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jaguar57 Added a reply to 2010 Yz125 squish
1/28/2026 6:18pm both squish and compression affects how fast combustion completes which affects the ignition timing need. Increasing the squish means you also need to retard the timing. That increases power and avoids detonation.
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jaguar57 Added a reply to 2022 YZ125 Jetting Once and for all.
5/22/2024 11:38am Years ago I had an unsolvable jetting problem and so I made a jetting calculator to help me get it jetted right. After 1.5 years of suffering bad jetting (stock bike from Suzuki factory) I finally got the jetting spot on thru the whole throttle range, something few bikes have. I recommend people get my spreadsheet or hire me to...
jaguar57 Added a reply to Issues with PWK on KX125
9/11/2020 9:11am "pilot circuit or needle starting diameter or clip height" or slide this is a perfect illustration of why a jetting calculator is needed. You can virtually change any of these and see the results on the jetting graph
jaguar57 Added a reply to Issues with PWK on KX125
9/7/2020 12:27am That is needle related and you need a computer program to figure it out. I've been there and done that and pulled my hair out for a year trying to figure out correct jetting until I used that program.
jaguar57 Added a reply to 2002 yz125 fouling plugs
9/7/2020 12:24am Air filter needs cleaning. If not that then you used to use gas with ethanol and now you are using gas without ethanol which made it go from correct to rich. Lean out the main jet and if it is too rich mid throttle then check out my jetting guide: www.dragonfly75.com/moto/carbtuning.html
jaguar57 Added a reply to Issues with PWK on KX125
9/7/2020 12:10am my god man, why would you settle for "a little bogging" when you can have it running super crisp all thru the whole throttle range? Here's an easy to use software program that can make you a jetting expert: www.dragonfly75.com/moto/carbjetting.html and it only costs $20. That's about the cost of one needle and yet people order and try many needles...
jaguar57 Added a reply to Castrol A747
8/28/2020 7:31pm Why oh why do people quote oil ratios without listing the oil? The ratio only matches the oil. There are no universal ratios. Heavy viscosity synthetics are used much more sparingly than crude petroleum oils.
jaguar57 Added a reply to Castrol A747
8/28/2020 7:20pm "I’ve ran 40:1 in my 2012 250sx with maxima k2 and never fouled a plug, and never smoked excessively" Maxima K2 in a water cooled engine reving to 9500 should be used at 52:1 according to my oil ratio calculator so you gave it more oil than that which is fine because its 90% synthetic which is why it still...
jaguar57 Started a new thread Maximum Squish Velocity
8/27/2020 4:50pm The higher your engine revs the faster you want the combustion to happen and the higher the squish velocity, the faster the burn* except that too much velocity actually slows down the combustion time by overtly dispersing the flame kernel. . Blair recommended a max of 20m/sec at peak power RPM which to him was a safe high which wouldn’t...
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jaguar57 Started a new thread Carb Size Calculations
8/10/2020 11:42am "Bigger is Better" is the common theme when it comes to carb size but in reality there is a sweet spot for size, and other than trial and error the only way to determine it is by calculations. Changing the carb size is changing the air velocity and the air velocity past the needle is what determines the fuel droplet...
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jaguar57 Added a reply to Castrol A747
8/10/2020 11:41am People use that up to 60:1 no problem. It's super oil. For you I would recommend 50:1. Keep in mind that manufacturers always say what oil they are talking about when they say to use it as such and such a ratio. That is because each oil has a different viscosity and that is the main factor in determining ratio...
jaguar57 Added a reply to Cdi programming questions
8/10/2020 11:37am You can't go wrong with a programmable CDI, Lectron or no Lectron. I'd give it a go.
jaguar57 Added a reply to Kx125 2002 jetting
8/9/2020 2:08pm heavy smoke at 40:1 may indicate running too rich or a crank seal leak letting tranny oil in. If your needle jet isn't wallowed out then you probably should be looking for a different needle. see www.dragonfly75.com/moto/carbjetting.html
jaguar57 Added a reply to Yz 125 jet problem (now seized piston)
7/29/2020 12:36am opinions are like assholes, everyone has one
jaguar57 Added a reply to Yz 125 jet problem (now seized piston)
7/22/2020 9:34pm 32:1 is a typical ratio for a semi-synthetic engine oil. It is too much oil for a full synthetic and not enough for a totally non-synthetic oil. Which one did you use? If you plug was whitish and your jetting is typical and no trash got in the main jet to partially block it then you need to check for...
jaguar57 Added a reply to Rm250 jetting
7/21/2020 9:57pm Looks nice. Ride it like ya stole it!
jaguar57 Added a reply to Rm250 jetting
7/19/2020 4:55pm hmm, I'd think a partial castor oil would be a tad darker. Post a pic of the plug after the next full days ride. Has the engine compression been modified to be high? Did they shave off the head without shaving off the squish band and now maybe your squish velocity is too high? (causing tendency to ping) What cranking...
jaguar57 Added a reply to Rm250 jetting
7/19/2020 4:06pm curious to know what oil you are using
jaguar57 Added a reply to 2 stroke oil swap
7/17/2020 10:31pm Putoline is only half synthetic and half dino oil. http://www.dragonfly75.com/moto/oil.html