- Joined
- Nov 20, 2001
- Messages
- 17,028
- Location
- Ely, England
Had the good fortune to strip a sherco 4.5i this week and have a look at the innards. so i thought i'd saher some of what i've seen with you.
the counterbalancer is on a seperate shaft infront of the engine and all it is is a triangle of metal held on one corner and the weight is thrown between the flywheel cheeks while the con rod is elsewhere! cool!
the rocker arm to cam is identical on the exhaust side to a husey, however the pressing part is much shorter - say 10mm or so and the end of the foot is the more normal domed 'knob' as apposed to the husey 'pad'. each valve has a very thin shim on it with a 2mm shoulder. the total depth is as little as 1.4mm plus the 2.
springs are conical and about 3mm shorter than mine plus a coupla mill narrower.
at the stem there is more valve showing above the collet groove but the collets are far smaller than the husey and the VS cap isn't so deep. it's fffffffffffaaaarrrrr easier to get the ph&^&n collets out. i think husey may share this now.
because the included valve angle is less than the husey (10mm + 10mm off the rocker arm length means the valve tips are 20mm closer) it's very hard to get the 10mm spark plug spanner between the 'bumps' on the end of the rockers - impossible so i had to 'modernise' a new plug socket!
same system as husey regarding the bolts through the end of the rocker shaft caps and also the other bolts, the split head to hold the cam etc.
the cam looks like it could well be the same dimensions as husey/ktm but surely a wicked profile given that the cam must do more work to get the same lift as a husey.
the inlet rocker shaft is far shorter than the exhaust and the shaft has no hole or groove whilst the middle of the rocker has no 'eye hole' so how any oil gets around i. do. not. know! shout **** up!
the decompressor, a weakness before is similar to husey but lighter pivot shaft.
oil is fed into the top of the cover via an external oil pipe and the enters above the two follower bearings. the bearings share the same outward dimensions as husey but the pins they turn on are 8mm and not what 7.9mm (i get confused?). the valves are about 2mm shorter than mine but will be the same as later huseys and their dimensions are 35/30 for both the 510 and 450 engine.
ports are very, very well cast and very little would be required to do to them. like really narrow seats and no restrictions. they've actually taken all the meat away from just inside the port which isn't very bright.
plug is nippon with two earths. code - forgotten for now!
nikasil lined barrel which isn't removable. piston usual and just to say that the bore is 94 by 64 stroke. 'ours' is 100 x 57. mine will be 97 x 60 but remember that kurt nicholls experimental engine was 94 x 64....
gearbox is confusing as it's all the other way around and to change gear they have a similar set up but a shaft goes across the back of the engine to facilitate LHGC.
ignition is in oil behind th left cover and the engine has a wet sump in that the oil falls through a false floor.
camchain has really tiny links which when held side-by-side the links line up every 5th or 6th so that tells ya! same amount of teeth though at 18 and 36. split link while it was once soft link.
there is a kickstart on it and the boss on the back right works with the simple 'Z' teeth and a light spring to push them apart when running. there are several gears in the sidecover that are light and delicate - they transfer power from the usual mitsuba SM14 down to a huge sprague on the end of the crank.
the clutsh is by simplex and is huge! it is spring damped in the back hub.
con rod length is 120mm for the 64mm stroke so it's very short by today's standards. little end is a husey like 20mm and the b/e is 35mm same as the later 628 huseys.
mains are 13 roller each side with shoulders only one way so when you split the engine half goes one way and half the other! same dimensions as husey at 62 - 30mm.
the camchain tensioner is a spirally sprung screw so in order to make it wait till you're ready you need to put a screw down the middle to press against it. fit it and release the screw and it spirals into the TB.
the TB guide is about 10-12" long on one side and on the tensioner side is about 8" - so it's still longer than a husey!
now the oil circulation is interesting. it is picked up like a car from 10mm off the floor so if you're short of oil you can have plenty but if the intake can't reach it you're knackered. there is a filter on this. the oil then enters an eccentric pump which is a 4 cornered star in a five cornered chamber. the oil goes from the right back across to the left case, up and then across to the oil filter. from here there is a bleed down ont part of the casting at 45d over the gearbox assembly so this splashes everywhere.
the main feed then goes along the top RHS of the engine and goes behind the barrel for an external pipe to take it up and over to the middle of the cam cover whilst the other feed carries on till it's over the RHS main and with a little nipple it squirts straight up under the piston.
on huseys we collect oil here for the RHS main.
there appears to be catch or a feed to the waterpump end of the cam which i haven't checked out and BTW that waterpump is alloy and it's HUGE! it's 2" i think.
i've also been around a 250 beta tonight and that has the same locknut and screw set-up as husey but it takes the oil pipe idea that sherco have. who was first? not sure but the oil poipes appear to be identical to the point that they fit correctly on the beta and badly on the sherco. definately borrowed!
oil is allowed out behind the raer of the sump and on the right. the rear has a 1" tampon filter and a magnet on the side one.
the garboxes could be similar but i can't be arsed to check. if i strip it and forget are you lot gonna help me? no!!!!!!
so
that's it.
a run around a sherco engine. hope you could imagine it and maybe some of it resonates widchyu.
regards
Taffy
the counterbalancer is on a seperate shaft infront of the engine and all it is is a triangle of metal held on one corner and the weight is thrown between the flywheel cheeks while the con rod is elsewhere! cool!
the rocker arm to cam is identical on the exhaust side to a husey, however the pressing part is much shorter - say 10mm or so and the end of the foot is the more normal domed 'knob' as apposed to the husey 'pad'. each valve has a very thin shim on it with a 2mm shoulder. the total depth is as little as 1.4mm plus the 2.
springs are conical and about 3mm shorter than mine plus a coupla mill narrower.
at the stem there is more valve showing above the collet groove but the collets are far smaller than the husey and the VS cap isn't so deep. it's fffffffffffaaaarrrrr easier to get the ph&^&n collets out. i think husey may share this now.
because the included valve angle is less than the husey (10mm + 10mm off the rocker arm length means the valve tips are 20mm closer) it's very hard to get the 10mm spark plug spanner between the 'bumps' on the end of the rockers - impossible so i had to 'modernise' a new plug socket!
same system as husey regarding the bolts through the end of the rocker shaft caps and also the other bolts, the split head to hold the cam etc.
the cam looks like it could well be the same dimensions as husey/ktm but surely a wicked profile given that the cam must do more work to get the same lift as a husey.
the inlet rocker shaft is far shorter than the exhaust and the shaft has no hole or groove whilst the middle of the rocker has no 'eye hole' so how any oil gets around i. do. not. know! shout **** up!
the decompressor, a weakness before is similar to husey but lighter pivot shaft.
oil is fed into the top of the cover via an external oil pipe and the enters above the two follower bearings. the bearings share the same outward dimensions as husey but the pins they turn on are 8mm and not what 7.9mm (i get confused?). the valves are about 2mm shorter than mine but will be the same as later huseys and their dimensions are 35/30 for both the 510 and 450 engine.
ports are very, very well cast and very little would be required to do to them. like really narrow seats and no restrictions. they've actually taken all the meat away from just inside the port which isn't very bright.
plug is nippon with two earths. code - forgotten for now!
nikasil lined barrel which isn't removable. piston usual and just to say that the bore is 94 by 64 stroke. 'ours' is 100 x 57. mine will be 97 x 60 but remember that kurt nicholls experimental engine was 94 x 64....
gearbox is confusing as it's all the other way around and to change gear they have a similar set up but a shaft goes across the back of the engine to facilitate LHGC.
ignition is in oil behind th left cover and the engine has a wet sump in that the oil falls through a false floor.
camchain has really tiny links which when held side-by-side the links line up every 5th or 6th so that tells ya! same amount of teeth though at 18 and 36. split link while it was once soft link.
there is a kickstart on it and the boss on the back right works with the simple 'Z' teeth and a light spring to push them apart when running. there are several gears in the sidecover that are light and delicate - they transfer power from the usual mitsuba SM14 down to a huge sprague on the end of the crank.
the clutsh is by simplex and is huge! it is spring damped in the back hub.
con rod length is 120mm for the 64mm stroke so it's very short by today's standards. little end is a husey like 20mm and the b/e is 35mm same as the later 628 huseys.
mains are 13 roller each side with shoulders only one way so when you split the engine half goes one way and half the other! same dimensions as husey at 62 - 30mm.
the camchain tensioner is a spirally sprung screw so in order to make it wait till you're ready you need to put a screw down the middle to press against it. fit it and release the screw and it spirals into the TB.
the TB guide is about 10-12" long on one side and on the tensioner side is about 8" - so it's still longer than a husey!
now the oil circulation is interesting. it is picked up like a car from 10mm off the floor so if you're short of oil you can have plenty but if the intake can't reach it you're knackered. there is a filter on this. the oil then enters an eccentric pump which is a 4 cornered star in a five cornered chamber. the oil goes from the right back across to the left case, up and then across to the oil filter. from here there is a bleed down ont part of the casting at 45d over the gearbox assembly so this splashes everywhere.
the main feed then goes along the top RHS of the engine and goes behind the barrel for an external pipe to take it up and over to the middle of the cam cover whilst the other feed carries on till it's over the RHS main and with a little nipple it squirts straight up under the piston.
on huseys we collect oil here for the RHS main.
there appears to be catch or a feed to the waterpump end of the cam which i haven't checked out and BTW that waterpump is alloy and it's HUGE! it's 2" i think.
i've also been around a 250 beta tonight and that has the same locknut and screw set-up as husey but it takes the oil pipe idea that sherco have. who was first? not sure but the oil poipes appear to be identical to the point that they fit correctly on the beta and badly on the sherco. definately borrowed!
oil is allowed out behind the raer of the sump and on the right. the rear has a 1" tampon filter and a magnet on the side one.
the garboxes could be similar but i can't be arsed to check. if i strip it and forget are you lot gonna help me? no!!!!!!
so
that's it.
a run around a sherco engine. hope you could imagine it and maybe some of it resonates widchyu.
regards
Taffy
