Engine Sounds Like Arse

gerg · Borekit Bruiser Joined: 09 Mar 2016 Karma :

as the title says... it's a 2 stroke RXS 100, I drive it like I stole it, it's pretty old now I doubt the engine's been rebuilt before, the engine has slowly gotten worse and worse now it doesn't rev properly, sputters and misfires, doesn't run smoothly like it used to at all. Can still get to top speed but not very smooth when you are trying to stick to one speed if you get what I mean?

Does this sound like symptoms of needing rebuild or something else? I've heard these particular bikes are quite hardy and can take a thrashing. I recently put an expansion chamber and all these symptoms got much worse.

chris-red · Have you considered a TDM? Joined: 21 Sep 2005 Karma :

Did you change anything else?

If you just bunged an expansion chamber on it would have fucked the fueling. You need to set it for the new exhaust.

What exhaust did you put on? RXS performance exhausts are pretty rare.
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gerg · Borekit Bruiser Joined: 09 Mar 2016 Karma :

It's a micron, yeah I've heard they're pretty rare

will it just be the air screw I need to adjust or will it need a bigger jet or something?

chris-red · Have you considered a TDM? Joined: 21 Sep 2005 Karma :

Hahadumball · World Chat Champion Joined: 07 Oct 2015 Karma :

its an rxs 100 not fireblade.
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Polarbear · Super Spammer Joined: 24 Feb 2007 Karma :

gerg · Borekit Bruiser Joined: 09 Mar 2016 Karma :

what's a fireblade i've never heard of them...do they need rebuilding a lot??

What else can you change on the carb apart from the air screw and jets?

gerg · Borekit Bruiser Joined: 09 Mar 2016 Karma :

Polarbear · Super Spammer Joined: 24 Feb 2007 Karma :

Put the original exhaust back on and start from there.
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chris-red · Have you considered a TDM? Joined: 21 Sep 2005 Karma :

gerg · Borekit Bruiser Joined: 09 Mar 2016 Karma :

exhaust got run over by a cager

gerg · Borekit Bruiser Joined: 09 Mar 2016 Karma :

so is it fueling related and definitely not piston related? it also used to make knocking sounds but it stopped doing that lately

Hahadumball · World Chat Champion Joined: 07 Oct 2015 Karma :

Hahadumball · World Chat Champion Joined: 07 Oct 2015 Karma :

get off your bike and learn about 2 strokes before you turn it into a pile of parts.

you cant get on it every day rag the shit out of it, race tune it bruv and then expect it to last.

give it a complete top end rebuild because its like £30 tops

then focus on the exhaust otherwise youre gonna fuck the fueling up, put the already badly worn engine under more strain and destroy it.
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Fin: no matter how much I look at It I can't understand what was going through my head, all I remember is going about 80 and redlining it to stop it seizing.
360 Deg... Five 1/4 turns. :- Teflon-Mike 18 Jan 2015

gerg · Borekit Bruiser Joined: 09 Mar 2016 Karma :

ok thanks I will do that... gonna have to continue ragging it for now cos well it's fun and i'd be late for work otherwise, circumstances might change soon, hopefully it doesn't blow up in the meantime

331X2 · Crazy Courier Joined: 10 Jul 2013 Karma :

Do a plug chop and post a picture Thumbs Up

nitrosurf · Trackday Trickster Joined: 18 Jun 2010 Karma :

Back when I was considerably younger I played around with 2 stroke scooters a lot. Apart from the way the power is put to the back wheel the principles are the same. I spent a lot of time setting carbs up to match the Italian exhausts I was getting a good deal on at the time. It was a pain in the arse! Worth it when you're 16/17, my Piaggio beat EVERYTHING off the lights up until 30mph... and topped out at nearly 60mph on the (probably very optimistic) speedo (50cc). The thing is, if you're just looking for cheap fast thrills bolting stuff on won't work. It's cheaper to just buy a bigger bike. Trust me.

Fun if you like tinkering though (just don't start me on variomatic transmission weights...)!

Pete. · Super Spammer Joined: 22 Aug 2006 Karma :

Might be the main bearings need doing. Does it smoke a lot more than normal?
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stevo as b4 · World Chat Champion Joined: 17 Jul 2003 Karma :

Have you done a compression test yet?

It probably wants an engine rebuild, as others have said the bits should be cheap enough for that bike, if your doing it yourself. If it needs a crank and main bearings, you might get an exchange item from a specialist, cheaper than having your crank re-built.

If the motor was good and healthy, simply bolting on a different exhaust won't kill it, or make it run that bad and sound like a bag of spanners IMO, it's just you might end up with poor midrange Carburation or flat spots, without some careful re-jetting to suit.

gerg · Borekit Bruiser Joined: 09 Mar 2016 Karma :

It's not about getting cheap thrills, just want the thing to run smooth really. I know ragging it doesn't help though. Don't really know much about 2 stroke engines but would like to learn more

It does smoke a bit, don't know if it's more than usual though. Why would main bearings cause that?

Haven't done a compression test yet, that'll be my next course of action then!

Thanks for ideas