Still no increase in power.

[JMcDonald]

With stock gearing, I had no problem reaching top speed in 6th gear even if I was just cruising at 80mph at around 10k and went WOT. Peak power occurs on these (stock) bikes at like 10.5-11k, so a downshift to 5th actually never helped much (either emperically, or mathematically). In any case, shifting out of 5th at about 11.5-12k (because it was already running out of power by then), 6th would land at about 10.5krpm. As my gears sit now, the RPM drop after a shift from 3rd at redline puts me at about 10.5k in 4th. As you can see, the difference is really only marginal as for as how well it should pull in top gear from 10k+. Starting a top-speed run from 10.5k in stock 6th (at about 85mph), given that I could already easily reach 11-11.5k from a 10k start, it is easy to see that if power didn't drop off so quickly that a continued run would have netted a higher top speed limited only by power or possible gearing. And since my current 4th is actually a bit shorter than stock 6th, it would be even easier.

Right now, I run out of 4th gear at barely 100mph. If I were to ever get the bike going closer maybe 105 or so, I'd have to be in 5th and the RPMs would be below peak HP (not by a lot, but every little bit counts here). Conversely, a 37t would put the speed range of 101-107mph in 4th gear within a few hundred RPM of 12k RPM, which is right where peak power seems to be made on most tuned bikes.

As a side note, Wayan you are exactly right that the same amount of energy (fuel) is used to move the bike at a given speed, regardless of engine revs (sans a very small difference based on the energy required to keep the engine itself spinning faster).


I would never ride an automatic bike, or even a scooter for that matter :P . Brownie Points for the Family Guy reference .

BTW, shifting at 14kRPM in even stock 5th (assuming a reasonably accurate tach) is 101mph. What are your mods to 1) go that much faster than stock and 2) keep the engine making power that high up into the rev range? Also, how fast did you end up going in 6th (on the tach and on the speedo, unless you were using a GPS meter)?

Thanks.

[Racer x]

The top speed is going to be 104 to 107 regaurdless of gearing. The air wall will hold the 30 hp bike at the top speed .then wind and grade will help or hurt. Just remember 5th gear is 1to 1 in the trans and
6th is over drive.

[JMcDonald]

Well then Im obviously nowhere near 30hp then, if thats how faat I should be going heh. The "why" is the mystery id like to solve, heh.
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[wayanlam]

Originally Posted by JMcDonald

BTW, shifting at 14kRPM in even stock 5th (assuming a reasonably accurate tach) is 101mph. What are your mods to 1) go that much faster than stock and 2) keep the engine making power that high up into the rev range? Also, how fast did you end up going in 6th (on the tach and on the speedo, unless you were using a GPS meter)?

Thanks.

my mods are as listed:

• AP CF/custom 15" Quiet Core,
• K&N pod Filter,
• Sportisi Jet Kit #40 pilots & #108 mains & e-clip#2,
• Kleen Air System Removed,
• BRT TIS programmable,
• RX2 Koso Gauge,
• Z.Gravity - DB

and the last dyno run i did the bike was getting just under 30 Hp




the mechanic said that he could maybe get another 1~3 hp if i were to let him port and tune the bike some more. hes tuned several bikes up to around 32~33 Hp after porting them. something that i will eventually get done maybe.

the problem is that i haven't had the occasion again (there are like no empty roads here in Bali, haha) to test the top speed since ive done the last couple mods; change pilot jet, and bigger main jet, pod filter, and the BRT-cdi. and i don't fancy risking my life just to check my bikes top speed either.

the only time that i did have a chance to try and WOT to the top speed was when i still had stock air filter, with snorkel removed, dynojet kit stage 2, and the Area P exhaust, and i got up to 170 kmh, which converted to miles, and minus 10% results to 95 mph, or 97 mph if i reduce by 8%... i don't know how far off my stock speedo was.

now i have the Koso speedo, which should be really accurate, and it logs the top speed as well, but i haven't been able to test it... meh!

changing the subject, im not sure anymore now what rpm reading is accurate. i know that with the stock cdi, on hot days (which are most days here) the rpm reading was off by at least 1k. since i changed to the BRT, it seems to be reading quite accurately. i was getting similar rpm readings as others were reporting, while going 100km/h. but now matt said that the BRT might also be off by about 600rpm... so, i wonder what should be right.

can you do a calculation for me, with stock gearing, in 6th gear, driving 100 kmh = 62.1 mph, what SHOULD the rpm be at? i know my speed should be accurate with the Koso, so i would like to see if the rpm is too.

cheers!

[JMcDonald]

Thanks for the comments and info!

62.1mph should be 7650 with the stock 14/45 in 6th gear.
http://gearingcommander.com/

I don't know if my tach error is particularly worse with the TIS, because in general I haven't noticed any difference in how the tach and speedo indicate together. For example, ~32.5mph on the speedo was always 6k on the tach, because I would always look for that knowing 6krpm was exactly 30mph in stock 3rd gear. And later, I started looking for ~7800rpm in 3rd for 50mph.

I also have been watching the GPS meter, and it seems either it or the speedo actually varies with speed. At slower speeds, below maybe 45mph on the GPS, it seemed to indicate that ~8% error. Going faster, like 50-70mph, it would sometimes read as much as 11-12% lower than my speedo! However, as I went faster and faster, the error would actually go even lower, like down to 6% or so, with 108mph on the speedo reading as 101mph on the GPS (6.5% error). I am unsure whether the speedo itself varies with speed (I explained above how it could vary, being as a system it isn't purely mechanical), or if the GPS's accuracy varies with speed.

This weekend I might play with the mains some more to see if maybe it is running out of fuel around peak airflow (around 11-12k).

I am a little disappointed I didn't feel any difference in going to the advanced map, though.

[Flashmonkey]

29.8 hp at the wheel. Very impressive!

Gotta love that torque curve too.

[mrlmd]

Don't forget that the GPS reading is not instantaneous speed, like with the readout from a speedometer or radar gun. It has to be at a constant speed for a short time period (10-20sec) for an accurate measurement.

[JMcDonald]

Yeah, I am holding these speeds for typically about that long, until it starts reading constant. Matt of Sportisi said the exhaust should actually make more power with the silencer in place, but i took it out to eliminate another variable.
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[Racer x]

From testing exhaust systems and open headers . I lost both top end power and torque with the silencer removed. The jetting was good but there was about a 1 hp drop across the board.
Loud pipes may save lives (Or not) but they do not make more power anywhere.. From what I have learned .It has more to do with the length of the pipe than the back pressure of the muffler. But I have not done any dyno testing with different lengths of exhaust pipes.

[JMcDonald]

Yeah I am not expecting any increase in power, but just wanted to eliminate it as an issue. I took out the silencer today while at work, but realized I forgot my wallet so I just headed strait home without any high-speed detours :P . And then I was just too cold to go back out, heh. But, tomorrow I will test it. But I am looking forward to getting it back in, lol.

[ztrack157]

On the dyno it makes more power with the Suppressor in. Just like the Leo Vince setup on my racer Kirk Korenko's Sportisimoto bike. Video courtesy of On the Throttle.

Link to original page on YouTube.

[Alex]

Originally Posted by mrlmd

Don't forget that the GPS reading is not instantaneous speed, like with the readout from a speedometer or radar gun. It has to be at a constant speed for a short time period (10-20sec) for an accurate measurement.

It's true that it's not instantaneous, but it doesn't need to be held for anything close to 10 seconds either. All modern units are sampling speed multiple times per second, and displaying updates at least once per second. If you are seeing the same speed for 2 seconds, that's displaying your current speed to the level of accuracy of the GPS (which is pretty darned good at this point).

[JMcDonald]

Matt, do the Sportisi jets share the same sizes as the Keihn jets, or is it a different scale like Dynojet?

[ztrack157]

Supposed to be keihin size but I haven't measured to confirm. Don't use wayan's base line jetting though. Things over there tend to be jetted a little richer than here

[wayanlam]

it might have to do with the temp and humidity? or maybe fuel just isnt expensive enough... lol

although matt is right, i think my bike is running a little rich, if i wot the bike while parked, i can see some smoke when i hit the higher revs.

ive actually come down from 110 mains, which was really too rich.

the guys at sportisi finally have an A/F meter now (hope its till working, lol) so next time i go there with my bike I'm gonna get them to tune the bike with that.



i got to the same point like J. where i just could not be bothered to open the bike/carbs AGAIN to test another jetting, hahaha... the bike was/is running quite good, so i left it as it is.

im taking my brothers 150 d-tracker to sportisi tomorrow to get ported and tuned, and possibly change the stock CDI out with a BRT one. and also the engine block of my dads old Honda CB200 which im getting repainted (pic below). that should give them something to do for a day or two


thats the before pic, if i remember ill get an after pic done once the bike is re-painted and re-assembled. gonna go back to its original metalic dark green color

[JMcDonald]

I was actually asking because I was wondering if I couldn't go leaner, since people with the Sportisi kit seem to often use 106 and 108 mains with the mods I have, as opposed to the 110 minimum supplied with the FP kit. Before, it did run well up top all the way down to 102 mains, so maybe this weekend I will switch to 108s and see how it does from there.

Thanks for the words of encouragement, Wayan .

[rockNroll]

a twenty shot of nitrous

[JMcDonald]

At this rate, even nitrous probably wouldn't do jack on my bike :P .

[menno]

Originally Posted by ztrack157

On the dyno it makes more power with the Suppressor in. Just like the Leo Vince setup on my racer Kirk Korenko's Sportisimoto bike. Video courtesy of On the Throttle.

Link to original page on YouTube.

hey matt,

this is maybe a bit off-topic but,
i have a leo vince slip-on and want to put the pipes aswell.
now these guys from the shop told me that the leo vince pipes of a full system wont fit on a slip-on, but if i look at the drawrings here it should fit???
can you enlighten me a bit?
http://www.leovince.com/files/F11126/DT-8111-8268.pdf
http://www.leovince.com/files/F10692/DT-8110.pdf
btw imma try my insert too now!

[JMcDonald]

You might PM him instead.

[JMcDonald]

Btw, it ran terribly without the silence. I only tried onr short run, but t would barely rev past 12 and felt like when I tried 115 mains and it was way too rich.
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[scotty]

Originally Posted by JMcDonald

Btw, it ran terribly without the silence. I only tried onr short run, but t would barely rev past 12 and felt like when I tried 115 mains and it was way too rich.
Posted via Mobile Device

What size jets have you used that worked well? 108,110's? What about your Pilot jets? Did you up those also?

[JMcDonald]

With the stock exhaust, I tried everything frm 102s to 112s with the exact same performance up top. The 102s were too lean as they required the needle clip to be in the 5th position PLUS two washers underneath, just to run without stuttering. I am currently running 110s with the needle clip in the 4th position, but I might try the 108s today to see if it levels out the torque curve up top.

[JMcDonald]

I did a little Eenie-Meenie-Miney-Mo (sp?) with jets, and decided to try the 112s as opposed to the 108s. Noticable drop in performance for sure, which I suppose is a good sign since before I couldn't tell a difference at all. At least I now know the exhaust did something, heh. Tomorrow I will go the other direction and try the 108s. While on the 112s, I also tried removing the silencer and it still reduced performance. I figured it would, but wanted to try since it was quick and easy anyways.

[GiGs]

Must admit I didn't read everything, and that i've come across your threads a few times (thought you would have it sorted by now )....

I want to make 1 suggestion which completely changed my bike (and believe that I/you/whoever is just guessing without one)...an A/F meter. In short if you like to work on your bike go this route, otherwise, take it to a dyno and by the time they are finished it will end up costing the same if not slightly more.

Too add to it also, max speed with a BONE stock bike I could achieve was roughly 165KM/H (by the spedo) - my weight is 105 pounds + gear.
Now, max speed I can reach is 180KM/H (that's with some time to get there).

Mods are:
Full Yoshi Exhaust (silencer in), K&N, Clean Air System Removed, pre-gen CDI (using Motul 300V Factory Line ... Full Synthetic if that makes any difference, oh and I have a slightly warped front rotor if that makes any difference ).
110 Mains, 2.5 Needle Clip, #40 pilot, 2.8 turns out (if I remember correctly).
Note: I could achieve the same top speed without the pre-gen CDI.
At WOT if I remember correctly i'm running around 11.6 - 12.2 A/F ... when cruising I am getting around 14.3 - 14.5 A/F. Elevation is 40ft above sea level.

Check that your rubber intake boots aren't cracked at all (will give false plug reading and make it way leaner). If they are cracked, replace them (I had to, $30AU each from the stealer). Don't forget to sync your carbs either....



Suggestion is to make one change at a time, if you do too many things at once you won't be able to tell the difference.

Good luck and I hope you finally get it figured out ~ !

[JMcDonald]

About syncing carbs, I am really starting to wonder about that. I noticed yesterday the color change on my headers is really indicating the left cylinder is running significantly hotter than the other. The shade of blue right at the header inlet on the right cylinder indicates around 600*F temps, while color at the same location on the other side indicates steel temps of more like 800*F. The EGTs to get there are probably even more disparate. Of course, I don't really know how hot the headers should actually get, just that there is a definite difference in how each cylinder is running.

The potential causes I can think of are:
1) A torn intake boot on that cylinder, causing it to suck in extra air and thus run leaner.
2) Carbs terribly out of sync, though I would think low-opening response would be terrible, if the engine would run at all, if the carbs were this out of sync.
3) A torn slide diaphragm on that side, preventing the full vacuum differential from developing and thus preventing the slide from fully opening. This is tricky because I've never heard of anyone having a torn diaphragm and still run, but in principle the right amount of air leaking could cause this to occur. If this were the case, it could also explain the flat spot that occurs up top, which might be that one cylinder running lean until intake velocity increases enough to get adequate lifting from the diaphragm.

As far as option three goes, last time it was open I noticed a small tear right along the edge of the seating ring. It wasn't in an area that could be repaired using the tire patch method (being right at the edge), so I globbed some grease into the area. In any case, I hadn't noticed anything major (like I said, everyone else reporting a torn diaphragm also reports the bike barely running, but I hadn't noticed any differences), so I kindof just forgot about it. But, considering this principle of carb slide operation, that explanation does make sense. I might try to repair it today with some RTV since I was going to remove the carbs anyways to mess with jetting, so maybe that will make a difference for now. Unfortunately, I have no idea when the original crack occurred, as I've taken the tops off a good half-dozen times.

But, at least this seems to give a clue as to something which can be fixed. I will seal it with RTV today, and check the intake boots, but if that doesn't make a difference I will just buy a replacement set of carbs since it costs the same as a new slide.

[almost40]

I said I was done posting on this topic, now, I cant help myself. All the hype about sprockets and jets and and everything else is out the window. One look at the picture above tells me you dont know a thing about engines. (Or you might have noticed this little problem a while ago.) Quit playing with the jets and sync up your carbs. ASAP (most likley cause of the problem) If that doesnt fix it you might need a new set) This was suggested LONG ago. Just by the look of the picture your left side is way to lean and your right side is way to rich. (that is if you made all the top speed runs that you claim) I rode my 250 on the track for a whole summer and couldnt turn my headers as blue as your left side.(i tried)
Now, dont take any of this personal or the wrong way but there is a reason that your not getting the performance you desire. YOU DONT TAKE ADVICE WELL. There are alot of people here on this forum, who know how to fix your problem but........ YOU THINK YOU KNOW MORE THAN THEY DO. Alex, Kkim, RacerX and many others, have alot to offer. I dare say, they are authorities on the 250. They quit posting as did I. You think thats a coincidence?? I spoke up because I want to save you the cost of a new engine. Keep ignoring those of us who know about these things and you will be out the cash. Go back and re-read this thread. All the info that has been suggested before will solve your power problem. Read the thread on how to sync up your carbs. Find the thread on how to read spark plugs. (Read it, you should have noticed the out of sync thing long ago just by looking at your plugs) Humble yourself and get the motor running right. Take a little advice and then follow thru with others suggestions and we will help you solve your problems. Then you can run whatever sprockets your calculator tells you too and ride off into the sunset. HAPPY.
Sorry dude but you need some tough love and a piece of humble pie.

[JMcDonald]

It was kkim who told me that syncing was a step that only preceded fine tuning the mixture screws. It was Alex who said carb sync is not really a factor at WOT. I also posted pics of the plugs, and again, kkim is the one who assured me that cylinder wasnt lean. Ill upload the pics of those plugs again when I get home, but they are in the jetting discussion thread on the 3rd or 4th page if you would like to have a look. Kkim is also the one who told me a torn diaphragm wasnt likely my problem, because that usually makes the bike almost not run at all. So yes, I have been listening. If ANYTHING, it was BECAUSE these acknowledged authorities stated these thing thatvexplains why I have been hesitant to believe otherwise.

This new discovery points to a different problem which, like I said, likely means the left side is somehow starving for fuel (slide not fully lifting) or getting a lot of extra air (torn boot), relative to the right side. I had previously checked the boots, but I am going to check again to make sure.

Off to remove the carbs.

Edit:

Hell, it was your posts that gave me direct justification to say increasing power will allow higher tp speed. It was RacerX who said my gearing isnt what is preventing me from hitting around 105 saying a 30hp bike should easily do that. It was various dyno graphs postedby both vendors and members showing 30hp or more with similar setups that made me believe I should be seeing some gains.. It was kkim and many others who recommend somewhere around 110 mains for most similar setups, which is why I started there.

So again, I do listen and take in informaton quite well, I think.

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[ztrack157]

I wish you were here I would dyno tune the thing myself for free.

[almost40]

I agree with Kkim if the diaphram was torn more than likely the bike wont run right. As far as sync up goes, thats something I do every time I pull the carb. (good habbit to get into. It doesnt take that long) I cant speak as to which jets to use as I have nothing to base my opinion on. (I still have the stock airbox) The 110's or 112's seem to be where its at for the pods. I havent checked the jetting thread in forever so I had no Idea what was posted there.
I want to help, and please dont think that im just trying to be a jerk.

As far as the plugs go do you still have the stock plugs? Did you switch brands and or type?? Looking at the plugs is VERY helpful in tuning but if you have the wrong plugs you get a false reading. If you changed plugs, clean them up and go back to the stockers for a while. (or buy a new set EXACTLY like the stockers. When you pull the carb use ALOT of carb cleaner. Spray the hell out of it. EVERYWHERE. Look for stress cracks, anything that might expand with heat. Sometimes carb problems boil down to a hairline crack. Post a few good pics of your carb off the bike in a state of disassembly so we can take a look. Whatever the problem is its no doubt affecting your power output and from the look of it is costing you horsepower.
It was Alex who said carb sync is not really a factor at WOT. In most cases this is true but I assume your headers pic was taken after a WOT run or 2 or 3. In this case theres no doubt you have a sync problem.

[JMcDonald]

For a more technical update, when lifting and dropping the slides, they both drop at the same rate and crease the same hissing sound resulting from the vacuum creates. The left side definitely doesnt drop quickly and solidly like the video posted in the thread on diagnosing and repairing the carb diaphragms.

And so far, sealing one end and making suction on the other, I cant notice any perceptible difference in how well that side's intake boot holds air compared to the other. Neither are acting like they are leaking.

Oh, thanks for the post, 40. I will take some pics. Yes, since I put on the exhaust Ive probably spend several total minutes at WOT. Maybe ten or twelve 20-30 second runs, and then a few shorter bursts here and there.
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[JMcDonald]

I had the plugs changed when I first got the bike, to what I assume were stock replacements. I didnt notice any performance gain. But these have about 6k miles on them.
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[JMcDonald]

Oh, and thanks Matt . At least I am still enjoying the look at sound of the exhaust :P .

I have really looked around the carbs and have found anything that looks like a crack. I had capped off the T-fitting that originally went to the kleen air system, so I just ran a single hose in its place so I can eliminate those joints from the equation.

Playing with the slides, I realized at the top ~1/4" of its stroke, the resistance goes way down compared to everywhere else in its stroke, or the same point in the other slide's stroke. I am wondering if the crack at the edge remains sealed until the diaphragm flexes at its most at the top of the stroke, at which point the crack widens and leaks? Just an observation and hypothesis.
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[almost40]

Can we find out what plugs you are running? Are they both the same?? I want to eliminate this part of the problem before moving to the next. I have made the mistake of thinking it was a fuel problem when it was a spark problem. (more than once) Have you checked to see if the coil is putting out the same power for both cylnders? All the wires good?? I have had plug wires (on the drag car) that work fine until you heat them up with high rpm use. I just want to eliminate the electrical system as the source. I assume the CDI is good because of the BRT.

[wayanlam]

carb syncronizers aren't that expensive to buy, and even cheaper to make!


thats my $2 carb sync, lol.... and it works!

there is a thread somewhere explaining how to make one with some pipe, 2 glass bottles, and some cork.

i didn't have any glass bottles handy at the time, so i used those stiff plastic cups.

after having taken the carbs apart so often, its possible that you might have shifted the sync screws unknowingly, even the slightest turn of that little bugger makes a difference in the sync.

or maybe you didnt, but it would be good to strike that off your "to be checked" list

my carb was out of sync, even though i never touched that screw, and had only taken the carb out maybe half a dozen times or so.

[JMcDonald]

Those are really good suggestions, 49. How do I check the coil output? The plugs and wires were supposed to have been replaced around 6k miles ago, and I havent noticed any drop in performance since then. But i have no idea about the coil. Silly me, earlier I removed the plugs to take pics of their hot ends, and never thought to check the model. In any case, it is about due for plugs and wires anyways, so Ill take care of those soon.

Edit: Yeah, next weekend I might try to sync the carbs, indeed just to see if i cant check it off my list.
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[JMcDonald]

Haha nice sync kit! I didn't see the image earlier (phone).

Ok, so I RTV'd the diaphragm, wrapped the carb boots in electrical tape (didn't find any cracks, but I've used e-tape to temporarily fix cracks in intake boots so I figured I'd just do it to be sure), and sealed the boot connections with grease (since they are actually held in place mechanically, rather than by friction). I decided to try out the 108 mains while I was in there, and Im going to run these until next weekend. I made the change to check overall performance, and I figured I'd be able to see in a few days if the header color starts evening out. Overall, it feels a bit more responsive in the midrange, and the dip from 10-12k seems gone, but overall power didn't change (still hitting 105ish on the speedo, both ways). But, it is better than it was when I started today so that's a good thing.

The next step while I wait to see if the header color changes will be to look into the ignition system. Almost40?

[ztrack157]

And what do you hope to find in the ignition system?

You know there are some of these bikes that are just flat out slow motor wise there is a chance you ended up with one of those motors. So no matter what you chase it's not going to be what you want it to be.

There are just so many factors. Even down to how tall you are. I've seen where chaning out the wheel bearings freed up horsepower on a racer of mine's bike. No matter how he built up the bike to run CMRA endurance he was always chasing hp never made above 30. Swapped out for the ceramic bearings and was then making 32 and change.

[almost40]

Ztrack It looks like (by his pic) hes way outa sync. Left side is lean right side is rich. just tryin to fix that first. Im sure hell take any sugestions if ya got a few. After you sync up the carbs this should even out but if it doesnt gota start looking elsewhere. Electrical is the cheapest and in my opinion the next obvious place to check.
BTW wayanlams pic shows what your headers should look like after they cool down. Mine look exactly the same.

[JMcDonald]

Hmm I might try to sync the carbs some time this week. I'll start putting together the components tomorrow.


What can I do to check the condition of the ignition components?




And I really hate to think I ended up with a lemon, but it really wouldn't surprise me because that always happens to me, heh.