A float slowly filling up with gas seems to be inline with the problems you had, first it running OK and now not running well at all. Fowled plugs means you're running rich.
Kurt in S.A.
'78 R100/7 '69 R69S '52 R25/2
If so, take a ride and see if it behaves the same way....running good initially and running poorly as it heats up. When it is running poorly, pull the plugs and see if you still have a good spark.
Rough running and hard starting when hot are classic symptoms of a bad magneto coil. Other ingnition maladies that would affect both cylinders are the condensor (and making sure it is well connected and grounded.)
Differential timing can also affect performance, but I don't think it would differentiate between hot and cold running.
My guess is either you are running so rich that you quickly load up the plugs or your coil is on the way out. Do both cylinders heat up/cool off approximately the same?
If the bike is new to you, you should make sure the valves are in adjustment, do a compression test and check the timing. If it is delivering a good spark, the carbs are not hard to deal with and parts are readily available from Vech/Bing.
When you make changes or adjustments, I like to do one thing at a time and check the results.
- You said the plugs were fouled. Are the plugs oil or gas fouled? (Oily residue, or fluffy carbon?) Low compression could cause oily residue due to valves/guides/rings?? Fluffy carbon is too much fuel.....
- Does it backfire through the carb, or through the exhaust? (Carb backfire might be carb passage obstruction/float problems/idle or air jets plugged, etc. Backfire through the exhaust could be electrical/points/condensor/magneto timing/coil issues.)
That used to be a general automotive rule...well, sorta.
I had much the same issues on my R-50. I had 90 PSI compression hot on both cylinders, but the fouling was worse on the right cylinder. I did the following:
- Installed two in-line filters.
- New points and condensor.
- Disassembled and soaked the carbs in carb cleaner, and installed new idle jets and air mix jets, float needles.
- Installed a new air filter.
- "Reseated" the float needles using valve grind compund.
- Went to "one hotter" range plugs.
- Installed "non-resistor" spark plug caps.
-Static timed per Barrington manual - then dynamic timed, (a couple degrees different). Checked differential timing was within a couple degrees.
Guess what - still gas fouling on the right cylinder! I took the front cover off, and in the semi dark, noticed it was sometimes arcing across the "10mm" gap from the coil to ground.
- Increased the gap slightly between the coil and the ground discharge point.
- Dropped the needle one notch on the right carb slide.
- Set the air mix jet at 3-1/2 out on right carb.
- Went "two heat ranges" hotter on the right plug.
- Syncronized the carbs.
The last ride seemed to give decent looking plugs - no fouling.
I realize this is a temporary fix until I can get the engine gone through - but that is VERY expensive and I hope to get a FEW miles under my belt before sending it off to the REAL experts to rebuild it...
Today I took a look at the plugs which where brand new prior to the ride and they where completely fowled
What am I missing?