TRX250R.ORG
Workshop => Carburetor, Intake, and Exhaust => Topic started by: zcarlson12 on October 31, 2013, 09:42:36 PM
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I recently picked up a 38mm Air Striker and am gathering mains and pilots. I know some people use different needles, what are some of the ones you guys would recommend for a ESR 310 on race gas? I'm going with mains 170-185 and pilots 40-52. Located in Kentucky if anyone is close and has a similar setup. Thanks.
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Kentucky,
DGH or CEL, but do a compression check first.
Neil
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Thanks Neil will do.
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Those 2 seem to be a common choice.
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Kentucky,
DGH or CEL, but do a compression check first.
Neil
There is a big difference in the initial diameter between the H and L at zero to about 1/4 throttle position on those two needles. What other engine specifications besides compression would influence you to choose one needle over the other?
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Well bad news. I did a compression check on my freshly rebuilt motor, I have about 4 rides on it with probably 3-4 hours at the most on it, and the compression was at 155psi on my harbor freight gauge and 120 on autozone's loaned gauge. I hope it's just because of the quality of the gauges I was using but I'm not sure. I found my leak down tester so that's my next step. All cylinder head and base nuts are tight. Not sure what else it could be besides an air leak.
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i never bother with gauges. besides youre using one from china and the other from taiwan. if everything is new and no leeks you should be good
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i think you guys been listening to carlos to much :D
maybe jerry could chime in on the subject ?
my thoughts have always been static pressure is pretty much useless info, to me anyways. a ton of things influence it. varying gauges, altitude, porting. hell the pipe and carb size probly do as well. and possibly even the reed stiffness ? besides soon as the engine is running the cylinder pressure changes. so what does a static number tell you. not much that i can see.
some people use a pressure gauge as a quick and easy way to determine when the top end is wearing out and i can see the usefulness in that respect provided you always use the same gauge and dont make any engine modifications but still you should confirm with tool measurements and examining the suspected worn parts.
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As soon as I get my head pipe off I'm going to do a leak down test. The motor ripped when I rode it with the 38mm TMX carb. All that I changed was putting the air striker on which started this entire reason for what I'm currently doing. After I put the carb on it wouldn't start so I took it off and cleaned it and thought while I have it that far apart I would do the compression test and other checks. It is a brand new piston and 72.25 bore, all new bearings and seals in the motor, new stock stroke new style Hot Rods crank, new Boyesen rad valve, new spark plug, and new race gas dome with fresh Sunoco 110. It definitely has more than 150psi compression because it kicks over harder than my Blaster that had a Baldwin ported national motor on the same fuel with a 34mm carb and over 150 psi compression. When I took the air striker carb apart it had a 52 pilot and 170 main but to me that doesn't matter at this point because it should still fire up so it may be an electrical issue as well. I'm confused but will head out to the garage tomorrow and see what I can find out.
udontknowme- I agree with you some what but to me with only 3-4 hours on a fresh motor it should definitely be over 155psi no matter what so I'm glad I decided to check it when I did. Hopefully it's just bad compression gauges. Would there be anything besides a air leak that would affect the compression that much?
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well you were using 2 cheap ass gauges. most likely neither was reading correct. i doubt a airleak would have much influence unless it was a huge gaping hole. see if a local mechanic has a qaulity gauge you can borrow, still theres no gaurantee its correct but the odds will be higher than a cheap taiwan unit
if you got a big exh port it will have a large impact on static pressure. plus i think elevation is -5 to 7psi every 1000'
personally if the leakdown shows good i would ride and not worry about nothing but thats just me
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I uses a brand new Matco gauge and and pretty new Cornwell one from work a couple years ago on my motors 1 gauge said with a stock piston,head gasket never touched motor it had enough compression it over 180 psi the other gauge said I needed a rebuild and had below 145! what do you believe??? I run a 330 with a 39 mm, ATC 5 ESR pipe, full air box with the lid off and trx 9 porting with a 50/50 dome a cel pinged like crazy went to dgh and still pigs I just havent had time to try a ccl next I believe is what rsss396 suggested. I know alot of people run a 52 or small slow jet but in Wisconsin I run a 55 in the summer,but the ccl needle may make the 55 to rich.
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Me too Martin.
Thanks for the help everyone. If the leak down checks out I'll keep running it but I just don't want to put it back together and first ride out it blows up because I didn't check something. I guess that's the 'labor of love' part of these R's. On a side note, what do you guys use to plug the exhaust flange for the leak down test? Tape it off? Plug it with a towel?
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Try a pipe test plug to plug the exhaust port.
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I uses a brand new Matco gauge and and pretty new Cornwell one from work a couple years ago on my motors 1 gauge said with a stock piston,head gasket never touched motor it had enough compression it over 180 psi the other gauge said I needed a rebuild and had below 145! what do you believe??? I run a 330 with a 39 mm, ATC 5 ESR pipe, full air box with the lid off and trx 9 porting with a 50/50 dome a cel pinged like crazy went to dgh and still pigs I just havent had time to try a ccl next I believe is what rsss396 suggested. I know alot of people run a 52 or small slow jet but in Wisconsin I run a 55 in the summer,but the ccl needle may make the 55 to rich.
Does you engine ping at partial or full throttle?
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Pantera fellow northlander I run a cel in the summer, dej spring and fall, and I raise the dej a groove in the winter. dgh's and dgj's both run lean at half throttle on my midrange play bikes.
First letter: length of needle after the taper starts.
Second letter: 1/2-5/8 throttle
Third letter: 1/8-3/8 throttle
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My motor ping from 1/8 to just over 1/2.
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Well good news, the motor held 6psi for 12 minutes. Am I right thinking the rings may not be seating all of the way or didn't seat all of the way when I did my break in?
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i think you guys been listening to carlos to much :D
maybe jerry could chime in on the subject ?
my thoughts have always been static pressure is pretty much useless info, to me anyways. a ton of things influence it. varying gauges, altitude, porting. hell the pipe and carb size probly do as well. and possibly even the reed stiffness ? besides soon as the engine is running the cylinder pressure changes. so what does a static number tell you. not much that i can see.
some people use a pressure gauge as a quick and easy way to determine when the top end is wearing out and i can see the usefulness in that respect provided you always use the same gauge and dont make any engine modifications but still you should confirm with tool measurements and examining the suspected worn parts.
Your top ring will seat in about the first 5 to 10 minutes of break-in running after a new bore job, providing you have a good bore that is less than .0005" of being round. We see a lot of freshly bored cylinders that are unacceptable. The bores will be out of round, or tapered, or have 6 high spots where the studs are located or a combination of all three common problems.
Choose a shop that has good boring equipment and uses Sunnen type wet mandrel hones to finish the bore after machining. Do not let anyone put a ball hone, de-glazing flapper type hone a flex-hone or a hone that is mounted on the end of a drill motor in your cylinder. A ball hone, flapper de-glazing hone, or flex hone will make any bore look good but they will not correct out of round or taper in a bore. Ball hones severely damage the vertical bridges in two stroke cylinders and cause the bridges to ware slots in the ring where the ring makes contact with the bridges at an accelerated rate.
We have customers constantly wanting to know how much compression their engine should have. We seldom use a compression gauges on a two-stroke cylinders to diagnose cylinder condition because of the wide variety of fittings, hose lengths and where the check valve is located. The combustion chamber volumes on the small two strike engines are rather small in comparison to the volume that may be between the combustion chamber and the gauge. Run a compression test on a 400 cubic inch V8 engine with ten different gauge/hardware setups and you may only see a 10 psi difference between gauges. Run a compression test a 250 cc engine with the same ten different gauges and you may see 10 to 50 psi difference between gauges.
A compression test on an engine that has not been run since it was assembled is usually meaningless. If you want to know how much compression your engine has, I would use the following procedure:
1. Run the engine for at least 30 seconds to a minute to remove excess oil on the cylinder wall and combustion chamber.
2. Kick the engine over as vigorously as possible with the throttle held wide open.
3. Continue kicking the engine over until the pressure will not rise anymore.
4. Write the number down and do not share it with anyone because you will only get into arguments with other riders and engine builders on what number is correct.
The cranking pressure is another area of controversy when it comes to determining what octane fuel to use on a particular engine build. The pressure in the cylinder near ignition time, the peak cylinder pressure during combustion and the combustion chamber shape as well as long list of other variables is what primarily determines what octane fuel your engine needs to protect it from detonation. The cranking pressure has nothing to do with what octane fuel your engine may require.
I have seen two-stroke engines with over 200 psi cranking pressure with a very poor pipe and port combination, run detonation free on pump gas. I also have seen a lot of our highly developed two-strokes that have 130 to 150 psi cranking pressure that need fuel with an octane rating of well over 115. Fuel octane requirement for a particular engine has to be determined by dyno and field-testing
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My motor ping from 1/8 to just over 1/2.
The noise that you are calling "pinging", is the noise ringing off of the engine or do you hear it coming out of the muffler?
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The noise that you are calling "pinging", is the noise ringing off of the engine or do you hear it coming out of the muffler?
As I went richer on the needle the noise went away. It only does it under acceleration mostly in 1-4 gear in the 1/8-1/2 throttle positions. It sounds like taking a hammer and hitting the engine cases.
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most 2t engines make alot of noise. the spur gears, waterpump, clutchbearing, rattling pipe springs and just the combustion noise radaiting through the pipe walls and cylinder etc etc. pretty sure most noises people hear are just normal sounds.
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I know in my case it was lean the richer I made it the more power it had and it revved up better plus the noise got less and less.