waynerobshaw Posted October 22, 2011 Author Report Share Posted October 22, 2011 I'm assuming the "33" is the pilot and this is a standard Keihin PWK28 on a 300 Raga (usually mid-40's works well). That seems way lean for a pilot on this configuration. That would be way lean for a Dellorto in fact (usually #36-38) and may be the cause of the chop/pink problem. Air screw adjustment should be done according to ambient conditions (blip throttle and in/out to get best reponse). The backfiring problem is somewhat of a puzzle and could be flywheel alignment related, as well as an air leak (usually manifold). The shock loads on the flywheel/crank taper for a Trials bike are huge in comparison to most bikes and the flywheel bolt needs to be checked now and then. Jon Hi Jon, I did forget to mention that it has a Dellorto although the 06 Raga 300 should have a Keihin (I think a previous owner must has swopped it from another another bike - ). So maybe the problem is the 33 is way too small for the 300? Just to help matters, I've taken a photo and labeled each jet: Picture of carb and jets It does seem to make sense since engaging the choke makes the whole bike sound better and the pink its almost completely eradicated. Which jet then would you recommend? Its a complete mystery to why it went all lumpy, backfiring as its now back as it was - generally running well apart from the pinking. Its an absolute head scratcher! Surely the bikes timing can't just change and then correct itself, but it did seem like the timing...I will keep tabs on it, but I just feel problems like that don't just disappear over night! Thanks for all your help Cheers, Wayne Quote Link to comment Share on other sites More sharing options...
waynerobshaw Posted October 22, 2011 Author Report Share Posted October 22, 2011 Yes, you are confusing us! Depending upon which condition you are referring to with your symptoms. Basics #1= Throttle chop ping is something of a normal condition, as you have just cut off the fuel to the motor(goes lean). I presume this is a dellorto carb? Increasing pilot jet size can help minimize this(33 to 35/36) range, as the carb is then able to provide more fuel through tht transition circuit on throttle chop. Will likely require you decrease the fuel screw setting a bit for best idle.(2turn range rather than three) Is it still running ok otherwise now? Yes, sorry chaps, its confusing me as much too! Its seems to be running as it was before now, still pinking but not farting and backfiring etc, so it is a complete mystery! I've now taken a photo of the carb and labeled all the jets, so it might shed some light on it (its a Dellorto by the way, not the Keihin that the 300 Raga came with - a previous owner must have robbed it ) Picture of carb and jets Maybe a bigger jet? Cheers, Wayne. Quote Link to comment Share on other sites More sharing options...
jse Posted October 22, 2011 Report Share Posted October 22, 2011 Yes, sorry chaps, its confusing me as much too! Its seems to be running as it was before now, still pinking but not farting and backfiring etc, so it is a complete mystery! I've now taken a photo of the carb and labeled all the jets, so it might shed some light on it (its a Dellorto by the way, not the Keihin that the 300 Raga came with - a previous owner must have robbed it ) Picture of carb and jets Maybe a bigger jet? Cheers, Wayne. Wayne, If the timing, due to key shear, has retarded/advanced slightly, this could lead to possible overheating and poor running. It could also be stale fuel or water in the fuel. I'd go with a #38 pilot jet and drop the needle one groove (raise the clip one groove). The other jets seem to be in the ballpark and the #300 float needle flows more than enough fuel to prevent high-speed starving. Check the float level by tilting the carb body so the float arm tab just lightly touches the spring loaded pin on the float needle. If the arms are then parallel with the gasket surface of the body that the bowl contacts, you're fine. While you have the carb off, I'd take the manifold off, check the reeds (hard to know what else the previous owner took off) and then use a little sealer on the gaskets when re-assembling it. It's probably a standard steel/rubber reedcage/manifold assembly, so don't overtighten the four screws holding it in (that will "bow" the manifold between the screw holes and allow air in). This will eliminate a manifold air leak as a cause. Jon ps. Fear not. Everything can be fixed..... Quote Link to comment Share on other sites More sharing options...
waynerobshaw Posted October 22, 2011 Author Report Share Posted October 22, 2011 (edited) Wayne, If the timing, due to key shear, has retarded/advanced slightly, this could lead to possible overheating and poor running. It could also be stale fuel or water in the fuel. I'd go with a #38 pilot jet and drop the needle one groove (raise the clip one groove). The other jets seem to be in the ballpark and the #300 float needle flows more than enough fuel to prevent high-speed starving. Check the float level by tilting the carb body so the float arm tab just lightly touches the spring loaded pin on the float needle. If the arms are then parallel with the gasket surface of the body that the bowl contacts, you're fine. While you have the carb off, I'd take the manifold off, check the reeds (hard to know what else the previous owner took off) and then use a little sealer on the gaskets when re-assembling it. It's probably a standard steel/rubber reedcage/manifold assembly, so don't overtighten the four screws holding it in (that will "bow" the manifold between the screw holes and allow air in). This will eliminate a manifold air leak as a cause. Jon ps. Fear not. Everything can be fixed..... I may take the flywheel off just to inspect. Incidently, what the best way to undo the flywheel bolt? How do you stop the flywheel turning? I'll get a #38 ordered on Monday and see what happens. Not sure what you mean by "drop the needle one groove"? I'll take a look at he manifold too. I've checked the rubber while its on the bike and I can't see any splitting, but I'll give it a going over. I shall keep you all posted with the results... Cheers, Wayne. Edited October 22, 2011 by waynerobshaw Quote Link to comment Share on other sites More sharing options...
jse Posted October 22, 2011 Report Share Posted October 22, 2011 (edited) I may take the flywheel off just to inspect. Incidently, what the best way to undo the flywheel bolt? How do you stop the flywheel turning? I'll get a #38 ordered on Monday and see what happens. Not sure what you mean by "drop the needle one groove"? I'll take a look at he manifold too. I've checked the rubber while its on the bike and I can't see any splitting, but I'll give it a going over. I shall keep you all posted with the results... Cheers, Wayne. 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). Edited October 22, 2011 by JSE Quote Link to comment Share on other sites More sharing options...
jandyb Posted October 22, 2011 Report Share Posted October 22, 2011 Would never had thought about the rope trick! Smart If you have an air pressure wheel nut tool, it will do the job too. Both loosening and fastening. -Jan Quote Link to comment Share on other sites More sharing options...
jse Posted October 22, 2011 Report Share Posted October 22, 2011 Would never had thought about the rope trick! Smart If you have an air pressure wheel nut tool, it will do the job too. Both loosening and fastening. -Jan Jan, An air gun is good for taking off the bolt but you'll have no idea what the torque setting is if used to install the bolt. I could probably get away with it because I have a feel for how the air gun works/feels and about 50 years experience, but even then, I like to use a good torque wrench.. Jon Quote Link to comment Share on other sites More sharing options...
toofasttim Posted October 23, 2011 Report Share Posted October 23, 2011 Would never had thought about the rope trick! Smart Just be careful you don't get the rope hung up in the exhaust port. It's a lot of work to get it out again. I found this out the hard way Quote Link to comment Share on other sites More sharing options...
jandyb Posted October 25, 2011 Report Share Posted October 25, 2011 Jan, An air gun is good for taking off the bolt but you'll have no idea what the torque setting is if used to install the bolt. I could probably get away with it because I have a feel for how the air gun works/feels and about 50 years experience, but even then, I like to use a good torque wrench.. Jon Ohh ****.. Quote Link to comment Share on other sites More sharing options...
gasser_david Posted October 25, 2011 Report Share Posted October 25, 2011 No idea of your flywheel size...but on 2001 TXT 200 I use an old style 'fabric' band car oil filter wrench around perimeter of flywheel with a ring spanner on handle for extra leverage. Unfortunately it's a 2 man job getting it to hold tight while nut 'shocked' loose & when torquing nut back up...unless you have 4 arms... Hope this helps...works for me every time....Occasionally it can slip but persistence pays off..and contact cleaning perimeter of flywheel helps band to bite. david Quote Link to comment Share on other sites More sharing options...
waynerobshaw Posted October 25, 2011 Author Report Share Posted October 25, 2011 Hi All, Just to let you know, I got my #38 jet today so I'll be fitting it in the morning. I shall let you know how things go... Cheers, Wayne. Quote Link to comment Share on other sites More sharing options...
waynerobshaw Posted October 26, 2011 Author Report Share Posted October 26, 2011 Hi all, As per Jon's recommendation, I've now fitted the #38 jet and dropped the needle one notch. Its early days (only a quick 15 minute ride), it does seem better but there is still the odd pink. It seems a little lumpy at part throttle, but fine at the top end (arm ripping ) I'm tempted to put the needle back to where it was (second notch from bottom) and try again. Any thoughts Jon? Cheers, Wayne. Quote Link to comment Share on other sites More sharing options...
jse Posted October 26, 2011 Report Share Posted October 26, 2011 Hi all, As per Jon's recommendation, I've now fitted the #38 jet and dropped the needle one notch. Its early days (only a quick 15 minute ride), it does seem better but there is still the odd pink. It seems a little lumpy at part throttle, but fine at the top end (arm ripping ) I'm tempted to put the needle back to where it was (second notch from bottom) and try again. Any thoughts Jon? Cheers, Wayne. 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 Quote Link to comment Share on other sites More sharing options...
waynerobshaw Posted October 27, 2011 Author Report Share Posted October 27, 2011 (edited) Hi All, Dropped the needle back to it original position (second notch from bottom) this morning and.... Perfection! About a 20 minute ride without one single pink! Seems to run nicely too! I'm going to treat it to a new spark plug and see how we go from here. Still a complete mystery as to why it backfired etc, just hope it was water in the fuel or something (drained tank and fuel can). I will keep tabs on it and when I get a flywheel puller I will check the woodruff. Thanks everyone for your input and wisdom, much appreciated, I wouldn't be where I am now without you all! Kind regards, Wayne. Edited October 27, 2011 by waynerobshaw Quote Link to comment Share on other sites More sharing options...
benbeta23 Posted October 28, 2011 Report Share Posted October 28, 2011 (edited) Had the same problem this summer. As it turned out my base gasket was shot. Look around the bottom of cylinder for any oil or combustion residue. It progressively got worse as the gasket was dieing. --Biff 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! Edited October 28, 2011 by BenBeta23 Quote Link to comment Share on other sites More sharing options...
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