How do you know when you need a rebuild?

[fuzz]

What signs are there that tell you it's time for a rebuild on a 2t? I ask as the NSR is around it's 10,000 mile mark, but I know they can go up to twice that mileage before needing a rebuild. I'd like to find out before it pops on me.
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https://www.bikepics.com/members/fuzzbcf/
Bikes: '99 NSR125R, '00 SV650S, K1 GSX-R600, '97 CB500, K3 SV1000S, '16 VFR800

[stinkwheel]

Mostly I would expect the small ends to last for 20k miles. Other than that, you would be looking at wear in the bore/rings which doesn't really cause them to go bang, they just go down on power.
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“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[Kye]

I'm pretty sure its a new piston / rings every 8k on most 125cc strokers, and for the sake of a few hours labour, why risk your bike?

[pipnet11]

[binge]

What about on a 70cc (tuned) scooter... When should I replace my piston ring...
Ive done about 600 miles on it now (since the rebuild)...

<|Binge|>

[DM]

[Kye]

[cagiva gezzer]

Any strange noises such as rattles indicate that something is getting worn and needs changing. Worn top ends also have poor starting, if changing the plug doesn't improve the starting its prob something to do with the rings/piston.

However, if you don't know what a good engine sounds and feels like, you're shafted as you've got nothing to compare it to.

I'm the sort of person who likes to stip engines and check everything. I've been the person who says "umm, sounds strange, i'll sort it next week..." and it cost me too much $$$.

As said, once you know what your upto its only 2hours max for a topend and less than a day for a full rebuild.

And yes, that nice crisp feeling is wonderful!
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"because one stroke isnt enough and four strokes waste two"

[stinkwheel]

Well my 350YPVS did 16k miles before it needed a rebore and that was tuned (professionally) off its nuts. It is essentially two 125s stuck together so I am not sure what they are doing to them these days if you only get 8k out of a piston and set of rings. Maybe a feature of plated barrells?
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“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[Git]

You know when you need a rebuild when.

The bike just dies and sounds like a wet fart
You have an awesome firework display out the exhaust on motorway better than any carbon show
Little compression on starter
A scaffold pole has trouble moving the kick start


I got into the habit of changing the top every 10,000miles then at 30k new crank bearings and rods, never had a 2stroke let me down blow up wise, apart from my first lesson :mrgre

[fuzz]

The MOT needs renewing in a few months so I'll get them to do it first. It'll probably in the 11k-12k region by then, and they're less likely to find minor faults if I give them some work too. Cheers
____________________
https://www.bikepics.com/members/fuzzbcf/
Bikes: '99 NSR125R, '00 SV650S, K1 GSX-R600, '97 CB500, K3 SV1000S, '16 VFR800

[Kickstart]

Hi

The NSR seems quite good on piston rings. The exhaust port has a bridge across the middle of it which will do a good job of supporting the rings and reducing wear. As such I would just do a compresson check and see if it is withing spec (142psi give or take 28psi).

Everything else I would just tend to wait until there is a problem (the whine of main bearings or the knock of the big end bearing).

All the best

Keith
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