High RPm

Yes, adjust the sync screw while the bike is sitting there idling (or racing at 3K). That's the only way you'll know if and what your adjusting is doing. If it does start bringing the idle down, eventually you'll need to start turning it back up with the idle speed screw on the left carb or the bike will stall.

Yes, if the sync adjusting does nothing then it could just be lean carbs. Like I said, this '76-'77 set is quickly out-paced by mods. You should also check the float settings. If they're way off to the lean side, that will affect it too.
 
Alright thanks. Yeah I just checked the float lvl was at 25-26 just set them both down to 24 per manual.

Raining now so can't do the sync screw :/ . Times I wish I had a garage. Will update once I do that.
 
5twins which jets and mains should i get then. What you recommended was for the 78-79 I believe by how you worded it .

76-77 with the pods and straight exhaust. in the picture on page 1
 
No, what I recommended was for a '76-'77 set. If you're sure that is the carb set you have then 27.5 pilots (one larger than stock) and 130 or 132.5 mains should get you started. The pilots should be good but on the mains, you should try a couple sizes in succession, like 130 and 132.5 or 132.5 and 135, to really dial them in.
 
So I went threw the carbs again , pretty much a second pass didnt see much out of the ordinary. Replaced 1 o ring , on the jet where the needle jet goes into. Re synched and put the mix screws back to stock. Fired it up and its now ideling a lot better. Does not race anymore like before. Did not find any air leaks and re sprayed the entire carbs and boots.

What it is doing now is idleing good 1,200 , but will increase a little like 200-500ish rpms(estimate dont have tach) and the engine will shake a lot. But will subside and go back to original idle

I did not put the new piolt jet in yet should come within next few hours. Would this be the problem? or is there still some air leak somewhere?
 
A wrong jet size usually doesn't exhibit symptoms like you're seeing (random rising and falling RPMs), so I doubt that's the problem. An air leak is a possibility but you mentioned having the stock ignition. Have you serviced the advance rod? The ends of the cam that it turns in need to be cleaned and greased periodically. If it gets dry in there, the advance rod can stick or hang in the advanced position. Advanced timing means increased RPMs.
 
So i put in the new pilots and mains. Idling is a lot smoother. I adjusted the mixture screws, no dead cylinder method, and found that right side if i move it out at all the idle increases so I have it all the way in. The left side is good at 1 turn out.

About to upload videos of it idling. Also the bike randomly shuts off after about 5 min of idling, not sure why. Also I have smoke coming out the right exhaust...rings? I did put Marvel mystery oil in.
 

first video the idle is racing just a tad


2nd much better idle with the mixture screws adjusted, to note that rattling noise is not the engine but the top engine mount shaking underneath the tank.
 
The Marvels Mystery Oil helped the rings I'm sure, but I think that smoke is one of the right cyls valve seals.

What does the inside of the right intake port look like? Oily?
Cam chain and valves adjusted???
Remove pods, any change?
Alternately, lightly cover the bellmouth of each carb with your hand, one at a time, and blip throttle, any change?
Spark plug color?
Vacuum slide test? Rubber diaphragm condition?
 
Well on a seprate note I pulled the plugs and the right cylinder is fouled with oil i believe.

014.jpg

To note the right side exhaust pipe after running 10 min is not that hot. The left side i cannot grab but I cant grab the right fully in my hand and its not bad. serious problem??
Also the bike hasnt been driven or started in 5 years should I drive a while to see if it will reseat the rings?

With the idling if I try and adjust it so both exhausts (dual) blow same amout of pressure the right ride never matches the left due to the above problem. I also cannt move the mixture screw out inn the right side or it starts to backfire .

Also the slide diaphragms are worrking corrrectly.

Cam chain and valves adjustied. I remove pods and it does the same things.
I lightly cover the bellmouth of each carb all that does when I rev it is kick a lot of gas out and stalls the bike.
Forgot to look inside intake port.

Rings? or valve seals?
 
Have you done a compression check on it yet? Does a little bit of oil in the right side change the compression readings?
 
You should have a large fan in front of the engine for those long idle tests.The way you are running it, 5 to 10 minutes at idle, the engine will overheat, the oil gets really thin and the engine seizes up. The oil will actually get so hot that it carbonizes and no longer provides lubrication, which could explain the smoke you are seeing. I would change the oil before proceeding.
 
with kickstarting both cylinders are at 145 with 10 kicks they are even at 145. Now with 5 kicks they go to 120.

Thanks for the fan tip pete. However the right side exhaust has been doing this since I started the bike up, not sure what this could be.

Im guessing next idea is to do leak down test?
 
well i think pete was right about the oil, i changed it and dont see any smoke coming from it now :). I went threw the idle circuts again for like 10th time to make sure it was no blocked. Bench synced them again and put back on, fired up on 1 kick. Put the mix screws to 3/4 turn both sides.

However there is a lot of backfiring with the mix screws adjusted at this position out the right side exhaust. I have to turn the mix screw in all the way for it to stop...wouldnt that kill the right side cylinder?

The right exhaust pipe is also hotter now, but still does not sound or have same pressure as left.

Anymore ideas?

Still getting the idle problem as well.

Also timing to double check

001.jpg


with the timing light at idle it says within the square on the left
at 3k rpms it goes halfway between that bracket on the left and the right side bracket. About where the letter M and 4 is on the bottom of the rotor.
 
well I checked the floats to see if they were level

this is the right side....

006.jpg

the float seems to be way off....however I checked the float level and it was set at 25

this is the left , looks good to me

007.jpg


how come the float on the right is way off....it is adjusted at the correct level...
 

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The second one the main needle jet will no go in and seal with the o ring. That is the right side carb..problem carb. That is a brand new o ring on it. Im pushing it stright down from the position of the picture and it will not seal, just pushes back up and looks as above.

Could this be causing my float issue with the gas.

Also I tried to use the main from the left side and seal it on the right side and it does the same thing....not sure why its not sealing on that side it looks fine inside no grooves or anything.
 
First off, there's no such thing as a "main needle jet". There's a main jet and there's a needle jet, no "main needle jet". Your pics are of the needle jet. The o-ring groove on the '77 and earlier needle jets is very close to the protruding ring on the jet that butts against the carb body when it is fully inserted. It's common for these not to want to push in all the way, especially with a fresh new o-ring on there. When you install the float bowl, it will push the jet in fully and hold it there. Eventually, the o-ring will work its way into the body. Put some light lube on it like WD40 to assist it in this. Heating the carb body with a hair dryer can also help.
 
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