Damn Bike..Wont Start!!

[Chickenone]

So I did an engine swap. I used a manual and did all the right steps when installing the other engine. I got it all reconnected and cleaned up. I filled it with 2 quarts of oil and put new gas in it. Went to start it up and after about 15 seconds of cranking it a loud bang was emmitted from the exaust pipe. I thought it might be a carb setting so I adjusted the carb. I tried to start it up again and every once in a while it would pop quietly, but it still wouldn't start. I don't have any idea why it wont start. Does any body know why it wont start?

 

[hardtailed77]

So I did an engine swap. I used a manual and did all the right steps when installing the other engine. I got it all reconnected and cleaned up. I filled it with 2 quarts of oil and put new gas in it. Went to start it up and after about 15 seconds of cranking it a loud bang was emmitted from the exaust pipe. I thought it might be a carb setting so I adjusted the carb. I tried to start it up again and every once in a while it would pop quietly, but it still wouldn't start. I don't have any idea why it wont start. Does any body know why it wont start?

Have the valves been adjusted? I think it sounds like a carb issue too though. Have the carbs been synced? I had sort of the same initial problem with mine, and the sync was off even after the 2nd time of syncing them. I also had my float level off in the right carb.

 

[dongrady]

double check the timing if u had it apart. my chain was off 2 teeth and it did all kinds of funky things.

 

[HoughMade]

I would try starting it on WD-40 or raw gas in the carb. If it starts and idles for a few seconds, it's not the timing and it is fuel supply. If it still does not start, take a plug out and check for spark with the plug lying against the head. If you have fuel and spark, but no run- then check the timing. If it starts on raw gas, the the carbs need a closer look.

 

[gentlemanjim]

Spray some carb cleaner in each carb, no or 1/2 choke, throttle closed or slighlty open and see it starts or gives a bit better effort. If it does then you have dirty plugged jets in the carbs. Syncing and mixture settings don't matter on initial start up they will certanly effect running performance. If the carb cleaner makes no difference, then its on to ignition and valve, adjustment.

My money is on the carburetors - the sigle biggest sin committed on bringing an old bike back to life - dirty carbs. This issue is repeated and repeated on every forum I read. Thoroughly disassemble and clean them, remove the jets make certain they are not clogged, spray carb cleaner though every orifice or a fine wire, blow compressed air to be certain, change the needle and seat, be certain the slide diaphrams have no tears or pin holes and are seated properly and aligned in the bores before putting on the top caps and lastly make sure there are no leaks in the mounting boots.

 

[mcrowell75]

Did you re-install the timing advance mechanism off by 180 degrees? As I remember, it can only fit on one of two ways and its very easy pick the wrong one.

Your symptoms sound very familiar...dont ask.

And be careful, I actually started a small fire while I was fruitlessly kicking over my bike with a reversed advancer. Is that pop you are hearing coming from the pipes or the carb?

 

[jayel]

Did you re-install the timing advance mechanism off by 180 degrees? As I remember, it can only fit on one of two ways and its very easy pick the wrong one.

Your symptoms sound very familiar...dont ask.

And be careful, I actually started a small fire while I was fruitlessly kicking over my bike with a reversed advancer. Is that pop you are hearing coming from the pipes or the carb?

or coils/point wires reversed

 

[drewpy]

my mates xs400 ran backwards once!