750 Formula-Engine fix, what to do?

hello Piet,

don't take offence, (seem to be upsetting people all over the place at the moment and its not alcohol since I am restricted to 1 litre of fluids per day!) all I was trying to say is that mistakes can and do happen, the longer the timescale, the greater the risk, can every single person in the building be entirely trusted? what about the visiting parcel delivery man, or the council blokes collecting the trash? if the engine is not dismantled then there is almost no risk, but if it is disassembled then the risk is greater, and the only way to exactly know what is needed is to dismantle.

As Lothar points out (after my posting) he admits that at least he is partly to blame, and from what he posts regularly I always thought that he did his own engine work?
CLEM
 
Hi Clem,

well - assumptions, eh... :D

I do my engine maintenance and everything around the engine without taking the head off or the crank/gearbox out, as I simply don't have the tools to do the work properly. Even for valve adjustment, I go to OCT or Piet as I don't have the necessary shims to do it, even though I know how to do it and would be capable to do it on my own. It is simply the fear factor to pull a thread and not having the right tools to fix it. If that happens at OCT or Piet, I know it's fixed in an hour or so.

I stripped several engines (including the Jota engine, the 750 SF engine etc) and also put the Jota engine back together once, have done several 2-stroke engines (Triumph of my father, sooter of my son, DT125 barn find that I restored etc. etc.). I focus on what I know I can do 100% on my own and the rest I leave to the pros.

I decided therefore that there are way to many things that could go wrong on a Triple 4 stroke engine that I can't fix so I leave that part to the guys that know what they are doing. Haven't been disapointed yet except for the waiting time. But then: It took me almost 3 years to get the crank lightened on the Motoplast engine as to many promised me to do something and never did (neither OCT nor Piet meant here please!).

I rebuild carb sets, brake systems, clutch systems, suspension, do electrics and electronics installations, construct my own parts etc. but everywhere where machining needs to be done, I am out. I have and have had several Ideas in terms of tuning and modifications that I discussed with professionals and many of them I have done (like the Keihin carb modification), but mostly with a company executing what I planned (like Topham did the re-spacing of the Keihins for me etc. as parts needed to be made that I did not have the proper tools for).

I think I pointed that out before already but with the frequence of this forum, it is hard to remember every single post from evey single member, I know. Hope it is clearer now though, basically I do everything except engine rebuilds.
 
Hi racing gentleman please for your sake get the crank repaired either Volki or OCT I thought I would be ok the conrod came off my crank luckily OCT had spare bits to repair mine also I needed new  barrel and pistons I had to repair the engine cases and get them machined. Piet at OCT was a gent sorted all bits for rebuild and always available for advice. His work mate Dirk was always helpful alas not here. So don't leave it's a manufacturer fault if repaired as mine now is the bike is an awesome piece of kit
 
I told him they use the same air filter as Zane 750s...
Click to expand...

Hum! Will this filter work on a 71 750 SF with 30 VHB's?

Been fighting fuel stand off and dirt since 71 on them open mouth VHB's ;o)
 
Laverda SF said:
Hum! Will this filter work on a 71 750 SF with 30 VHB's?

Been fighting fuel stand off and dirt since 71 on them open mouth VHB's ;o)
Click to expand...

If you bild an according airbox to mount it and change the jetting accordingly, sure it will. ...
 
I had the original (oval type,under the battery tray) air filters re-made as a no modifications fit and then couldn't sell the  first batch that came in, and there were only ten, this may have been 50% due to the fact that the pre-oiled Unifilter was getting bad press at the time, and 50% because the older twins are not getting used much and the tight arsed ones who do use them, make up a "wrap" for the original cage with a piece of filter media from the HVAC industry, this works fine (up to a point) but the battery and the rear wheel affect the cleanliness of the filter (and that is why it got repositioned for the 36mm carbed models) so the media deteriorates, I have even seen a nice clean media filter that was cable tied to the original cage with big air gaps where it overlapped itself, so in effect was 100% inop.

K&N pods may be the way to go followed by a trip to the dyno, they can be hidden if you are crafty.
CLEM
 
I think I have to accept that engine work is required, I will accept that the strange noises are in fact a prelude to an impending disaster as described by many posters over the forum. Once I have dropped the engine I will look at the starter problems, whether it is the sprag clutch or a burnt out starter motor. In the time I have awaiting the engine work I will change the battery leads, starter solenoid and try and do something with the abysmally dim headlights. I changed the lamps for the 150% brighter type but still it seems to be dim, or is that just me?
I can't just watch such a great riding bike rot away so I will do my bit to preserve the Formula legacy. I am almost (I say almost) inspired to have a tinker with the spare (read; Knackered) engine and have a tweak or two to see what can be improved whilst maintaining (don't laugh) reliability. I'm sure something can be done to reduce the strain on the rotating mass in the engine and improve oil flow. I know one of the racing formulas had an electric oil pump and would like to know how to achieve that little mod. Answers on a post card please.
 
No amount of extra oil will improve matters in that engine as long as it is in stock form.  Neither will any fancy oil filter, the stock pump and filter more than up to the task on hand.  FYI, it flows about 5 times as much as the old 500 pump, the engine from which the 750 actually derives.  The liquid-cooled 750 is quite healthy temperature wise, a very different story with the air-cooled 650/668.

The issue is NOT oil-related, the main issue is incorrectly machined cranks (amoung a whole list of other things).  Not much rotating mass on them either, the engine shows no "flywheel effect", it revs digitally, all or nothing!

The sooner these engines are looked into, the smaller the bill... :D

piet

 
I can only support what Piet wrote. If there is a noise already, don't use the bike anymore, don't even start it. Every time it runs, there is a fair chance it completely collapses. It is not a question IF the big end bearings do give up, it is just a question WHEN. I had enough people telling me that they would not be affected because they exchange oil frequently and warm up the engine properly etc. This all helps to push the day a bit ahead when the engine needs modification, but it does not prevent it. Most engines show the signals between 10.000 and 15.000, very rarely beyond that point (though I have seen one Formula 2000 lasting up to 28.000 before it happened).

So - as Piet said: the earlier you get it done, the lower the bill. And a true 2000 Formula is more rare than 750 SFC's, maybe except for the first badge... Well worth the effort, both financially and from the fun factor they offer afterwards again...  ;)
 
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