only runs with choke on

[fullercameron]

OK. Got the new coils put on and the bike started right up on the first kick with no choke. It was running good, so I left the choke off and got the bike warmed up a little bit. Since I recently pulled the clutch apart, I went to pop it into first to make sure that the clutch was working properly and it stuck and died.

Turned the switches off, since it felt stuck again, I put it into third and was able to feel it pop loose and I could then roll the bike in gear with the clutch in without the engine turning. After freeing the clutch, I went to restart the bike and it wouldn't start up.

I checked the plugs and they still appeared bright and clean. Possibly a little carbon on the insulator, but the electrode looked spotless - then again it was only running for about 2 minutes. It smelled a bit gassy so I let it air out a bit and tried again. One pop and then nothing. Pulled the air filters and noticed a bit of gas on the inside of the lip of the air filter.

I believe that the problem is probably my float level. I pulled apart the carbs to clean and check jetting because of the older choke problem. I reset the float height but found myself without a rule with metric measurements at hand, so I used did a little conversion and set the float height with a regular standard rule.

The fact that it started so easily without the choke leads me to believe that it is running rich, I have read that the float bowl height can lead to a rich condition like this and the more I think about it, the more I distrust my standard metric conversion and float bowl height.

Does this sound like I'm thinking straight to anyone?
I also though that since it started so quickly today after the carbs were recently off, and didn't after the petcocks were open for a couple of minutes might indicate that it took a minute for the bowl to fill up enough for the height to be a problem.

I also rechecked the jet sizes on the bike since the PO had been running a 750 kit that was removed. The old pilot jets were pretty chewed up and really plugged so I ordered new jets, but mike's was out of the stock pilot size so I went up one. I am running pods and more open pipes, so I thought this would not be a huge problem.

Does anybody think that the problem lies in the new pilots and not the float height?

I'm pulling the carbs off again as soon as I get a minute and was hoping for one more kernel of advice. Running, not-running, running, this is getting frustrating. I feel like I'm close enough now that even though it's 100 degree outside here, I put on my boots and pants every time I go over to the shop.

Maybe this weekend.

Putting a picture of the bike on this one. A friend helped me finish the seat about 2 weeks ago and I just took some new shots the other day.

 

[5twins]

If you went one up on the pilots (42.5 to 45), that shouldn't be a problem. '70-'71 and '74-'75 models used that size and the '70-'71 carbs are pretty much the same as yours as far as all other jet sizes go.

Float spec is 25mm for your carbs. That converts to just under an inch (.98"). What did you set them at? If you're going to own one of these bikes, you really need to buy a 6" steel rule graduated in MM on one side. You will use it to check much more than just float levels. I consider it an essential tool if you own a metric bike.

 

[fullercameron]

I set the floats at 15/16" of and inch. I used 2.6cm per inch as the conversion which is a little off. I think 15 16th amounts to .94". Is this enough to be and issue?

If I imagine the float working, I would think that the fact that this float setting is a bit low would actually mean that the fuel level in the bowl is higher than it should be before it shuts off. I cleaned the float valve and seat but is it possible that this problem could also stem from a leaky needle and seat?

 

[5twins]

You may be about a MM off, to the rich side, but honestly, I don't think that would make it not start. Do reset the level but you may still have other issues, spark issues. Is the timing set exactly? That can make for hard starting if off.

 

[fullercameron]

5twins

Thanks for the continued help. I will check that carbs and timing and let you know what I find.

I static set the timing and it appeared to be dead-on the other day, but I'll make sure something didn't move, or that I didn't forget to tighten a screw or something. Was going to double check it with a timing light but haven't had it running long enough to do it. I checked it with a light after static timing before I monkeyed with the points the last time and it looked like it was right where it should be.

Time to check things one more time I guess.

 

[5twins]

Besides timing, points gap is important. Too big and it would be hard to start.

 

[fullercameron]

OK. Went to the shop after work and re-checked float bowl levels. They were a hair on the low side, but pretty close. Put the carbs back on, opened the petcocks and it started on the first kick - no choke. It doesn't seem to be starting hard when I first get the carbs on. It was idling pretty low, and I let it die once and it started right back up.

I let it run for a couple of minutes, checked to see if the clutch was working today (it was - one down) and as it ran, it seemed to idle slower and wanted to die more than when it was first started.

I am wondering if the problem could be that the mixture is getting progressively richer because the float needles and/or seats are leaking. Does anyone think that this could be the cause of the problem?

I didn't have time this afternoon to double check timing, points gap, etc (will do tomorrow or Saturday)But it seems to have no problem starting quickly when the float bowls have been emptied and the fuel has just been turned on.

Just for accuracy's sake, while doing the work today, I started with the mixture screw 5/8 turn out rather than 3/4 trying to lean it out slightly, and I started it with the pods off.

So close.......

 

[fullercameron]

By the way I didn't say it in the previous post, but I did adjust the floats accordingly.

 

[5twins]

Yes, slowly leaking float needles can overfill the bowls causing the idle to falter and drop, then eventually stall.

 

[fullercameron]

Ordered new float valves. I really think that this might be the problem. I cleaned the carbs and looked at the parts, but didn't replace most of the hard stuff. Put new diaphragms, pilot jets and float bowl gaskets, but otherwise what is in there is what I got when I bought the bike.

Float needles did look like I could see where it was seating in the valve and I guess that this didn't register as excessive wear. We'll see if this fixes the problem.

Let you know when I get some tiny parts.

 

[fullercameron]

Just thought I'd let everyone who helped me know that I got the bike up and running. The float valves were definitely the biggest part of the issue.

Seems to be running like a top now. Put about 300 miles on it in the past four days. I have a few spots that seem to be a little flat in the acceleration, but I went back to stock jet sizes as a starting point, and now I think that I probably need to go up a size or so on both the pilot and main jets to compensate for the exhaust and pods.

Thanks again for all the help and patience.

Now that the bike is moving, I am only really having one last problem. Usually it starts on the first kick, but every once in a while, it wants to puke a little gas out of the overflow on the right carb when I stop, then it wants to be a little stubborn about starting (sometimes takes 6-7 kicks). This seems to happen most if I am parked on an angle so I am not carrying a small block to put under the kickstand when I stop.

I have checked and double checked float levels but noticed the other day that when I filled the tank, I seem to have a tiny pin hole at the very upper top front of the tank that will allow a tiny drip of fuel to run down the top of the tank. Could this little pinhole be affecting the venting in a way that could cause the carb to puke gas for some reason?

 

[I am Carbon]

good to see that you got her runnin I don't think the leak will cause that, check your float seat sounds like it is not seating to me and the bowl is overflowing

 

[weekendrider]

Glad to hear you are on the road.
To stop the overflow shut the petcocks off a min or so before shutting down. Gas is to expensive just to pour on the ground.
The pinhole in the tank would be more of a safety issue than a mechanical problem?