compCoder Posted September 12, 2010 Author Share Posted September 12, 2010 ITS ALIVE!!! Got it all put back together today, filled with gas, put on prime let carbs fill, and had to try to crank it like three times, but it started, and ran well. I was able to go for a nice ride around the neighborhood, never died on me once, everything running great, the engine runs very smooth now. I got it up to about 50 at one point and from 1500 to 8500 RPM it pulls very well. End all, all the work done it is still working and running very nicely. I will be able to do an oil change next weekend, once that is done, and i get my license, I will feel fine that its reliable enough to get me to work and back . Now, on to the question portion Whenever the bike was cold when i just fired it up, it would hesitate a bit getting up from idle, and even made a 'pop' sound coming out once or twice. From reading, i would guess this means its a slight bit lean at idle, which is fixable by turning out the mixture screw just a hair. They are currently at 3 turns out right after the build of the carbs, so if i back them out I should go a quarter turn at a time, and 'retest' after it gets cold. Is this all correct? Also, is this really needed in my case, as once its warm (like 5 mins) it completely goes away, no hesitation, no popping, just perfect running. Next question, during my ride, after a while the RPM would not drop below say 3500 at idle, it would stick there. If i dropped it into first gear and let the clutch out just a bit it would break it from high idle, though still stay around 1800. If i revved it while in idle, it would stay again around 3500. i drove it the rest of the way home with the high idle, and once I got home, i made it do the drop by letting the gear catch and it was sitting again around 1800. So i backed out the idle screw (i had removed it while cleaning) slowly until it got back down to around 1200, took about 6 turns and the screw appears to be about half way out. Once I did this I could rev it up again and it wouldn't get stuck at the high idle, i could rev up to 8k and it would drop right back down to 1200 perfectly, fast both up and down. Could backing it out fix the idle catching at the high point...is this now fixed by that? Is that the normal issue or could it possibly be something else? Also, I have only balanced the carbs so far by eye when putting them back together, I think i have it very close, but still need to hook up my manometer and get them perfectly balanced, though it will be tricky with having the tank off and the gas line still connected. Also, i was going to order the quarter inch gas line and was told it was too big, but its extremely hard to get the smaller line on there, and the clips from the old line do not fit on it, is the 3/8 line the right stuff, or do I need to pick up some wider stuff that goes on a bit easier? The petcock is workign perfectly, i filled tank with gas while it was on the on position, and nothing was going into the line at all, moved to prime, it pushed fuel in, once i started it and let it run for a minute i put it back to on and its driving perfectly with it in that position, was able to restart it a few times with it there too. Thanks for all the help I received in getting these small problems fixed and now it seems more reliable, just have to see if the push button will work again after it sits for a full 24 hours, works fine right after taking it of the float charger I got... Link to comment Share on other sites More sharing options...
compCoder Posted September 12, 2010 Author Share Posted September 12, 2010 Alright, trying to sync them up now, and no matter where i set the sync screw (my visual sync is screwed now...lol) the right side always has more vacuum, where if i don't kill it just after starting it will suck in the fluid in my manometer. So, from reading the manual, I may need to adjust the mixture screws on one side or the other, any idea which? Also, which way to turn the sync screw to make it go one way or other once i got it closer? Since it always pulls on right side very hard, it makes ithard to tell which way I should go, any help is appreciated. Link to comment Share on other sites More sharing options...
Moderator drewpy Posted September 13, 2010 Moderator Share Posted September 13, 2010 do a compression check first to see if you have out of balance cylinders. check valve gaps and ignition timing next, to manually adjust the carbs, place a 2 x 2mm bits (with the carbs off) under each butterfly valve and slowly pull the throttle up. the idea is to get the bits to drop at the same height as the butterflies begin to open. Link to comment Share on other sites More sharing options...
compCoder Posted September 16, 2010 Author Share Posted September 16, 2010 I still need to check the valve gaps, but I think the timing is perfectly on, as the bike is running wonderfully after re-eyeing the balancing. While the right side still has more vacuum, the bike is running pretty much perfectly. I will get to the valves next chance I have, first need to get on painting the house To start now, I found when cold, it won't start with the choke all the way in, it will start with it half way out, but struggle a bit, takes a bunch of cranks from electric starter. I pull it all the way out, and it fires up in 2 cranks, maybe 3 sometimes, so just perfect. I let it run there for about 10 seconds, probably at ~2k rpms, then i push it half way in while i put on my helmet and get ready to ride. At half way, its right around 1600-1800rpm, and when ready to ride, about 2 mins later, i push it all the way in, idle drops to ~1200-1300rpm, and it runs perfect. I found if i start with it all the way out, and push it all the way in right off the bat, it dies, but giving it a minute or two, and it runs great (so using it for what its for ). Also, on the brake line leak, i don't think its leaking. I drove it on the 'real' road the other day, instead of just in the neighborhood, but stayed close, as I still have no license, even got it up to 70mph. Anyways, I have reinspected the brake lines, and there is no longer an fluid on outside of them anywhere, maybe the last person that filled it just spilled some all over it... Link to comment Share on other sites More sharing options...
JonB Posted September 13, 2011 Share Posted September 13, 2011 I am loving this thread. I just bought an 81 XS400 Special with 7600 miles on it. Not as shiny, but the price was right ($400!!!) I'll probably be going down this same path soon, but as long as the weather holds, I'm just riding it daily. I just have one quick question for the gurus here. I need to do an oil and filter change since I have no idea when it was last done. Where can I find the o-ring gasket for the filter cover? As you can probably guess I am WAY new at this stuff. I got the 400 to ride since the 79 xs750 I got for free apparently needs a LOT more work than I can get done this year. THanks! Link to comment Share on other sites More sharing options...
Moderator drewpy Posted September 13, 2011 Moderator Share Posted September 13, 2011 you can get the O ring with some oil filter manufaturers. HIflo I think do them. I always use gen yam oil filters so get one from them if you order. oil filter part # 1L9-13440-00 O ring part # 93210-88324 also clean out your oil gauze, held by 6 m8 bolts underneath the engine block. be prepared to make, buy a new gasket for that one! number 9 in the schematic Link to comment Share on other sites More sharing options...
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