New cylinder break-in

[Mongo]

I have run 93 octane through it since I first started it at a 20:1 mix. I was told by a friend that the bike needed to be jetted for the pipe and bore AFTER I had run it for a few hours. I went up slowly because I thought the bike was running great at the time but the more and more I went up it seemed like the worse it got, hence the checking the reeds and cylinder.


I'll see if I can get the motor pulled this weekend and post some pics of the damage.

[barnett468]

hello

thanks for the info. your first post said it ran rich yhen went lean then you jetted it.

is your amsoil synthetic?

believe it or not few of the factory guys use 20.1 we typically all use 32.1 unless it's a high rev machine like road race etc..

more oil does NOT mean more protection and it can cause other problems.



MORE FROM HARRY KLEMM


Piston Seizure Vs Piston Scoring - Piston “seizure” and piston “scoring” are two different stages of the same problem. When the oil film on a cylinder is momentarily burned or brushed away, the bare metal surfaces of the piston and the cylinder wall will actually touch. When this happens, there is a sort of scraping that takes place between them. If the oil film is quickly resumed, the marks from this scraping will often remain on the piston and (or) the cylinder wall. A momentary scraping or "scoring" seldom causes any permanent or performance robbing damage. In a momentary scoring event like this, no significant damage takes place because the oil film is resumed before the piston and cylinder have a chance to start exchanging material onto one another.

Scoring is commonly seen on the piston face directly below the piston ring end gaps. The blast of combustion can get between the large end gap of a worn out ring and burn the oil off the piston and cylinder in that area...Hence the surface scoring. In most cases, score marks can simply be sanded off of the piston and cylinder. However when ever you see scoring, it's a good idea to find the source so that it doesn't develop into a full blown seizure.

Piston seizure is a case of scoring where the oil film does not immediately return. After a few moments of constant scoring, the piston and cylinder will scratch each other hard enough to remove material from each other. This floating material grinds itself into the piston and the cylinder as it continues to grow in size. As this snowballing material grows, it will drive the opposite side of the piston against the cylinder wall with a pressure so terrific that scoring on the other side of the piston begins to take place. While all this is going on, your engine is still running wonderfully at full throttle. However if there is a momentary lifting of the throttle, the force of this scoring can cause the piston to “seize” in the bore. In a “light seizure” event like this, the rings often escape any damage, and the engine will easily re-fire as soon as the engine cools down slightly.

The death blow of a “power-on” seizure comes when the mass of material between the piston and the cylinder wall finds it's way to the piston rings. This nearly molten mixture of aluminum and iron can lock the ring in it's groove. This ring locking, not the piston surface scoring, is what actually causes your engine to quit when you experience a “throttle-on” seizure. When the piston ring becomes locked back in it's groove, it's incapable of providing compression sealing against the cylinder wall. This instant loss of compression, while the engine is at speed, causes a dramatic loss of power. That power loss, along with the added drag of the badly scoring piston, makes the engine quit or lock up in a nanosecond. In fact this entire seizure process, from the first scoring scratch to the piston locked solid, takes less than a second at full rpm. In such a failure, a single cylinder engine will seldom restart.

[barnett468]

Hello

Here's a question which amsoil did you use, hp, interceptor, dominator or saber? Dominator is what you should use in amsoil brand not the others even though interceptor says good for power valves it is high detergent and you do not want high detergent motorcycle oil in a 2 stroke.

The maxima 927 that ride-red250r and yaegerb use is the best, however you don't need it, it's expensive and does not mix with ANY other oil.

Do not reuse your ring even if it looks good i guarantee you it is not.

JETTING TEST - Your piston can also seize if this is done improperly. You can not rev it to the moon then simply close the throttle with it still running. It may seize especially on a new bore.

Are you beginning to see your problem is not so simple as just running lean but it is a significant cause.

It seized because it got hot then the piston then either swelled up and dragged on the bore or it got hot and burned your hp or interceptor oil away.

Why do you use amsoil instead of bel ray or other's etc?

SPARK PLUG - The plug you have is perfect for ideal conditions unfortunately your conditions are not ideal yet. a br10es or b10es might be better to use untill it is broken in nest time but it still probably would not have saved you here..

REEDS - If your reeds were leaking your bike would not idle prooerly if the were leaking this is bad.

HEAT CYCLE - this is just because a new motor runs hot and they want you to shut it down before its too hat and seizes. if it is bult right this is unnecessary but it doesn't hurt if you run it under light load for 15 minutes at a time for 3 cycles once you break it in as i mentioned.

[RIDE-RED 250r]

2 things I disagree with you have said barnett,

#1: A STOCK spec 250r engine does not require race fuel. Straight out of my Honda service manual, 92-100. Octane rating is octane rating. Rate of fuel degradation amongst different types of fuels/additives IE, ethanol vs non-ethanol is a different story... But the 92-100 fuel octane range gives you options, and you may have to address running on the lower side of that range with jetting... You are right about squish band. But at normal overbore sizes for a stock cylinder the effect is minimal. Compression/compression ratio is not increased on say a stock cylinder vs boring that stock cyl .050" over.

#2: Unless that engine has a CR250r ignition, or aftermarket adjustable timing CB carrier, there are no timing marks to check and no way to adjust. Stock 250r ignitions are not adjustable.

But I do agree, it sounds as though he just started too lean on jetting for the bolt-ons he is running...

How are the crank seals?? Replaced? If so, it's possible they were not installed or the crank not installed correctly??? May have folded a seal lip over and now is leaking??

This is why I do my own engine work other than machine work... And I only dont do that because I don't have the access to the machinery needed. When I put an engine together, I know that everything is right... at least to the best of my ability.

[fastatc70]

Looking at the cylinder it looks like you may have a air leak between your carb and air filter.( unfiltered air). What ever you run for oil you must go very rich on your main, pilot and needle.

Run through three heat cycles and start to go lean.
I have been running a 250r 4 wheeler for 4 years before rebuilding. Sand, road, ice racing and trail riding. Just started to loose compression. Just jet a little rich. It keeps the combustion chamber a little cooler and just a little more oil and some people say it adds a little more compression due to more oil around the rings.

Also check your ports for knife edging. If your ports are sharp it will shave oil off of the piston and you will seize and have accelerated ware


I my opinion run what oil you like ( brand name). Everyone likes something different and discussion about what oil is best is like discussing religion or politics.

I have run almost everything out there due to sponcers and friends that race and it all starts at jetting.

[barnett468]

Hello Mongo

Fast atc70 has added something else to look for. I don't think you're damage is from sucking sand into your cylinder however simply because sand would cause damage random damage throughout your cylinder and if this was the case I wrongly assumed that you would have mentioned some damage to the intake side of your piston skirt also however even if there was damage to the intake side of your piston skirt it in no way eliminates the possibility that your piston started seizing it merely increases the likely hood that sand may be at least a contributing factor to the damage. If the damage is confined to the exhaust side only however than it virtually 100% eliminates the possibility of sand being the sole cause if any, of the damage. This thinking process is called deductive reasoning. That being said by ALL means check that too I certainly would.


My sole purpose is to determine exactly what your problem is if possible and prevent it from happening again and NOT to simply suggest putting a band aid on it because it is easier, including less typing for me, or simply because I don’t realize that I don’t have the depth of experience and knowledge that some others do. Although these people mean well it can be like taking medical advice from your friends.

All the information I have provided are proven facts, I occasionally have educated guesses “opinions” but never misconstrue the two or attempt to offer known opinions as facts as some others do. If I did this I wouldn’t have been employed long.

I suggest that you carefully read ALL the information supplied from EVERYONE so far and do what you think is best. I will 100% guarantee you though that simply taking the EASIEST approach to your problem may not be the best.

To Red [and Mongo]

I am giving you the benefit of the doubt by your comments that you CLEARLY did not understand the entirety of my post or the statements I posted from Harry Klemm which were NOT mine.

Quote from big-red-250r - "You are right about squish band. But at normal overbore sizes for a stock cylinder the effect is minimal. Compression/compression ratio is not increased on say a stock cylinder vs boring that stock cyl .050" over.

#2: Unless that engine has a CR250r ignition, or aftermarket adjustable timing CB carrier, there are no timing marks to check and no way to adjust. Stock 250r ignitions are not adjustable."


Do you know if his cylinder head has ever been modified by anyone in any way including that which would increase his STATIC compression or alter his “squish” band? I do not and the owner does not so since I am not there and am not psychic as others appear to be I assumed it was reasonable to err on the side of caution and until it is determined otherwise speculate that it might be. My personal experience with squish bands including testing them for Harry Klemm on pre production t3's and my company sponsored pro level t3 [which did not detonate and holeshot many pro races two of whuch included Jimmie White, of which one also included Marty Hart which I won] that changing the squish band and subsequently the quench area including that of simply boring out a cylinder does have a significant affect on some models. I do NOT know about the magnitude of this effect on the atc250r models however but it obviously makes basic as well as scientific sense that it would have some and none of these effects would be beneficial!

1. Nowhere in my posts did I EVER say Mongo NEEDED to run race gas in his STOCK bike however now that I read my comment that I posted again below, I realize that I merely could and should have added the word “MAY” in front of the word “NEED”. So in the interest of trying to keep the peace I will agree with Red that in all the individual words that I have voluntarily spent typing in an attempt to help Mongo understand some of the potential causes of his problem that I did in fact CLEARLY make a comment that I agree is less than exactly what I meant to say and for that I apologize to anyone that takes exception to it. I have rewritten my statement below in a way that I hope more clearly explains what I was trying to say in my previous abreviated statement.

“Since these motors were designed to run on 100 octane the lower octane gas today contributes to deto etc so they need to be set up with less comp unless you are using race fuel.”

Since that in my extensive personal first hand experience I as well as others including obviously Honda has determined that these motors were IDEALLY designed to run on 100 octane gas that due to the current “blend” of todays pump gas and it’s occasionally inaccurate octane ratings that If you determine that you are having levels of detonation that can cause engine problems one easy, but not always guaranteed, way to reduce your levels of detonation to those that are minimal and acceptable then one can simply use gas with a higher octane rating.

The problem with this technique is that not all detonation is easily heard and not all people are experienced enough to know what deto sounds like and therefore might not know when this is occurring. Also you may be having unacceptable levels of detonation that are either difficult or impossible to hear. Both audible and audible levels of detonation that can either contribute to, or be the EXACT cause of the type of engine damage you currently have.

2. By your own comments you say the Factory Honda Owner’s Manual says to run octane levels of between 92 and 100. I personally have no idea what the Honda manual says regarding proper octane levels for their bikes. I would assume if that’s what they say then that is absolutely correct. The problem I personally have with running 100 octane pump gas in ANY bike is that where I live they quit selling it at the local gas stations around 25 years ago! This leaves me with the following dilemma, if my bike dertonates on 93 octane pump gas and I want to run a higher octane gas to try and reduce the detonation instead of properly modifying it so it will run on 93 octane, or if I want to run a higher octane gas because I simply like the smell and/or exhorbinate expense of it or whatever then I have the option of using additives, which have never been very successful for me or buying race gas and mixing it with regular gas or just running it straight if I want.

3. I never said his STOCK timing was adjustable so again, it’s impossible to disagree with me regarding a statement that doesn’t exist. I merely felt that because I honestly did not know whether it was adjustable or not and his bike is around 25 years old and has had previous owners that could have changed ignitions etc over those years that it might be beneficial to suggest this just in case it was adjustable since no one else mentioned this possibility. I again apologize for not being psychic and therefore not knowing what his current ignition system is.

Quote from ride red - "You are right about squish band. But at normal overbore sizes for a stock cylinder the effect is minimal.

Excerpt from my previous post - "When you bore a cyl out you change the ratio of the squish band to the bore size this will contribute to deto and pre ign. Also a replacement piaton like a wiseco often does not have the same dome angle on it as the orig. This angle difference changes the angle of the piston to squish band. This can also contribute to deto and pre ign. If your builder machined your head for increased comp but didn’t correct the squish angle like most don’t then this is one of the causes of your problem.

I can only suggest to you that if you want to debate the FACTS I posted that you contact either Harry Klemm, builder/tuner of bikes, trikes, quads and jet ski’s that easily claimed over 30 National AMA Professional motocross titles, National Pro Watercraft titles, National Pro 250 ATV titles [enter “Jimmie White” in your search engine] series championships like mickey Thompson off road champion ships and annual annual pro race championships of which I have two, beating Team Honda at both of them or Dave Miller currently Previously of FMF or DG the owner of Miller Mano [whom I was sponsored by] and currently of DMC products. Sorry I forgot to mention that you could also call Honda, Kawasaki, Yamaha etc. also to discuss the issue with them if you are so inclined, I’m sure they’d love to do that.

Do you know if his cylinder head has ever been modified b anyone in any way including that which would increase his STATIC compression or alter his “squish” band? I do not and the owner does not so since I am not there and am not psychic as others appear to be I assumed it was reasonable to err on the side of caution and until it is determined otherwise speculate that it might be.

EFFECTS ON BORE SIZE VS COMPRESSION – In the case of the 86 250 r as well as the tecate t3 and other 2 stroke engines of the era with similar compression ratios, increasing the bore size from a stock purported bore size of 70.0 mm [that of the 86 250r per online info], to your current purported bore size of = .050” which converts to 71.25mm. Using the free online compression calculator [url posted below] your compression increases by an approximate factor of .4%. This may not sound like much but as I mentioned these motors were high compression and the tecate t3 definitely had NOTICEABLE detonation under hard riding conditions as delivered stock from the factory [causes of which are not necessary for me to go into here]and the smallest increase of compression can EASILY push it to the level of engine damaging detonation. I can absolutely guarantee you that if one bored out [which you can’t]a box stock t3 to .040 over or more I guarantee you it would not last long. Race gas did eliminate the audible detonation on the stock t3’s 100% in research testing ergo another one of the reasons for my suggestion you might try using higher octane gas etc.

[barnett468]

Quote from ride red 250r - "Remember, when you "richen" your premix (ie adding a higher amount of oil) you will actually LEAN your fuel/air mix for combustion. Premix oil displaces fuel, and as such, adding more oil will actually lean your combustion fuel/air mix."

Ride Red 250r

The above statement from you which is posted on the internet in dozens of places is in fact correct for most intents and purposes however I have yet to see any of these individual statements fully and accurately explain the complete effects that different gas/oil ratios have on a 2 stroke engine. If you know anything additional regarding this topic including that which you can locate on the internet if you feel a need to please post it for others to read as I'm sure it would be interesting and possibly beneficial to some peoples understanding of the subject and how it can affect their engines performance etc.

I personally avoid making statements I do not understand within reason unless I supply links to and/or excerpts from qualified articles that accurately and adequately support my statements. Occasionally I will still supply supporting documentation when I feel others might want to contest my statements.

FYI - You could also use the word 'enrich" in place of "richen" if you wanted to be more technically correct in your statement above however I certainly don't always use the most technical lingo either but in my case it is usually by choice and not due to a lack of a technical vocabulary.


I will be happy to answer ANY questions that ANYONE has for me including any from ride red 250r to the best of my ability if in fact I have an answer for them in the first place as long as they are intelligent and meaningful and NOT intentionally designed to be argumentative or create problems. I will rarely if ever answer the same question twice within the same post. If one doesn't read my answer or ANYONE else's for that matter I don't think they are either intelligent enough to understand the question or courteous enough to read ones reply in the first place.

I am the last person to think I know it all and there have been many on this site that have come up with things I didn't think of and/or explained their answers in reasonably to very concise articulate ways. This is a very difficult thing for anyone to do.

I never argue as there is no point in it. I try to do it right the first time or I realize I may possibly have to do it again later at probably a much higher cost. I never assume anything where that assumption could have a negative impact of any consequence.

[atc300r]

Did the mechanic relieve the exhaust bridge and drill holes in the piston where it rides against the exhaust bridge.I always break in a new engine or two stroke on non sinthetic oil.

[RIDE-RED 250r]

Ya know Barnett, you seem a smart fellow with alot of knowledge..

But, your attempt to bismirch and discredit me for factual information I posted is neither warranted nor appreciated. I like your sarcastic invitation to be educated by you and your indirect accusation that I post about subjects that I don't understand.

I'm not going to go to the trouble of qouting examples of this from your posts.

If you want to discuss it further, PM me.

[barnett468]

Hello Mongo

Ride Red 250r

Unfortunately for you anyone that reads our posts can easily see that you were the first to question [disagree] with my FACTUAL statements not the other way around like you are now trying to make it sound. So using your own terminology, you were the one who tried to “besmirch” and discredit me first not the other way around. My subsequent reply to your original attempted “besmirching” of me was merely a corrective one to counter your inaccurate, incomplete and or “out of context” information. It was not designed as an attack or a first strike which all can see.

Another problem you have is I supported my statements with documented FACTS and also with articles from other professional sources, you supplied no such documentation to support your counter claims did you? Is this because it doesn’t exist?

Another problem that everyone can also see is that for some reason it “reads” like you are absolutely 1,000% positive that Mongo’s head and cylinder etc are 100% stock and unmodified after going through previous owners and over 25 years of existence. After reading this statement for the third time now are you still going to tell everyone here that you believe this is true. I guess we’ll just have to wait and see.

Mongo has a problem, I assume nothing and try to find out via photos and hopefully from his builders info EXACTLY what he might have. I as well as everyone here including you are trying to help him “blindly” from a computer. Now you want to try and berate me for simply trying to help the guy using my accumulated knowledge [what ever that may be] and for trying to cover ALL the bases not just a few? Why would you do this to anyone? It looks to everyone that you are missing the point which is trying to HELP Mongo and you instead want to try to turn it into a “who’s right” contest.

I have no desire to make enemies but I will not sit back and allow someone to tell me I’m wrong when clearly I am not. I will also be the first one to admit I’m wrong if I find out I am. I am all about FACTS, I am not about being RIGHT.

FACTS or NOT the facts, friends or not friends the choice is up to you!

[Howdy]

barnett468, Do you have ANY friends? I ask because I don't see you gaining any here. Custom user title is under review.

FYI, We do have a rule that allows us to ban stupidity.
Howdy

[Mosh]

There is more text in this thread than the whole damn service manual for a 250r. Mongo. Your jetting on a stock carb with over bore cylinder and FMF system should be in they 48 pilot and 165-170 main range in my experience. Without seeing better pics of the jug I will make the assumption that your machinist did not chamfer your ports and your rings were clipping causing premature: wear. But run anything other than Amsoil. I have no confidence in that stuff. Regardless we need more pics of the jug and piston and how you ride and in what conditions.