Seized engine - non permanent. Maybe cylinder glaze/varnish?

[feetupfun]

8 hours ago, bikerpet said:

Looks like it, but not. 100% confident that hasn't happened.

That sounds logical to me. Under that scenario the Putoline may not be a cause. It could be that given the quantity of oil in the exhaust when I got it, the rings stuck quite early due to excessive oil, then the Putoline goo was a consequence not a cause.

Or the Putoline could be crappy.

Or I just might need to go for a solid blast from time to time to keep things clean. That seems a bit odd - my riding spots are several km apart on hilly forestry road so it gets a reasonable run most days. But I just tootle along usually, maybe more speed required.

Sustained steep uphill does a great job. One of the places I ride has a decent hill with an incredibly steep concrete access road to a phone tower on top. The climb provides about 90 seconds of sustained load on the motor. Third gear on a trials bike.

I like the replies you got from the oil supplier. It's good to know that they know about trials bike issues.

[bikerpet]

26 minutes ago, lemur said:

" The oil mixing ratio needs to be adjusted slightly 130 ml 2-stroke oil on 13 liters of petrol is a mixing ratio that still functions well in practice. However, with a higher proportion of substantial taxation, this may be too little and this really depends on the degree of taxation."

They are confirming you should run 100:1 ratio same as your service manual says. ... for what it's worth I run my TRS 300RR at 100:1 like the manual calls for and it hasn't seized up yet with more hours then you have on yours.

That crap about higher taxation is to cover their butt, in the event of a failure they want it to be your failure.  Lots of producers have taken to not even suggesting an oil mix ratio on their packaging, so if in doubt buy one that states it can be run at 100:1 on their documentation or packaging.  That's what Amsoil says right on their plastic bottle "100:1 pre mix"

Yeah, I get that. I opted to go just slightly over 100:1 (93:1) because I regularly climb fairly steep hills several KM long climbing several hundred vertical feet (up to 1,000 vert feet). I figured it was safer to run slightly more oil than the 100:1 to allow for that non-typical trials use. Obviously I'm too gentle on the climbs (I often muck about doing trialsy things on the way up) to clean up the oil.

[bikerpet]

3 minutes ago, feetupfun said:

Sustained steep uphill does a great job. One of the places I ride has a decent hill with an incredibly steep concrete access road to a phone tower on top. The climb provides about 90 seconds of sustained load on the motor. Third gear on a trials bike.

I like the replies you got from the oil supplier. It's good to know that they know about trials bike issues.

I thought my hills would be enough - the exhaust is often smoking after a good climb, but I do tend to take it pretty easy most of the time and tend to back off if I see the exhaust start to smoke - I'm nervous of melting exhaust guards having done that on a couple of bikes now.

I was quite impressed that Putoline took the time to respond too. They definitely get a gold star from me for being responsive and not dismissive.

I'm reasonably happy that a change of oil and a bit more right wrist action should solve this problem in future - once I've gone back in and cleaned the piston & rings up fully.

[lemur]

It's not terrain that will cause your combustion chamber temperatures to be wrong or even engine revs, it's the actual fuel to air ratio.  More oxygen = hotter burning so if you run too lean in any range of operation you will see more heat, right up until there is not enough fuel mixed with air to ignite and then you will have fuel residue.

If the manual calls for 100:1 oil to fuel and you run 60:1 how much excess oil are you putting through your engine?   Something in the range of 40% more oil than the engine can burn.  

[bikerpet]

14 hours ago, lemur said:

It's not terrain that will cause your combustion chamber temperatures to be wrong or even engine revs, it's the actual fuel to air ratio.  More oxygen = hotter burning so if you run too lean in any range of operation you will see more heat, right up until there is not enough fuel mixed with air to ignite and then you will have fuel residue.

If the manual calls for 100:1 oil to fuel and you run 60:1 how much excess oil are you putting through your engine?   Something in the range of 40% more oil than the engine can burn.  

You're over thinking it.

It's not about combustion temps being "wrong", just the simple fact that if you light more and bigger fires it gets hotter. ie if you rev the bike hard under high load the combustion chamber is going to get hot. Pretty simple.
As Putoline said in their reply, if you run an engine hard you might need more oil.

The manual figure is a guideline that should be sufficient for typical intended use, no more, no less.
Adding oil also makes the effective mixture leaner (more oil, therefore less fuel per unit volume), so if A/F ratio is the be-all and end-all then adding oil should increase combustion temps and so improve oil burn. Generally not so.
I've been running around 7% extra oil - I doubt that's the single biggest contributing factor here, just one of several.

I used to manufacture nano-light aircraft (sub 70kg). Those engines get hammered on climbs, wide open for prolonged periods against a prop that was designed to keep the engine almost exactly at peak power, but dawdle around once up and using thermals or ridge lift. My most popular engine used to sit at 10,300 rpm for as long as you wanted to climb - sometimes 15 minutes+. 50:1 edit: I racked the memory banks and remembered it was 32:1 full synthetic was very marginal to keep them safe on climbs, but you had to give them regular revs once up and just dawdling along or they would oil up in fairly short order. Yes, there's a reduction in O2 at altitude, but I can assure you the same effect could be seen even if you were ridge soaring at 100ft amsl.

Edited August 8, 2023 by bikerpet

[faussy]

3 hours ago, bikerpet said:

GG recommend GRO Performance 2t. Fully synthetic.
Beta & Sherco recommend Motul 800. Fully synthetic.
TRS show Nils Duo Synt S. Fully synthetic.
Putoline technical support manager advises fully synthetic.

I'm going to take the hint.

GG recommend motorex, a fully synthetic, but thats the only offroad oil they make.

Using motul 800 in a trials bike is only asking for more trouble, never seen it being recommended by any manufacturers for their trials bike. Ask anybody who knows and they will straight up say dont use 800.  The UK sherco importer recommends rock oil, a semi sythetic, before that it was ipone, also semi.  Find it odd putoline  have a dedicated trials oil, yet are now recommending you to use their mx oil. 

If a bike has 120 hours on it (i also remember you saying in a post you had over 300 hours on a bike), and you werent the owner from new, there can be other reasons for this than just the oil

Edited August 7, 2023 by faussy

[reggie]

Betamotor recommends  " Liqui Moly Racing Synth 2T "    @   1.5%

[lemur]

Quote from the TRS Owner Manual (same for all displacement models)

"This motorcycle uses two-stroke synthetic oil mixed with 1% 98 octane fuel. Do not use any other kind of lubrication without previously checking with an authorised TRS mechanic."

Recommending a synthetic oil labeled 100:1 pre mix ratio is not over thinking, that's just reading and applying the instructions correctly.

[bikerpet]

7 hours ago, faussy said:

Using motul 800 in a trials bike is only asking for more trouble, never seen it being recommended by any manufacturers for their trials bike. Ask anybody who knows and they will straight up say dont use 800.  The UK sherco importer recommends rock oil, a semi sythetic, before that it was ipone, also semi.

6 hours ago, reggie said:

Betamotor recommends  " Liqui Moly Racing Synth 2T "    @   1.5%

It depends which manuals you read, or not. Sherco & Beta above.
All my quotes for the various manufacturers were directly from manuals on the manufacturer website, perhaps different year model to the ones you looked at. They were examples, not intended as inviolate gospel.

Manufacturers change oil suppliers, I'd guess due to changing financial incentives as much as anything. They also choose a supplier for their entire range, not discipline specific, so it's always quite possible they have to recommend a less than ideal product because that's the best in the suppliers range. But I doubt any of them are going to recommend an oil that they believe is likely to cause serial consumer problems - that's financially not viable. I would have to question if the UK Sherco importer has or had a relationship with Rock or Ipone - I wouldn't have a problem if they did, but it would cause me to wonder if the oil was chosen purely on it being "the best".
I don't doubt that Motul 800 isn't the best oil for trials, I seem to recall looking at it several years ago and noting that it had quite high flash point which tends to suggest it needs a higher temp to burn clean (it's not a direct reflection, but a loose indication). My point was that it's sold as fully synthetic, like all the others.

Putoline made it quite clear why they have a trials-labelled oil but also suggest using a different oil, and it mirrors what I just said - financial imperatives often influence what's available and recommended. I certainly accept that, hence why I'm not wedded to a particular brand of oil or believe it's strictly essential to stick exactly to manufacturer recommendations under all circumstances.
I do take away from this that my assessment of what is a good hard ride is obviously not appropriate. I'll re-calibrate my mind.

Rhetorical question - I wonder how the manufacturers determine 100:1 is the magic ratio of fuel:oil for all trials riders under all conditions, rather than, say, 90:1, 95:1 or 105:1?

My take-away remains that I'll move to a full-synthetic oil at 100:1. Which one will be determined largely by price, availability and more frequent monitoring of the bore and piston.

[b40rt]

All the complexity of water cooling, then it runs at too low a temperature 😂😂😂😂

[sherpa325]

When my son was riding at a very high level and I was maintaining his bikes I kept reducing the oil ratio until the bike stopped blowing smoke at full throttle. We found that about 80:1 was the cutoff point for blowing smoke. Every time we pulled the engines down they were in great condition with plenty of oil visible on the crank. In all my years of working on two strokes, including air cooled twin shocks, I have never seen engine damage like yours, very strange.

[bikerpet]

30 minutes ago, sherpa325 said:

When my son was riding at a very high level and I was maintaining his bikes I kept reducing the oil ratio until the bike stopped blowing smoke at full throttle. We found that about 80:1 was the cutoff point for blowing smoke. Every time we pulled the engines down they were in great condition with plenty of oil visible on the crank. In all my years of working on two strokes, including air cooled twin shocks, I have never seen engine damage like yours, very strange.

Judging oil ratio based on smoke seems a very arbitrary criteria. The base oil can make a big difference to the amount of smoke and obviously 'smokeless' oils are going to have totally different visible smoke threshold to regular oils. Of course the acid test is whether the engine sustains damage - if not all's well.
I did once read an article where they measured power output with differing oil ratios. They went to great lengths to isolate the oil quantity as the measured variable - accurately calibrated jets to maintain consistent fuel/air ratio, etc. I forget what ratio gave max power, but it was at what I would consider an insanely high amount of oil. So lubrication is a significant factor to how freely the engine spins. Yes, I know, who'd have thought?

I don't really consider this "engine damage" - a decent clean and it came up good as new, or at least good as a 130 hour engine. Excessive maintenance - yes, damage - no.
I really suspect now that the problem probably spiraled from a build-up causing the rings to get sticky which allowed more build up on the bore, more blow-by, so more sticky rings etc.
What caused the initial stickiness is anyone's guess - could be too much oil before I got it, or the Putoline I was using, or not enough time by either the previous owner or me at high power (previous owner only rode shows on it). I'm not overly convinced that going from 100:1 to 93:1 is a significant factor, but certainly not ruling it out as contributory. Take your pick.
I'll be adjusting all 3 variables in future.

[tony27]

Your question about MRS having a relationship with Ipone & Rock oil can be easily answered. My Jarvis replica has Ipone at 2% & 98 lead free petrol as their recommendation on the stickers either side of the headstock, from memory earlier models has Valvoline as the oil so the recommended oil has changed depending on who was giving the best deal at the time

I had the same varnish issue on my Jarvis a while ago but it has a heap more hours on it, I put it down to a failing fan at the time rather than the oil