To clarifie, the throttle I hold wide open during the two squirts with no turning the motor over, then a slow kick to drag the fuel in with the throttle open. This is because the primer nozzle is placed right at the carb on the filter side, in the rubber boot on top. After this priming close throttle with choke on and kick it like you mean it. I have also heard the 250 kick starter is shorter and will give you a faster revolution and with the decompression on the 500 you can use it. Has anyone tried this?? Thanks. Garry
Smart carb egt's
- Thread starter the gman
- Start date
Tom is the one I talked to. He did not sound hopeful! I guess I can give him another call, and see if there is any chance of getting yours, but it sounded like there was a list of people ahead of me. So the .078 was too rich for u? what bike are u running? Thanks for the help guys!
if you would part with it I would buy it. If you would rather keep it so you have a complete set that is understandable. Luckily I got my 4stroke going today so I have something to ride. I guess pm me if you would sell it. I'm in Montana. Thanks!
What bike?
Frankly the Millar Engines bike has been the oddball of the companies builds being a problem to start at the best of times since the first day I got it, even after changing the ignition twice, changing PWK carbs/slides, Smartcarbs and jetting 50 different ways.
I do have the EGT threadolet welded in the pipe just haven't tried it yet.
It does have amazing torque/hp, if I can get it to start run reliably I will get the track kit. The 38mm billet SC with Summitboy's .080 needle i have set a 62 clicks from full rich at this point and runs crisper than anything I've ever ridden (4000+ ft asl) and yes the .078 was too rich but other guys at lower elevations (700ft asl) do run the .078
I think lots of guys agree the ultimate would be the Smartcarb with the Pulse Injector but that would be a few years of development to get there.
I'm running a CR500 with Millenium nikasil, same cyl/case porting engine as Summitboy. I haven't done the timbersled thing yet because my frame is a 2004 CR125 aluminum conversion and I don't think there is enough room for carb heaters.
Frankly the Millar Engines bike has been the oddball of the companies builds being a problem to start at the best of times since the first day I got it, even after changing the ignition twice, changing PWK carbs/slides, Smartcarbs and jetting 50 different ways.
I do have the EGT threadolet welded in the pipe just haven't tried it yet.
It does have amazing torque/hp, if I can get it to start run reliably I will get the track kit. The 38mm billet SC with Summitboy's .080 needle i have set a 62 clicks from full rich at this point and runs crisper than anything I've ever ridden (4000+ ft asl) and yes the .078 was too rich but other guys at lower elevations (700ft asl) do run the .078
I think lots of guys agree the ultimate would be the Smartcarb with the Pulse Injector but that would be a few years of development to get there.
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300 EGTs
Gman or others, do you have any updates on your EGTs on the 300? I have a very similar setup (Gorr porting, S3 Head, SX ignition, 38mm SC...) and I am having a hard time keeping the temperatures down at a safe level. I switched to the 78 metering rod, but didn't notice much change. I can hit 1300* fairly easily and have to back off. We have poor snow conditions, so this is on the trial and some very simple climbs. I started at 80 clicks out from full rich. Any comments are appreciated! Thanks!
Gman or others, do you have any updates on your EGTs on the 300? I have a very similar setup (Gorr porting, S3 Head, SX ignition, 38mm SC...) and I am having a hard time keeping the temperatures down at a safe level. I switched to the 78 metering rod, but didn't notice much change. I can hit 1300* fairly easily and have to back off. We have poor snow conditions, so this is on the trial and some very simple climbs. I started at 80 clicks out from full rich. Any comments are appreciated! Thanks!
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mxracer299
Well-known member
Stock rod is Q11, 78 rod is Q09, Q07 might be ok but Q05 is what you want on your 300.
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mtn-doo
Well-known member
After testing several new 300's the past week I have found the correct fuel rod for this particular engine. The Q9 was close everywhere but a little soft in the mid range and still hitting 1300F on a long pull. I ordered several Q7 rods on Monday for testing. I had none in stock. I did have two Q5 rods for another application and decided to test them yesterday on two new 300SX bikes. The Q5 gave the added fuel in the mid range to make the bike super aggressive in that "soft area" and held 1230 to 1260 on extended WOT pulls. Most excellent. I have several Q5 rods on order as of last night.
This may not be the rod for everyone. These engines are moving so much air we are needing to add a lot of fuel. Having to add fuel is a good sign.
It means you're making a ton of HP. I recommend each bike be tested and tuned independently. You are looking for either an EGT in the mid 1200's or an AFR in the 12.8 to 13.0 range on an extended WOT pull.
This may not be the rod for everyone. These engines are moving so much air we are needing to add a lot of fuel. Having to add fuel is a good sign.
It means you're making a ton of HP. I recommend each bike be tested and tuned independently. You are looking for either an EGT in the mid 1200's or an AFR in the 12.8 to 13.0 range on an extended WOT pull.
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mtn-doo
Well-known member
You need to add fuel. Remember turning your tuning knob only adds or subtracts fuel in the pilot circuit. That will have no effect on your running EGT's. Only the idle and first 1/3 of your throttle are being changed. If you need more fuel up top, you need a richer rod. Based on your engine build, I would recommend the Q05 rod. Then tune the bottom end with the knob for a clean idle and throttle response. The added fuel from the richer Q5 will be seen at WOT. That should get you in the money. Hang on! The added fuel in the mid range is super aggressive.
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mtn-doo
Well-known member
They are a single grind but the base is proportionately different. A richer rod will need to be set a little deeper in the nozzle for the correct pilot setting. Testing again today. From what I see so far, the 40mm draws more fuel and is happy with a leaner rod. The 38's are perfect with the Q05 or Q07. The 40's seem to be Q07 to Q09. I will let you know what I see today. Tuning a new 40mm on the mountain today.
What egt were you getting to with the 7 ??. I have the 9 in my 40 and it seems to idle best at 98 clicks. With the non marked .078 I was over that but burbled down at 1/4 throttle and mileage was worse than the 500 2 stroke. I was pushing high 1200's with the .080 in the 38 and was way low temps (1120)with the .078 in the 40 on the same 300 so I will let you know were it ends up. I bet I end up with the .080 in my 40 as the .080 I had in the 38 when I was getting 1250-1280 measured .081. If my 40 draws more fuel like randy is seeing then the 40 with a true q-11(.080) will probably settle out at 1280 or so. Will post when I get out again....garry
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mtn-doo
Well-known member
I believe I went one step richer. The .078 or Q09 rod. The Q11 would hit 1300 plus. The Q09 would settle at around 1240 to 1260 on a long WOT pull.
Needle Seat...
I talked to someone today that said there may be a problem with the needle seat or metering rod seat in the smart carbs. They said Randy was working on the problem. Is there any truth to this? I have the Q05 metering rod on order to hopefully fix the high EGT problem, but now I am worried there are more problems. I'm starting to regret doing this build (300 XC). My 450 SXF is so much less work and so much more riding! Randy, can you confirm or deny that there is a problem with the seat in the SC? Thanks!
I talked to someone today that said there may be a problem with the needle seat or metering rod seat in the smart carbs. They said Randy was working on the problem. Is there any truth to this? I have the Q05 metering rod on order to hopefully fix the high EGT problem, but now I am worried there are more problems. I'm starting to regret doing this build (300 XC). My 450 SXF is so much less work and so much more riding! Randy, can you confirm or deny that there is a problem with the seat in the SC? Thanks!
I don't know what u mean by problem ? The carb works the way it was intended. Its kinda tough to have a needle that works for all bikes in all conditions. Its still a carb and still needs tuning. The problem is on the 500 nothing is constant and every bike has a different state of tune. I find the Smarty too lean for my bike. I can go to a richer rod but it starts to exacerbate other problems like idle and starting and vibration.
Some guys say their 500's run perfect which may be true. My porting is a lot different than anyone else unless they have a TWIRP motor. Smartcarb is smart but is at the mercy of its needle just like a PWK. It still needs tuning !
I have since gone to a Pulse intake and the tuning has been ultra easy once the baseline is set. I just tune with the airscrew. Jets are easy to get and swap out. Its the age old tale. Some like to tune others don't. Carb will always be a carb !
Some guys say their 500's run perfect which may be true. My porting is a lot different than anyone else unless they have a TWIRP motor. Smartcarb is smart but is at the mercy of its needle just like a PWK. It still needs tuning !
I have since gone to a Pulse intake and the tuning has been ultra easy once the baseline is set. I just tune with the airscrew. Jets are easy to get and swap out. Its the age old tale. Some like to tune others don't. Carb will always be a carb !
I can tell you this I have a 36mm Lectron on my 300 and once I had it tuned.. It took 8 or so rides to dial... I never touch it again from 3000 to 11000 20 degrees to 90 degrees... Now on the high and low end of temps it does feel a little rich or lean but still never stutters ect... It's wheels only. The nice thing about the Lectron is it has a power jet adjustment for the top rpm range which the smart carb does not have... You have to switch the rod.
Now on my cr500 which is snow only I have ridden from 7000 to 11000 from -14 to 40 no powder to 4ft... Never a hicup... I had to go 90 clicks richer on the stock rod. Now mine is ported for race fuel and I do use a little higher octane than I should need ...
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mtn-doo
Well-known member
The Smart Carb doesn't need "tuning" after the initial set. The atmospheric signal ports maintain consistent fuel delivery from sea level to 24000 feet msl with no adjustments or tuning. They are air tight and sealed. No vent lines at all. Completely different than a conventional carb like a PWK. They have no temp or altitude compensation capabilities. They have vent lines like an octopus and open to the atmosphere. They need to be jetted daily based on conditions. The "needle" of a conventional carb and the fuel rod of a Smart Carb are "not" the same. Completely different. The conventional carb has it's "main jet" regulating WOT fuel. The Smart Carb has no jets. With the Smart Carb, you need to simply install a fuel rod for the WOT demands only. The rest is adjusted for idle with the adjustment knob. Once your WOT rod is selected, you adjust your pilot circuit for idle and you are done. Never touch it. Not even from -40 in the winter to +90 in the summer. EGT's are exactly the same. No jetting, no tuning, ever. That is why military UAV's are using them. No jetting or tuning required, around the world in different altitude and temp conditions with precise consistency. No "jetting", no "tuning". They can't turn a power jet on a UAV at altitude.
If you had a lean rod, we can install a richer rod for your WOT requirements, then adjust the bottom end for that clean, crisp idle. I do several a day and would be glad to help.
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