The pump itself can be taken care of, too.
Arthur has done 3 things:
1- drill the main pumpshaft to make it lighter
2- machine the sprocket to make it lighter
3- have 2 o-ring chambers machined to replace the original gasket.
Item 1 isnt doing much but the weight shedding in considerable.
Item 2 is fun, as the gear itself is 15mm thick. Arthur has machined this to 8mm, just like in his racer. After all the track kms at full throttle it showed no sign of wear at all. These, and the other gears, will survive the engine many times over!
Item 3 is done to eliminate the gasket which sometimes damages when removing it from the cases. Sometimes they stick so well to the pump housing it can’t be removed without breaking the gasket somewhere.
To tackle that problem, Arthur had 2 chambers made to fit o-rings, just like on the modern Ducati bikes. The suction has 12.7 x 2.62 and discharge 9.2 x 2.62mm o-rings. The chambers are diameters 18mm and 15mm respectively, and the depths 2.2mm.
Note: the pump housings are cast, and when examined carefully you will find casting ridges in the holes for the suction/discharge. Remove these before the vibrations and flowing oil do!
oil pump mainshaft drilled out for weight saving.
oil pump gear wheel thinned for weight shedding, front side.
oil pump gear wheel thinned for weight shedding, back side.
oil pump gear wheel total thickness 8mm.
oil pump with o-ring chambers, hollow main shaft and lightened sprocket.
During the Benelli 350RS period the front hub drew attention: it had the same brake discs as the Guzzi 350/500 models and the hub looked similar to that of the beveltwin SS spoke hubs, just a bit smaller.
I managed to acquire a hub from another Benelli model (250 2C) and machined the bearing housings to fit the (standard) PT bearing size 6004, as the Benelli hub has a smaller axle size. Also a new spacer was machined to fit between the new bearings.
Quite possible the hubs on some Guzzi models are same/similar to the GTL, and when the major distance between the discs are same to that of the GTL, they can be modified to fit the PT front forks with original yokes.
Yes, that does mean that fitting wider fork, from a pantah for example, is possible so fitting pantah wheels, or wheels with larger major distance between the discs, is possible.
Personally, I prefer the GTL/SD/GTV yokes with GTL/Benelli hub as then the spoke wheels are kept and they are less bulky on such a small nimble machine.
GTL gearboxes have the tapered end with keyway, and new sprockets for them are as hard to find as new crank bearings.
Until I have found a commercially viable method for alternatives for GTL sprockets, I have diverted efforts into the SD/GTV gearboxes as these have the “regular” 6 spline shaft like the pantah. Again, ploughing through the JT Sprockets catalogue an alternative was found, although it was a 520 chain rather than original 530. The thinner chain is not so much an issue as modern 520 chains are extremely strong, but it does mean sprockets for the GTL have to be modified. SD/GTV wheels have the same sprocket carrier as the pantah/750Paso/Sport 16″ wheels, and those sprockets are still readily available.
the front sprocket was found to be the same as a Yamaha 250 dirtbike, and available in Z12 and Z13, just like the 350 and 500 models. A distance bushing is required to ensure correct chain alignment.
front sprocket 520 (SD/GTV): JTF431.12 (350) and JTF431.13 (500).
rear sprocket 520: JTR491.38 and JTR491.40
rear sprocket 530: JTR1022.38/40/41/47
fitment 520 front sprocket: place the collar to the outside so front sprocket backside is flush with rear sprocket backside.
spacer required for 520 sprocket: 22(+0.2/-0) x 28(±0.2) x 6.7(±0.3) mm
advised: strong belleville spring washer DIN2093 22.4 x 45 x 1.25 with loctite 242/243.
We are currently in negotiations to get GTL sprockets manufactured in 530 chainsize
(5/8″ x 3/8″) for both 350 and 500 models, z=12 and z=13 respectively.
Many riders with the desmo head on their PT have come across the need for thicker closing shims. With my 500 head without shims I needed to start from scratch. Having some shims left over from belt drive desmo heads, the valves only needed to have a new groove in the stems roughly 4~5 mm lower than the original to have them instead.
As the 500 head needed new valve seats, larger 600SS/Monster valves were taken and those modified with new grooves, and now desmo adjustment can be done with standard available shims from your local Ducati dealer. Problem solved!
These are increasingly difficult to find. When I still had my Benelli 350RS it also needed a new filter, which was the same as the Honda CB350/400/500/550 Fours. But remarkably these looked very similar to the PT filter, with the exception they are not flat on one side. So the easy thing to do was to make a spacer ring to accommodate for the flat part of the original filter. And it works.
While dismantling few GTV engines I noticed the oil filters were identical, and these may well be the next best alternative to the Champion X315 oil filter:
Of all the parts used in a parallel twin, these are on the top of the list of hard to find items. Not a single bearing distributor nor manufacturer has these bearings in their standard supply, so the best (economical) decision is to make them yourself.
The design has been slightly adjusted with more lubrication groves in the flange to accommodate the axial load of the crank, and the groove in the inner diameter is now whole as compared to the original. The first test samples were made of Aluminium bronze, which was used as bearing material in heavy gas powered combustion engines for the crankshaft and camshaft and rocker arms, hens the first reason for selecting them.
The did not pass the test, as the crank locked up twice on the dyno once above 4000rpm. The cause was found to be the wrong material, and this was supported by literature on bearing designs and backed by experience from several engine tuners.
So with more information I set out to find more suitable material and have at this moment put out quotations. While the test specimens are made, a separate engine will be put together with these new bearings and bolted into leftover GTV frame for dyno endurance testing.
Another trial is converting the crankshaft from plain bearings to ball bearings. This is parallel to the above project to manufacture new plain bearings.
Using the same approach as the Pantah, the left side will have the same steel bearing housing as the pantah (and subsequently all modern beltdrive ducs) together with the angular contact bearing (7207). This is because the angled primary drive pushes the crank to the left under accelertion and therefore almost all of its rotating life.
The right side will get a conventional ball bearing to take the radial load and the occasional axial load during engine deceleration.
The crank does need modding to get the oil into the crank (right side) and to both bigend journals. Oil supply will be from the oil gallery where the oil pressure sensor is located.
right side welded up to add material
left side welded up to add material
Parts & Bikes for sale.
As of today I added a menu where you can offer your parts and/or bikes you want to get rid of. It might help your fellow Parallel Twin owner to keep these beauties on the road. If you send me pictures of the parts or the bike you want to sell I will put it on my site
There are many ways to upgrade the Parallel Twin engine. One of them is realizing an external oil feed as Arthur van Til did. He didn’t weld small manifolds to the top of the cylinder head like Mototrans did but he used the left hand cam bearing cover. To make sure the oil reaches both camshafts he made a connecting piece as well. With this “easy” way you don’t have to weld directly to your cylinder head. The options are to either open the engine cases and block the oil passageway at the bottom of the studs, or block the oil orifice on the left hand side of the cases just below the cylinder bank.
Blocking the oil passage in the orifice
The oil orifice/restrictor bolt in the top left case can be blanked off.
I did this by tapping M4 into the crossover hole and putting a threaded plug in here with thread sealant. Peen the edges so the threaded plug cannot get loose.
The theory is: the oil goes through the 1mm orifice and into the crossover hole. It cant cant go past the o-ring so it must go through the orifice. Since drilling and tapping a threaded hole into the 1mm orifice leaves you with an o-ring stuck on your drill/tap, the crossover hole is large enough to fit a grub screw. The added advantage is that if it were to get loose the grub screw cannot fall into the channel and into the main bearing.
the orifice/restrictor bolt with threaded crossover hole M4
the grub screw made from M4 screw and slot made by sawing
grub screw in the orifice with thread sealant. I am not advertising the brand as shown, there are other alternatives.
Connecting the camshafts together:
Using an Aluminium bushing with 2 orings and a passageway provides the oil form the lefthand camshaft to the righthand camshaft. You will need to removes the Aluminium blanks from inside the camshafts, and drill/grind a hole in the lefthand camshaft, diameter 4~5mm. Note: the camshaft is hardened, I grinded the first 3mm with a pencil stone bit in the die-grinder and then with a normal HSS drill. Wash and blow out the camshafts!
Similarly, instead of using a pencil stone bit, a solid Carbide drill can be used in one go to make the hole.
Lefthand camshaft drilled through, 5mm hole.
Just to let you know that here at the PT-headquarters work is always in progress. Not allways with bikes, parts and projects but sometimes allso with things not directely related to our beloved bikes. Throughout the world I am contacted about the Ducati Parallel Twin and what would be nicer than to show your fellow riders the affinaty with Panigale Twins. I can present you now with a Panigale Twins patch which you can attatch to whatever you like. The patch is aprox 8×8 centimeters as shown in the picture. For €10 ex shipping you can be the proud owner of one of the patches. Please contact me if you are interested.
Last week I came across some parts. The former owner told me that he bought these parts long time ago from someone who was involved with racing. I know there has been racing with Ducati Paralleltwins but concerning race parts and teams there is very little known. On one of the stripped bikes I bought there is a sticker on the forkleg seen in this picture. If anyone has information about Racing Team Mosna I would really appreciate it.
Okay I agree….. it is not a Paralleltwin but I just whant to share this picture with you. This guy in The Netherlands took a 500 SD and modified the frame so it would take a BMW 650 engine. Not a bad job I might add !