Triumphrat

shoegaze · 11-04-2012, 11:48 PM

You are spot on, and I'd like to echo your sentiment. Hardened valve seats are somewhat important, but a lower compression lead-designed engine will run for a long time before the need for conversion to hardened seats occurs. The tetraethyl component did help reduce knocking on high compression engines, and it also cushioned the valves from "hammering" their seats, but on lower compression mills, and mild to moderate cam lobe ramp profiles, the need for it was not as great. Good oil, however, is always critical.
Regards-

Quote:

Originally Posted by JohnA

The craze for special valve seats that would work ok on unleaded petrol was a con, and a surprising (and disappointing) number of engineering firms sepcialising in 'classic' cars & bikes cashed in on people's fears. If you were running an old iron-head bike or car, maybe it would benefit from (or in some cases definitely need) new steel seat inserts to replace the existing iron seats, when switching to unleaded. Otherwise, there's nothing to gain and a lot to lose (a fair bit of money, and the risk of loose seats in the future). The additives might act as anti-knock agents but unless running unusually high compression, there shouldn't be any knocking/pinking/pinging or whatever you call it on straight superunleaded. On straight ordinary unleaded there might be some pinking on heavy throttle openings, but it should be avoidable with careful riding.

roadduster2 · 11-06-2012, 08:22 AM

I've been using 103 Octane Low Lead Av Gas after running into an old buddy who has access to it. In my 73 Tiger & 74 Bonneville the valve train is quieter, and the starting, tick over, and power is outstanding. I remember buying 98 Octane Leaded Premium pump gas back in the late 60's, as I'm sure a lot of you here do, and using the Av Gas is just like the old days!! Plus, you don't have to be concerned about it going 'bad', as the ethanol gas today does. If you know any pilots, or plane owners, you can get the Av Gas too.

Roadduster2

Mr.Pete · 11-06-2012, 01:52 PM

Quote:

Originally Posted by Redmoggy

Standard compression for your bike was 8.5-1 so you may get away with normal unleaded. Try it, if the old girl pinks go for a higher octane.

Not many 650 Triumphs are likely to still have pre-'68 pistons 8.5:1.
They're more likely to have Hepolite 9:1 domed pistons,
or JCC 9.5:1 pistons.
Even 8.5:1 is too much for standard unleaded with 38 degrees ignition advance.High risk of detonation/holed piston.

You need premium fuel in a Triumph.

TridentT160 · 11-06-2012, 10:22 PM

In my experience, Union 76 and Chevron premium work well for high-compression, air-cooled engines, and Arco or Valero gasolines (regardless of grade) should NEVER be used in a motorcycle or a high-performance car (causes knocking or plug fouling).

grampsomr · 11-07-2012, 07:57 PM

Quote:

Originally Posted by JohnA

The craze for special valve seats that would work ok on unleaded petrol was a con, and a surprising (and disappointing) number of engineering firms sepcialising in 'classic' cars & bikes cashed in on people's fears.

Had a guy talk me into getting the valve seats like that. Was very convincing

ramengr · 11-07-2012, 08:11 PM

I've been using unleaded premium (91 or 92 octane). No pinging problems. I haven't had the head off. So to be safe, I'm using a lead substitute additive. I just don't want to take the risk.

BTW, in Australia or Britain is it "pinging" or "pinking?"

shoegaze · 11-07-2012, 09:30 PM

I have never heard of it called "Pinking", and I was a professional mechanic for years. Further, I like to think that I'm up on the lingo of the Motherland. I think that was either a misprint, or it was heard or recited incorrectly.
Knocking and pinging are a part of incorrect tune (typically an over-lean condition), or too low an octane rating. Valvetrains specifically designed to be padded by lead can become abused through the lack of tetraethyl lead, but again, we're typically speaking of engines running a compression ratio of 9.5:1 or higher and engines with camshafts that exhibit radical lobe ramp profiles. In these situations, the valves get hammered into the seats, and destroy them, ultimately. A mildly tuned, well cared for engine that was designed in the Lead Era will run nicely for many, many years before destroying the valvetrain. Ultimately, all engines should be torn down for freshening up and bearing replacement, at which point adding hardened valve seats is typically a good idea. Whilst I'll not discourage you from using a lead substitute, it is most oftentimes unnecessary--especially on an 8.5:1 engine. Ill engine tune is more likely the culpret of valvetrain issues. Making sure your points are adjusted correctly and seeing to it that valve lash is within spec are far more important.
Cheers-

Quote:

Originally Posted by ramengr

I've been using unleaded premium (91 or 92 octane). No pinging problems. I haven't had the head off. So to be safe, I'm using a lead substitute additive. I just don't want to take the risk.

BTW, in Australia or Britain is it "pinging" or "pinking?"

DAVE M · 11-08-2012, 04:23 AM

It's been called Pinking in the uk all my bike life. (30 years plus)

Mr.Pete · 11-08-2012, 05:01 AM

There's always been a language barrier between the USA and the English-speaking countries.
I'd call it "pinking" or "death-rattle".

JohnA · 11-08-2012, 05:37 AM

I'd never heard it called pinging before I came on this forum. Maybe someone should publish an American-English dictionary of motorcycle engineering terms?! I must admit, pinging seems a more descriptive word.