Lemans 2 performance build information

[wallice]

I currently have my 1000cc MK2 engine and gearbox stripped down for vaqua blasting. I'm looking for a "recipe" of modifications I can do to get the best out of the motor and box while I have it apart.

A drawing for the machining of the flywheel would also be great.

I am aware of Peter Ropers' info on gearboxes, but I haven't been able to find anything much on the motor.

Help would be appreciated!

Regards, Greg

 

[Nordicnorm]

The LM 2 needs an automatic cam chain tensioner and the timing case converted to a full oil bath. This stuff was junk back in the early eighties, after MG ditched the timing gears. The after market may still offer a chain tensioner, but start with a fresh chain.
For the timing case mod see the MGNOC tips Vol 3, page 54. Easy to do when your engine is apart.

 

[V700Steve]

Best bang for buck is flowing the heads & manifolds. Improving the combustion chamber.

 

[wallice]

Best bang for buck is flowing the heads & manifolds. Improving the combustion chamber.

Thanks for tips. I'll follow them through. Regards, Greg

 

[Chris R]

For me most of the mods are about making the bike more liveable/reliable rather than outright performance - as Pete Roper was fond of saying enjoy it for what it is not what it aint and it will never be an H2:

- Fit nicasils if not already fitted. Set the squish as tight as possible . This helps a lot with detonation which is a problem with the fuel we have.
- If it is still using points ditch them and fit an electronic system.
- Twin plug - you will have to find someone competent who can do this. Recurve the distributor to suit - typically you can take out 6 degrees of advance at max timing which tells you are going in the right direction. The second plug has to be 10mm and you need to use a bolt instead of stud.
- Yes fit the improved tensioner. Aftermarket gears are a waste of money and will not produce a measurable improvement - I had my engine on a dyno and saw no difference.
- Yes lighten the flywheel as much as possible. Be aware that the metal Guzzi used is a bear to machine and eats carbide cutters.
- 40mm Exhaust pipes help. I don't think the first crossover helps much and cooks the alternator. Not sure if the second one helps much either.
- Improve the oil-separator box by moving the PCV valve to the 'to atmosphere' line and lightly stuffing the box with a curly kate /stainless steel wool. Fit a sump extension if not already fitted.
- Yes flow the heads but finding someone who knows what they are doing is tricky- there are a lot of charlatans out there. If they don't have a flow bench and polish everything to a mirror finish then you are wasting your time and money. I don't know if Guzzitech flows heads and if they don't I am sure they have good recommendations - they would be the first I would talk to. A lot of people recommended Mike Rich - I have never met him and he won't be cheap I am sure but he does have a flow bench, dyno and many years of experience. In Ontario, Canada I would be talking to Gord Bush.

The main problem with the Guzzi is the short turn inlet port- that should be where most changes happen.

I would not make any mods to the combustion chamber short of twin plugging.

Fit the geared starter - the Bosch is nice and rebuildable but is marginal on high comp engines. The geared starter saves quite a bit of weight and you can fit a much smaller battery.

I am of mixed opinion about charging systems - the old bosch system is easy to fix and very reliable if somewhat underpowered. Fitting LEDs is a good move.

Things I would not play with:
Bigger valves: this is very swings and round abouts: the bigger valves may flow more air but limit lift and give you a 'lazy' port. Finding the optimized valve size will require a lot of experimentation and fixing the inlet short turn radius will generate much more results.
Fancy cams. IMO you won't find a lot more power with fancy cams because the Guzzi is limited by its geometry. Most cams just move the power curve. Again yes if you have infinite resources but if you don't and you aren't racing specific tracks what you want is general tractability.
Titanium pushrods, valve caps etc: the gain in RPM when you do the calculation is marginal. If you are rich fine but it is has the least ROI of all mods.
Carrillo rods. Carillo makes beautiful rods but the factory rods are fine. If you intend on changing the stroke, using a longer rod (which is definitely helpful), yes get Carillo to make you some rods but you better know what you are going.

 

[john zibell]

Chris, I did notice one change on my Mk V when I went to timing gears. With the timing chain you could tell when approaching red line. She would run out of steam so to say. When I put in gears, she would pull like a freight train right past red line. Next modification was a Dyna Rev limiter.

 

[Chris R]

"Chris, I did notice one change on my Mk V when I went to timing gears. With the timing chain you could tell when approaching red line. She would run out of steam so to say. When I put in gears, she would pull like a freight train right past red line. Next modification was a Dyna Rev limiter."

Interesting - I didn't find that on the dyno but I did not play with it for long. It was a direct swap and I did time in the cam to the same openings. the bike was fitted with the standard Lemans cam and the revised chain tensioner. Obviously the timing gear locks the timing in pretty solidly and there may be all sorts of resonances going on with the chain causing changes in timing which obviously might have an affect on performance.

I decided to go to the chain after some online conversations with Pete Roper who hates the things.

If there is a performance advantage then great but I think the main thing is too avoid the aftermarket all aluminum timing sets - they will ultimately fail causing aluminum paste and bits to flow through your engine. Proper engineering practice would be to use a harder/tougher material for the smaller gear - i.e.. steel for the crankshaft gear. I know Pete Roper has seen plenty of failures of the all aluminum gears and he sees a far greater sample of modded bikes than probably any one else.

Hope you and your loved ones are surviving the crisis