Pinking - preignition
 

Hello,

I've a 2015 Ec250, haven't had it long.

Start fine runs well but at low speed ie in traffic on the road etc. I can hear pinking. Soon as you open it up it goes.

I use the bike on green lanes so there is a fair bit of low speed riding .
Is this normal with these?

What's this 'traffic' you talk of?

So can we assume that you live in a country that requires that the pipe requires a Cat in it? That will make it run dreadful as I found out when trying a spare pipe I was given.

To check try run some flexy curtain cord up there. Cat would be in the fattest part of the pipe.

Failing that try winding the idle mixture in 1/2 a turn and raising the needle by moving the clip down one notch. Actually I did just this yesterday for the same reason. It's coming on winter here and I was getting some detonation pings on part throttle.

I believe he is in the UK. At least he posted in the UK section. I don't think there is a Catalyzer involved if we are talking UK.

Sent fra min E5603 via Tapatalk

Pinking.
 

Hello,

Yes I'm in the UK - In the UK we have "Byways " which are old farm roads, you can ride these with a legal motorbike. The bike must have insurance, road tax and if it's over 3 years old you need an MOT.

To get to these "Byways" you have to go on the main road and there you ride in the traffic.

The bike doesn't have a Cat in the UK.

Hope this make sense. I will have a good look at the set up at weekend.

Cheers Bill

So just to be a pendent, it is not preignition, it will be detonation which is the uncontrollable ignition of end gases. None of which matters but is a symptom of lean, over advance, low octane etc. Expect lean.

F5 are you aluding to what we call "knacking" where there are explosions in the pipe from unburned gases? My experience is it occurs as a result of overly rich low or mid speed jetting. It goes away as the revs climb when the engine clears out. Knacking is a random event. A steady event would not be knacking. Unless the original poster is just talking about typical 2T stuttering from running in an unloaded condition (part throttle).

in the US many ask about "pinging" (also called pre-ignition). A slightly loose chain at lower RPM's can sound much like the same and is the cause of many of the complaints. Check your chain tension before you do anything too time consuming :)

Detonation sounds like some evil gremlin with a hammer trying to get out.but sometimes you just can't hear it.

I've never had pipe explosions on a 2 stroke I believe however it has been a feature of my triumph street and quite a bit of remap attempts to banish it (think I'm there). And yes that was too rich on closed. But 4 strokes are funny like that.

Hello again,

I'm running the bike on the super unleaded fuel that you get.

Chain tension is correct.

I'm not talking about low speed stuttering.

I'm pretty experienced with 2 strokes - but they are the older ones. I had a Yamaha RZV 500 Stan Stephens tuned with pipes for 15 years, RD 350 F2 which I tuned using Kr1s carbs , zeeltronic ignition, different pipes etc. More Dt 175 mx's that I can remember.

This modern bike set up is new to me. small cylinder , big carb.

As I mentioned I haven't had the bike long, but this weekend I will strip the carb and have a look at the needle clip etc.

I can't find any info on the timing.

Cheers Bill

OK I'll clue you in on the timing. Its digital, and its fixed. The little red rocker button for rain retards the curve a few degrees. Nothing more to worry about.

Read the jetting thread and check what needle you have. Stock N1etc are miserable.

Your 350 had 28mm carbs (KR1) but only on 175 cylinders. My RZ bigbore is a 496 but I'm running the conservative 35mm carbs.

Hello,

I have read that these bikes can have jetting issues and that people use a JD jetting kit. That's why I asked on here ;)

Will read the jetting threads and take it from there.

Cheers Bill

I click new posts.
Now I see you've posted in UK section.
Yeah have a look around, there's heaps of info, but try needles suggested here rather than bought kits.

To eliminate the possibility of chain noise, add a thin piece of foam weatherstripping under the swingarm chain guide. 3mm thick by 20mm wide will do nicely. As previously mentioned the swingarm creates a rattling sound at low RPM.

If you are riding at low throttle/too high a gear in order to keep the engine from buzzing, you could have this chain noise.

As to timing, assuming you have the 2K3 flywheel, the stator plate is located by an oval washer on one of the mounting bolts. There is a slight possibility that a previous owner elongated the bolt hole to rotate the stator plate.

Hello,

Thanks for all the info, looks like I'll be busy this weekend ;)

cheers Bill

Hello again,

Well I had carb off, it was set as Gas Gas standard. Main 175,Idle 42,Needle N1EF 3rd from top.
Checked float height , set at 16mm .

Fuel pipe fell apart when I took it off ! , it appears to me that it's an 8mm pipe.
I have only only 6mm pipe.

I decided to repack the silencer, a fair amount of oily gunge is present around the exit. - it's one of those jobs that you wish you hadn't started!. Anyway got it apart and the rear by the exit is really coked up.

I have ordered some correct size pop rivets and some fuel pipe, I also need chain and sprockets plus a rear tyre.

Now going back to what I said about modern 2 Strokes - I find it interesting that the jetting for the 200 ,250 and 300 is the same , according to the Gas gas owners manual the only difference is the throttle valve/slide on the 200.

So the 200 has the same main jet as the 300! Seems strange to me.

Cheers bill

N1EF is not a good needle. You will get a lot of spooge and poor low speed operation.

Hello,

I've read the posts on jetting and I will get a CCK needle that seems to be a good choice.

The plan is to put it back together, new plugs and mark the throttle at 1/4, 1/2 3/4 and WO. Do a plug chop and see what's what.

You are wasting your time with that needle. Proven time and again.

There is a thread running currently.. http://www.gasgasrider.org/forum/showthread.php?t=22742

You need to compare apples to apples. There have been numerous updates to crank volume, port layout, head clearances, etc over the years. There are also a couple different carb models fitted over time as well, and if you go back I'm sure the older engines probably ran different reed valves too. What worked in the early 2000's isn't relevant anymore.

Stock gas gas jetting leaves a lot to be desired. It appears they have an endless supply of N1EF needles and put them into everything. They might work well somewhere, but I haven't found it. Too short on the straight section makes for a hard to set idle. Way too rich on the diameter. Wayyy too rich on the first taper encourages you to lift the needle to clean up off idle. This typically leaves it too lean in the mid range... or you run too rich off idle and it loads up and won't pull clean into the mid top.

Suzuki/Ktm-Yamaha series needles will get you 2 or 3 tapered OEM needles which will allow you to fine tune in half clip positions and any diameter you need, for about $10 a piece.

Hello,

Well she's all back together, I put a NEDW needle in, repacked the silencer, new plug, cleaned filter etc.

Well the difference is night and day:D.

So much nicer to ride, no more black gunge coming out the back. Pulls well, nice and smooth.

Haven't been far on it.Need to do a few more miles on it - let it settle down etc.

I bought a CCK needle as well, read about it in a thread but can't find it now!!! Was going to have a play with that but not sure If I can be bothered .

Cheers Bill

Hello again,

Been running it for a while, I had to go up to a 45 pilot on just under 2 turns out.

Went out yesterday on the Greenlanes, bit of road work ,bit of fast work on parts of the lanes and a fair bit of slow work on the ruts .

Total distance about 50 miles - used less than a gallon / 5 litres.

Plug a lovely colour, nice and dry.

Cheers.