2t oils

[zman]

gday all im in the proceed of rebuilding my 82rm250 motor i run bel ray HR1 at 40-1 but thinking of changing to 25 or30-1 after reading shortshift post on 2t oils last year.is this oil ok to run at 25-1 and would i have to re jet a bit leaner. i also read on that tread that castrol tts  is a good filming oil (if i can put it that way) i dont know what oil it was running on before ibought the bike or its last rebuild

i am happy with the HR1 and the piston was clean but did notice not a lot of oil on the skirt . like you say more oil more hp better cooling and ring seal and reliable engine and thats what id like 

cheers

[evo550]

Zman,
Any of the good quality synthetic or castor based oils should run 40-1 no probs. Without knowing your riding ability, I would hazard a guess and say the RM will spend most of it's life @ 4000 to 5000 rpm for stints of about 15mins (average club moto time).
Not alot of hard work really.
I run my sons ktm 50 sx @ 50-1 on rc-30 (castrol castor oil) that bike lives at about 15000 rpm for hours at a time, and have never had an issue.
Re jetting would change your air/fuel ratio nothing to do with fuel/oil ratio, if you where to do any to suit the richer fuel/oil ratio, I would go richer on the jetting, as a richer oil/fuel ratio has the possibility to LEAN out your air/fuel mixture.
I can see the puzzled look on your face from here
Anyhow, well done you've managed to open an old oil debate, lets see how many pages we can get from this one.

[zman]

that was a great thread but to long most of it i will admit went over my head. and it seems most guys prefer the 25-1 or 32-1 mix and i suppose it makes sense the  more oil in there the better

[LWC82PE]

i would go with what ratio suzuki recommends for that model.

[Rossvickicampbell]

I had one - I thought it was the old stock standard 20:1?

Rossco

[CamP]

I've been running 24:1 w/ an injector compatible oil similar to CCI in my '82 RM250. These bikes like leaded fuel so I also use 100LL Avgas. I have gone down one size on the main and dropped the needle one clip position. The '82 RM250 works best when you rev it to the moon, so more oil and leaded fuel are a good thing.   

[southnztim]

Zman, if you are concerned as to what oil ratio you should use, go back to that epic on 2t oils. There is so much excellent info and reasons for in it. Worth persevering to read through it. Just ignore the, "I've used this ratio for X years, and it's never done me any harm" posts, and read the facts.
Seriously think about the factory 20:1
Cheers, Tim

[zman]

so how does going richer on fuel/oil ratio lean out the air/fuel ratio. does this mean you have to adjust the air screw or just leave it and go bigger on the main jet. and yes my minds made up 25-1 its gonna be and ill stick with the HR1 and see how it goes

[LWC82PE]

Just ignore the, "I've used this ratio for X years, and it's never done me any harm" posts

That’s the best comment ive heard in a while

Standard carby specs are jetted for 20 to 1

If you have adjusted the jetting to use Belray HIR at 40 to 1, then just revert back to standard jetting specs to use a different oil at 20 to 1 and then fine tune the jetting to suit the track, your riding style, temperature etc from those standard settings. If you havent changed the standard jetting specs from standard when you have been using 40 to 1 then going back to 20 to 1 shouldnt require much jetting changes at all.

As Lozza says, just get out there and do some plug chops. The plug will give you the answers.

I would recommend Belray Si-7 at 20 to 1 or similar synthetic or semi synthetic. Minerals are not all that bad either but its hard to convince people they can still be good to use these days. Theres no real need to spend big dollars on HIR and then mix it at 20 to 1 which it may not like anyway and you wll just be wasting extra money on oil.

Rule of thumb, use the ratio the manufacturer recommends and if its anything above 35 to 1 then i would serioulsy consider ingnoring the factory specs, re-jetting and comming down to 20/25 to 1. Usually though i reckon its safe to go with what the manufacturer says.

And as the others have said, go back and read through that big topic started by Shortshift as all the info is pretty much in there. The key is the oil viscosity, that will tell you what oil is ok to mix at what ratio. Before you go mixing HIR at 25 to 1, find out the viscosity of that oil, you may find it wont like being used at that ratio. Ask Shortshift as he will know the rating of that oil.

[zman]

thanks LWC82pe thats what i like to hear. and yes i was thinking HR1 will be costly running at that mix thats why i was thinking of changing to a cheaper oil  but hell there all around the same price range and theres only 1 bike shop that has it and im sure they dont have SI-7

so in shortshifts thread i was thinking of trying tts as it seems a good oil to run at 20\25-1.look ive always used HR1 and never looked at other oils thats why im not sure of which one to buy. whats the next best oil besides SI-7 at this mix

[lukeb1961]

Alex and Dale on the PE list are both oil experts with a bazillion years in the industry.
Alex said he recommends Motul 710, Bel-Ray Si7 or Castrol Power 1 TTS; at 20:1

see also: http://cid-407d7ef0965d3991.skydrive.live.com/browse.aspx/Racing%20Model
and read Alex on Oils.txt 
and if you really want to wade in, read Alex On Oils (DETAILED) !!

[evo550]

zman,
A fuel/oil ratio of say 25 to 1 is a "thicker" mixture than say 50 to 1 (has twice as much oil to the same amount of fuel) therefore less fuel can be drawn into the carb venturi through the jets, even though you are adding the same amount of air as the mixture is drawn into the engine. So a richer fuel/oil mixture has the possibility of leaning out the fuel/air mixture.

Leith,
You mentioned in your post to follow manufacturers recommendations, were you refering to the motorcycle or oil manufacturers?

[zman]

ok everyone thank you for all your help. you have given me great  information. it wasn't going back to 20-1 that worry'd me it was what other oil to use at that ratio but now i can go and  rebuild it and hope fully it will last for a few race seasons longer

[Lozza]

Alex and Dale on the PE list are both oil experts with a bazillion years in the industry.
Alex said he recommends Motul 710, Bel-Ray Si7 or Castrol Power 1 TTS; at 20:1

see also: http://cid-407d7ef0965d3991.skydrive.live.com/browse.aspx/Racing%20Model
and read Alex on Oils.txt 
and if you really want to wade in, read Alex On Oils (DETAILED) !!

The technical detail in the article was limited to viscosities at XX deg C etc etc no actual emperical evidence. The article's are light on tuning experience and tuning experience will tell you if the jetting and ignition timing are spot on and the engine ran in the rpm range where it's on pipe, all  smoke and internal deposits  disappear(except for some exhaust port and piston wash). Getting the carburation/ignition correct(I don't mean lining the stator/rotor/crankcase marks up) is NOT confined to race bikes.
A contact who worked on the TULARIS project used to have all kinds of snake oil saleman approaching them saying use this oil at XX ratio. After one idiot tried to sell them a 100:1 oil Dr Tulie replied "Don't you realise oil IS a fuel". Dr Rob is an Astrophysicist by trade and now heads Renault F1 engine development a job he didn't get by accident. 
HERE is a proper test performed under controled conditions with some conclusions at the end. Polybutene is what you should be looking for.

[lukeb1961]

Herr Stolk - what are YOU running in YOUR dirtbikes, pray tell? :-)