Topic: Back pressure and oil usage

[trueblue]

On my 650 I have recently replaced my original 4-2 headers with crappy aftermarket slip on mufflers with a new Motad 4-1 exhaust.  There were a few things I noticed straight away after I fitted the new exhaust;

1-it is a lot quieter
2-it has more power
3-the front end got a lot lighter ie. it now likes to pick up the front wheel a lot more than it used to.(ref point 2)
4-the clutch has now decided to start slipping a little (ref point 2)
5-It pulls a lot harder above 140kph, before it used to pull like a tractor until it hit 140 then it felt like it was getting strangled, it would still climb till I backed off at just over 160kph, but felt strangled. (ref point 2)
6-One last thing I wasn't expecting, it seems to have stopped using oil.

It used to drop about 1/4" on the dipstick every 300km, I was never overly worried about this, I just kept it topped up.  Since fitting the exhaust I have done about 500km, I topped up the oil about 100km after fitting the exhaust.  I checked it as usual after 300km and it hadn't dropped, I checked it again today and it still hasn't dropped.  How can this happen?  The only theory I have come up with is the old mufflers had too much back pressure (they were quite restrictive) and this caused an overly rich mixture at higher revs, which caused it to burn oil.  The plugs were aways dark but I just put that down to the fact it was burning oil.  Anyway, I'm rambling.  What I'm asking is, does anyone have another theory as to why it would all of a sudden stop using oil, or can verify my theory.

[lrutt]

I'd say your old pipes were not too restrictive, I'd guess less so causing a lean top end condition. The new pipes rectified that. That only addresses your power and performance. Can't say why on the oil other than you were likely twisting the grip harder which might contribute. not sure.

[trueblue]

The old pipes were definately more restrictive, the mufflers I had are now destined for my 200 twin, and I think they will be about right for it.  The hole in the end of the new system is about twice the size of what was in the end of the old mufflers, this equates to about double the area in the single pipe as there was combined in the twin mufflers. 

[dave500]

you might have been exploring the higher rev range now?you can use less oil at higher rpm as the vacuum is lower,less gets pulled through the guides,when you tootle around or sit on the limit with out fanging oil can pass the rings easier aswell,i think its an rpm thing?id see how it goes over a month?

[trueblue]

Thats definately another option Dave.  I know I'm using the 6k plus range more, it gets there so easy now.