Suzuki 2 Strokes

New outer crankshaft seals arriving soon and I want to refresh my memory about the correct way to install them. I replaced the crank in 1980 but am unsure now of the correct orientation.

The Suzuki T350 Parts Catalogue exploded diagram shows the left seal with its flat side facing inwards to the centre of the crank while the right side seal appears to have its flat face facing outwards towards the primary drive pinion.

The 1973 Haynes 250/350 manual shows a photo with the left seal facing flat side in (as per Parts Catalogue) but a hard to read photo of the right side seems also to show the seals flat side facing in to the crank (not as per catalogue).

A spare motor has the left seal with flat side facing in but I have not had a look yet at the right side.

Anyone with advice about the correct way to install them?

Joe
Maleny Australia

Joe, IIRC, for sure the seal behind the primary drive is flat side facing out. My H2 engines are all built that way and if it'll hold a Kwakker together, it'll be more than good enough for a Suzi.
As to the alternator side seal, it's strange that they show the seal with the flat side facing inward. To my mind, it should be facing outward.
You need to consult with Fred (buffalo-guy) on this because his wife owns a T350J that, I believe, has not had the bottom end disturbed.

I installed the seals on my T350 crank with the flat side facing outwards and tjat is 30000 kms ago...

Thanks for the replies but I went ahead and put the seals in with the flat sides against the main bearings for a number of reasons:

1, the flat sides have small raised ribs that seem to fit nicely against the outer main bearings as if they were designed to act as a spacer and fitted this way also reduce the volume of the crankcase area, possibly speeding gas flow up through the transfer ports.
2, the motor I worked on (admittedly rebuilt by me in 1980) had the seals this way,
3, two spare motors had the seals in this way,
4, the tensioning spring around the seal lip faces in towards the centre of the crank installed this way,
5, the Haynes manual and the parts catalogue shows the seal mounted this way.

The suspect left seal had no grip on the crankshaft at all and a first ride today with the new seals confirmed the motor was now back to full power without all the cranky behaviour such as pinging and erratic running when hot.

Anticipating a return to normal running the carb jetting was set back to the way it used to be with #30 pilot jet, needle clip 2nd from the bottom, air screw 1&1/2 turns out and 107 main jets.

With the leaky seal I had to use #35 pilot jet, needle clip at the bottom and airscrew nearly right in, all to compensate for the air leakage which meant having to suffer 4 stroking at light throttle.

From the replies it seems fitting seals the other way does not harm things anyway so it will be interesting to see how it goes.

I will have to experiment with the old seals by extracting the springs and if they are not endless, undoing one, snipping off a couple of mm and see how they grip with increased tension. If successful they can be parts of last resort if nothing else is available at the time.

On my Honda CX a fork seal leaked at 20000km in 1985 and after shortening the leaky seal's spring back in it went and today, 207000 km later, it still has not leaked a drop.

the flat sides have small raised ribs that seem to fit nicely against the outer main bearings as if they were designed to act as a spacer

Ahhhh....in that case you are exactly correct in your fitment with the flat/ribbed side inward against the bearing.
I'm glad to hear your lean mixture probs have disappeared.

I will have to experiment with the old seals by extracting the springs and if they are not endless, undoing one, snipping off a couple of mm and see how they grip with increased tension. If successful they can be parts of last resort if nothing else is available at the time.

On my Honda CX a fork seal leaked at 20000km in 1985 and after shortening the leaky seal's spring back in it went and today, 207000 km later, it still has not leaked a drop.

Normally, I'd call that a textbook example of bodgery.......however with some crank seals currently in the "unobtainium" category that's an idea that makes a lot of sense. The trick is to calculate how much of the spring to remove.
As for the fork seal "modification", fork seals are so cheap nowadays (and have been for a long time, in North America at least) that, IMO, it's not worth the time to mess with them in that manner.
I see now that at least one distributor we deal with is offering the NOK-Freudenberg OEM seals as originally fitted to 99% of Japanese bikes at the factory. This is surely a sign of hard times for OEM parts suppliers, at least in the motorcycle biz. NOK is a huge company that supplies zillions of seals annually to manufacturers of all kinds of stuff around the world. It's interesting to see that they feel that it's profitable enough to offer their stuff to the motorcycle aftermarket. They have done this on occasion in the past....but their stuff came in a box with someone else's name on it.
Old bike riders/restorers can take heart from developments like this.

Joe.

I have a question:

You mentioned running 107 main jets in your T350.
Stock is 112.5, is it not, why are you using smaller ?

I am having some trouble with mine and wonder if smaller main jets would help.
Everything in mine is stock, new crank, cylinders, pistons, yet it seems to bog down on full throttle and runs better without the air filter.

What do you think ?

I had the same problem with bogging down at full throttle so logic said - use smaller mains even though it used to run happily on 110s. Perhaps its the unleaded fuel we now use. I run a stock paper filter and plug colour is fine with the 107s, no pinging and it revs out well. Sustained running at 100-110 kph has not brought any problems.

One strange thing with my bike since new is that for sustained high speed use (with any main jet size) I have to screw the air screws in to 1 turn out, otherwise it pings on the overrun and is erratic at idle after slowing down. For normal running around town the air screws go back to 2 1/2 turns out otherwise it 4 strokes lightly at small throttle openings.

interesting, tomorrow I will try 107.5 and see what happens

before I do that, I may try using a big K&N filter in place of the stock system and stock jets (112.5) and see how that goes too.

I am thinking, could we both have some restriction in the air flow inside the carbs ?
What about the Needle Jet ?
It has air holes in it has it not and if those are blocked could this be the problem ?

Just to let you know, got it fixed.

As Joe recommended: I fitted 107.5 main jets and everything else stock.
Air screws about 1 3/4 out and it idles nicely at that.
The motor pulls strong and cleanly to the red line with most power from around 5 - 7,500.

The plugs look good colour too.
I am running NGK B9HCS.
Stock is B77HC but all the mechanics here say those plugs are too old and B9 is better,

I don't understand why a stock motor would not run on stock settings, but I guess as long as it works that is OK.

Thank You for your help.

Rodney.