T500 `74 problem

[greens888]

Hi. My T500 has had the full run down over the months. Checked or replaced carbs. coils, exhausts, petcock, plugs, top end, air box, ;plug leads, etc etc. I am convinced everything is as should be. Running 100 mains, 3rd clip pos, 27.3 float level. Plugs always look a bit lean. Starts quite well and runs ok, when warmed up goes better, then after a few minutes or 10 or so it suddenly seems to be a bit missy, then it gets worse and worse and I can just nurse it back basically missing so bad. Just now did it and returned, pulled both plugs. Right plug has an oily residue around the outside, not the electrode. More importantly there was a distinct vapour or smoke came out of right plug hole. Can`t think of anything I have not checked except the crank seals and apparently the right one is prone to going first. But does not blow smoke after warmed up, only just the right amount of blue 2 stroke smoke I think. So frustrating. The only thing not standard is the main being 100, and I drilled a few more holes in the baffles as they seem so restrictive. What puzzles me is that it goes so well for a short while then, just so bad. Steve.

[jabcb]

The coils could be OK when cold but then have problems when they warm up. This also applies to the capacitors.

Is the battery fully charged up? Did you check to see if the alternator is charging properly?
The twins (T250/T350/T500) vary a bit. Some run fine without a battery (except for burning out the lights) & others only run good with a fully charged battery.

[Glyn.G]

Hi,
I don't know if this could be the same problem as I had on my GT380 as you didn't say whether you replaced the points, or perhaps your running electronic ignition. Anyhow I had exactly the same problem, I could set off with everything running fine then about 20 minutes into my ride the misfire started and like you I managed to limp home. After a lot of testing and head scratching I sourced the problem to the new points that where sticking when the engine got up to full operating temperature. Apparently it was a common fault back in the day.
As the points heated up the small pin on which the points anvil rotates on expanded causing them to stick. I found a quick spray with WD 40 did the trick. Eventually after about 100 miles they bedded in and no more problems.

[greens888]

Ok thanks for your advice. I think I have answered it now, after I restarted it there was a distinct smoking coming from the right exhaust, and that`s the one always missing. I have replaced the points and the right coil. I found there are bolt plugs under the sump which access the crank chamber and I pulled these and there was some oil, I reckon tranny oil not 2 stroke, worryingly some grey metallic residue and crap. So I`m satisfied I need to split the cases and have a look. I have ordered the outer 2 crank seals as they are cheap and genuine Suzuki part numbers, and will clean up and replace them if it looks right other than that, or if centre seal is suspect or any other wear on the bearings or whatever I will have to get the crank redone. Steve.