pre mix

[shane2011]

ive have a 350lc and i am going to pre mix what is the best mix? and what is the best oil to use?

[lcowner]

this is a real can of worms! 33-1 ratio is what i use

[lcrider]

6 FL oZ to a 4.5 L i was told for a road bike and 7 for a race bike .

[higgsy]

I run my race YPVS/LC on 33-1 using Gulf fully synthetic. Whan I ran my 400 on the road it was on 25-1 (made it easy to measure fo a tank full) on Silkolene comp2/Putolene semi synthetic - no apparent wear after 10,000 odd miles.

So if your planning on using a fully synthetic, then 30-1 is probably a good compromise, you should really be using an oil designed to be pre-mixed btw, not all are

Best oil? Now that is a real can of worms!!!

[arrow]

Feb 14, 2012 19:23:33 GMT 1 lcrider said:

6 FL oZ to a 4.5 L i was told for a road bike and 7 for a race bike .

For anyone wondering that works out to 25.36:1
or 21.74:1 for a race bike.

[barbarossa]

Glad to see someone else is going down the pre-mix road.
My RZ250RR - see many old posts on this subject - now runs premix @32-1. My oil pump cable snapped which buggered an engine which had recently been rebuilt - meaning another expensive rebuild.
Never again.
I KNOW Yamaha spent squillions developing oil pumps.
I KNOW a properly adjusted pump theoretically delivers the correct amount of oil over a wide range of engine revs.
I also know that if the oil pump cable snaps, it costs a few hundred quid to rebuild the engine.
And I also know that when I put oil with the petrol, I KNOW the oil is getting to the engine.
Don't forget to go up one size on your main jet.

[bare]

I run Both :-) Pump and premix.
a) to get the mix up to 24:1
b) as insurance.
Also doing this means I only have to carry a smallish amount of premix oil.

[arrow]

Feb 15, 2012 20:36:33 GMT 1 bare said:

I run Both :-) Pump and premix.
a) to get the mix up to 24:1
b) as insurance.
Also doing this means I only have to carry a smallish amount of premix oil.

Can I ask what ratio you are pre-mixing to then ?

[midlifecrisisrd]

Feb 15, 2012 20:36:33 GMT 1 bare said:

I run Both :-) Pump and premix.
a) to get the mix up to 24:1
b) as insurance.
Also doing this means I only have to carry a smallish amount of premix oil.

Exactly what I am doing now for similar reasons as well as stopping the tank rusting.

Steve

[shane2011]

Thanks a lot for all the info very helpful!!

[ianboom]

Another different answer, 40:1 on rock oil fully synth-never needed to upjet for the premix!!

[twostroker]

ive previously used 40:1 in a few bikes with no problems.

[LC'Adam]

40:1 I would say is plenty if your using a good oil (castor/ester is the best) any more and it won't get completely burned and foul up your plugs on cold starts and clog everything up. Always used 40:1 on all my bikes and never had a seizure............. yet lol

[shane2011]

looks like 40:1 mix is the top answer thanks all for the help!!

[47x]

yep,i would say 40-1 is the best way to go.at the end of the day at least u know your motor is getting oil!!!!

[arrow]

Feb 17, 2012 11:30:50 GMT 1 shane2011 said:

looks like 40:1 mix is the top answer thanks all for the help!!

I know modern oils are better and the people that have posted here had no problems. But for what its worth a 350 lc with an oil pump and running at full throttle will be shifting a lot more oil through the motor than the equivalent of 40:1. At full bore it is around 20:1. Bare runs 24:1 and I'm sure he's not changing plugs all the time.
I know you won't be on full bore all the time, but sometimes you will.

[higgsy]

Have to agree, I've never had cold start problems or plug fouling, even on Champion N80 race plugs, the LC/YPVS starts first time no matter what the weather, I'd be wanting a bit more oil in there myself than 40-1. Just my opinion of course.

No wear on the bores of the LC on 33-1 and that's at full bore a lot of the time :-)

Was thinking of going down to 25-1 for the reason Arrow pointed out, we'll do some testing and see how it burns.

[arrow]

The trouble with pre-mix is its only correct for a small part of the rev range. You can set it up for full bore use and not worry too much about a bit more smoke when your pottering about. Much better than going the other way and under oiling the motor at high speed.
Different thing but, I have heard TZ 750's running 'R' on as rich as 12:1 (they don't spend much time pottering about)

[shane2011]

thanks arrow for all the advice

[rich]

All I can say is that a mate of mine tried running his 31K on the road at 20:1 and it was far too much oil. The ends of the silencers were dripping with the stuff and you and the bike ended up splattered if you rode behind him. I guess the answer would be how do you ride? If you ride sensibly most of the time with the odd blat then 40:1 is probably ok (this is what I have run for years but like Martin I have found some minor scoring on my pistons) but if you ride hard then 33:1 might be better?

[higgsy]

One of the downsides of premixing as pointed out is the same amount of oil is going in no matter what the throttle position, if you do a lot of town work or tend to potter around, I think 40-1 would be about right, but if you hold it open for a length of time then I'd be wanting more oil. Like you say it depends on how much you thrash it :-)

[arrow]

If I was running pre-mix myself I would go for 30:1 and a top of the range full synthetic oil.

[rdstars]

How many jet sizes do you need to go up going from pump to pre mix?

[Norbo]

1 size for pre mix