I've got 99 problems...and they all involve my XS

[poorman9]

Hey guys, So I've rebuilt, rewired, and reassembled this 81 650H over the past three months. I can get it to fire up, but it won't stay running.

Back story - I bought the bike in pieces from a guy who was running chopped straight pipes and basically wire mesh as carb filters.
Here's more info about my engine rebuild. More info about my wiring. And some other advice which I've followed.

What I've done

• Checked compression, 150PSI in both cylinders.
• Done my best with my timing, (without a timing light).
• Synced my carbs using the paper strip method.
• Adjusted the valve lash.
• Got clean gas, a clean tank and a replaced fuel filter.
• Made sure none of my jets are clogged and my float bowls are clean.
• Retorqued my head bolts, which some how got pretty loose.
• Felt the pipes and both get warm, so it's running on both cylinders.
• Messed with my idle settings back, to no avail.
• Cleaned my carbs again, just for good measure.

Specs
Carb Set: 1981 so BS34 (I think)
Airbox: K&N
Iginition: Boyer Blue Box
Exhaust: Emgo shorty reverse megaphones
Main Jet: 135
Pilot Jet: 42.5
Needle: stock (I think)
Needle Position: stock (I think)
Mix screw: 3 turns out

My 99 problems
Over the course of trying to get this thing running, I've kicked like a thousand time, so my leg is tired, that's my first problem. I'm getting a really strong kickback every now and then, I jump on it with all my weight and just about the tip the bike over and kicker stay upright, regain my composure, try it again, and it kicks fine.
I'm also seeing some oil seeping from somewhere in the vicinity of my head gasket which I just replaced.
After a few kicks the it'll fire up and run for about 4 seconds, then die. If I give it any gas it dies right away. If I give it gas while kicking it, it won't start at all. I don't know if it sounds like its supposed to, because I've never heard the bike run before. Also, over the course of messing with the air mixture I got some flames shooting out of the exhaust, which was exciting, but probably not good.

Lets hear it boys (or girls, if there are any in this forum).

 

[retiredgentleman]

I don't see any mention of the float bowl level. Are you confident the level is set correctly? I like to use a clear plastic tube from the float bowl drain as a level gauge, and set it at the bottom of the float bowl flange.

The choke circuit needs to be working in order to start a cold engine. Here's a pic of my float bowl from my BS38. I'm not familiar with BS34's but they should be similar. Check that the passageway (jet) is clear for the choke fuel supply.

Is that rubber plug in place and in good condition for the pilot jet in the B34 carbs??

 

[5twins]

Your timing could be off as well. That can cause hard starting and kick backs. If everything's right, these are very easy one or two kick starters. Mine sat all winter with gas in it and started this spring on the 1st kick.

If your needle is stock then it only has one position. The BS34s came with a non-adjustable needle.

You can't accurately set a Boyer without a timing light. You're just guessing if you try.

 

[poorman9]

Your timing could be off as well.

Is there anyway to check this without a timing light? I can go rent one from Autozone, but my bike needs to be able to idle at 3k, which it can't right now.

Thanks

 

[poorman9]

I don't see any mention of the float bowl level. Are you confident the level is set correctly?

I'm gonna go check that I have a 22mm measurement from the carb body to the top of the float...

 

[5twins]

Idle should be 1200. To check the full advance on a Boyer, you need to rev it up to 5 or 6K. 3K (or 3500) is full advance for the stock ignition. The Boyer doesn't stop advancing at 3K, it keeps advancing until much higher. You need the timing light or, like I said, you're just guessing.

22mm is correct if you have plastic floats.

 

[poorman9]

I can only get it run for 3 or 4 seconds, is that long enough to check timing?

 

[5twins]

Probably not, lol. You may want to experiment and move the timing adjustment a little at a time to see if you can get it to run longer. Scribe a line between the timing plate and case where it's set now so you can put it back if need be. If that won't help then maybe you have other issues like carbs or fuel delivery (lack of).

 

[poorman9]

Well the floats were right at 22mm, so that's not the problem. I put the carbs back together and now can't even get it started. Guess I'll try tweaking the timing back and forth.

Can the kick back on my kick starter be fixed by adjusting the timing? Or to I need to tear my engine apart and move the cam chain one tooth over?

 

[5twins]

Yes, kickback can be eliminated by setting the timing correctly. You can easily check your cam timing without disassembly of the top end. Details are here .....

http://www.650motorcycles.com/CamTiming2.html

 

[alfredo]

Just wanted to jump in and explain that I am having extremely similar problems with my rebuild and boyer setup . . . . so I feel your frustration amigo.

 

[poorman9]

5twins, thanks for sticking with me on this. So I've checked the cam timing, put the motor at TDC (verified by putting a dowel in the spark plug hole) and the small hole and the end of the ignition advancer is pointing straight up. So I'm gonna quit worrying about that.

Now, I've set the crank position so the white dot is visible through the timing hole of my boyer iginiton, like so -

And you can see marks on the rotor are where they should be right?

I've tried rotating the pickup plate slightly clockwise and counter clockwise, and it didn't seem to change anything. Still breaking my leg on the kick back and not starting since I've taken my carbs off this afternoon.

 

[poorman9]

Just wanted to jump in and explain that I am having extremely similar problems with my rebuild and boyer setup . . . . so I feel your frustration amigo.

Hey Alfredo, I actually found a couple of your posts today in my frantic searching and I was thinking, man this poor guys sounds just like me.

Thanks for the gif, took my mind of my problems instantly.

 

[5twins]

I don't know, you seem to have set everything up correctly. The only other thing might be your battery. You need the full 12 volts to power a Boyer so if your battery is low or going bad, that could cause problems.

 

[alfredo]

It looks like the pickup plate is dead on to me. Pretty much exactly where mine is when I can get mine to run. Have you tried switching which plug the wires go to? Have you tried switching the wires that connect to the coil?

 

[poorman9]

So this morning I took my K&N's off and sprayed in some started fluid, the bike fired right up, and stayed running as long as I was spraying the stuff.

Which tells me it's not a battery problem, or any electrical problem right?

I'm lost

 

[poorman9]

Here's what my spark plugs look like -

Left float and bowl -

Here's a dumb question, should there be a gasket in that picture between the bowl and the carb body? Because neither side has them.

Right Float -

 

[kopcicle]

Am I looking at a PLASTIC MAIN JET ???!!! Just say no , as in don't ever . Just take my word for it on this one .
That's one
Under the rubber plug is a pilot/idle jet . remove it and VISUALLY confirm that not only is the hole clear but there isn't anything living in it .
That's two .
Now for the educated guess . Your crank position should be nearly 20 degrees counter clockwise somewhere between the two marks to the left of the "T" unless Boyer has done something different in the last 20 years (it has been that long so I could be full of ....)

All I have for ya atm .

~Dennis

 

[nj1639]

Ya know, I was thinking...'Where's the gasket?'

 

[poorman9]

Am I looking at a PLASTIC MAIN JET ???!!!

You sure are, I thought it was a bit strange too the first time I pulled it apart. You think it'd be worth buying a new one? I've got 135's in there now, should I maybe a different size too?

Under the rubber plug is a pilot/idle jet . remove it and VISUALLY confirm that not only is the hole clear but there isn't anything living in it .

Done. Just last night I pulled them out again shoved a little piece of wire though them and sprayed them out with carb cleaner.

Your crank position should be nearly 20 degrees counter clockwise somewhere between the two marks to the left of the "T"

According to the Boyer instructions, I've lined up the timing mark to "full advance position" which is 38 degrees BTDC. I don't have a degree wheel, but I read that little gap in the edge of the crank case cover marks the advance position. I found the same information here too - http://www.650motorcycles.com/BoyerMicroPower.html