spark, gas. no boom. possible timing?

[81gs450l]

i just rebuilt the carbs on my 1981 gs450l. i have spark and i have gas. when me and my buddy pulled the carbs, i loosened the 2 bolts that hold the timing tensioner, i retightened the 2 bolts that hold it in without taking it out fully. the spark plugs are new and i have triple checked the carbs and they are assembled correctly. the bike cranks, but won't fire. i have heard it backfire. could the timing chain have slipped? maybe just throwing everything off a couple teeth? i don't know where to start. any information is greatly appreciated.

 

[koolaid_kid]

Download the service manual for your bike from BassCliff's website: http://members.dslextreme.com/users/bikecliff/
and follow the procedure to check your timing. It is pretty easy.

 

[FreshmanJoe]

Download the service manual for your bike from BassCliff's website: http://members.dslextreme.com/users/bikecliff/
and follow the procedure to check your timing. It is pretty easy.

I'm having the same issue. My question is how do you adjust the timing if you can't get it started?? Doesn't the bike have to be running in order to check it with a timing light?? Are there other ways of checking the timing?

 

[81gs450l]

you have to pull the cam cover and the right side timing cover. line the right piston at tdc. remove the chain tensioner. then line the ex cam marks. then with mark 2 in the proper place you go 18 links and make sure the intake cam mark 3 is at the 18 th link. if i remember from what i read last night. i just want to make sure that i am on the right track before i open things up. does my issue sound like timing?

 

[tom203]

if i remember from what i read last night. i just want to make sure that i am on the right track before i open things up. does my issue sound like timing?

Always best to make sure, since tensioner was somewhat fiddled with.

 

[tom203]

I'm having the same issue. My question is how do you adjust the timing if you can't get it started?? Doesn't the bike have to be running in order to check it with a timing light?? Are there other ways of checking the timing?

No, this is camshaft to crankshaft timing, not ignition timing- making sure valves are openning and closing at right time.

 

[apopleptic]

Same problem last year. It was an improper air/fuel mix. basically flooded engine trying to get it to start.
replaced boots on both the engine and airbox side of carbs. Also had a weak battery that made troubleshooting near impossible. I was only able to start it with starting fluid before changing the battery.
make sure plugs are gapped properly too, that will effect the spark in a negative way.
runs like a champ now.