms like you have (only runs on choke, won't rev up).
 
Well, first I tried it with filters off. Put my hands in front of the carbs and it was spraying gas out. Put the mix screws back to 1 1/2 and put on the foam filters, since that was how it was going to be anyway. Got it to stay running, and it seems to throttle okay, just spits a little, even as it is idling. So it appears to be working, just really need to find someone local who actually knows what they are doing to fine tune it.
 
I wanted to remind everyone to go through everything. Don’t assume you have an original set of carbs. I’ve spent the last few days on here doing research on ID of carbs. The certain jets and parts by these years. Found the set of carbs I was using had wrong slide needles and were not jetted right. All the info is here. Find it. Carb guide. Plenty of charts, pics, etc. I, at first was one to ask first. Now I’m used to navigating this site, it’s easy to find info.
 
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