QuestionHi Bill,
I've looked through a good number of posts on here for a similar issue/answer, but didn't find one. Hope this isn't asking twice now.
This is regarding a 1975 Honda CB200T. From what I gathered, it sat for the most part during the 6 years before I bought it. It ran without having to do much to it at all - just new plugs and gas I think (we couldn't make ourselves wait for a full tune-up). It sat for a while, then my brother and I took apart the carbs, completely cleaned them, replaced carb jets/seats/screws from new kits, reset the air mixture and idle, made sure the air filters were clean, mounted two new exhaust pipes with new gaskets, and took apart the pet cock and made sure everything was clean and clear in there.
We started it up and rode around for about 15 minutes with no problems - it ran great. Small idle/air mixture adjustments, and it ran even better. A few weeks later, we took it out for a long ride, which is when the issue arose.
After about 15-20 miles of normal condition riding and reaching speeds of about 60mph tops (but no high-revving or hotrodding), the bike just started losing rpm's and slowing down. No matter how the throttle was moved or what gear it was put in, there was no response - just constant slowing down until we came to a stop and it died. Neither kicking it over or using the electric start did anything (didn't even sound like it wanted to start). We let it sit for about 15 minutes and then it started right up. We chalked it up to a mystery and kept going. Then about 2 miles down the road, the exact same thing happened. We repeated this "ride for a couple miles, sit for 10 minutes" pattern the rest of the way home, and it worked the whole way. I let it sit for about a month until riding around the neighborhood a few times before putting it away for the winter. No problems starting, and it ran fine for the 5 minutes I was out.
My brother thinks it might be one of two things: 1) a small bit of something has clogged the fuel somewhere along the way. This would explain it dying from a lack of fuel in the bowl, and then starting after it sat and some fuel leaked past the clog or 2) the coil is bad, and once it heats up, it stops the plugs from firing. I read on other posts here that Honda coils seldom go bad. My brother says that you can get coils tested, but the shops around here can't do it because they don't have the specs to test it.
Do you know where I can find the specs? It's just the one coil going out to the two plug wires/plugs.
Other info i can tell you about the mechanical condition: after we got home from the issue ride and let the bike sit, I pulled the plugs. They aren't fouled at all, look to be a good color, and both look to be in the same shape (meaning one's not more fouled than the other). The air cleaners are in good shape. The gas was good. The inside of the tank has only small amounts of surface rust here and there.
Also, I was wondering if you know where I could find the torque specs for the exhaust pipe nuts. We put a brand new gasket on each pipe, and there's still an air leak ticking from one side. We thought maybe new gaskets and a proper torque tightening would help.
Anything you could provide would be greatly appreciated. Thank you in advance.
Josh
AnswerJosh, What I didn't see here was a reference to setting the ignition timing and checking the mechanical spark advancer for proper function.
I will hope that the engine dying off was due to fuel flow stoppage and not piston seizure from incorrect timing. You would see that on the plugs though... flakes of aluminum if seizures were taking place.
Do check the spark advancer and make sure that the points are gapped around .014" and they open at the F mark alignment on the rotor.
Coils can be tested with an ohm meter on the primary side.. usually about 4-5 ohms on bikes with points and condensers. There used to be nice little coil testers that would fire the coil up and you can see the size of the gap it will jump before misfiring. Maybe not too many of those are still out there now.
If you have checked the whole fuel system and all is clean, including the fuel lines and any debris that sometimes backs up behind the float valve, then I'm willing to put my best guess forward as a blocked vent on the gas cap. Common problem with bikes that sit for years. Gasoline fumes slowly vent out of the cap and gradually the varnish deposits close up the cap venting holes. This causes a vapor lock in the fuel flow, because it is running out faster than the vent can allow air to come back in to balance the pressure.
The thing to do when it dies is to immediately check it for spark, then check the float bowls for fuel levels. You might have weak spark plug caps, which should measure around 5k ohms. Sometimes they will break down, especially when they get hot.
Torque on any 6mm bolt is around 5-7 lbs. I just tighten them by hand and "feel," until they get snug w/o trying to tighten until it won't go no more...
http://www.dansmc.com/torque_chart.htm
You probably had some old gasket material up inside the exhaust port that is causing the exhaust leak. It is best to get the mufflers set roughly in place with the attachment bolts, then tighten the exhaust flanges first, working your way towards the rear mounting bolts. If you see that there are gaps between the bracket and frame, then use flat washers to shim up the gap, rather than forcing the muffler up against the bracket, which puts the parts in a bind and causes misalignment up front.
Hope that helps...
Bill Silver
