petrol/oil mix

[huntn1]

hi all i have now finished my 1991 cr500 complete rebuild,and am ready to start it,how much oil [ml] do you guys put in per [litre] of petrol, in my 1991 cr250 i put 125ml to 5 litres of petrol,i have also been told to use super unleaded [97 ron] many thanks any tips on starting it would be nice to

[redrocket190]

Pick a ratio and religiously stick to it. I use 32:1. Mix consistently using a Ratio Rite jug or similar. Pre-mix ratio does not have as much impact on jetting as folk lore suggests. But if you take someone else's jetting tips it makes sense to use the same pre-mix ratio. Putting less oil in the pre-mix will not affect the spooge factor at the exhaust junction. That is a product of how hot the engine gets which is in turn a product of jetting and how hard you are riding. Buy a "known" brand of oil but don't sweat Maxima v Bel-Ray v Yamalube etc. Vintage guys love castor, but I would recommend synthetic. You don't need exotic gas for the CR500R unless you have changed the compression ratio.

Cold - prime with two or three slow kicks. Ease the kick starter past the first resistance. Let it come back up to top. Give it a nice big all the way through kick. It will start 1st or 2nd time. If it won't start you have an ignition setup problem not a kicking problem.

[AlisoBob]

I run Maxima 927 @ 44:1

If I didnt, I'd run Yamalube.

I've seen photos of motors running Yamalube torn down.

Its good stuff.

[huntn1]

thanks redrocket190 when you say 32,1 is that 32ml of oil to 1 litre or petrol,

[DitchWitch]

No, its 32L of petrol to 1L of oil.... wow are you sure you are ready for a cr500? Just remember to hold on, you'll be right...

[thestuz]

32ML TO 1LTR IS CORRECT.

make sure if you have a pj carb to make sure the idle screw cap is at least 8 full turns anti clockwise maybe 9 1/2 from the bottom.(when i first built mine i spent countless kicks wondering why it kept stalling and not idling doh!)
this will make sure you got enough to get her idling.
some people also lean the bike over wher cold with the fuel on then stand it back up. this puts a little fuel in the carb and can assist in starting.

i hope youve recessed the bridge, and make sure you break it in over a few rides. good luck

[redrocket190]

thanks redrocket190 when you say 32,1 is that 32ml of oil to 1 litre or petrol,

32 parts gas to 1 part oil, but of course that's no use to you and I sense you are in metric land too. Go get a pre-marked jug from your cycle dealer and never worry about it again. I simply fill my jug to the mark for 16:1 for 2.5 US gals and then when I pour that oil into 5 gals of gas the end ratio is 32:1.

[nmdesertrider]

Never bothered with those stupid measuring things, 1/2 a quart in 5 gallons and I am good to go.

[britincali]

That stupid $5 measuring thingy is the best $5 Ive ever spent on a uni-tasker

[huntn1]

please dont think im being thick,ive just spent alot of time and money doing this bike and realy dont want to mess it up over confusion thanks for all your input ,i have other twostroke bikes but my nsr250r2j [mc18] is autolube,and all my cr250s i run on 25ml per litre of petrol,this is my first cr500, and i dont know another person any were in england who i can ask,these bikes pop up on ebay now and then but are getting extreammly rear hear,

[KE 336]

Never bothered with those stupid measuring things, 1/2 a quart in 5 gallons and I am good to go.

X 2 I get my oil by the gallon and keep a quart bottle to measure with.
fill the quart bottle to the 16oz line and dump into 5 gallons of gas. Plus when I'm done you just put the cap back on the bottle and it is ready for next time without have a cup to wipe out and keep clean.

[redrocket190]

please dont think im being thick,ive just spent alot of time and money doing this bike and realy dont want to mess it up over confusion thanks for all your input ,i have other twostroke bikes but my nsr250r2j [mc18] is autolube,and all my cr250s i run on 25ml per litre of petrol,this is my first cr500, and i dont know another person any were in england who i can ask,these bikes pop up on ebay now and then but are getting extreammly rear hear,

http://www.maximausa.com/technical/oilratio.html
25ml of oil : 1000ml (1 lite) is 40:1. This is just fine for your CR500R and it means you can have one supply of pre-mix for more than one bike.

http://www.maximausa.com/technical/oilmigration.html
The bottom line of this article is that smaller engines and engines used more aggressively (i.e. road racing v off-road) need more oil. 32:1 to 40:1 is fine for a 250 and a 500 could probably get away with less.

Anyway I checked my jug and actually I use 20:1 on the jug which gives 40:1 in twice as much fuel. I use the same ratio in every bike from a 1979 CR250R to the modern CR500R.

[AlisoBob]

The bottom line of this article is that smaller engines and engines used more aggressively (i.e. road racing v off-road) need more oil. 32:1 to 40:1 is fine for a 250 and a 500 could probably get away with less.

Remember too that the oil is suspended in the fuel.

A bike that burns 1 gallon of fuel per hour mixed at 20:1 ( a CR250 for example) , and a bike that burns 2 gallons of fuel per hour mixed at 40:1 ( A CR500 for example) both have the same oil consumption rate.

[nmdesertrider]

A big slug of oil gets stuck to the crank and the walls around the crank- faster rev riding and faster revving bikes like a 125 are going to atomize more of the oil sending it out the exhaust.

If you use a good quality clean burning oil a lower ratio isn't going to gum up your 500.

[crf69]

amsoil dominator 32:1.....cant go wrong!!!!