Tiny Leakage and Idle issues

[WesV]

To start out, I do not know the history of this bike as far as oil changes and all go mainly because my dad can't remember but here is my issues:

I changed the oil in my 450L at 7,800 miles and it now has 8,560. When I changed the oil, I changed out the oil that had been sitting in it for over 10 years then run for a couple hundred miles (I know not the best thing for the bike, but it wasn't black so I figured it was fairly fresh when the bike was parked.) I put Valvoline Dura-Blend synthetic/dino mix 10w-40 as the casting calls for. Well at about 8,200 she started leaking very slowly from around the bottom bolt ove the clutch/countershaft cover (I guess that would be the bset name for it.) It drips a drop or two overnight after being run good. Is this because I went to synthetic? Should I switch to a little heavier oil or back to dino juice? I have read through past threads about oil and haven't found this exact problem.

Number 2.) After being run for a while (minimum 20 min) usually in city traffic, but sometimes on highway too the idle jumps from about 1000-1100 to 2000-2100. Well it doesn't jump but will slowly rise ending at at about 2100. I had the carbs rebuilt and cleaned by our local dealer in Nov. and have just lived with it until now. what might it be?

Thanks ya'll!

[Can_O_Tuna]

There is a lot of opinion regarding oil on this (and others) site. I personally use and have used Castrol 20w50 for over 20 years with no problems. Synthetic has its place (in cars) but I think that in your 450 a good quality 10w40 would do for normal use.

The fact that it has sat for so long might call for (more expensive) motorcycle oil, for at least one or two changes. I cannot personally vouch for it, but I had read some convincing reviews on this site for it.

Every Suzuki I have owned has always jumped the idle when running hot and hard. There probably is a fix for it but I can adjust my idle sitting at a light now. (Just remember to turn it back before starting cold again).
Good Luck 8)
Jim

[Dink]

the leak is probably more to do with a seal that sat and hardened for ten years than oil. It sounds like it is only the gearshift shaftseal, may not even be worth changing if two drops per day is all it is leaking.
The idle may be due to aged and cracked intake boots, try spraying a little starter fluid on them with the motor running and see if the idle changes, if it rises replace them.
Dink

[KEITH KRAUSE]

The "high idle" means you have intake leak(s). Most likely the o-rings in the manifolds. Sometimes it's the manifolds too.