tried-them-all wrote: ↑18 Nov 2021 22:51
BTW is there a simple way to distinguish between a strada and sport engine without looking at the naked pistons? I can drop a camera into the plug hole if needed...
A sport engine would originally have had an 'S' stamped on the crankcase below the front barrel on the right hand side
But that doesn't really tell you anything as after 40 years the important different parts could have been changed out.
Those parts are really only pistons and camshaft
Pistons- placing sport and strada pistons side by side you can see the difference due to the fact that the sport pistons are taller to reduce the squish volume. I don't know how you could tell with the cylinder head still fitted. You could do a compression test but that won't really tell you anything as there are too many other factors at play (wear, valves, cam profile etc etc)
Camshaft- Probably the easiest thing to check with a bit of measurement. With the valve clearance set at the reference check clearance of
1.0mm a dti on the valve, and a timing disc set up then you should get the following:
SPORT CAM:
intake valve opening at 28 deg btdc
intake valve closing at 55 deg abdc
exhaust opening 57 deg bbdc
exhaust closing 25 deg atdc
STRADA CAM:
ivo 12 deg btdc
ivc 42 deg abdc
evo 42 deg bbdc
evc 12 deg atdc
If it's a kanguro or a late 350 then it probably has an M cam:
ivo 24 deg btdc
ivc 49 deg abdc
evo 55 deg bbdc
evc 23 deg atdc
Or it could have an E cam if it's a kanguro but I don't have the timing data at 1mm lift for an E to hand.
If setting up with a degree disc is not possible then you can get a quick indication of the cam type by measuring max lift. I measure lift at the pushrod because I have measured cam profiles and so doing it at the pushrod means you don't have to take into account the rocker ratio.
Max
cam lobe lift (intake and exhaust) of a sport cam is 5.8mm whereas a strada is 5.3mm and an E is 5.6mm
An M cam has a slightly higher lift at 6.2 intake and 5.9 exhaust (That doesn't necessarily mean an M cam is better than a sport as the duration is shorter.
Let us know what you find!
By the way, just for others reading this thread, I think it's important to point out that there are other changes made to the engines over the years, which may not make a performance difference per se but should be aware of, particularly if building up an engine from parts. The main ones from my perspective are:
different types of stator/flywheel- later ones with wider bobbins and increased output, flywheels with starter shoe drum. Some alternators have an extra white wire which is an additional earth and can be run to the transducers, and of course the mixed 6V/12V charging system of some of the offload bikes.
Main bearing- Early 350s had a ball bearing on the alternator side, later engines had a plain bearing. It doesn't really matter which type you have but be aware that they increased the oil pump flow with the plain bearing so if you have a plain bearing make sure you have a 7 start on the worm gear rather than a 6 start oil pump. You can tell if you have a plain bearing as behind the alternator there will be 3 small caphead bolts which go through the crankcase and bolt the plain bearing holder in place.
Barrels- Later 350s had nikasil coating on the barrels. You can tell these as they are one piece with aluminium liners rather than inserted steel liners, and the nikasil barrels have 'gilardoni' cast into the pushrod tunnel between the fins. Nikasil barrels wear significantly less and can run a tighter clearance. It was probably done for noise reasons but nowadays on our worn out bikes the most significant benefit is that they are probably still not worn out compared to their steel counterparts. It doesn't matter whether you have nikasil barrels or not but you need to make sure the correct pistons and rings are used for each type.
Pickup- Don't go putting an engine into a different bike 'as-is' without making sure that the pickup on the donor engine is compatible with the transducer in the frame. Again, it doesn't matter which pickup/transducer combination you have, so long as they are the correct pairing with eachother.
Finally, all the above engine differences relate to the pre-kokusan engines. When you get into Cougaros, Darts and Late excalibur/new york then there are further differences around the ignition system and starter motor/primary drive.