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06 300 Raga - Pinking sound but stops with choke on...Fixed!


waynerobshaw
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Exactly what was wrong with my 2009 300, Mine used to pink/knock like mad, Changed jetting, Nothing seemed to cure it, Until one day I noticed the base gasket was leaking & got worse everytime I rode it, Which was the cause of it pinking. It Didn't help with the fact that it was an ex GG Team bike & who had it before me had put the wrong gasket on (to thin) Probably to make it higer compression which would have caused it to pink even worse.

Wayne: Hope your bike stays running good, I know it's an annoying problem, I hated it!

Hi Ben,

I did try and squirt WD40 around the base gasket hoping it would affect the idle or make the WD bubble if it was leaking. It didn't do anything noticable, so have to assume its ok. I'll see how things go.

You're right on how annoying the pinking is, it makes the engine sound like its on its last legs - the noise go right through you!

Cheers,

Wayne.

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The flywheel bolt is a standard right-hand thread. You can hold the flywheel by using some plastic or cotton rope, about 3/8th in. Take the plug out and poke a little of the rope through the hole while turning the flywheel to feel when the piston is coming up to TDC. Before TDC back the flywheel off a little and push some rope through the hole to fill the chamber, then turn the flywheel to lock it up. If you locked the flywheel on the wrong side of TDC, be sure to remove all the rope before doing the process again so as to not get it caught in a port.

Drop the needle one groove means to place the circlip on the top of the carb needle one groove higher, which will have the needle lower at the static setting. (it "leans out" how the needle operates in the slide opening range).

Jon

Forgot to add: when installing the bolt, go to about 54 Nm and re-check after a couple of heat cycles (rides).

\

I have done the rope trick on my gg and other bikes which works great. We recommend the rope trick all the time at FO MO Co another reason. If you ever have a 4 stroke and want to remove valve springs or valve stem seals back off the rockers or remove the cam (so the valves won't push down) and use the rope to hold the valves into the head. Make sure that you don't rotate too far to bend the con rod but you can hold the valve into the head and do everything you need to do with out removing the head from the block. Sorry about the unrelated note.

As for your concern. are the reed valves cracked or blown out? a cracked reed valve can appear after a back fire and can cause a lean burn. Lean burn will cause pinking after the bike is warm. OR you might have a fly wheel side air leak causing a lean burn. Wd40 on the flywheel crank seal would cause that to show up.

--Biff

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Had a good couple of hours ride today...hell of a lot better with the #38 in, but still it pinks/knocks at certain times when shutting the throttle off, especially under load.

Strangely, it doesn't do it constantly.

So I suppose I could up to a #40 or is this really point to an air leak somewhere? More investigation required this week I think!

Cheers,

Wayne.

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Sounds like you need to turn the fuel screw out (richer) 1/2 a turn and go from there. Pinging on throttle chops are a sign the progression circuit is lean and is controlled by the fuel screw.

Edited by laser1
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I read all that about gaskets and stuff...

All I can say is mine felt weak when I got it. The the 'knock' sound when pulling 1/4 throttle and up.. I dropped the clip a notch on the needle and bingo. Super stong power delivery with no funny knocking sounds.

After reading all the other bits I was going to suggest that it must be a Friday aftenoon bike, but I have learned over the years that all 'non Jap' trials bikes are produced on a Friday afternoon!

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Sounds like you need to turn the fuel screw out (richer) 1/2 a turn and go from there. Pinging on throttle chops are a sign the progression circuit is lean and is controlled by the fuel screw.

I think you are almost correct there, within the exception of the fuel screw does not control the progression circuit, as it it is open to demand. Still ultimatly controlled by the pilot jet, as they share the source pilot jet which is the limiting device. Yet a larger pilot does let them both work on throttle chop to mitigate a lean chop condition(as it will suck fuel from both), reguardless of screw setting.

On the other hand, too rich a pilot will give a lumpy transition to the needle, as it is unregulated by bthe screw. :rolleyes:

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Mate please pull the head off. There will be 6 years of carbon on the piston and head. It needs polishing off and probably put the jets back as they were. All 2t bikes need this maintenance.

Have you a recommended procedure for decoking? Simply remove the head and clean? Do any gaskets need replacing in the process?

Cheers,

Wayne.

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I think you are almost correct there, within the exception of the fuel screw does not control the progression circuit, as it it is open to demand. Still ultimatly controlled by the pilot jet, as they share the source pilot jet which is the limiting device. Yet a larger pilot does let them both work on throttle chop to mitigate a lean chop condition(as it will suck fuel from both), reguardless of screw setting.

On the other hand, too rich a pilot will give a lumpy transition to the needle, as it is unregulated by bthe screw. :rolleyes:

You sir are correct - I had the progression (under the slide) and idle circuits backwards in my prior explanation. Thanks for clearing that up. :icon_salut:

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Have you a recommended procedure for decoking? Simply remove the head and clean? Do any gaskets need replacing in the process?

Looky here for the head.... http://www.youtube.com/watch?v=jyTAnumRTWY

Looky here for the cylinder..... http://www.youtube.com/watch?v=XgKLrVBn2O8

Clean off the oil with petrol and polish off the carbon with 600grit sand paper and polish with autosol alloy polish. DO NOT get the emery/sand paper grit in the engine. Clean again with petrol. Lots of times.

Fit a new plug and your bike will be amazing!

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  • 4 weeks later...

Just an update chaps:

I went out for a 3 hour ride last Saturday, the bike was still pinking now and again when the throttle closed. Just as we was about to put the bikes away, the bike died. I kicked it back up, but it coughed, spluttered, knocked and generally sounded dreadful. It wound't run for more that a few seconds. I sounded exactly like before when it started backfiring etc.

So, this week, I have:

- Pulled the flywheel: Woodruff key is intact. Changed it anyway, as the key had a little scoring on it but the flywheel was still definately keyed into it. - no real problem there. Put it all back together and it still wounldn't start! :angry: I changed the spark plug (the one I took out looked ok, black with soot, but looked ok) and it fired up first time!

I took it for a test ride and there was still an odd pink now and again....back into the garage...

- Took off the head and decoked: Head was particularly coked. Left piston alone, I didn't want to get any crap down the cylinder.

I took it for a test ride, no notiable pinking so far, but its early days.

So, woodruff key was fine and the plug seems to cure the odd running....This bikes has a mind of its own...

All I can do is see how things go.... :huh:

Cheers,

Wayne.

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Well done wayne. When you do get around to decoking the piston spend some time polishing the piston top with Autosol polish (after some 600 grit emery paper) to slow further coke buildup.

I was a little nervous about decoking the piston, so I just did the head. Whats the best way do do the piston without getting crap down the cylinder?

UPDATE: I put the plug back in tonight (the one causing the misfire) and sure enough, it ran like a dog again...its is definately the plug. To look at, this plug and a working one look the same (coked up), the gap looks the same and the electrode looks fine. Infact the dodgy plug is only a couple of week old! Not sure whats caused it to fail, but the spark does look week and arcing down the electrode....How long should a plug last, is there a specifed cleaning regimen?

Cheers,

Wayne,

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I was a little nervous about decoking the piston, so I just did the head. Whats the best way do do the piston without getting crap down the cylinder?

UPDATE: I put the plug back in tonight (the one causing the misfire) and sure enough, it ran like a dog again...its is definately the plug. To look at, this plug and a working one look the same (coked up), the gap looks the same and the electrode looks fine. Infact the dodgy plug is only a couple of week old! Not sure whats caused it to fail, but the spark does look week and arcing down the electrode....How long should a plug last, is there a specifed cleaning regimen?

Cheers,

Wayne,

A plug on a trials bike should almost be a consumable imho, run it a few months then change.

Always set the gap.

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Wayne,

I'd do it. Each bike is a little different and the settings will vary now and then. The needle drop was to compensate for the 33 to 38 pilot, as changes to a pilot are a little more dramatic than the same number of steps in a main. Sounds like you are on the right track.

Jon

Jon, possibly their fuel is getting just as bad as ours! :rolleyes:

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