APT SmartCarb
- Thread starter gasgasman
- Start date
APT will be posting a lot of new pics,videos and tech talk about the SC and riders testimonies on our newly updated FB page.
https://www.facebook.com/PowerAPT
erniebearskin
New member
Whats the latest on possible shipping dates? Still early August?
Well, the good news is that after lots of testing I figured it out! The bad news is that this won't help most since it requires making your own parts and invest lots of time.
The key has been the spare parts I ordered together with the R080 rod which have been all over the place regarding tolerances and fitment - this made me realize I had to question every part inside the SC if I wanted to get it right. Long story short I found that the additional length of the R080 rod in combination with the stock nozzle (tube where the MR slides into) would emphasize the lean condition at bigger throttle openings. While working OK on the mildly tuned stock engine, the optimized head with the stronger signal caused havoc on the settings - much like on my 300 with the optimized head also. Looking at the nozzle it was clear I had to make my own if I wanted to change something there. Got a few 3.2mm reams and 3.5mm drill bits. On the stock nozzles the upper part is reamed while the lower is just drilled out (with a very bad finish). With changing the ratio of length between those parts I'm now able to determine the rich/lean characteristics of a specific rod in regard to clicker position. The shorter I make the 3.2mm part (naturally there are boundaries) the richer the rod will work at bigger throttle openings - translated this means I can run a lean clicker position for crisp and clean idle area yet have the right mixture once the throttle is opened. Right now I'm running the slightly modified A100 rod (I left nothing untouched) with a 3.2/3.5 ratio that is a few mm different to stock at near 70 clicks - bike runs like I always imagined it should
Call me crazy, but I'm never happy with less than perfect and as delivered the SC just was not up to my standards. I said it before and I repeat it here - if APT can't fix the quality of their peripheral parts all the cast SCs will not help as people will continue to have issues.
Michael
The key has been the spare parts I ordered together with the R080 rod which have been all over the place regarding tolerances and fitment - this made me realize I had to question every part inside the SC if I wanted to get it right. Long story short I found that the additional length of the R080 rod in combination with the stock nozzle (tube where the MR slides into) would emphasize the lean condition at bigger throttle openings. While working OK on the mildly tuned stock engine, the optimized head with the stronger signal caused havoc on the settings - much like on my 300 with the optimized head also. Looking at the nozzle it was clear I had to make my own if I wanted to change something there. Got a few 3.2mm reams and 3.5mm drill bits. On the stock nozzles the upper part is reamed while the lower is just drilled out (with a very bad finish). With changing the ratio of length between those parts I'm now able to determine the rich/lean characteristics of a specific rod in regard to clicker position. The shorter I make the 3.2mm part (naturally there are boundaries) the richer the rod will work at bigger throttle openings - translated this means I can run a lean clicker position for crisp and clean idle area yet have the right mixture once the throttle is opened. Right now I'm running the slightly modified A100 rod (I left nothing untouched) with a 3.2/3.5 ratio that is a few mm different to stock at near 70 clicks - bike runs like I always imagined it should
Call me crazy, but I'm never happy with less than perfect and as delivered the SC just was not up to my standards. I said it before and I repeat it here - if APT can't fix the quality of their peripheral parts all the cast SCs will not help as people will continue to have issues.
Michael
Jakobi
Super Moderator
SO Michael.. how long before mine arrives in the mail??
Congratulations on the break through. Now to see what happens from here. Also, what material is the nozzle actually made from? Is this the part that wears during initial 'break-in'? If so it would explain why my bike continues to change characteristics each and every ride. I wonder if they reach a point in which it stops wearing, and how this will effect the overall performance.
Can of worms..
Corey, what do you think? It makes sense as my engine is also modified, which will likely be why I'm noticing things more as well.. (not to mention that I'm always looking for perfection).
Congratulations on the break through. Now to see what happens from here. Also, what material is the nozzle actually made from? Is this the part that wears during initial 'break-in'? If so it would explain why my bike continues to change characteristics each and every ride. I wonder if they reach a point in which it stops wearing, and how this will effect the overall performance.
Can of worms..
Corey, what do you think? It makes sense as my engine is also modified, which will likely be why I'm noticing things more as well.. (not to mention that I'm always looking for perfection).
How could I refuse the wish of a Supermoderator, but things are not that trivial!
1) There are possible differences in outside dimensions of the nozzle depending on the revision of the carb body.
2) Since making a new nozzle anyway you want to make it in such a way that the tip is perfectly level with the venturi of the carb body for best performance. I made an height-adjustable one for testing, but the effort is high.
3) Inside dimension of the nozzle depend on several factors: rod length, possibly even clicker position to some extend, specific engine and state of tune - I found my current one through lots of testing and it may not even be close to what is possible. But as soon as I found a combo that worked so much better than what I had before I stopped. The 300 kit will possibly be a whole new ballgame, but it is working so close to what the SC was originally advertised as that I'm confident it will be fine with different "hardware" also.
Actually the nozzle, which is made of brass, is very simple in design so every machine shop should be able to duplicate/modify one. Only problem is finding a ream that is close enough in tolerances.
But regardless of my efforts it actually should be in the responsibility of APT to provide a solution for the guys having problems. I know of two other 38mm billets that work not satisfactory at all for the owners (both bikes not stock) - APT is trying, but to no avail yet. I don't know anyone with a well working SC personally, just the reports that have been posted on various forums.
Michael
I understand the pursuit of perfection.
I have provided a great deal of information though PM's to Michael, notwithstanding I think drehwurm, Jakobi and my friend Ivan have a combination that has some deficiencies that the carburetor tends to magnify. Most people stock or modified are getting exceptional results without all the modifications that has been described, which in my mind is just tolerancing that helps make up for some other issues. But in all honesty it may be bad parts as it is true we have struggled with our parts vendors and are continuing to source from other places that will build the parts to our specs. QC is our primary concern at this point.
Usually several good rides of a couple hours or more is all that is required for a good break-in. If your bike is continuing to change characteristics, then I would have to question things like fuel quality/consistency and head modifications. Some of what I mean is like a really tight squish clearance, that can change with thermal growth as the engine heats and cools, which can change this clearance by several thousandths, depending on how tight the crank,rod, wristpin and bottom end are. Also piston silicon content variance can change these thermal growth characteristics. Pipes, PV rates, muffler packing/plugging, air filter cleanliness can also affect running characteristics that the carburetor cannot fix.
All things considered I am glad that drehwurm is finally happy.
Jakobi
Super Moderator
Good points Corey.
I'm quite confident that the engine/bike is not the culpret here. Maybe magnifying something, but definitely not the cause due to a poor design. The heads squish band width and angles are the same as the stock engine. The squish was reduced but is far from what I would call a tight configuration at 1.35mm. The compression ratio was corrected to run on the fuels I have, which are always sourced from the same servo, 98RON, with 50:1 Amsoil Dominator. I never run a dirty air filter unless if its the end of a dusty ride, but even then shouldn't the smart carb be compensating in theory, and just running not quite as strong? Pipe has been pulled. I have no spooge from the silencer, the header has been removed, inspected and no blockages, the o-rings have been replaced and spigot sealed with rtv red. The spark plug gapped correctly. The top and bottom end was fresh when the smart carb went on.
Any other thoughts?
I'm quite confident that the engine/bike is not the culpret here. Maybe magnifying something, but definitely not the cause due to a poor design. The heads squish band width and angles are the same as the stock engine. The squish was reduced but is far from what I would call a tight configuration at 1.35mm. The compression ratio was corrected to run on the fuels I have, which are always sourced from the same servo, 98RON, with 50:1 Amsoil Dominator. I never run a dirty air filter unless if its the end of a dusty ride, but even then shouldn't the smart carb be compensating in theory, and just running not quite as strong? Pipe has been pulled. I have no spooge from the silencer, the header has been removed, inspected and no blockages, the o-rings have been replaced and spigot sealed with rtv red. The spark plug gapped correctly. The top and bottom end was fresh when the smart carb went on.
Any other thoughts?
andoman
New member
Try a different plug?
Not just a new one but a different one.
I mentioned before that my only real SC issue was hard starting when cold. When it was leaned to the desired characteristics I would have to kick it 10 -15 times when cold. The problem was completely solved with an NGK B8EIX fine wire iridium plug. It's now one kick to start hot or cold.
At this point I know it's desperation, but perhaps worth a try.
Not just a new one but a different one.
I mentioned before that my only real SC issue was hard starting when cold. When it was leaned to the desired characteristics I would have to kick it 10 -15 times when cold. The problem was completely solved with an NGK B8EIX fine wire iridium plug. It's now one kick to start hot or cold.
At this point I know it's desperation, but perhaps worth a try.
Jakobi
Super Moderator
I've tried my BR8ES that I always ran, as well as the BR8EG that was installed after the rebuild and ran great with the Lectron. I've had no issues with starting hot or cold. The main thing I am finding is that I need to run the MR rich, get a bit of smoke, and a bit of burbling, and set it that it will load up a bit if puttered around at small throttle, to have it provide decent torque through the mid range.
I'm just going to leave it at this setting and ride it until I have access to double check the floats. I'll inspect to see if its been rubbing or hanging anywhere.
I'm just going to leave it at this setting and ride it until I have access to double check the floats. I'll inspect to see if its been rubbing or hanging anywhere.
Latest SmartCarb video at the pre X Games ride.
https://www.youtube.com/watch?feature=player_embedded&v=nLv8-OLLu9c
https://www.youtube.com/watch?feature=player_embedded&v=nLv8-OLLu9c
Seems like we have fixed Ivan's bike also - he is on a 250 link bike and was always complaining about a heavy bog when accelerating hard. Carb had been sent back to APT for a check over, but it didn't really change things. When making my modifications I also made some tests with sanding the rod to make it a little richer at bigger throttle openings. Basically you use a 1000 grit euro spec (600 US spec) wet sandpaper on a perfectly flat (plate of glass) surface since you don't want to change the shape of the flat part on the rod, just make a tiny change on the angle. Put the emphasis of pressure somewhere near 1/3 from the bottom (part opposite the threaded end) on the rod. You know you have been successful when you need to set your clicker a few clicks leaner and your lean midrange/acceleration condition is gone
Michael
singletracker
New member
What a pain in the a$$ for an $800 add on. So much for plug and play.
hamilton
Gold Level Site Supporter
Yep, I'll stick with my AS 1 works great.
Exactly! 1000 euro grit worked best for me. Take your time, you want a really nice sharp edge on the flat part. I cut the sandpaper in small stripes a bit longer than the rod. A "stripe" will get dull pretty quick - 20-30 seconds, then I switch to the next one. I just push down with one finger on the rod at 1/3 of the length of the rod from the bottom end - you get a feel for it quickly. About 5 stripes will get you a noticeable difference in performance. If you want, finish off with a 1500. Test! The moment you need go a few clicks leaner you know it worked. Works well on both the A100 and R080.
Michael
Jakobi
Super Moderator
Thanks Michael, another job for a day off. I can see how it would work too. The bottom end is really nice when clean, but the mid range suffers because of it. I guess it just shows that the one metering rod for all purposes is flawed theory. Maybe Lectron were onto something after all?
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