Triumph ST wont start - 5psi compression ?

I just went to the Triumph link you posted, John451. This is definitely bizarre. And had I gone to the site before writing my previous comments, I would have known that the spark plugs were checked... Doh!

If this was a Triumph (or Norton or BSA) from the sixties, this would almost seem normal...

 

Update - He went to the shop last night and had a look at the head and bore and
confirmed the carbon had build up is high and the carbon buildup stuck around
the valve seals was irregular which is cause of the leakage which they found during
their Static leak down test.

They went to blame High Octane 98 Ron ( 94AKI ) mixed with city commuting and while the first they've seen on a Triumph but apparently they have seen the same issue more commonly happen to Ducati engines which they also service.

They have recommended he use Medium Octane 95Ron ( 91AKI ) in the future when the motor gets back from its de-coke as it has less additives.

 

Out of curiosity, have you heard of that happening to cars over there? I don't think serious carbon build up happens much in the USA anymore.

Thanks for the follow up, by the way. It makes me wonder just how much difference there is in the fuels that every nation uses.

It also seems weird that carbon build up wasn't noticed on the spark plugs, but who knows about these things...

 

Should be an easy fix: VFRworld Classifieds - 2007 Interceptor "Anniversary Edition"


:biggrin:

 

I'm with Lgn... I've never heard anything about carbon build-up recently. Not to say they aren't telling the truth (especially if it fixes it). Just one of the last things I'd ever think of... or even think of, lol. Maybe it is more of an issue when going from county-to-country.

 

I've never heard it happening to cars or bikes and often use 98Ron myself although there has been recent rumours the Gas companies have been cheating the refinery process by adding Octane raising chemicals rather than extra refining.

Mind you I have also noticed my VFR feels off if I only use it to city commute my 35 minutes each way over a 3 weeks period and how much better the engine quickly feels after an "Italian tuneup" during a subsequent mind clearing day ride. :biggrin:

After previous occasions teasing him about riding the VFRs natural enemy I had started to mention such a suggestion early on when it was'nt looking so expensive but he didn't seem to be taking it in good humour so stopped... :redface:

 

Some people can be rather narrow-minded at times... :biggrin:

 

This sounds very bogus to me. Yes I believe in carbon build up. BUT not over night no way. To go from a running motor with good compression to nothing! Sorry I don't buy it. Sounds like a smoke screen to me. Yes today's gas will leave deposits on valve stems. But it's more of a hard gooey substance and not on the valve face. Even if it was on the valve face it would have to be huge in order not to register compression. 5# is no compression.
The valve seals are on the top side of the valve stem, the oil side of the head. No way carbon can build there. Even if it did the valve wouldn't open all the way. Has nothing to do with closing. If carbon was built up on the stem so it wouldn't close. It would have to be in the port itself. The exhaust port will bake most of it's oil/residue to carbon. There is no way to build up that much to hold the valves open for zero compression over night. No way.

I did get thinking though. Seeing I don't know anything about this motor I'm just going to take some swags. Seeing it has a timing chain it has to have a gear on the crank. Most likely pressed on. Gear could be bogus and have slipped rotation on crank? This would put the cams out of timing and no compression. Did they actually check cam timing at all. Did they do an alcohol test to see leakage on valves? Or did they just take everything apart first? If the cams out of time it could have bent some valves. Then you might get zero compression if all intake or exhaust were bent. Sorry just don't buy the carbon B.S. If that truely is the case then they should fix their problem of it happening. Unless the bike has over 100,000 miles on it.

 

:fencing::focus::crazy:

 

Well it seems that the dealerships servicing might have been the cause.

He received a call from them advising that a severely blocked air filter was the cause of the carbon build up and asked him how much dirt riding he did, this did not sit well with him as the only dirt he had done was a fair distance of road works early in the year and he had since had a major service performed by them with mainly city commuting and the odd road only day ride in the months since.

As they have been the only people doing the scheduled servicing on his Triumphs over the years the implication is they did not check let alone replace the air filter at the last service, he is steeling himself for the obvious conversation that needs to occur re why the Filter wasn't checked/replaced at the last service.

 

Like I said before....amazing, this is still an on going issue. Air filter?

 

If the carbon buildup was on the valve seal side, and not in the port, then the oil is not being changed regularly enough. I've seen cars that have gone 30K miles with no oil change, and the inside of the motor just coaks up.