Seca help

Hey all. Newbie here. I’m gonna try reposting in the hangout sectio. Looking for some help.
I have an 81 seca 750. Doing a full restore.
Here’s what I have done.
New fork seals
rebuilt calipers
New wheel bearings
Every fluid changed
Rebuilt rear brake drum
Stem bearings
Added air box back (came with pods)
Valves checked and reshimed
Except that 3 exhaust valves are still tight by .05. (2 are 2.65 need 2.60 1 is at 2.60 needs 2.55)I am waiting on 3 shims to correct
FULL CARB BREAKDOWN AND CLEAN
Ordered new throttle seals and fuel rail seals from Len ( awesome dude)
Wet set carbs twice
Bench synced 3 times at least
Full carb clean 3x
Polished slides and bore
New fuel bowl gaskets
All manifold boots have been inspected and Rtv’d.
Waiting on fresh manifold caps. Old ones are a little hard and suspect.
New fuel line
New vacuum line.
checked the petcock with vacuum method making sure fuel was pulling with vacuum on vac line
New plugs
New battery
All kinds of beautifying


ok
So this may be counter productive until ALL valves are within spec but I just have to know
I have finally got the bike to start. Killed one 1/2 dead battery in the process.
At first it was a run away idle. ( hang on to that thought)
Plugs where black sooty and dry
Did the throttle seals and rtv’d the boots
Adjustment screws 2.5 turns out
Will crank over eventually. Full choke will get it warmed up. Once warm the idle is funny and boggy, kinda of low (800 rpm) and twisting the throttle stalls it. If I turn up the idle screw the idle gets worse. Seems like it’s a mirror image of the throttle behavior. Gets boggy and wants to die. If I back out the idle screw the idle hunts or shoots up to 3k and stays there. No noticeable effect with adjusting the 4 mix screws. I’ve tried 2 turns out, 2.75,3 and 3.5. i am going to get the new valve shims in and then retry the process but it doesn’t seem that far off. ( like I said 3 intakes are out .05 shim measurement. ). Correct me if I’m wrong but The starter at times sounds like rocks in a blender and im wondering if the 3 tight exhaust valves have anything to do with that. Before I changed out the shims I couldn’t even rotate the engine with the timing head bolt(19mm square one). Could the out of spec valves be too tight still to crank consistently?
My next thought is to check for air leaks propane style. But I did rtv those suckers pretty good. I’m not giving up cause this bike seems like it will be fun. I really wanted a gs to work on but you can’t always get what you want. My wrenching has been limited to enduro thumpers thus far ( 90 dr350 ) and a vstrom that never needs anything. The Toyota Corolla of motorcycles. I’m excited for a sweet ol street bike.
Even though I checked vacuum with the petcock I’m suspicious that the petcock in the on position is not pulling fuel. It may have run out of fuel a few times and died after I switched from prime to on. At that point it wouldn’t start again until I switched back to prime position and refilled the bowls. ( I think) Then it would crank over with the same idle issues stated above. Weird huh? The vacuum test told me the petcock was ok but…. It’s hard to know for sure because the idle has been so erratic and the bike has died a lot while diagnosing but for sure at times I have switched back to prime position and then it would start.
If this isn’t worth getting into until all valves are within spec then just shame me and we will see what happens after the valves are 100% shimmed. I appreciate you all for the efforts you have made in helping so many others. It has been a wealth of knowledge in this process.
thanks
J

 

Can you believe I forgot to mention something.
At first go around before the throttle seals were replaced and full cathedral experience the rpms would surge bad and die back with a twist of throttle then die out. After the throttle seals etc replaced and boots rtv’d the idle just hangs around 3000 once warmed up and if I totally back out the idle screw it dies. The throttle now has no effect on the hanging idle
For anyone who has read all of this you must really love these bikes….

 

This thread may have done better in the technical chat section.

Is it running any better now?
Did you synchro carbs?

My XJ650 was a world of difference after synchronizing carbs with YICS plug then removing YICS plug and starting it up the next day.
Before and during carb syncing, I think one or more cyclinders had heated up pretty good. When I let it cool down, and start the next day I was able to reliably get it to idle 5 minutes @ 1000RPM.
I'm replacing shims this weekend. One was off really bad if you read my thread. I'll have to re-synchro and have a color tune kit to also use. I still have mixture screws at 2 1/2 turns from closed. Testing for leaks is easy with starter fluid.
Last 5 times I've cold started it with Choke / Fuel enrichment turned on, it started no problem.
To check fuel flow of petcock, turn it to prime to see if it changes, if so, it is likely the petcock/fuel flow.

 

I agree it still seems like a fuel flow issue. Make sure the carb bowls are filling with fuel.

Lots of work you have done and it can get frustrating but stick with it.

As far are polishing the slides and the carbs.....what did you do? There is a thin line (or some say there is) between clean and polishing. Others will chime in here but depending how much polishing you did to the carb slide and the venture area might cause some issues.

Does the choke work on your bike. @Melnic mentioned that above that their bike works with the choke ckt, does yours function?

 

My enrichment (choke) does function. I have re set the wet set a number of times. Even had it go out of adjustment on its own. I had set the floats and then tried to get the bike synced. Noticed fuel in the oil so I re checked the float levels and they were way off. Re set again and I can just get the bike to start and warm up and then perform a running sync. After the sync the bike still doesn’t want to evenly rev through the lower end. It’s real boggy. Turning the 4 pilot screws out to about 4 and a 1/4 seems to be the best spot which has me thinking I still have a vacuum leak somewhere. I just can’t find one. The starter clutch is starting to act up so I have to wait for a full battery charge to do anything. 2 steps forward and 3 back it seems. I’m going to check compression next to see if I’m fighting something I can’t fix with a sync. I don’t have the yics tool but I’m reading that it doesn’t seem to make a huge difference. Maybe that’s incorrect for my bike. ??????!!

 

Keep working at it. No the YICS tool is not needed, you will get it close enough and just fine without the tool. Lots of use don't use the tool when we sync.

When you did the wet set you didn't have any gas bleeding by? If you are getting gas in the fuel are your main stop jets working?

New spark plugs? Have you taken a little off the end of each spark plug wire to make a better connection? The fuse holder is okay and has been checked out to make sure good current flow and now bad fusees?

Compression test will be nice. If the bike firing and spuddering and or back firing or just running high rpm once ot does run? Keep trouble shooting and lets hope you get it soon.

 

Thanks timbox
The bike initially had a run away idle which seems to have been fixed by new throttle seals fuel line o rings and new intake boot gaskets. Now it almost sounds like it’s sluggish at idle. It doesn’t have that nice purr it should. “Just chuggy “. It will pop a little if the pilot screws are set where they “should be” 2.5 turns.
Plugs are new. All 4 wires trimmed back. New plug caps. Ohmed out the coils wires and caps within spec. I’m looking to replace the older float needles from Len. I’m using whatever was in the carbs when I picked it up.