So heres the set up, i bought this bike for 1200. guy said he road it for a long time till a spark plug started popping out of the head and he included a replacement head. got he bike back and replaced the head, set the timing according to the manuel and got it back together, replaced the spark plugs and the gas in the tank (it had been sitting for a bit) now i have managed to get it to crank up a couple times by taking the tank off and the air box off (because i thought maybe either too much fuel or not enough air) but each time it will only stay running till i let off the gas. i put it back together thinking i had drained out all the excess fuel that was flooding it and now it won't crank back up at all... carbs are clean as can be. does anyone have any ideas? if you need more info just let me know, ill be monitoring this post as i work tonight.

Thanks in advance for any advice anyone has.

An update. got it to crank again by disconnecting the gas tank again but its back firing like hell. checked the timing, it was one tooth off so i corrected that and reset the timing. still back firing and still won't stay running. could it just be working out all the **** in there and all the excess fluid from being flooded? and why is it flooding when i reconnect my gas tank, any ideas?

 

Flooding of the engine is almost always due to a problem with the carburetors. Generally the floats and float valves are not working properly to stop the flow of fuel into the bowls. I know you said the carburetors are as "clean as can be", but I suspect there is an issue there.

Popping and backfiring is usually an ignition problem. It's not uncommon to get the spark plug wires attached to the wrong place. Both Ignition Coils have a Black/White wire going to them. The coil for plugs #1 & #4 has a Blue wire with a Yellow stripe, and the coil for plugs #2 & #3 have a Yellow wire with a Blue stripe. The plug wires have numbers written on them to indicate what plug they go to. I'd suggest visually confirming the plug wire numbers and coil combinations to make sure that they go to their respective coil.

 

Thanks for the advice. I actually did discover this morning that 2 of the wires were mixed up and its fired up fine but i then noticed a knocking and decided to strip the engine back down and found that i had broken a rod which damaged a piston... so i just ordered parts to replace that so no more work till they come in unfortunately...

 

Ouch !! Any thoughts on how the rod got broken ? You think it was a previously undisclosed flaw from the PO ? How sure are you that the rest of the rods, bearings and pistons are ok ?

 

Sorry, terminology failure, it was like the bottom side of the valve, it flipped around and basically the convex side was punching in to the piston. so the piston has a huge gash in it and all the pieces of that valve are done. No I don't think its a undisclosed flaw, I'm pretty sure it from a combination of things (1) all the stuff i did trying to get it to run I.E. starter fluid and constant attemps to crank it (2) the timing being 1 or 2 links off (already fixed that) and (3) the spark plug mix up. I don't think its unlogical to think that this could have caused the valve to fail.

I've already got the engine apart, just waiting on the new pistons to come in (I figured i'd replace all 4 while i'm in there), i can pull the parts for the valve out of the old head. I'm probably gunna try to get the shims to do a valve adjustment if i can find them, cause of they are off then obviously that could have been a major player in the failure.

 

The cam timing being off is probably the culprit. They're pretty tight tolerances in that area. 2 teeth is quite a ways. As for donor parts from the old head, if you take any of the valves, I'm sure you're aware that they'll need to be faced and dressed up to work properly in a different head, the valve seat too. Curious where you're getting your pistons from, local dealer or online ?

Since you're doing all this work, I think you've got most everything covered. Adjusting the valve clearances is a good idea as well. How do the cylinders look ? Any damage there ?

 

Cylinders look fine. Yeah i know about the valve parts, its gunna be some work for sure. I ordered the pistons through a local honda dealer, could have gotten used ones for way cheaper but seemed like i should play it a little safer on this part. You have any advice for dealing with the valve parts? or do you have any good How To's to help make sure i do it all right?

 

I'd really recommend having a machine shop prepare the head and valves for you. Take a look at this series of videos that describes the proper procedures for refacing valves. It also discusses the valve guides as well. Since you had damaged valves, you'll want to check the guides too. This first one just talks about the different components, but following the series through, you'll get a good sense of what has to be done to get it right.

Valve grind 2 - YouTube

This is some old school stuff, but this type of thing hasn't changed much. Not sure what you paid the local $tealer for the pistons, but RonAyers has them for $42 each.

 

Update:
Got the bike back together but now when i try to turn the bike over, the starter is whining really loud... i may be wrong but it doesn't sound right. everything is turning to include the crank shaft but the battery died before it cranked up, may have just been low charge but even still that whining just didn't sound right, any ideas?

 

Managed to figure it out last night, the starter wasn't aligned just right. runs like a dream now.