Two stroke issues! HELP!

Bishopbiking · Derestricted Danger Joined: 06 May 2016 Karma :

Hi everybody. New to the forums and I'm in desperate need of help.
I've recently acquired an NSR125rr foxeye. Ran well when I got it however I've chosen to run premix for safety.

Since I've owned it. A little over two months I've noticed its complete inability to hold coolant for more than a few days.

I have not modified the bike at all however got home from a small ride yesterday to a change of tone from the engine, the bike won't idle and just cut out when I let the throttle off and wouldn't start again.

Today I've cleaned the carb and new fuel put on and still nothing. The bike will only start by bumping and rides fine but engine sounds completely different to how it normally does. And once again still won't idle.

There's a ticking type noise coming from the engine.

Any ideas? All help appreciated. I paid little enough to justify scrapping just need an idea.

andy_uk · World Chat Champion Joined: 13 Aug 2011 Karma :

I'm no expert (apart from having had a rather 'needy' 2-stroke...) but here's my idea:

Did you re-jet or adjust the needle height after switching to premix?
If not then it would be running lean - which means hotter...that could maybe explain the coolant issue if it's been running too hot.

The change of engine noise could be a few things but given the fact it could be running hotter it may have briefly heat seized, possibly scoring the barrel/piston. This would explain the poor starting & lack of idle.
A compression test would be the sure way to tell though.
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Aprilia Classic 125, GS500E, ER5-A1, ER5-C4, ER6 & an XJ6 project frame...

kurmit123 · Derestricted Danger Joined: 13 Apr 2007 Karma :

as andy says seized up i think
also could be head gaskets gone, that would course your water to spit out
what does the plug look like?

Ste · Not Work Safe Joined: 01 Sep 2002 Karma :

Stop running premix whilst praying that not much damage has been done?

Bishopbiking · Derestricted Danger Joined: 06 May 2016 Karma :

Thanks for the advice

i was thinking headgasket but it all looks good.

it does get hot that's for sure so maybe i should return to oil injected instead of premix and hope that sorts it, i've also noticed that there's not as much gas pumping from the exhaust either?

Bishopbiking · Derestricted Danger Joined: 06 May 2016 Karma :

Bishopbiking · Derestricted Danger Joined: 06 May 2016 Karma :

Update. got her started on the button but had to situate the throttle a slight bit back and it was going up between 0 and 1k revs if i pull the throttle any more it would just not have any of it. after i held it at a certain point it started and reved just fine but wouldn't idle still..

MarJay · But it's British! Joined: 15 Sep 2003 Karma :

Ste · Not Work Safe Joined: 01 Sep 2002 Karma :

Don't suppose the previous owner told you why he was running it on premix?

Bishopbiking · Derestricted Danger Joined: 06 May 2016 Karma :

Bishopbiking · Derestricted Danger Joined: 06 May 2016 Karma :

is 40-1 ratio too much, i will be switching to oil pump soon.

kurmit123 · Derestricted Danger Joined: 13 Apr 2007 Karma :

40.1 is way to much oil, this would fowl your plug in no time.
gasket may look good, but that only works if you know what a bad one looks like. i dont so would just change it out if it was me.

Guest · Posted: 07:01 - 07 May 2016 Post subject:

redeem ouzzer · World Chat Champion Joined: 06 Oct 2015 Karma :

iooi · Super Spammer Joined: 14 Jan 2007 Karma :

Guest · Posted: 07:58 - 07 May 2016 Post subject:

Bishopbiking · Derestricted Danger Joined: 06 May 2016 Karma :

So any suggestions on a fix or ideas of the fault. Shall I try running it on fuel with a lower ratio?

redeem ouzzer · World Chat Champion Joined: 06 Oct 2015 Karma :

Who do you think your talking to, son?

I don't think too many folk on here would argue that my 2t knowledge and experience is rather broad, i'm not "some kid".

Fully synth (and yes i'm aware it still has some mineral content) is better at everything, i assume you don't remember the days of decokes and clogged silencers and fouled plugs from running mineral oil? Also fully synth produces next to no exhaust smoke on a warm engine. For the small increase in cost per litre (and how many people do big miles on a 2t these days?) It's a no brainer.
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Be a REAL MAN!

Guest · Posted: 08:17 - 07 May 2016 Post subject:

https://www.klemmvintage.com/oils.htm

Guest · Posted: 08:52 - 07 May 2016 Post subject:

Bishopbiking · Derestricted Danger Joined: 06 May 2016 Karma :

Update. New fuel no difference. It backfired when trying to start it though.

MarJay · But it's British! Joined: 15 Sep 2003 Karma :

Bishopbiking · Derestricted Danger Joined: 06 May 2016 Karma :

Bishopbiking · Derestricted Danger Joined: 06 May 2016 Karma :

Piston has a hole. New piston time.

Kickstart · The Oracle Joined: 04 Feb 2002 Karma :

Hi

Any damage to the barrel?

As to oil pumps, I have never had one fail. But I am sure that if running pre mix I would have gotten the mixture wrong occasionally.

As to mixture ratio, Aprilia list the oil used on an RS125 as equivalent to 0.9%~2%. (ie, under 100:1 to 50:1). Oil pump doesn't squirt oil in, and the quantity pushed in is tiny.

However my concern for your bike now is that it has been run with the pump connected but with no oil for a while. Rotating pump with no oil in it to lube it is likely to wear. I don't think I would trust that particular pump now, and would suggest you source a replacement.

All the best

Katy
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