Fuel type and mixture.

[TommyD]

Hi there - sorry it this seems a draft question, but I've just got myself a CR250 and would appreciate some advice on suitable petrol type and the oil/fuel ratio to use, as I haven't a clue.

Cheers :ride:

[Trakxntrials]

Hi Tommy D, welcome to KB - I can't help you there, but if no-one else helps you through the day - check back here tonight and I will ask Terry for you - he will know. Where did you get your bike from - could they tell you what they used in it? If not, check here tonight, I will have some info for you. All the best :)

[cowpoos]

ring your local honda dealership...they will happily tell you what you need to know.

are you new to motor bikes??? or just 2 strokes???

[Cary]

Hi there - sorry it this seems a draft question, but I've just got myself a CR250 and would appreciate some advice on suitable petrol type and the oil/fuel ratio to use, as I haven't a clue.

Cheers :ride:

Been a while since i've owned a 2 stroke (KX250) but here goes;

Use 98 if you can get it mix at 33:1.

For some good advice try private message to XTC, knows his stuff and would not mind giving the advice (I hope :))

But 33:1 is the general mix & use a good quality 2 stroke oil.

Hope this helps, it's not a silly Q we've all got to start somewhere.

[Brian d marge]

I have a cr 250 91 ..
Yes It runs quite happily on the cheap Sh$%&'

I use 40 to one reasonable quality oil

pilot jet #55

needle # 1369 in the 3rd position

main # 175

This is a good starting point for a 91 cr .... If yo tell me the year I could be more of a help

Stephen

[WRT]

I got an '01, I normally run race fuel (or 98 if race n/a) at 40 to one with Motul oil (the one that smells like strawberries . . . . mmm). I'm no expert tho, I just go off what the guys I go riding with run . . . this is my first two stroke too.

No probs so far tho . . . after several months of regular and prolonged use.

HTH

[Flyingpony]

Excuse me, but aren't all 2-stroke bikes self mixing?
Why are you worried about oil|petrol ratio's?

Just ensure the right grade of petrol in the fuel tank and good quality 2-stroke oil in the other tank. Being self-mixing, the bike does the rest for you.

Well at least that's how it's worked on all the various Suzuki 2-strokes dating from the 70's right through to the 90's I've encountered. Surely it's standard on other brands too.

[Ixion]

Excuse me, but aren't all 2-stroke bikes self mixing?
I've encountered various Suzuki 2-strokes dating from the 70's right through to the 90's, and all were self mixing.
Why are you worried about oil|petrol ratio's? Just ensure the right grade of petrol in the fuel tank and good quality 2-stroke oil in the other tank. Bike does the rest for you.

Older 2 smokers, and some modern racing/competition ones use petroil.Dunno about the CR250. But competition riders sometimes remove the oil feed system even if it has one, to save weight and the power needed to drive the pump

[Wellyman]

Run Race fuel or 98 and use Motul 2 smoke oil. Motul is the best brand I recommend

[Brian d marge]

Older 2 smokers, and some modern racing/competition ones use petroil.Dunno about the CR250. But competition riders sometimes remove the oil feed system even if it has one, to save weight and the power needed to drive the pump

The Cr range ,,use petroil ..and you can chan the mixture strength by varying the oil ..ie richer leaner , by adding subtracting oil ...,,Also you would be suprised how much wieght you notice ,,,A full tank feels like a ton of lead bricks ,,,I usually mix only what is Neccessary ,,,ie for changes in suspension ...I mix a litre ,,,that gives me enough time to think about the changes I have made ...

On a lighter note ,,I use the cheap crap fuel syphoned out of me truck,,,have been doing that for a a year or so now ,,,and after many enduro , MX ,,and this will be coming up to the second rebuild this year ,,Last check the ring pegs showed signs of moving ,,so the piston is up for it soon ,,,I will screw this engine into the ground over the summer and rebuild both spare and Race engine ,,,end of october ...
Anyway there were NO signs of detonation ,,,,,,surely the gas in NZ cant be that bad???

What the race fuel in NZ like ...highly oxygenated?? or 98 with a ton of additive ...Snake oil ??

curious ...( thinks ,,,Hmm crusty demons ,,,,or Pahorrrrn:nono: nnn or an google search for fuel......\(^0^)/

Stephen

[Oscar]

Modern synthetic two stroke oils should be run at the recommended ratio (which is usually 40 or 50 to 1). Ever wondered what that brown crap you scrape off the top of the piston is?

I also don't see what difference octane rating is gonna make to a two stroke. As far as I can see any rating over 90 is gonna suffice...Motu? Any opinions?

[Ixion]

Modern synthetic two stroke oils should be run at the recommended ratio (which is usually 40 or 50 to 1). Ever wondered what that brown crap you scrape off the top of the piston is?

I also don't see what difference octane rating is gonna make to a two stroke. As far as I can see any rating over 90 is gonna suffice...Motu? Any opinions?

I'd reckon to agree. Two stroke, can't get the effective compression ratio high enough for octane to be an issue. (Flame propagation time could be another matter on a racer)

[Motu]

2 strokes always used regular,I don't think modern ones are any higher in compression.My DT pings bad when cold,and runs crap on cruise - but I even tried aviation fuel with no change,octane rating doesn't seem an issue.I'd go as Oscar says,40 to 50:1 with a good synthetic,or semi - Silkolene and someothers do a castor blend,doesn't gum power valves and smells like heaven.

[TommyD]

Cheers to all for the advice on the fuel/oil mixture. Spoke to a bike shop and they recommended 91 with a 40:1 ratio for a CR250 2001. All seemed sweet at my first outing at Woodhill. I had a blast! :ride:

[Oscar]

A handy dandy old tip:

On wet rides, add a half a cup of meths to your 20l fuel container. It will combine with any moisture and stop it hanging about where it shouldn't...

[WRT]

Interesting to hear all the tips, I might try running 91 for a bit, see if there is any difference (other than it being a heap cheaper!). Have also run the bike on 50:1 from time to time, without any probs as yet, from what I'm reading here, then I might switch to that full time. Have noticed when running 40:1 I have a little wift of smoke while running, where as with 50:1 I get a small amount of smoke while warming up, and then once hot no smoke. Does this sound normal?

And just as a point of interest, would the different octanes have any effect on running temp?

BTW - TommyD - congrats on your first ride, good to hear you had a blast. Perhaps sing out next time you are heading up to woodhill, I am up there most weekends, can catch up for a ride if you are keen? Or anyone else for that matter . . .

[spiller]

Wow, its interesting to see what people run in their bikes.

I have a 01 cr125, and use ELF HTX 2 stroke oil @ 30:1 with av gas.

I've had bad experiences with Motul 2 stoke oil, but some swear by it.

Woodhill is great, maybe Ill see ya out there!~

[TommyD]

Hey - WRT. Would be good to hook up for a ride sometime as I don't know the tracks at the moment and it would be good to ride with someone with some knowledge (and the same bike). I'll give you a shout when I'm next heading up there. Cheers

[WRT]

TommyD - sweet as, sounds good - same applies for anyone else in the area. Maybe we should all be posting in KB or PM'ing each other when heading out that way? Only thing is I only tend to check this from work . . . not on the weekends.

Also, at the moment, I'm out of action, need new rear axle dust seals (the old ones didnt survive getting removed while checking the wheel bearings . . . ) which I have on order thru Botany Honda - but they are two weeks away.

Gutted . . .

[Cary]

Excuse me, but aren't all 2-stroke bikes self mixing?
Why are you worried about oil|petrol ratio's?

Just ensure the right grade of petrol in the fuel tank and good quality 2-stroke oil in the other tank. Being self-mixing, the bike does the rest for you.

Dead wrong there :no: sure most Road going 2 strokes run an oil tank but off road MX/enduro bikes don't have one. Run straight petrol in one of them it i'll seize in about a km.

This is done so oil/petrol mix can be changed/tuned for performance.

[Stevo]

Dead wrong there :no: sure most Road going 2 strokes run an oil tank but off road MX/enduro bikes don't have one. Run straight petrol in one of them it i'll seize in about a km.

This is done so oil/petrol mix can be changed/tuned for performance.
Two reasons this is done.
a) to save weight
b) because a lot of oilers aren't able to change as well as the fuel rate. ie will under oil at high revs and over oil at low revs and also response time lags a little from what I understand. Hence why race bikes are best on pre mix

[Motu]

With a race bike it's just one more thing to go wrong,they cut the chances of pump failure.On a street bike it's for convieniance,mixing at the pump if it took 6.37 litres is a bloody nightmare.My DT230 has a motor based on the YZ motor,but has an injection pump as it's a street legal bike.Suzuki and Kawasaki street bikes had oil feeds to mains,so it was not a good idea to go pre mix,but Yamaha have only ever used an oil feed into the intake port,changing them to pre mix was easy.In the good old days you could buy pre mix at the pump - BP ZOOM.

[tonyg26]

25mls of castrol 2 stroke racing oil (blue stuff) to 1litre of 98 octane, cant wrong!

[flyingcr250]

Cheers to all for the advice on the fuel/oil mixture. Spoke to a bike shop and they recommended 91 with a 40:1 ratio for a CR250 2001. All seemed sweet at my first outing at Woodhill. I had a blast! :ride:

boyds in hamilton told me to run my 2001 CR250 on 35:1 98 octane. i use that CASTROL TTS 2T oil.

[B0000M]

Modern synthetic two stroke oils should be run at the recommended ratio (which is usually 40 or 50 to 1). Ever wondered what that brown crap you scrape off the top of the piston is?

I also don't see what difference octane rating is gonna make to a two stroke. As far as I can see any rating over 90 is gonna suffice...Motu? Any opinions?

funny the posts posted here in 2005 like this one is one id argue, 95 or lower and my cr will eat a piston.

other funny things like "dont all bikes have auto mixing"

something cool i just thought of though that would be awesome would be if they had a button you press on the pump at the gas station that added the correct amount of oil to your fuel. (and it was a decent oil)

[flyingcr250]

funny the posts posted here in 2005 like this one is one id argue, 95 or lower and my cr will eat a piston.

other funny things like "dont all bikes have auto mixing"

something cool i just thought of though that would be awesome would be if they had a button you press on the pump at the gas station that added the correct amount of oil to your fuel. (and it was a decent oil)

i think in auzzie they have pumps like that.