Hi All,

It's been a while since I posted a question but have an important one here. Is there any way to replace the lhs crank seal without splitting the cases.

I know how lazy that sounds but with the amount of work I am doing at the moment I will not have time to do a bottom end rebuild, work and keep my family happy.

Cheers again

Andy

Bandit7

If its the same as the '18 & '16 then No! The Seals are lipped to locate in the cases unfortunately..
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More **** two strokes than you can shake a **** stick at.

Being all cases are similar I guess that's a big NO.

Dam it!!!

I guess some silicon is out of the question?

Andy

Bandit_7

bandit_7 wrote:
I guess some silicon is out of the question?

Not at all... unless you fancy a $1000 rebuild in the immediate future?
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Vampire?

NSR-lizard wrote:

bandit_7 wrote:
I guess some silicon is out of the question?

Not at all... unless you fancy a $1000 rebuild in the immediate future?

Not very good with jokes eh lizzy.

That's alright. I have a good sense of humor so I'll laugh for the both of us.

Randy

Bandit_7

Oh yeah. After a little more testing I've found out that:-

1) Yes the lhs crank seal does leak (not as much as first thought).

2) The reeds are sealing perfectly.

3) If there is a center o-ring, it's doing F-ALL.

4) As it turns out, yes, grown men do cry.

Andy

Bandit7

bandit_7 wrote:
Not very good with jokes eh lizzy.

Call my cynical, but you just don`t know with some of the questions here! You could easily have been serious... or taken seriously, as was the case!

I never wished a $1000 rebuild on you though.
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There`s no cure for stupidity… but with the endless supply of stupid people around me, I must be close to finding it!

The Lizard tells it like it is!

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Vampire?

Crankcase seal integrity is paramount for a 2T engine, once any of the seals start to fail, your only ever heading in one direction.

I've been down this road at the very start of my NSR ownership, it seemed a bit of a big job when I first realised the cases must be split, but its actually far easier than that.

You really do need to split the cases, and replace all seals which may be passing. Make sure you have a clutch drum holding tool, flywheel puller and engine frame / stand, this will make the job much simpler.
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Rich
MC21 Track Bike / RS250 NF5 'Spencer', NX5 'Cadalora' & NXA 'Aoyama' / RS500 / Two Brothers Racing RC30

You can even do the crank seals on the NSR without even removing the motor if you want!
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Andy.
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Not bad really,

Top and bottom cylinder off, clutch off then top half of the crank case off.

Crank and its seals are sat there looking at you.
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If I have to take the carbs off once more...

Cheers for all your positive words of wisdom gentlemen.

I guess if I'm going to do the job, I might as well do everything.

New crank, clutch plates and seals all round.

Cheers again

Andy

Bandit7

If said L/H or R/H crank seals are leaking, do they weep fluid that is visible from the outside of the crankcase, or do they only draw air through the failing seal into the crankcase and no fluid goes the other way ?
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Winning isn't everything, but loosing isn't anything

When I did the leak down test I started with the top cylinder as I thought that was the weaker one. I didn't bother to seal the lower cylinder just to see what would happen. I pumped the top up to about 12 psi and started timing. After 3 minutes it fell to about 8 psi and after another 2 minutes it had no pressure at all.

Next I did the same process but with the lower cylinder blocked off. Pretty much the same result. It may have held a little longer but not much.

I then decided to pump up the lower cylinder with the top one unplugged. I noticed that it took a little more air to fill the lower cylinder. BUT the second that I pumped the lower I tried to press on the top cylinder reeds and they were hard.

It would appear that cross leakage is the main problem in my case.

After a few more tests it seems that the outer seals do have a slight leak but the center o-ring has seen much better days.

Any more advice would be much appreciated.

Anyway I'm off to buy another box of tissues. I've cracked the sads big time.

Andy

Bandit7

80XAR wrote:
If said L/H or R/H crank seals are leaking, do they weep fluid that is visible from the outside of the crankcase, or do they only draw air through the failing seal into the crankcase and no fluid goes the other way ?

The left generally draws air and makes the top cylinder run lean, the right will draw transmission oil in and cause the lower cylinder to pump out grey or white smoke.

The centre O-ring can fail and promote leaking across cylinders, but it's more likely the centre seal (which is an integral part of the centre bearing) and not the O-ring that has failed, in my experience.
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Andy.
NSR-WORLD.COM

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