Hi all, I need help 1977 not starting

Could be a lot of reasons for the bike not running. To check the governor (ATU) for being 180 out, take it out and the three slashes on the cam lobe and the notch on the backing plate should line up.
DSC03754.JPG This is a new never used one. It also looks the same as the one in my 79.
 
Could be a lot of reasons for the bike not running. To check the governor (ATU) for being 180 out, take it out and the three slashes on the cam lobe and the notch on the backing plate should line up.
View attachment 34431 This is a new never used one. It also looks the same as the one in my 79.

So i am assuming the ATU can be 180 out and bike will still run?
I will do this once i get home, hopefully, it is not going to rain today and i can get some work done. Im familiar with the 3 notches on the cam, not sure about the notch on the backing plate, but i suppose ill see it when i have it out.
Thank you
 
The notch is by the arrow. If the bike ran perfect when you got it and then after you started to adjust things it developed issues, I would think that's the problem. If you never had the ATU out it should be fine. Those do need to be pulled apart cleaned and oiled from time to time. But I would do that after you figure other things out.
 
The notch is by the arrow. If the bike ran perfect when you got it and then after you started to adjust things it developed issues, I would think that's the problem. If you never had the ATU out it should be fine. Those do need to be pulled apart cleaned and oiled from time to time. But I would do that after you figure other things out.

I see the notch, thank you

The bike didnt run perfect under my hands, in fact the only two times i drove it was on a test run, and on my way home. I couldn't kick start the bike (kick only) when i got it, the previous owner could, it started for him on the 2nd or 3rd kick on several occasions. It had the mikexs pwk carbs and was idling high (around 3k), I drove it home and got a set of BS34, cleaned, rebuilt, and replaced the carbs. Still couldn't start it, did the fuel in the plug hole test, and it started for half a second. Long story short, was suggested to check my timing, and this is where i am. I never had the ATU out, but i im not sure what the PO did or did not do.
 
Could be a lot of reasons for the bike not running. To check the governor (ATU) for being 180 out, take it out and the three slashes on the cam lobe and the notch on the backing plate should line up.
View attachment 34431 This is a new never used one. It also looks the same as the one in my 79.

looks to be ok i believe, it seems to turn and move freely. I will try setting the timing again as Mike suggested. Reading over the thread, i see it is normal that the engine will want to turn right when reaching the LF mark, ill see if i can hold it there again.
 

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So after a long (medically forced) break, I got back to working on the bike. I was finally able to get the timing done, valves, and take care of an electrical issue (with professional help). The main issues were valve adjustment, inconsistent plug spark, and many many (a lot more than I would have thought) kicks. It starts now, still take some work, will not start cold even with starting fluid, but will start in the afternoon, i was able to bench sync and tune it, although i may have messed it up yesterday. I will need to sync and tune the carbs, and see where i am at once I'm done.
Thank you so much for both @xschris and @NewHavenMike for all your help!!

Any idea what can be used as a knob for the chock (mine is broken), @xschris maybe? looks like you have a lot of parts :)
Also, i think my idle screw unscrews from the vibrations, is it possible? It seems to work fine for a couple of minutes and RPM drops down again and ill have to turn the idle screw again.
 
Make sure to use a manometer to sync the carbs. Check to see if your idle screw is not stripped or the spring is missing. I have a choke rod I can sell you. I will P.M. you with details on that.
 
What happened to the choke knob?

The idle will change as the bike warms up. The bike needs to be fully warmed up when you make your carb adjustments. My bike does not like being cold lol. Its fine when its warmed up though. You should always need the choke to start it. Try priming it by kicking a couple times with the choke on before you attempt to start it. Youll need to leave the choke on for a minute or two while it idles.

Obviously its possible for a screw to back itself out. I havent experienced it with an idle screw, even on my harley and I can adjust it using my fingers. Id think it would be more gradual rather than a drop-off to a stall.

Seems like youre on the right track, just need to do more fine tuning. The carb sync with manometer is crucial. The carbs wont be truly balanced until you use a real gauge.
 
What happened to the choke knob?

The idle will change as the bike warms up. The bike needs to be fully warmed up when you make your carb adjustments. My bike does not like being cold lol. Its fine when its warmed up though. You should always need the choke to start it. Try priming it by kicking a couple times with the choke on before you attempt to start it. Youll need to leave the choke on for a minute or two while it idles.

Obviously its possible for a screw to back itself out. I havent experienced it with an idle screw, even on my harley and I can adjust it using my fingers. Id think it would be more gradual rather than a drop-off to a stall.

Seems like youre on the right track, just need to do more fine tuning. The carb sync with manometer is crucial. The carbs wont be truly balanced until you use a real gauge.

Choke knob was broken when i got it, but the rod is fine and working perfectly.

It was starting and running over the weekend, still needed a tune and sync, but was working. I looked at my spare jets to see which i ended up installing and realized i had two different sizes (from all the installs and cleaning i did :doh:), so i opened and changed both to 145 (had 145, and 142.5 installed). Its not starting since, it wants to, but not starting. Not sure if this is the reason, it was also 15 degrees warmer over the weekend, so im not sure. Im going to try again, if not working ill install 142.5's and see if it helps.

The second thing that changed is that the choke stopping ball (the tiny ball and spring that holds it on each stage) wasnt installed, so i just stuck a screwdriver to keep it open, and now it has the ball back and holding itself on each stage.

As for the idle screw, I can twist it with a very gentle touch, almost no resistance, the screw is in the threads, and takes full turns to make a difference, I will check if the spring is mounted correctly.

Thanks
Nir
 
What air filter and exhaust setup are you using?

Had the mike xs pods on it but changed them to UNI yesterday (it started with the mike xs ones), have a 2 into 1 setup, not sure by who but seems to be the cheap one (emgo?) image attached, but this is with the old carbs and filters

It also seems to like the middle choke setting best if it says anything

yamaha 77.jpg
 
Well, you should be able to get the bike running with that setup. As to how close you can get it to perform as if it were stock???

The aftermarket stuff can complicate things, especially when tuning and trying to diagnose things.

The manometer sync needs to happen first. You need to do this. Make a gauge or buy one. I ended up buying a Motion Pro gauge after buying bikes that are 4 cylinder. Its expensive, but its well worth it if you have multiple bikes, the tool sees quite a bit of use.

I did make a manometer out of 2 beer bottles, air supply line, and used JB weld to seal it all up, it was complete trash lol. I cant believe how long that thing has lasted and how accurate it was. I still have it somewhere out there.

I do not know if pod air filters will make the manometer not work accurately, this is where it gets complicated. I just dont know the answer to this one... The cylinders will never be perfectly balanced and Ive ridden with them very slightly off before. Anything more than "very slightly off" and youll be stalling and erratic idle and bad power.
 
Pods wont effect a manometer adjustment as it's only for your butterfly plates. Shaft seals can make a difference. Those should be replaced on any carb rebuild or at least checked for rips and hardness.
 
Here is a pics of a cheap to do home made manometer. A member made this. It's a little big but works as it should.
120-1294889478-f10f1e522507568254831aefc5ad755f.jpg
 
Here is a pics of a cheap to do home made manometer. A member made this. It's a little big but works as it should.
View attachment 34634

Got to take a better look yesterday and it looks like i lost the throttle stop screw spring, not sure how i clearly remember installing it after cleaning the carbs. That thing turn like crazy from all the vibrations :)
I have attempted syncing the carbs with a similar tool to what you attached, i got close enough, but not perfect, i am pretty sure there is a vacuum leak to some degree(old bike) from somewhere on the intake system or the tool, but hopefully, it is manageable. I did inspect the shaft seals but did not replace them, I also have the manifold vacuum barb loose (the one with the tank line connected), i did the best to seal it for the sync, will have to find a more permanent solution.

At this point, i am waiting for the throttle stop spring so i can proceed with tuning.

I couldn't get the carbs to perfectly balance, no matter what, they will stay balanced for a couple of seconds and then one side will rise a little (maybe half an inch to an inch). I attached a video link, I was later able to get it a little better balanced as well as slightly lower RPM than on this video.


Thanks again
Nir
 
Well, you should be able to get the bike running with that setup. As to how close you can get it to perform as if it were stock???

The aftermarket stuff can complicate things, especially when tuning and trying to diagnose things.

The manometer sync needs to happen first. You need to do this. Make a gauge or buy one. I ended up buying a Motion Pro gauge after buying bikes that are 4 cylinder. Its expensive, but its well worth it if you have multiple bikes, the tool sees quite a bit of use.

I did make a manometer out of 2 beer bottles, air supply line, and used JB weld to seal it all up, it was complete trash lol. I cant believe how long that thing has lasted and how accurate it was. I still have it somewhere out there.

I do not know if pod air filters will make the manometer not work accurately, this is where it gets complicated. I just dont know the answer to this one... The cylinders will never be perfectly balanced and Ive ridden with them very slightly off before. Anything more than "very slightly off" and youll be stalling and erratic idle and bad power.

Did the sync (attached a video in the comment above), or as close i could get using the DIY tool for now. next step is tuning idle and air/fuel
Thank you
 
Your valves sound very loud ( tappets). Make you adjusted them correctly. There are threads on this in the forum and specs in the manual. Fix any and all vacuum leaks then sync again. Make sure the oil is 20w-50 for wet clutch bikes. Check your oil level with the bike cold and on it's center stand. It's the only way to make sure it's full.
 
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