Hello all !!

Hope all of you are doing well. been gone for a while, been in the road and working. The old Ultima is doing well. need some advise from my knowledgeable friends. Friend of mine bought a Big Bear Chopper-"Sled"- 100" smooth S&S engine. He brought it wanting me to tear it down because it was running very bad. After a few checks came to the conclusion the front cylider wasnt firing. So, i replaced the plugs. still not firing, so repaced the plug wires. still not firing so I replaced the coil. Still only one cylinder will fire. Checked the compression -120 lbs on both cylinders. if i take the plugs out and hold them against the frame they look like they are fireing the same amont of intensity. change the plugs to different cylinders the back is the only one that will fire. if while the motor is running irradicaly and I pull the plug wire off the front cyl. it will knock my d**k in my watch pocket, but not fire the cylinder. It will do joult me hard if I hold the plug wire and spin the motor. If I had hair I would have a frizzed style by now ! It has a Stampede igniton module in the nose cone, I assume it has the same brand coil. I am not familiar with this brand and the wiring of it. i went to the web site but cant match any color wires as it was wired at the assembly plant. I dont think it has been changed. it has a white/blackstripe wire and red/green stripe to one terminal and a black/green striped wire to the other terminal. I dont know why I can get this thing running. I need help please ! Front plug is damp from gas, so i assume it is getting gas from the S&S super G.

Big Bear Chopper____model--Sled
S&S 100" Smooth
Stampede ignition
Dual fire coil
HD plugs
120 lbs compression
S&S Super G

Thanks ! Steve

 

Do a leak-down test, check the timing, if all is well replace the ignition and coil with an Ultima. You need compression, air/fuel mixture, and spark at the right time for combustion. 120 lbs is low for a 100" $&$ engine, you need between 65-80 lbs for decent combustion on most engines. I would think that you should have at least 150-170 with that engine. Hope that helps.

 

My guess is the timing is way off. Why it is off.... I have no idea. But that would be my guess.


___________________________

 

More to the story.
I asked .....What happened when it screwed up ? answer.... "we were at the bar and my friend did a burnout on the BBC. smoked the place up ! Then my wife was going to do one and when she hit the starter it backfired through the carb blowing the fancy air filter out in the floor. Took it to a fellow bar mate that just happens to be a HD mechanic, and he said it blew a pushrod loose in the rear cylinder. Said mechanic reinstalled pr and it hasnt run right since" Rechecked the compression and have 150 lbs on front and rear cylinder. Pulled the rocker boxs to make sure the front valves are opening and closing. both front and rear look the same as for mechanical. not broke springs or bent valves. Havent had time to check the timing. Going to try tomorrow. Any more suggestions are welcome ! thanks John ! thanks bikerlaw !

steve

 

The end to the deliemma was in fact the ignition module. Thanks John. after checking and adjusting everything we finally got a new ignition mod. Set the timing and new set plugs. Now off to the bar for more burnouts !!

 

Well done!

 

Usually if you have spark, fuel and compression and only one cylinder firing it's the module firing one cylinder at the wrong time. Glad I could help.