Closer on the carbs

[Mightyzod]

Hello, everyone. Enjoyed a nonstop 40 mile ride on my 74 GT750 yesterday. Part of my tuning concerns were the result of a fouled plug. It has been a long time since this was a concern, so it took me a while to think of it. At this time, the bike idles, but I do have the adjuster turned almost all the way in, and the engine spins cleanly from 3 grand up and really comes to life at 5. My biggest challenge right now is the hard starting. When the bike has sat over night, it is almost impossible to start. The choke is ineffectual, but after it has ran for a minute, engaging the choke dogs the engine. After the engine is warm, it starts so easily it is amazing. I am confident that it is something in my settings, but can't believe that it runs as well as it does with something major wrong with it. I am running pod air filters and one up on the main jet, two turns out on the mixture screws.
Hints, tips, or suggestions will be appreciated.

MZ

[tz375]

Turn those mixture screws back in 1/2 turn and then try another 1/2 turn and see if that leans out the bottom end.

[Mightyzod]

Tried that. No joy. I am all over the adjustments, rich to lean. Fresh plugs as well. I will scratch my aching head for a bit then dive back in.

Thanks.
MZ

[titan performance]

I'm more of a 500 twin man, but only 1 size increase in the main jet, sounds a little lean to me for running pods.

[Mightyzod]

The main jet shouldn't really affect starting, should it. Showing my ignorance here, but I am used to it.

MZ

[tz375]

MZ, you are right. Main jet will not make any difference to starting, but it may still be lean at the top end. If you adjust the mixture screws and that makes no difference, it's usually a sign that the pilot jets need to be changed. You must use the correct style pilot jets though. Try going up one size on the pilots.

It's also possible that the bypass holes may be partially blocked. The chokes not working says to me that teh tiny starting jets are blocked.

Try this for more info on both issues.
http://pinkpossum.com/GT750/carb/BS40carbs.htm" onclick="window.open(this.href);return false;

[Mightyzod]

Thanks for the help. I have read the information contained on the site you suggested several times. I even have it printed so I can quick ref it in my shop. I am running stock pilots. I tried one up and it ran terribly but was easy to start. I am thinking that the problem with the running was a result of something other than the pilots, since I made some changes when I went back to stock. Yes, I broke the cardinal rule of one change at a time. Yanking the carbs off twice an evening got to me. I shot carb cleaner across the shop through the bypass holes, so I am confident they are clear.
As soon as I am satisfied with the timing, I will pull the carbs off and check everything. If all is well, I will try the larger pilots.

My thanks for the help and suggestions.

MZ

[Mightyzod]

What a shock, it was the points. They were out of adjustment and need to be replaced as well. Adjusted everything by the book and it started right up. Now, to find out if the caliper rebuild did any good.
This has to be the most frustrating form of fun I have ever experienced.

Thanks.
MZ