Castrol TTS

[dadof2]

An updated version of Bell's book was published in 1999 but as you say both these books tend to concentrate on harder running engines. Having said that I've witnessed some pretty hard run 125 trials bikes.

The worst thing that can happen with too much oil is plug fouling but at 24:1 with correct jetting this in my experience does not happen.

At 24:1 with good quality mineral oil (shell 2T or castrol TT) an air cooled trial engine will be virtually unworn after several (6 or 8) seasons use.

At 40:1 with Putoline MX 5 (again a good quality oil) an air cooled trials engine will need reboring after about 2 seasons.

My experience on MX engines suggests that going from 24:1 to 40:1 approximately doubles the rate of bore / piston wear on cast iron linered engines and increases the rate of piston wear on plated cylinder engines.

Switching from semi synthetic at 40:1 to mineral oil at 24:1 noticeably reduces running temperatures on plated bore watercooled trials engines.

Perhaps the most likely drawback of a lean ratio say 40:1 and over is its inability to resist water penetration if you are unlucky enough to get water droplts in your engine.

Cheers

[sting32]

An updated version of Bell's book was published in 1999 but as you say both these books tend to concentrate on harder running engines. Having said that I've witnessed some pretty hard run 125 trials bikes.

The worst thing that can happen with too much oil is plug fouling but at 24:1 with correct jetting this in my experience does not happen.

At 24:1 with good quality mineral oil (shell 2T or castrol TT) an air cooled trial engine will be virtually unworn after several (6 or 8) seasons use.

At 40:1 with Putoline MX 5 (again a good quality oil) an air cooled trials engine will need reboring after about 2 seasons.

My experience on MX engines suggests that going from 24:1 to 40:1 approximately doubles the rate of bore / piston wear on cast iron linered engines and increases the rate of piston wear on plated cylinder engines.

Switching from semi synthetic at 40:1 to mineral oil at 24:1 noticeably reduces running temperatures on plated bore watercooled trials engines.

Perhaps the most likely drawback of a lean ratio say 40:1 and over is its inability to resist water penetration if you are unlucky enough to get water droplts in your engine.

Cheers

The problem is, that you are unable to see that the that the sresses that "oil" is set to protect in the engine are so extremely different in trials bikes and uses/demands of the oil in them are so different, than any other application. like chainsaw, MX, Enduro, lawnmower etc... Like Jon was saying, different stresses. our trials bikes tend to run at idle 80-90% of the time we're using them, in competition or practicing of TRIALS.

No other piece of 2 stroke powered equipment I own, is used in this manner like a trials bike in trials. Think about it, My weed trimmer/chaisaw is running full blast, when triming, just like race bikes. WHY they need more oil? helps with friction buildup by sheer volume, much like High Volume oilpumps are used in racing engines to keep a coating of oil in place, as best that can be attained, when the parts are centrifugally trying to fling the oil off the parts to be protected, so you put more oil hoping some of it stays in place, so yeah, racing engines it gets oil at recommended lower ratios.

In a trials bike, At idle, the gas oil mixture isn't but hardly drawn into the crankshaft area where it lubes the cylinder & crank bearings. then on next stroke it is pulled on into the cylinder side and lubes again, plus it burns a little bit. with trials, the oil and gas actually has a tendancy to build up in the crankcase area, because we're idleing so much. Too much oil stored up makes a trials bike run like crap when you need some rpm. plus the rest is pumped out the exhaust (smoke). so you will see our better_more engine demanding riders having to do "clean-out" throttle reving routines more often, on their bikes, to get that hard on the throttle jump to an obstacle, clean running engine pull.

What is nice is the storing of the oil in the crankcase area that happens, usually ensures that if I need a full throttle blast at something, there is more oil in the crancase, usually than would be if I ran full throttle all day long like a MX bike does, with its richer oil premix. But this condition is temporary when revving!

I would venture to bet, on the part about "wear" that: With NO oil in the gas, that a trials bike engine will operate for at minimum, 6x the amount of time, at such duty cycles they are prone to run at, vs the MX bike or other appication engine. So really what I am saying is, the wearing of the piston/cylinder is already soooo much less in trials, the difference of a percent of a very small percent of wear, would seem to be almost negligible. especially compared to the loss of performance with "over oiling" your gas.

My opinion of why oils for 2 strokes state "good up to 50:1" is the target audience. It is because 95% of the engines that use the oil need richer oil mixtures. I mean, who writes on twinkies that there is only 0 calories & Zero fat, if you'd just spit out the twinkie instead of swallowing? Who out of millions does this, and why write that? LOL.

Does "do not operate blow dryer in the shower" ring a bell?

[copemech]

There are a number of aspects to this equasion it seems, yet it does seem to be proven time over that the 80:1 ratio of high quality synthetic seems sufficient in the trials environment.

Lest one forget the effects of the deposits! Seems to me that excess oils in the exhaust do nothing but clog things, and seems to me the mineral oils seem to create a HARD burnt carbon that is something next to immovable! As by comparison, the synthetics seem to have more of a resistance to this type coking of the exhaust and seem to maintain a bit of flow under some heat and minimize restrictions of the baffling and such.

The less you can run, of better quality, the better off you will be, not to mention the emissions! I feel fully capable of running 100:1 on good oil, have done it many times! The 80:1 is just the insurance.

[dadof2]

I am well aware of the different stress levels in different engines having run karts, MX, grasstrack, and trials at various times over the last 40 years. Modern mineral oils are nothing like the mineral oils of old, they burn much cleaner and contain much less ash and suphur.

Go to any trial from world to club level and you will see riders giving the engine a good rev at times to clean it out even when they are on lean oil mixes. As I said in an earlier post " sure with modern oils and engine materials you are unlikely to seize even at 80:1" so I accept synthetic oils do work at lean mixes and if riders are happy to use them fine. Richer oil mixes do produce more smoke and exhaust deposits. A rich mix improves cylinder to bore sealing, heat transfer and compression and reduces blow by which contaminates fresh mixture in the crank case. However it is my belief that taking all factors into account, wear, performance, oil costs etc then 32:1 and richer offers the best compromise. The most significant factor in a good running responsive engine is jetting, slide cutaway and ignition timing, not oil mix ratio.

Cheers

[mexmex]

I would never go leaner than 32:1, sure with modern oils and engine materials you are unlikely to seize even at 80:1 but less oil means more wear. A good film of oil between piston and barrel is very important to conduct heat out of the piston to control piston crown temperatures.

Cheers

Actually, "lean" and "rich" applying to jetting and not for oil ratio.

And when you run more oil in your pre-mix, you actually make the gas denser which will couse leaner condition in your jetting, hence you will have to compensate with bigger jets or the motor can seize in extreme hot condition.

Sound weird but true.

[trialsmotopat]

from a more synical (sp?) point of view - the more oil you use the more product you will have to buy, and the safer you will feel about your engine wear.

as far as I'm aware, and that's not a lot, if most of us are using 70:1 or thereabouts and motors are not holing pistons or need the kind of attention a race bike engine needs then that's gotta be ok?

[dgshannon]

After gaining the input of two folks I respect, (one a National rider, and the other a trials bike shop owner, and mechanic) I decided to take their advice, and go with the Castrol TTS. Despite the 50:1 statement, from Castrol, it seems it comes highly recommended, for the 80:1 trials crowd.

Interestingly, if you look at the Castrol marketing, one of their claims to fame is how much longer an engine will run before seizure, at 1000:1 ratio, with the TTS, than with other major oil brands. So, as stated earlier in the post, the 50:1 is likely just a CYA statement, for the high reving, high performance, crowd.

[neo]

Despite the 50:1 statement, from Castrol, it seems it comes highly recommended, for the 80:1 trials crowd.

And thats whats I've been running for donkeys years

This Thread has been great reading gents but I have to admit that I've never once bothered to read the label on a Castrol TTS bottle .... far too busy pouring it

Best of Xmas balance.

Neo