My bike has been consuming oil for some time now. Its been getting excessive enough to where I need to fix it. Its an M900 with 33000 miles. The previous owner had a set of Feracci pistons installed along with stage 2 jets. It runs flawlessly. I need to do a compression check on it still. I have heard of valve guides being replaced in other posts and was curious if this was a common problem. One of my concerns is the rings may have not seated correctly or something of that nature. Any ideas?
Thanks, Jon
Pull the intake manifolds and exhaust, and look at the back sides of the valves, that will give you some clues as far as how well the valve stem seals are doing.
Do a leakdown test, that'll tell you how the rings are doing.
Okay gotcha. Thanks for the input. Is this a common problem with higher mileage bikes? I have a machine shop that is great with older aircooled Porsche heads, wonder if he could install valve guides into these heads if it comes down to that.
Dunno if it's a common problem, but I've heard a few folks here talk about it.
I suspect your Porsche head guy could do 'em, not a lot of difference.
(Imagine, you know a Porsche guy. ;D)
If you need new guides, I recommend the kibble-white brand. They are supposed to last longer and run tighter. They were also cheaper than OEM.
Had the Ducshop do mine [thumbsup]
http://www.blackdiamondvalves.com/ (http://www.blackdiamondvalves.com/)
Usually the horizontal guide is the big offender. Move the opening rocker over and wiggle. Ducati allows .08mm before replacing. You may be lucky and just need guide seals. Check the crankcase breather too.
What should I be looking for with the breather? There is no oil getting back to the airbox but there is a very little bit of residue around the breather itself.
The breather has a reed valve in it, if that's broken, it may be letting a lot of blowby into the airbox.
Though I would think that you would see a lot of oil in the airbox.
I was thinkig either cracked reed valve or clogged passage on the breather.
Oil consumption on higher mileage bikes is a known ish issue. A couple of reasons...
1. Valve guide oil seals - these are a bit cack when they have higher miles on them and will certainly explain high oil use - you'll probably also see some oil smoke from the exhaust too. You can change these without removing the heads but make sure the piston is at TDC when you do as you have to remove the collets and dropping the valve with a piston at BDC is a pain...
2. Knackered Oil Scraper Rings - my 900 showed good compression but burned oil (about a litre in 1000 miles!). When I lifted the barrels off, the original honing marks were present but the bores were glazed (sorted with scotchbrite) but the real reason was the oil scraper ring was toast, virtually no scraper edge left.
Combine 1 and 2 on a higher mileage motor and that'll account for the oil burning. Sorting both on my 900 dropped the oil comsumption by about 97%!
Also worth checking you're not loosing any - a knackered output shaft seal would loose a little (and keep the chain nicely lubed!).
Hope this helps