Hi all,

If I understand points made in other postings recently, it seems that one of the biggest risks to a motor in the first couple of hundred miles or so after rebuild is damage done by oil passing the rings and lowering the octane rating of the fuel causing a partial or complete seizure.

What are the views on using fuel additives to reduce the risk during this time? It makes sense to me, what say you?

Blapper

I have no idea what the benefits/risks would be of a fuel additive to break in an engine......

I would think that if the barrels, pistons, rings and valves have been prepped correctly, a nice spirited run at start-up should bed the rings and prevent the condition you describe?

Perhaps retarding the ignition a degree or two?

Cheers,

Steve

50's Triumphs came from the factory with the needle on one notch to the rich. At the 500 mi. service they would return it to the normal position. Not only does the octane rating drop with oil present but the mixture weakens when part of the incoming charge escapes past the rings. Not a happy situation for proper combustion.
Bill

Steve,
Risks should be none, benefit are that the situation JH describes so graphically can be prevented.
Bill,
Worth a thought.

Thanks, Blapper

Just as a more extreme example of breaking-in an engine:

On a fresh rebore and new pistons and rings started for the first time and broke-in my T120 with Routt barrel and MAP billet pistons during practice sessions at a road race meeting last year. At the end of the practice sessions (about 25 miles) had the throttle wide open and, of course, in my races as well.

Should mention that the bore was expertly honed with torque plate to the correct finish (by Marino's brother Terry) for ductile steel rings with 5.1/2 thou piston to wall clearance.

A subsequent strip-down revealed the bore and pistons and rings to be in good condition with evidence of good ring seating. Pistons did have slight scuff marks.

Course may have shortened the life of the cylinder, pistons and rings using this procedure but just trying to illustrate that high rpm doesn't necessarily result in seizure - admittedly with genorous piston to bore clearance.



P.S. Also should mention that I took the precaution of using Aviation Shell 100 (50w) for the break-in as it was very hot at that particular track at Albuquerue New Mexico

I've heard of 2-stroke racers using even more extreme methods, rinning it hard 'til it siezes then polishing the scuffs off the piston

The only seizure I've ever experienced on a newly rebuilt motor was knocking along at about 55mph at medium revs.

Since then, and after reading 'millions' of posts on the subject, I adopted the Britbodger 'ride it like you stole it' approach and have not had another problem.

John Healy's 'dry assembly' is also part of my routine now.

"John Healy's 'dry assembly' is also part of my routine now."

I can't claim this as it was told to me in 1978 by Ken Tipton of MTC Engineering.

http://www.mtceng.com/images/pdf_files/piston_kit_installation.pdf

Does anybody have any views on, or actual experience of, fuel additives? Has anybody had any (temporary as in caused by oil as per JH's scenario) detonation problems (temporarily) cured by it?

Blapper

Hi Blapper,

You keep asking this question. You are probably not going to get many answers, about fuel additives, for octane. Do a search. There have been mentions of them. Consensus is they do not work and may cause harm.

Why don't you search and find, Real gas. There must be a race track somewhere near you. Or a small airport for AV gas.

Problem is not just octane. Problem is alcohol, which burns slower. Thus causing a "premature end end to combustion" = detonation.

Thus AV gas. Race = real gas (no nitro). Or second spark plug, stronger EI ignition.

I doubt, you will find, just adding a can of this or that will work.

With all due respect Bob, alcohol (both ethanol and methanol) possesses very good anti-knock properties. Unfortunately it doesn't possess as much unit energy as gasoline so for the same carburation/jet size and C.R., power output is less for a alcohol/gas mixture than for straight gasoline.

Its academic for Blapper though as I don't think they use alcohol in Europe - yet.

I do agree that mixing-in a small amount of 110 octane leaded race fuel or aviation 100LL (actually about 108 octane using (MOM+RON)2 octane rating method)fuel might be helpfull if Blapper can get hold of some.

Personally though I don't think it is of real concern using pump gasoline as the rings should seat in much less than 200 miles and the oil bypass before then should be so small in my opinion as not to cause a problem .

BTW I think aviation is slow burning which isn't a bad thing in my opinion unless looking for out and out performance.

My

Still haven't answered Blapper's question re-octane boosting additives as don't know sufficient about the subject other than what I've gleaned from others

Thanks guys, at least I've got a response to the original question now.

I do have a small airfield near hear, I'll go and see if I can buy some gas from them nearer the time I need it. From what you say, a couple of gallons should do it. Good idea chaps.

Thanks :bigt:

Blapper

Hi Blapper,

Here in the States we have to tell them it is for "off road" use.

There are different colors of AV gas. I think I remember some are good for us others bad. Do a search, it was covered here.

Blapper,

100LL is good - contains more tetraethyl (spelling?) lead than the old auto leaded gasolines and is about 108 octane based upon (MON+RON)/2 formula so you don't need much.

HTH

"Personally though I don't think it is of real concern using pump gasoline as the rings should seat in much less than 200 miles and the oil bypass before then should be so small in my opinion as not to cause a problem ."

Most of the complaints we have received is with motors that had less than 100 miles on new pistons and rings. The typical mileage was 50... The complaints had started to slow down, but with all the internet sales of pistons and rings over the past couple of years the complaints have started back up again.

Being that the problem manifests it self through detonation, with the new rings unable to transfer the heat out of the piston, raising the octane rating of the gas used isn't a bad thing.

As small amount of "race" gas is about the best additive you can get, shy of using it straight up. IMHO the rest of the stuff sold as "performance" additives are suspect.

As an aside, we have had very good luck avoiding detonation twin pluging heads when we push the compression up in the 13 plus range. It works as well with stock compression. I think as time goes by we will see more people twing plugging their street motors that utilize hemispheric combustion chambers (Triumph).

To summarize several recent posts about how to treat a fresh engine::::: Best gas money can buy. Retard timing a couple of degrees and a tad rich until "broken in". Drier assembly, and earlier specification oils help. Cast iron rings are preferred in most instances, and last but not least; ride the thing like you mean it from the first start up. Sounds like all these years I have been doing it right... ah; serendipity!!!!

here in new zealand they stopped putting lead in the fuel. the quality of the fuel went from very good to very bad. i found that the bad fuel burns too quick and this caused too much heat and damaged the plugs. lots of people were blaming the plugs and going to hotter plugs. this caused more problems. i found that the higher your compression was the quicker your plugs stuffed out. we found a product called techni-lube fuel conditioner. this got rid of the problem by slowing down the burn rate of the fuel.there were a lot of complaints and the fuel is now a lot better. my 650 Bonni was high compression and would stuff a plug in less than 5 miles but with techni-lube i have never had another problem. i sold a lot of this product and it never failed to fix the problem, cars or bikes. the fuel is better now and i do not run it as much but can tell you that this product works. but it is a fuel CONDITIONER not additive. hope my 10 cents worth helps

Techni-lube.

Thanks Nutz.

Blapper

The aromatics toluene and xylene have extremely high octane and high btu (~115). These are sold as paint thinners. You can mix either with gas to raise the octane without changing the chacteristics of the gas too much. Aromatics are already in gas so not much change except octane. If you have a choice use toluene for no other reason than that is what the old turbo F1 cars used to use for such high boost and HP.

Tom Graham

Cheez Tom, Mix it myself? Without instructions? I haven't go the bottle (guts) for that!

Blapper

Girlieperson Alert !

Rubber gloves and Toluene are all required, rubber gloves are the most easily obtained component.

Tiger's right, when they were using toluene in F1 the refuelers used to wear very heavy duty gloves, aprons and respirators.

Evil stuff. You could smell it as soon as you walked through the gate at Silverstone!

the different colors of AV gas relate to the octane rating. I used to be able to tell you what each was but....been too long. as for additives ( oil and gas )... i consider the vast majority of them to be nothing more than "wishful thinking". most were used after a problem had occurred and people figured they could spend a mere $2.99 rather than a few hundred to fix it correctly. fat chance. I had shelves of different ones that made this claim or that... all in all they really didnt deliver what they claimed. for fuel additives the best ones were basic lubes. marvel mystery oil, etc. ones that provided an extra measure of upper end lubrication. some of the carb and fuel injector cleaners were good as well...but you had to watch how they reacted with the rubber seals and o-rings in the system. I have never re-assembled an engine with a "dry" top end. I just used a light coating of 30w oil and it was done. and i have never had an engine cease or take excessively long for the rings to seat. i dont see whwere dry assembly would be bad either..i just never did.
Blapper, if you put your engine together like i know you did you wont have a major problem. to use an additive to hedge your bets against a castastrophy is a waste of time here. if something is that drastic to cause it to cease or break ... miracle in a can isnt going to stop it. use a good grade of non-foaming oil and change it after a couple hundred miles. if you want use some top end lube in your gas.

Cheers Dale.

Blapper

That method works and you pretty much have no choice safety wise, good to walk around the pits and warn folks that you may be a little slow in the first practice sessions.

John H, I once tried to bump start a Z1000 superbike [10:1] on dry bores, the old Kawas would not select 2nd unless the crank was spinning and no way we could get it to turn over, had to put a half teaspoon of R Synthetic down all plugholes.

I wish I still had that bike.