1982 xs400 Maxim won't start after top end rebuild :(

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CaptainBeyond28

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I lapped the valves and made sure it was TDC and the 'o's were on top and whatnot. My neighbor helped me out and it looks like both spark boots give out a spark. I'm pretty sure I have good compression but I close up to the engine in this video so anyone can get a good look. Could it be the carb? My neighbor adjusted the choke screw a bit but it looks like it still slides in and out fine, though it may be a bit loose. I noticed gas was a little slow to fill the filter, but I have a full (new) tank of gas.

 
After you are sure that the plug wires were returned to the correct side (ask me why I mention this), spray some starting fluid into the carbs while cranking and see if it fires. If so, you aren't getting fuel. Start at the tank and work your way to the carbs and then through them if necessary.
 
HoughMade said:
After you are sure that the plug wires were returned to the correct side (ask me why I mention this), spray some starting fluid into the carbs while cranking and see if it fires. If so, you aren't getting fuel. Start at the tank and work your way to the carbs and then through them if necessary.
Click to expand...

I'll double check. I don't have starting fluid but I will pick some up. I still havent attached the air filter but I just want to make sure it fires before I waste my time putting everything together. Still haven't even put the chain on.
 
Makes sense to me. Carb cleaner will probably work too...or dribbling some gas in, but that's hard with sidedrafts.
 
I would pull spark plugs out, put bike in second gear and roll it(ignition off).. with my finger on spark plug holes - I want to feel that compression. It should be in both cylinders - this is my simplified compression/valve clearances check. In this video I don't 'hear' compression... when I crank my bike it sounds like it is 'fighting' compression (may-be because my battery is weak :) )

Also, I noticed that with kick-start my bike starts on first kick, but with 'button' I have to crank it for full minute. I think starter eats too much electricity so bike will either crank or start... basically - try starting bike by pushing it while in gear. It may just work that way.
 
I'll do the rolling trick, and I forgot to mention, I didn't put the chain back on or the cover for it, I don't suppose that along with the air filter would prevent me from just starting it...
 
I have a new vid:

You can see flames shooting out the exhaust. Still clueless :(
Is there a chance this could be an electrical problem?
 

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So you have spark correct? and you have it on the right moment? (timing) and on the correct side (i made mistake by myself by swapping coils, check that out)
If yes and yes, i would mount exhaust with mufflers, and airbox also. and then try to start. Give us the results.
 
After checking that the spark plug wires are on the correct cylinders (as has been repeatedly suggested), if it still doesn't start check compression using a proper compression tester. It sounds low in the videos. Did you check the valve adjustment and change the shims after lapping the valves?

If you get the engine to fire and run, do NOT run it without the exhaust installed. Doing so can quickly damage the exhaust valves.
 
Lego said:
So you have spark correct? and you have it on the right moment? (timing) and on the correct side (i made mistake by myself by swapping coils, check that out)
If yes and yes, i would mount exhaust with mufflers, and airbox also. and then try to start. Give us the results.
Click to expand...

I'm about 99% sure I didn't as the spark plug covers were ziptied facing the proper direction to the frame when I bought it.

Jeff0133 said:
Follow the timing procedure in the manual, pretty straight forward.
Click to expand...

I'm not sure this is the case because I haven't touched the flywheel or timing mechanism, I just replaced the top end of the engine and set everything to TDC as the manual said to do
 
It doesn't matter that you did not touch flywheel, if you rebuild top end, you have to reset 1.valves, 2. gap points, 3. set timing. As you can see, everybody is telling you the same. so lets do it and let us know result :) good luck
 
Lego said:
It doesn't matter that you did not touch flywheel, if you rebuild top end, you have to reset 1.valves, 2. gap points, 3. set timing. As you can see, everybody is telling you the same. so lets do it and let us know result :) good luck
Click to expand...

I looked last night, and mine says that this bike has a TCI rather then ignition points so check chapter 6, and chapter 6 mentions no way to set timing.
 
Since you lapped the valves, the valve clearances MUST be checked and adjusted. They will be too tight, possibly even holding the valves open. Shims are available from Yamaha and Kawasaki dealers, or you can buy an aftermarket kit that includes a variety of sizes.
 
16VGTIDave said:
Since you lapped the valves, the valve clearances MUST be checked and adjusted. They will be too tight, possibly even holding the valves open. Shims are available from Yamaha and Kawasaki dealers, or you can buy an aftermarket kit that includes a variety of sizes.
Click to expand...

Do I HAVE to replace the shims? Mine appear to be in perfect condition...
 

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