Winter project : J.S. pistons and rods +++

Upcoming winter I rebuild my MK3 engine.
My plan is then to insert J.S. Pistons and rods. Considering also cam and lightweight lifters. Had then intend to increase comresjonen to somewhere between 9 and 9.5., But am I afraid of problems with oil leakage from the pushrod tunnel. Had planned to go for stage 0 cam. I have already J.S. PWK flat slide 34mm carburetors.
Have any of you out there experience this settup. ? Is innteresert to hear about experiences with these products.? Will also install J.S. one-way reed valve breather.
I'm not looking for much increased HK., but more a smooth and strong motor that does not give me problems.
His products look very good.
Is this a good plan?
Will I achieve what I want?

Vidar

I run a JS1 cam and JS 10.5:1 pistons in my 850 and am very happy with it indeed.

I'm not exactly what you'd call a high mile guy, but in the miles I do manage to do, I certainly enjoy what these parts do to the engine!

IMHO I can't really see why one would choose the JS0 when the JS1 is this good!

I posted a longer meandering thread on the topic, see:

engine-build-prep-t18461.html

Fast Eddie said:

I run a JS1 cam and JS 10.5:1 pistons in my 850 and am very happy with it indeed.

I'm not exactly what you'd call a high mile guy, but in the miles I do manage to do, I certainly enjoy what these parts do to the engine!

IMHO I can't really see why one would choose the JS0 when the JS1 is this good!

Click to expand...

Same here with the JS1, lifter, and beehive kit. If ever I need to split the cases again, the JS rods and pistons will surely go in.

Doe it man, and if you have some money left, buy Jim billet cranckshaft to.
I run 10.5CR with a Fullauto head and the original head gasket, no oil leak at all
I use JS 2 camshaft on the road, with a TTI 5 speed gear box and I like it, even the police take pics from me when I am on the road, they are so kind to send me the pics with the speed I was doing,
They just ask me some money for the pics.
To me a Maney cranckcase is a must also, If you rise the power you must do the whole engine with the best parts
doing cheap can be very expensive!
Yves

Ill give you the other side of the coin.
I took the road of reliability and longer life for a road going bike that isnt going to have too much demanded of it.
Gone are the days of hard riding and high speeds. Im older but mostly it is the cost of doing business with The State.
Now even the smallest town police forces are radar if not laser equipped. With the low speed limits on most roads
you are just low hanging fruit.

I have the Stage 0 cam, with the light cam followers. TTI five speed. BNR clutch and belt drive. Fullauto head.
Balanced crank and rods. New Amals.
Mick Hemmings supplied the adjustible isos. John Bould the fork internals. Pazon the ignition. Geoff Goff the
solid state rectifier voltage controller. Sleeved down master and lightened brake rotor.

It goes well enough for me, just out for an early autumn ride, returned alive, without a summons or a appointment
at the doctors.

vidar hjelm johansen said:

Upcoming winter I rebuild my MK3 engine.
My plan is then to insert J.S. Pistons and rods. Considering also cam and lightweight lifters. Had then intend to increase comresjonen to somewhere between 9 and 9.5., But am I afraid of problems with oil leakage from the pushrod tunnel. Had planned to go for stage 0 cam. I have already J.S. PWK flat slide 34mm carburetors.
Have any of you out there experience this settup. ? Is innteresert to hear about experiences with these products.? Will also install J.S. one-way reed valve breather.
I'm not looking for much increased HK., but more a smooth and strong motor that does not give me problems.
His products look very good.
Is this a good plan?
Will I achieve what I want?

Vidar

Click to expand...

Sent you a PM Vidar.

Hi
Thanks for the feedback .
Had hoped there were several who had experience with JS setup, but it seems to be good stuff that he has.

Vidar

Hi Vidar and All,

I'm using Jim's longer rods, standard compression pistons, Stage 0 camshaft and his lifters and pushrods in my 750 Commando (1972) engine. The first objective was not to increase power neither top speed, but to avoid vibrations as the engine is "solidly" (i.e. without isolastics") mounted in a featherbed frame, and to try his parts which are not at all common here in France.

I'm really pleased with the result (very limited vibrations without re-balancing the crankshaft) and the behaviour of the engine, strong power coming from 3500 rpm up to ??? I can't say as I don't exceed 5500 rpm.
On top of that, Jim will provide you with very good recommendations about installing his parts (e.g. checking the valve clearance and pistons, especially if you plan to use high compression ones).

Re: the risk of oil leaks from the cyinder head gasket, I have none. I use one of his (annealed) copper gaskets and his method (thin copper wires glued to the gasket around pushrods and oil return tunnels)

Go for it!

Laurent

Hi Vidar.

I have Jims long rods, stage 1 cam with light lifters, beehive springs. Even with std. comp. (gabless rings) it needs a good kick to move the kickstarter.
I haven´t had the bike on the dyno after I did the engine, but it sure feels much stronger. It ticksover nicely (when on temperatur) easy to ride slowly, but really comes to live above 3000rpm. My Pazon ignition has a build in rev limiter set at 5500 rpm, so haven´t bin above that yet. I´ll have to get that changed and see what she´ll do.

I had the crank balanced, just to be sure. The vibrations dissapear at 3500rpm, I would have liked it to happend a little lower. My dad´s 750 with std rods and pistons is smooth from 3000rpm. This could well be the Company balancing the crank who didn´t understand Jims instruction.

I´d say, GO FOR IT!

Dan

Thank you all for chiming in and telling it like it is.

Looks really nice, but for me one question remains. As we know, in mechanics, problems are rarely really solved, we are just moving them.

So after mounting longer rods and lighter pistons, where have gone some of the vibrations? Magically disappeared? All in the isolastics? In the bearings? The crankcases?

Reducing the piston weight and reducing the angularity of the rods removes some of the stresses.

Not 'move' but remove!

Fast Eddie said:

Not 'move' but remove!

Click to expand...

:wink: