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Enduro Intake/Carburetion - 2 stroke Jetting, Reeds, Air Filters, etc.


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  #11  
Old 02-21-2007, 01:39 AM
Leon_gasgas Leon_gasgas is offline
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Thank you again for this discussion! I have learnt things I didn't know...

Best Regards,

Leon.

P.S. Tonight is the next test.


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  #12  
Old 02-22-2007, 04:18 AM
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iancp5 iancp5 is offline
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Leon,

It might not be the main jet that was why I wondered if it would run flat out after a few seconds. With mine it was too rich on the pilot and needle which allowed it to spooge up in the woods. It would then take several seconds of WFO to clear with much coughing & spluttering. The main was fine but the engine wouldn't rev because it was so full of oil and fuel and needed to spit it all out.

I have the 300 and now run it much leaner on the bottom than either the factory or LTR recommend - they are probably scared of causing seizures. There seems to be a big variation in jetting on these bikes - I guess there is a poor manufacturing tolerance somewhere - probably on the ports. The upshot is you have to jet them individually to get it right - if you have a good dealer they can usually advise you pretty close but the fine tuning has to be done yourself.

I doubt the main jet is the principal cause of your problems. Try dropping the needle a notch and maybe lowering the pilot jet size. It doesn't get very cold here but I see no variation in jetting requirement between 30 deg C & 0 deg C. I have found it critical at lower temperatures to keep the engine warm for it to run cleanly. I think they have a cooling system designed to work well in a Southern Spanish summer!

If your bike will not run WFO, when at proper operating temp after several seconds (eg 5 - 10) of full throttle I'd suspect something else. It is entirely possible for example to spooge up in the woods and then not run WFO because your float height is too low. But it normally does feel like someone turned the fuel off in that case.

As for cold carbs a friend of mine uses bubble wrap taped round the carb - I think some of the guys on here who ride regularly below zero have other ways to insulate it.

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Originally Posted by Leon_gasgas

On Saturday afternoon with the same jetting it was +3 about C and after a period of about 15 min with 2nd and 3rd gear tight tree driving I attacked a snow berm and gave full throttle in 2nd from the start of the berm. The bike coughed like crazy. Reduced the throtle and then I was able to accelerate pretty ok through the gears. I think this is a rich situation. Should I try the178 jet? The bike always starts first kick and works great if I keep the throttle at 80ยป90%.

Leon
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  #13  
Old 03-01-2007, 02:16 AM
Leon_gasgas Leon_gasgas is offline
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Hi!

Following your advices I did the following trying to solve the problem at full throttle.

1) Much less antifreezing liquid in the tank
2) Checked the needle position and it was in the middle (3rd). Put it to 2nd.
3) Cut the carb lines much shorter to avoid blocking from snow.

The result is even better operation in tight technical going without needing time to clean up and rev out in the faster sections. It was -3o C and still getting some spooge at the end of the silencer so I think the needle is in the correct position now. Still is not really happy at full throttle but the overall power is great opening the throttle max at 90%. Main jet is 180 so it might be a bit rich but I don't want to go leaner in these temps. The air screw is at 2,5 turns out. I will try it today at 2 and see... Still trying with 100% syn Castrol TTS untill I am 100% happy at full throttle.

Thank you again for your replies!

Leon
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  #14  
Old 03-22-2007, 02:52 AM
Leon_gasgas Leon_gasgas is offline
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Hi!

Checked the OEM Denso plug and it was quite black with some deposits on the top of the "anchor" (I don't remember the word..). Changed the plug to an NGK B8EG (has much smaller electrode than the Denso), put a 178 jet (one size smaller..) and adjusted the air screw to 2 turns out (it was at 2,5). Needle has been at the 2nd position. Bike runs even better and the WOT stumble is almost gone. Not 100% gone but close. Maybe it needs a bit more time to clear out. The filter needs a bit cleaning too... it's the next thing to fix.

Very soon I will change the silencer packing because the bike has been running rich for 2 months (for three rides I had the needle at 3rd pos and 185 jet... it was awful. The stumble was even at mid range rpms)... Maybe this helps too? What I like now is that even after minutes in tight woods the bike stays responsive and ready to rock whenever I open the throttle.

Ian you mentioned something about float height.. This 07 (and my old 98) is loosing petrol from the carb if I forget to close the petrol tap during a break. I heard that they are set up like this in order to be rich and to avoid seizures. Should I try to fix it? What is the correct height in mm and how do I adjust it?

Thank you all for the help!!

Leon
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Old 03-22-2007, 03:58 PM
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iancp5 iancp5 is offline
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Quote:
Originally Posted by Leon_gasgas View Post

Ian you mentioned something about float height.. This 07 (and my old 98) is loosing petrol from the carb if I forget to close the petrol tap during a break. I heard that they are set up like this in order to be rich and to avoid seizures. Should I try to fix it? What is the correct height in mm and how do I adjust it?

Thank you all for the help!!

Leon
I don't think that can be right. You are not supposed to jet on float height. Set the float height correctly then jet.
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