kiln Posted August 15, 2011 Posted August 15, 2011 Hi, This is directed to either oldgit/neo/cynic/anyone with experience on the topic Is it normal for carbon to form a layer on the head and piston crown within 600km of operation? Could it be that a)premix as at 20:1 is too much oil-plug chop revealed medium brown color,what should premix ratio be for a DT175? b)Main jet too large=160, idle jet=25-Normally main jet=140, idle jet=22.5 c)Unleaded fuel to be used rather than Lead Replacement Fuel Any advice on above welcome.
Moderator Airhead Posted August 15, 2011 Moderator Posted August 15, 2011 Hi, This is directed to either oldgit/neo/cynic/anyone with experience on the topic Is it normal for carbon to form a layer on the head and piston crown within 600km of operation? Could it be that a)premix as at 20:1 is too much oil-plug chop revealed medium brown color,what should premix ratio be for a DT175? b)Main jet too large=160, idle jet=25-Normally main jet=140, idle jet=22.5 c)Unleaded fuel to be used rather than Lead Replacement Fuel Any advice on above welcome. I would be happy with 30:1 and thats still oily, oils are better nowadays...see what the others think as for main jet and a nice colour plug chop...if you never ride full throttle it wont even come into play as it will be regulated by the needle taper and clip position. Have you plug chopped it full throttle...perhaps it wont be crisp at that load? 160 does sound a bit of a jump from 140
NEV Posted August 16, 2011 Posted August 16, 2011 (edited) I would be happy with 30:1 and thats still oily, oils are better nowadays...see what the others think as for main jet and a nice colour plug chop...if you never ride full throttle it wont even come into play as it will be regulated by the needle taper and clip position. Have you plug chopped it full throttle...perhaps it wont be crisp at that load? 160 does sound a bit of a jump from 140 After asking the chaps at Cornish Motorcycles who did my rebore, what they recommended as a pre-mix ratio, they reckoned 40-1 was a decent mix, I had usually pre-mixed at 42-1 anyway. Heres a program to download that will help you with any ratios you need. http://www.dansmc.com/mc_software.htm scroll down towards bottom of the page for the download. Nev BTW It was reccomended I use this stuff too, so I'll be giving it a go Morris Lubricants Supersport 2i Two Stroke Oil or Silkolene Comp 2 2-stroke Pre-Mix & Injector Oil you can get these oils on Ebay Edited August 16, 2011 by NEV
kiln Posted August 16, 2011 Author Posted August 16, 2011 Thank you for your comments thus far. Oldgit:The plug chop was done after riding wot for about 1km or so, so the only other thing would be to look at the premix ratio which I had at 100ml/2l (20:1) Nev:I am familiar with the ratio program and thus ran with a mix 100ml/2l (20:1)as suggested on Dan's website.However looking at what you and Oldgit suggests: either 67ml/2l(30:1) or even 50ml/2l (40:1). Any other suggestions on Pre-mix ratios? What does the rest of the DT175/Dt125 enthusiasts use on a daily basis as a Pre-mix ratio?
NEV Posted August 16, 2011 Posted August 16, 2011 Thank you for your comments thus far. Oldgit:The plug chop was done after riding wot for about 1km or so, so the only other thing would be to look at the premix ratio which I had at 100ml/2l (20:1) Nev:I am familiar with the ratio program and thus ran with a mix 100ml/2l (20:1)as suggested on Dan's website.However looking at what you and Oldgit suggests: either 67ml/2l(30:1) or even 50ml/2l (40:1). Any other suggestions on Pre-mix ratios? What does the rest of the DT175/Dt125 enthusiasts use on a daily basis as a Pre-mix ratio? You sure Dan recommended 20-1, Kiln, as I've never known a ratio that high in 2t oil
Moderator Airhead Posted August 16, 2011 Moderator Posted August 16, 2011 Thank you for your comments thus far. Oldgit:The plug chop was done after riding wot for about 1km or so, so the only other thing would be to look at the premix ratio which I had at 100ml/2l (20:1) Nev:I am familiar with the ratio program and thus ran with a mix 100ml/2l (20:1)as suggested on Dan's website.However looking at what you and Oldgit suggests: either 67ml/2l(30:1) or even 50ml/2l (40:1). Any other suggestions on Pre-mix ratios? What does the rest of the DT175/Dt125 enthusiasts use on a daily basis as a Pre-mix ratio? I'm still on a pumped system kiln, so's Cynic. matter of fact i just re-furbed my pump with new seals after lots of air bubbles in see-through pipe issues.
NEV Posted August 16, 2011 Posted August 16, 2011 I'm still on a pumped system kiln, so's Cynic. matter of fact i just re-furbed my pump with new seals after lots of air bubbles in see-through pipe issues. Just read this Kiln http://www.dansmc.com/2stroke_oil.htm Still not convinced Dans right,though, like I say when a motorcycle shop's engineer who has worked on bikes for nigh on 40 years recommends a ratio of 40-1 for my bike, my moneys on him being correct.
2 Wheels Posted August 16, 2011 Posted August 16, 2011 My DT125 is using the bikes oil pump But the fuel / oil ratio is about 40-1 or 45-1 Hope that helps ya ! 20-1 is just way to rich. If you never give the bike a good hard fast run then carbon buildup will occur faster.
Moderator Airhead Posted August 16, 2011 Moderator Posted August 16, 2011 One of the plus points of a pumped system is under high load it gives high oil to petrol ratio and under low load it gives low oil to petrol ratio thus less fouling and carbon build-up, premixing can never do this so the final ratio has to be able to suit high load applications and so is oil rich everywhere else. The reason you have a much bigger main jet that is apparently not making your bike run rich may be that you are premixing quite a high ratio of oil, if you premix less oil you may have to reduce main jet size too...#150
kiln Posted August 16, 2011 Author Posted August 16, 2011 The reason you have a much bigger main jet that is apparently not making your bike run rich may be that you are premixing quite a high ratio of oil, if you premix less oil you may have to reduce main jet size too...#150 I must admit, 20:1 sounded awfully rich but then again isn't that lubrication all that is available for the crank & conrod bearings... Keeping that in mind I ran with that ratio and in hindsight, I now see the consequences of that methodology. I will reduce the jet size in conjunction with a ratio of 40:1 and report on that experiences after the weekend. Thanks again for all the feedback. Is there any favourite of gasoline type to use on our type bikes? I.E. Lead replacement or Unleaded fuel.
kiln Posted August 16, 2011 Author Posted August 16, 2011 My DT125 is using the bikes oil pump But the fuel / oil ratio is about 40-1 or 45-1 Hope that helps ya ! 20-1 is just way to rich. If you never give the bike a good hard fast run then carbon buildup will occur faster. Thanks 2-wheels. I just love how this bike takes to the open road in top gear. "Top Gear"...."2-wheels"...sounds like a very nice combination.
Moderator Airhead Posted August 16, 2011 Moderator Posted August 16, 2011 .......I will reduce the jet size in conjunction with a ratio of 40:1 and report on that experiences after the weekend. Thanks again for all the feedback. Is there any favourite of gasoline type to use on our type bikes? I.E. Lead replacement or Unleaded fuel. Unleaded is fine. I would do 35/1 myself, after all you are in SA and its a lot warmer there with an aircooled bike than it is here with a watercooled like a DTR
2 Wheels Posted August 16, 2011 Posted August 16, 2011 Unleaded is fine. I would do 35/1 myself, after all you are in SA and its a lot warmer there with an aircooled bike than it is here with a watercooled like a DTR Aye that might be the best ratio Ogit,,,,,,,because i think a US litre is more than UK litre.
Moderator Airhead Posted August 16, 2011 Moderator Posted August 16, 2011 Aye that might be the best ratio Ogit,,,,,,,because i think a US litre is more than UK litre. a litre is a litre wherever you are however a Gallon, well that's a different story
kiln Posted August 16, 2011 Author Posted August 16, 2011 a litre is a litre wherever you are however a Gallon, well that's a different story 1 US Gallon = 3.785412 Liter 1 UK Gallon = 4.546092 Liter 1 US Liter = 1 UK Liter
NEV Posted August 16, 2011 Posted August 16, 2011 1 US Gallon = 3.785412 Liter 1 UK Gallon = 4.546092 Liter 1 US Liter = 1 UK Liter Other thing I'd check on would be the exhaust back box, dependant on how long you'd been running so rich, as a carbon clogged up baffle will affect performance too.
kiln Posted August 16, 2011 Author Posted August 16, 2011 Other thing I'd check on would be the exhaust back box, dependant on how long you'd been running so rich, as a carbon clogged up baffle will affect performance too. Thanks Nev.I am fairly sure the back box is clear since it is homemade, i.e double pipe design-top in-bottom out, sort of a free flow type. I have been running rich for about 600km.
Moderator Airhead Posted August 16, 2011 Moderator Posted August 16, 2011 1 US Gallon = 3.785412 Liter 1 UK Gallon = 4.546092 Liter 1 US Liter = 1 UK Liter a litre is 1000cc, a thousand cubic centimetre's, or enough to fill a 10cm x 10cm x 10cm box a Gallon is something someone just made up many years ago that got lost in translation as the Europeans colonised America
kiln Posted August 29, 2011 Author Posted August 29, 2011 Houston, we have a problem....After setting up with a pilot jet of 25,main jet of 140 I am unable to get this bike to idle. Idle screw fully turned in, air screw 1.5 turns out warmed up and no idling on its own.Maybe it is the Wiseco piston in the bike, it does not have the twin ports on the skirt but rather a half round entry point. Would it be better to get a piston with the long twin ports? I have opened the exhaust port a little and polished it a bit, could this be the cause of the engine not idling? Carb is new & clean with k&n air cleaner in the air box and Booyesens reeds.Premix is at 33:1, i.e. 30ml/1liter fuel. Thanks for the input in advance.
Moderator Airhead Posted August 29, 2011 Moderator Posted August 29, 2011 kiln can you give a little more detail we need to know all the facts what is the bike and its year this piston...is it new and has never been used?
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