Tell tale signs a 2t is gonna go bang?

[Martay]

Hi,
Bit out of the blue but;

I was once told a 2 stroke will only last about 10k before needing a rebuild. How true is this?
The bike in question is my Honda SH50 which i mainly use for hooning to town on so i dont have to drag the car out, or when i cant be bothered to fill the car up! The bikes done 11k, 400 fault free miles with me riding it flat out everywhere. Before me, it was a training school bike, im not sure if that means its been thrashed and crashed, or grannied around!
Is there any tell tale signs the piston/rings are on their way out? If it does go bang, provided the barrel ISNT SCORED will it be worn enough to warrent an oversize piston, or will a standard size be sufficient. They are available from a .25 up to 1.0 oversized. I understand you cant say for sure, sat there infront of your computer miles away, but an opinion would be nice
1 more question, a barrel + piston kit with rings, pin and gaskets is £40 delivered. Is that TOO cheap?
Thanks
____________________
Eat well, poo hard
Drives: Cavalier 2.0 16v
Rides: Slightly ratted Honda City Express

[cb1rocket]

thats a good question but I guess its down to mainteance or no mainteance (ie no oil) and an instance bang!

Usually they happen quite sudden without warning, my H100S did this when flat out and holed the piston!

Generally the 10k rule is usually for sport tuned bikes like the RS125 NSR125 etc which involves a new piston and rings.

You could service the bike with new rings and a new piston to be safe but someone would need to clarify that. Every top end rebuild I have done has been rebored and an oversize piston. I have only done it twice on two different bikes over my 7 years of riding.

I tend to favour the saying "look after the bike and the bike will look after you". So if you keep an eye on the oil pump and it's cable and checked that there are no leaks on the oil lines then I couldnt see any problems hitting 40 - 50k which by then you would of probably scraped the bike by then!

[cb1rocket]

And in answer to your question £40 quid does sound cheap then then its bloody good value for money if its a good kit. See if you find any reviews on the kit.

I wish my H100S was like that. You can get a kit for them MINUS the barrell so once my barrell is knackered and no more oversized piston then i'm screwed basically. Unless I went for a linear which is ££££

[Martay]

Ok that sounds good
I know for sure its getting oil, smokes like a trooper when cold, clears when its warm, i do keep an eye on the level. Im just worried about it going and either leaving me stranded or taking the bottom end with it!
Recently i took it for a jaunt which involved 45minutes on an A road. I dont know if it started to nip up or there was a headwind, but the speed dropped off and it wouldnt pull. I stopped to let it cool off. It smelt a bit funky, but after a burger it fired up and ran absolutly fine. I dont really plan on getting rid of it, just keep it going for ever!! I want to see triple figure thousands of mines before i get rid of it!! I might change the piston as a service item. Oversize or standard?
EDIT: Ok so i might get a kit from wemoto rather than this ebay special. 56quid from wemoto!!
____________________
Eat well, poo hard
Drives: Cavalier 2.0 16v
Rides: Slightly ratted Honda City Express

[cb1rocket]

ok if you were going flat out and it felt like it was nipping ie down on power then check the oil pump lever is actually working/moving and that the notches on the oil pump lever is in line or however it should be set up according to the workshop manual (or owners manual if it actually tells you how).

Check the air filter is present and not falling apart causing the bike to run lean. Do a plug chop at full throttle riding / A roads and check the condition of the plug. Coffee colour/tan is what you want. Bits of white spots is ash and your running lean. Black sooty/oily and your runing rich.

Check this guide

https://www.dansmc.com/Spark_Plugs/Spark_Plugs_catalog.html

[cb1rocket]

this is better

https://www.aa1car.com/library/reading_spark_plugs.jpg

[Martay]

Plug chop sounds like a plan, what is one!? Am i right in thinking its flat out, key off, coast to a halt, change plug, ride home, check condition of removed plug? Its got a new air filter as it ate its last one! Oil pump arm starts moving with the throttle, and reaches its end stop at full throttle
Thanks for all the help, its greatly appreciated
____________________
Eat well, poo hard
Drives: Cavalier 2.0 16v
Rides: Slightly ratted Honda City Express

[cb1rocket]

thats the idea but put the same plug back in if you wanted. Take photos at the road side with a good camera or do as you suggested.

Stick the picture up here!

[Bezzer]

[Piercee100]

My H100a is on 17500 miles and never been rebuilt. I bought it off an engineer who gave me its full history- it was laid up for 15 years until he bought it and discovered a duff stator plate. I told him I would examine the piston and barrel when I got it home but he told me not to bother, its running sweet so just leave it until it doesnt I have no idea how long they last but on these engines I've have been told that I should be more worried about the big end going.
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Rides: Honda H100a (Retired), VT500e (Sold), Kawasaki ZX400 (sold), Kawasaki GT550 (Sold), Suzuki Inazuma (Daily), Honda CD185t (Broken), LML Star 2t (Last run edition).

[Martay]

Just been for a lovely run and 'plug chopped' her. Was fun, throttle off, key off, lock up the rear to disengage the clutch. Pushed it into the garden popped the plug out and found this:
https://i279.photobucket.com/albums/kk125/MartayP/P230611_17330001.jpg

Cant really complain i dont think.
____________________
Eat well, poo hard
Drives: Cavalier 2.0 16v
Rides: Slightly ratted Honda City Express

[Vincent]

You need to do a compression test, that'll give you a good idea of ring/bore condition.

[Chriss]

Looks good from here but could do with a profile shot really just to be sure. Can't see the bit that the spark jumps across. The middle of the spark plug, what's that bit called?
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TheShaggyDA: I've got 3 or 4 pairs that predate my wife, so at least 11.5 years old.

[iooi]

[cb1rocket]

[jjdugen]

If its running, its going to blow up. If its not running, it has blown up.

[Martay]

[Vincent]

[temeluchus]

You know when they let up when the back wheel locks up solid and sends you weaving across three lanes of motorway traffic.
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Some shite cruiser. Now with guns and FREEDOM!

[kal9001]

Two strokes needing to be rebuild every 10k is a myth. Its true to an extent on two stroke sports bikes that are built for performance and sacrifice reliability.
If its not "tuned" then many two strokes will probably last longer then a four stroke before any replacements are needed as theres no cam chain or valves to worry about.
A mate of mine once had a Kawasaki KH100...or is it KX100...I dont remember. Hes had it for 10 or so years uses it in the winter or when its wet to commute (Uses an RSV1000 when its nice) and its never needed to be rebuilt since hes had it. Its needed a few new spark plugs but thats meh. He doesnt thrash it and it looks scruffy but the engine is built like a rock.
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Anyone stupid enough to think we will drag a load of wooden horses full of soldiers into our city is certanley stupid enough to drag all of ours into theirs!

[stevo as b4]

As long as a 2stroke bike or scooter is:
1, Well maintained and has the correct oil pump settings and is serviced as per the factory schedule.
2, Not home tuned or has aftermarket pipe and filter fitted without re-jetting etc
3, Is run on a decent fully sythetic oil.

then most bikes will last a very long time. The high performance 200bhp/litre+ bikes will experience much faster ring and piston wear than a low powered commuter engine. The 10'000m reccomendation is more of a guide than anything else, but any high performance engine will do well to run well for longer than this IMO. You normally get harder starting, poorer running and more smoke as engine wear gets more noticable. A compression check is one good indication, but then so is a dyno test. on a 60bhp 250cc bike you might not notice a 10-15% drop in power if it's a high performance engine with a sharp powerband. But if the same bike later only makes say 48-50bhp on the same dyno, then you have a noticeable drop off in power which is a good time to suggest a re-build should be considered.

I do agree that 2strokes can and do blow up, or seize or hole a piston etc with little or no warning from time to time, but assuming The first 3points are adhered to then often a blow up happens only from running a worn out engine for too long when it's overdue a rebuild. You can still get things like gaskets failing causing an air leak, and cold seizures from not warming up a bike properly etc, but a lack of maintainence, use of cheap oil and clueless idiots messing with the engine or exhaust, filters or carb are the most likely reasons for an engine to go pop within it's scheduled maintaince intervals.

I've known people who have said to leave an engine alone that starts and runs ok, and to a point this is good advice. You need to know what sounding ok is like though for your particular engine, as some engines still sound really crisp when they are on their last legs and vice versa. Some engines are more mechanically noisy than others.

My last KMX200 could have saved me a fortune if id known for certain when it was likely to blow up. You can usually tell with plenty of experience though when an engine is worn and sounds a bit loose and rattly etc. I know that on a well abused and bodged KMX that 19480 miles was too much to expect.

I wasn't at this point using it for anything other than short trips and leisure use, as i did'nt have the confience in a 19000mile engine with little history and in a bike that had obviously seen some really serious off road abuse. I was riding back from watchin some motocross racing and was just pootling along down a long 30mph hill less than a mile from my house, when a chunk of piston broke off and allowed the rings to move and get jammed in the ports snapping them and gouging out big chunks of Nikasil plated cylinder bore.

The result is far more expense and hassle than a full top end re-build would have normally been.