Finally got an airhead..

[hadabadachada]

Hello all.
I was referred to this forum by a good guy from another forum, said this is where the REAL DEAL information is regarding airheads.

I talk a lot and may not get what I’m saying across well, but that’s just me, I try my best.

Sorry this is going to be a long one as I try and lay out where I am.

I got a steal of a deal (starting to rethink that) on a 1978 R100/7 with 24,000km on it, it is apparently a Canadian bike so it’s in KM, as the previous owner bought it up there and now lives in south Florida. Who wasn’t a “real” rider, so to say.
Bike hadn’t run in over 10 years, and of course, had a half tank of fuel in it. He just set it up and left it since he couldn’t ride anymore. Wasn’t able to get the cap off to visualize it and try and get the price lower but I got it a bit lower regardless. Cap just clicked and clicked.

Finally got the cap off the can and man, varnish like a mofo! Cleaned the tank over a week with vinegar and baking soda and all that and it actually turned out s lot better than I thought. Put a screw in the cap as those things new are EXPENSIVE!
Took the carbs apart and soaked them and cleaned everything up pretty good imo. I’m starting to question that now..still think I did good, I took my time. Replaced the gaskets and seals but left the original diaphragms, they look and feel good still. Have a spare set.

I put new plugs in and doing that I checked compression which was at like 130-140 on each side, that seems good to me.
So at this point I have gotten the bike started and idling pretty good it seems. Fires right up. Choke cables are new and kinda a pain to get them tightened to the right spot where it’s all off and all on, gonna have to mess with that more. With the choke on half or full it seems kinda wonky running. but that might be related to something else.
Don’t really need the choke in Miami anyway imo.

Main issue this post is about is, I crank up the bike, get it warm to try and balance the carbs. Make sure the choke levers on each carb is fully off. Set the carbs at 1 turn out on the idle fuel screw as bing recommends, I tried doing the pull one wire off the plug and adjust each side but upon further research (since I’ve been non stop searching for information) I’ve now found I shouldn’t do that because the bike has that dynatek electric ignition. And I’m wondering if I messed that up now by doing that pull the plug wire balance thing. You all can tell me based on the info.

Either way I’m still going. Made another tube manometer as I haven’t sprung to get a nice pricey one. I’ve used these in the past on my R1100S and they worked for me there.
I feel I’ve gotten the idle balanced with the butterfly adjustment screws, I haven’t messed with the idle mixture screws, have left them at 1 turn out.

Issue I’m having now which will be the most revealing for finding an answer is, when I go to adjust the throttle cables which are brand new, as well as new seal kits in the carbs, when I turn the throttle to about 1500-2000ish, low revs, it will sit then give a little “poof”, a little misfire every 10 seconds or so give or take. Gets me thinking, damn, did I mess up the electronic ignition??
Then when I get up to 3000rpm it’s a hard vibration to about 4000rpm when it goes away.

So I’m thinking there’s something else wrong with this engine.
I’m wondering if maybe the throttle needles could maybe cause this? As they were pretty dirty, all the carb parts were super gummy with that lacquer fuel. I thought I did a good job cleaning all the passages and jets and everything. I didn’t use anything harsh to scrub through holes or anything. I did use some scotch brite lightly on the needles to smooth them out, but maybe they need replaced.

I’m hoping it’s just carb related or else it’ll start to NOT be such a good deal on the bike.
I mean I knew everything needs to be redone being such an old bike, that was granted going into this. I knew it was going to be a project for me. So I’ll soon be a regular here.

Thanks for your time.

[hadabadachada]

Shoot, forgot to mention, I took the head covers off and adjusted the valves. .15 intake and .20 exhaust. Also torqued the bolts to 25ft lb, as some were a little loose. Haven’t checked timing, I’ve never done anything like that nor do I have the tools. I’d hope the electric ignition is mounted right and I didn’t mess it up.

[gspd]

The very first thing you need is a timing light, a cheap one will do, just to confirm that you are in the ballpark timing-wise. S mark at idle, F mark at 3000 rpm and up.

Next, while idling, pull up on the left throttle cable, release it, then pull up on the right throttle cable, and release it. From this point on, act like you have two single cylinder engines, a left and a right. Are both ‘engines’ reacting the same when you open their throttle? They should. Turning the mixture screw (lightly) all the way ‘in’ should stop that side. Does it? You’ll know the mixture screw is pretty well spot on if turning it in or out 1/4 turn noticeably slows the engine down.

If you can’t figure it out, you can switch parts (plugs, HT wires, coils, carbs) from the good side to the bad side until you find the problem component by process of elimination.

The left and right ’choke’ assemblies are internally different. A very common error with people not familiar with these carbs is to mix the chokes up when they rebuild their carbs. Another very common thing is not properly positioning the inner and outer notches on the diaphragms. I’ve also seen seemingly perfect-looking diaphragms that were riddled with tiny pinholes that were only apparent when held up to a light and stretched a bit.