My fzr250 chomps through oil like no other. The oil is leaking from my engine breather hose. And no where else. I’d say it uses 1 litre of oil every tank of fuel.. Sent from my iPhone using Tapatalk
Assuming there are no other leaks anywhere (it's an old bike, there probably are), it sounds like you have a bad case of blowby with a side of burning oil. If it were me, I'd be going for the cheap fix, which would be a set of rings/pistons from aliexpress, and genuine head/base gaskets. The o-rings on the underside of the cylinder block should also be checked. If any are broken then coolant will contaminate the oil. I got away with standard size rings, but my barrels were within the service limit. If they are not, you should go to the next available oversize (48.25mm and then 48.5mm). But that costs money as you need to cylinders overbored. Your choice. https://www.aliexpress.com/item/4-S...FZR250RR-ZEAL-250-3LN-Piston/32735586164.html https://www.aliexpress.com/item/4-S...FZR250RR-ZEAL-250-3LN-Piston/32735408568.html https://www.aliexpress.com/item/AHL...YAMAHA-FZR250RR-ZEAL-250-3LN/32834276446.html
No leaks anywhere at all. So seems like I need a slight rebuild then. Cheer man Sent from my iPhone using Tapatalk
That's a lot of blow by, so when are you pulling the top end for a rebuild ? Do the head at the same time, lap the valve's and replace the stem seal's
Does it start with 2L of oil in it? (or 2.2L with filter change) .... do u check the level also via the sight glass?
Could try running a thicker oil and one of these http://yahoo.aleado.com/lot?auctionID=s598407108 just to try and vent the crankcase pressure a bit better to stop the oil being forced out but ultimately it'll need new rings like everyone else has said
I wonder if it just has sticky ring's ? It might be worth trying some Threebond Super Engine Conditioner in it? Pull the plug's out, then spray some into each cylinder and let it sit for a while, it'll seep down into the ring's and help loosen any carbon/oil buildup. You then refit the spark plug's and run it till the smoke stop's coming out the exhaust. It's sold at Repco for around $14 a tin (it's kept behind the counter so you'll have to ask for it)
Mine really pi$$ed the oil out when the dealer couldn't see through the site glass and added a litre of oil. I dropped the sump and cleaned it out but had to make my own gasket (1mm alloy cut out with shears and a scroll saw).
Did that fix it? I just dumped out 600mL of oil and the bike runs perfectly, but it still has a lot of oil blow-by. The sump gasket was brand new (genuine Yamaha) so I don't want to cough up another $100 or so just to clean the glass.
if it is blowing out the breather then the sump is being pressurised. do a compression test but better still would be a leakdown test.if below limits no choice but an engine rebuild.what oil grade are you running? a bodge temporary remedy is to use thicker oil as cheap car yards used to do[ maybe still].i have smelt some flogit cars and they had diff oil in the engine.either way if you want to keep the bike it has an indication of rings and valve stem seals at minimum.
Aren't the sump gasket's cheap, around $12 ? 3YX-13414-00 Should be able to reuse it if it's only new too.
Yes it does not leak any oil now(even when running 14sec quarters). I made the gasket as the originals are not available in the UK. A sheet of thin alloy didn't cost a lot and only took a few hours to do.
They are ex Japan or ex Australia https://www.ebay.co.uk/itm/Yamaha-F...h=item239e7f090e:g:FdMAAOSw9Txa0Y8V:rk:2:pf:0
I actually bought an engine to swap mine with and it turned out that the engine I bought had some oil stuck in the galleys that didn't come out until I heated up the engine. There was almost twice the amount of oil in there to begin with - that was causing the oil to come out. I don't remember how much I paid but it was off someone on eBay. The glass wasn't actually dirty, it was just that the oil level went above the glass and the old oil was very dirty. It came clear when I flushed the engine out. I bought a sheet of gasket paper online but decided against it since the gasket my bike originally had was made from gasket sheet and it was leaking quite bad. I have heard of a place or two that can make up a good gasket if you take the old one in there - but of course they are local workshops.
You could try putting 25ml or so of a seafoam substitute down the plug hole of each cylinder on compression stroke, reinstall the spark plug and turn the flywheel back and forth to coax it down past the rings Check here of the full explanation of what seafoam is and the DIY recipes http://hildstrom.com/projects/seafoam/ I've mixed it up with both kerosene and diesel as the light oil component, in Aus. Shellite from the hardware is petroleum distillate naptha, I've not searched for camping stove fuel and isopropyl alcohol without the water component or fragrance is available from the hardware - the only ridiculously priced component of the lot. When I'm doing an oil change on the car or bike (when I have one which runs) & time permits I'll put a few hundred mls - 5-10% of total oil volume in and let the engine idle for 10-20 minutes. Using it by hand, the mixture is great at cleaning gunk and built up carbon/gum which is why it might successfully release stuck rings and not strip away all lubrication in the process peace out
