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Discussion Starter #1 (Edited)
Those of you who have been paying attention may well be aware that I've purchased myself a '99 model F4S 750. You'll also be aware that it was supposed to have had a blown head gasket ...

So in an attempt to get myself a working running 750 I've started to breakdown the bike into it's component parts to find out what it is that has actually stopped this wonderful piece of machinery.

Relax, if you will, gentlereader & join me on a visual tour of the, slow, but progressing works of a complete strip & rebuild of my bike.

This is where it all starts:-



This image we've already seen ... as it's located elsewhere on the site:-



The top of the motor ... as investigation starts:-



A not so happy set of inlet valves (No. 1 cylinder):-



While the earlier pix are taken with the motor in the frame ... her heart is now in traction:-



A look at the tops of the buckets:-



The flip top lid (brought to you by Oral-B) ... it's at about this point that I drank a six pack of beer ... :-



We have a few "word plays" here in Australia ... Pist'n'broke is one of them:-



Something tells me that this is NOT the way that a head chamber should look:-



Yes. That's a valve head sticking up out of the piston crown:-



The damage done, the broken bits are well spread:-



This is what I call "Pist'n'REALLY broke":-



The underside of the "emperors" new crown ... & the jewels that were removed:-



What caused all this damage?
As best as I can tell it was due to a slipped valve collet.
How can this occur? I can only guess that the bike let go on the "over run"
 

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Faaaa.....RK, thanks for sharing that horror story. I have no idea what happened there but I guess you worked out by now it is not only a head gasket!.
Mate, I really hope it is not too much money and drama to fix. Let us know, I am interested in your "fun".

Regards
 

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DaDukeofOz said:
Those of you who have been paying attention may well be aware that I've purchased myself a '99 model F4S 750. You'll also be aware that it was supposed to have had a blown head gasket ...

So in an attempt to get myself a working running 750 I've started to breakdown the bike into it's component parts to find out what it is that has actually stopped this wonderful piece of machinery.

Relax, if you will, gentlereader & join me on a visual tour of the, slow, but progressing works of a complete strip & rebuild of my bike.

This is where it all starts:-



This image we've already seen ... as it's located elsewhere on the site:-



The top of the motor ... as investigation starts:-



A not so happy set of inlet valves (No. 1 cylinder):-



While the earlier pix are taken with the motor in the frame ... her heart is now in traction:-



A look at the tops of the buckets:-



The flip top lid (brought to you by Oral-B) ... it's at about this point that I drank a six pack of beer ... :-



We have a few "word plays" here in Australia ... Pist'n'broke is one of them:-



Something tells me that this is NOT the way that a head chamber should look:-



Yes. That's a valve head sticking up out of the piston crown:-



The damage done, the broken bits are well spread:-



This is what I call "Pist'n'REALLY broke":-



The underside of the "emperors" new crown ... & the jewels that were removed:-



What caused all this damage?
As best as I can tell it was due to a slipped valve collet.
How can this occur? I can only guess that the bike let go on the "over run"
I think that you send pics to MV AGUSTA,They will send to you one new engine in guarantee.
You should experience us!
Pier



Never pay again for live sex! | Hot girls doing naughty stuff for free! | Chat for free!
 

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No telling what happened for sure, but that looks very similar to a Suzuki I worked on after the engine was over-revved (rider downshifted at too high road speed). The valve keeper can be knocked off after the valve contacts the piston so it's always hard to tell which happened first.
 

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man...wonder if it's too far out of budget to do a 880cc kit build up? or put in a 1K motor? i've never seen anything like that, but if the guy riding it was revving that high and that happened, he came out pretty good to not have any bike damage from killing himself in a crash or intense panic.
 

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Its a simple explaination....the piston and valves love affair was taken to another level, and they became one. Great pics, do you think the cylinder head is salvagable, while you are in there will you do anything special? Mill the head down.....full port job...shit like this gets me all excited!
 

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I thought of exactly the same thing. If the conrod is not bent and the cost is not much more than standard MV parts then go for the 880cc kit.

If you get the SH!TS rebuilding her, I'll take if off your hands!!!

style_one said:
man...wonder if it's too far out of budget to do a 880cc kit build up? or put in a 1K motor? i've never seen anything like that, but if the guy riding it was revving that high and that happened, he came out pretty good to not have any bike damage from killing himself in a crash or intense panic.
 

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I never saw anything like that and I must tell you that I was already reading the 5th post after yours and my hand was yet at the back of my head, as surprised I was!!!
 

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i gotta believe that head is total loss - the combustion chamber is all messed up, the valve seats look completely destroyed, and i can't hardly make out the hole for the spark plug.

the block doesn't look too bad - from the photos at least.

i remember reading somewhere that the 750 has the same head as the 1kS motor. maybe someone can confirm this with a check of the part nubmers?

alex
 

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I'd like to know that too, I thought even the valve sizes were the same on the 750 and 1000?

I don't know, some amazing things can be done to salvage heads. A real artisan could weld that up and fix it I think.

On the other hand, I would think that at a minimum the big and small end bearings are toast, which throws into question the viability of the rod as well... Probably they are steel and will take a beating... But this one damn sure took a beating. I think I see that valve head wedged between the head and the wrist pin (gudgeon pin)? That's some force right there.

Ugh. Good luck to you sir.
 

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Discussion Starter #19
Well ... the story continues (& I'm starting to take a rather sick delight in just how deep the rabbit hole goes) ...

At the moment I'm still in a process of investigation. Sourcing parts, finding out costs of repair, etc ... examining an exit strategy :blah:

Andy,
You're right about the rod ends. They are the next point on the agenda. Once I get a few quotes & feed back from a few people here who've repaired this sort of damage, I'll be spinning her heart over to get at the "cockles" of the situation & check out ALL the plain & main bearings, the integrity of the crank & inspecting for any "inclusions" in any other part of the motor ... just call me a ferret ;)

Pier,
It is a WET dream of mine that I'd be able to convince the factory to "give" me a motor under warrantee ... the situation is, unfortunately, that the motor has previously been worked on by non-authorised workshop personnel & as such any manufacturer in their right mind will deny any further responsibility ... that's not to say that you're not welcome to try for me ;)

As for the 880cc kit ... WOWZERS ... I'd end up paying more for the kit than the bike cost me to purchase ... well ... not quite ... but it'd be a lot more than I'm currently budgeting on spending.

Thank you all for your input though. It's most appreciated.

Here though is the next installment in the story ... enjoy

Once I'd managed to locate & purchase a valve spring compressor, I began the path of stripping the head ...

Number 1 cylinder Left exhaust valve:-



Number 1 cylinder Left Inlet valve:-




Number 1 cylinder Right Inlet valve:-




In my usual Anal fashion, I've sorted & stored, even, the broken bits:-



Notice if you will ... the broken & abused valve collet:-



There's no point in showing you the last of the valves ... as bits of it are still in the piston it mated with.
The valve collet, as wedged into the spring retainer, is a rather interesting piece of information ... it would suggest that these bikes don't suffer the effects of "down shift over rev" terribly well. At least I'm assuming that this all occoured on the down shift as the vendor made the statement "it just let go..."

I've got the head with me at work today as I'm planning on taking it to a head repair outfit that isn't far by ... I'm hoping that with the number of "Japper" heads that do this on occasion that there should be a few people in the country who can repair the damage.

The story will continue. Hopefully it'll end in a victorious return to the road.
 

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a valve sping compressor maybe tough to locate. the radial valve layout makes use of a conventional one hard. be nice if there was an angled shim you could use....

and i'll be really interested to see what can be done with that head.

alex
 
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