125cc regolarita project

E

eglibob

Guest
Here's a pic of my current Laverda project, which is a nice original 125cc America Trail fitted with the US market 150cc barrel and piston . Over the next 6 months I`m hoping to transform it into a works ISDT type Regolarita Corsa 'Casa' with a view to entering it in next year's Land's End Trial and if all goes well, many more trials after that.
The factory Regolaritas were highly modified machines and were quite different from the production machines; larger wheels, trellis style frame, different forks, tank etc etc . It's going to be quite a complicated process to carry out the conversion so my timescale might be a little optimistic but we'll see how things progress.
I`ve had a ride up the road and intial impressions are favourable, I`m hoping the finished article will weigh approx 90kg and with a 200mile range should make a really good long distance trials machine
 

Attachments

  • america trail.jpg
    america trail.jpg
    63.7 KB · Views: 64
Nice one, Bob!  It's very good of you to provide us with these entertaining stories, you know  ;) ... Keep posting!

Buona fortuna!

Ciao

Craig
 
Indeed it was Keith, which was one of the reasons I wanted to get find one; these Massimo designed 125s are the link between the very successful 1950s Francesco Laverda period bikes and the glory days starting when the big twins came into production.
They are nice little bikes but very rare nowadays and quite difficult to get hold of. It took me quite a while to find this one and I can't remember ever seeing one in the UK. I think spares are going to be a challenge....
 
Hi Michael , I must confess that I`d already plundered your site for the RC images, in fact your site is just about the only resource on the web which has any reference for these machines. Despite the dearth of info my research is starting to come together nicely although I still have no idea what the origin of the Q/R rear hub is on these machines and I'd love to get hold of the works piston and cam spec.
Thanks, bob
 
Bob, I think that in every one of the 150 engines I looked into when I had them (all went to Bill and Wolfgang) the pistons had broken at the ring groove located near the bottom of the piston.  I'd suggest you find some alternative piston from another bike, preferably one a bit more modern.  I'm going to try a Suzuki GS500 piston in a 250 Motobi.  Same bore size, same wrist pin, modern rings, and it is a typically nice ART casting.  It also has a bit of a dome instead of the stock flat piston so there'll be a bit of compression boost.  The only issue is the deck height is lower so I'll have to shorten a cylinder a bit. 

The 150 is said to be 58mm bore.  The Wiseco catalog shows the Honda XR/CR100 of 1985-2006 with a 58mm bore and a 14mm wristpin.  The 2004-5 Suzuki DRZ125 is 57mm and Wiseco offers 57-61mm replacements.  That is also a 14mm wristpin.  It looks like an FZR600 was 59mm with a 16mm pin.

Replacement parts are where you find them.  :)

cheers,
Michael
 
...not all the pistons were broken...but they are still available. And I agree with Michael an alternate piston would be best since the four ring design leaves a very weak spot were it WILL break sooner or later

should make a really good long distance trials machine
None of the bikes I got from Michael had more than 2000 miles. I realize that Americans don't ride their bikes much but as Michael said the pistons on these bikes should have been in a Zane bike...that's a joke... :D
 
Thanks for the advice Michael [and Bill]. The engine is running very sweetly at the moment and for the time I`m going to concentrate on the cycle parts, which is quite a complex conversion to bring it up to Regolarita spec. Looking at the mods on the work's bike its clear that the factory predicted, or had experienced, serious problems with frame strength on the 125s when used in anger. The amount of extra bracing used on the competition machines is quite considerable and appears to have been very carefully thought out, in fact this is the most interesting Laverda project I`ve ever worked on.
I`ll look into the Honda piston situation, in fact I`m also looking for a 54mm four stroke piston for my 100cc Corsa , any suggestions?
 
The Wiseco catalog shows the XR100/CRF100F as having a 53mm bore, and Wiseco offers 53.5-55mm oversizes.  That's with a 14mm pin.  I got XR100 pistons to use in a CB160 trials project and they are pretty  flat on the top (Wiseco says 9.4:1 CR for their pistons until you get to the 12:1 58mm big bore piston).

cheers,
Michael
 
Thanks Michael , when I was in Italy recently I visited a 100cc Laverda specialist and he had a Honda piston in his hand which he said worked well in the Laverda 100cc machines. In my haste to buy up as many NOS spares as my pocket would allow I forgot to ask him which model the p[iston came came from. I have a feeling you've answered it! We never got the XR100 series of machines in the UK and so my local Honda dealer looked blank when I asked him about 54mm four stroke piston availability.
It's very kind of you to take the trouble to look this up and is very much appreciated, Bob
 
Bob, Wiseco, as do many other of the aftermarket suppliers, has catalogs available for downloading:

http://www.wiseco.com/Catalogs/Powersports/CompleteCatalog.pdf
http://www.wiseco.com/Catalogs/VTwin/CompleteCatalog.pdf
http://www.wiseco.com/Catalogs/Automotive/CompleteCatalog.pdf
http://www.wiseco.com/Catalogs/Snowmobile/CompleteSnow.pdf
http://www.wiseco.com/Catalogs/SportCompact/CompleteCatalog.pdf
http://www.wiseco.com/Catalogs/Marine/CompleteCatalog.pdf

I've got Carrillo, Kibblewhite/Black Diamond Valves, ProX, Ferrea, EBC, R/D Spring, Megacycle Cams, etc that I've saved so that I don't have to wait for downloads.  Luckily, it seems to be more common for there to be a fair bit of technical information in the catalogs, and not just blingy marketing hype.

cheers,
Michael
 
Well, due to other projects and commitmemnts, progress on the Regolarita Corse has been slow. It's just had a bit of a shove forward this week because my pal Gavin [Spencer] has completed the tank conversion. The works bike had a neat little toolbox /competitors score sheet holder let into the top and Gavin has done a fine job of replicating it from pics of the original bike. The frame has been converted from a spine type into a trellis arrangement as per the works bike . Still a long way to go but I'm hoping to enter it in the Land's End Trial next spring. I'm currently looking into the feasibility of converting from a 4 speed into a 5 speeder [the works bikes had 5 ratios]....
 

Attachments

  • ISDT regolarita.jpg
    ISDT regolarita.jpg
    274.2 KB · Views: 32
I'll be watching your progress Bob. My Renegade project hasn't had a bump in a very long time...
 
Hi all

Here's a 125 with only 89km - see For Sale

http://www.oldiesgoldies.eu/

Great project Bob

Cheers
Jason
 
Hi Bob,

perhaps a couple more options you could look at for piston suppliers:

www.powroll.com/index.htm

www.classic-motorcycles.co.uk/cgi-bin/ecom.cgi?Command=ListProducts&db_scid=118

I found them whilst looking at possible replacements for my 75's piston.  I was looking for XR75 pistons first, but they don't seem to be listed at any of the usual old Honda parts suppliers.  Small Honda ATC engines such as the ATC70 seem a possibility (I converted my Honda SS50 moped to 70cc and frightened FS1E owners :evil:) for the smaller engines and there seems to be a fullish range of bore sizes.

Chris
 
Thanks Chris,
I opted for an Aermacchi piston and have ordered one from Italy just last week. I've no idea which model it's from, but I know that it has worked well on the 100s and gives a capacity of 105cc. Despite being for an Aermacchi I believe it's a Japanese piston. It has different gudgeon pin height and requires the barrel to be milled off at the base to accomodate this and also a larger small end bush.
I've got two projects on the go at the moment and my brain is losing its capacity to retain details!
Cheers, Bob
 
Back
Top