|
SuzukiSavage.com
/cgi-bin/YaBB.pl General Category >> Technical Documents/Reference >> REV LIMITER???? /cgi-bin/YaBB.pl?num=1267565477 Message started by KNOCKDOLIAN on 03/02/10 at 13:31:17 |
|
Title: REV LIMITER???? Post by KNOCKDOLIAN on 03/02/10 at 13:31:17 Hi all, after playing with my carb and jets and things. It seems to work ok except. at max revs it cuts out. Ease off the gas a bit and it picks up again. I must stress this is MAX revs. normal riding not really a problem. Is there a rev limiter? Im also thinking coil problem. looking on ebay there are plenty of coils and cheep. That usually means that they are trouble and get replaced regularly Cheers |
|
Title: Re: REV LIMITER???? Post by dasch on 03/02/10 at 13:37:59 Most agree there is a limiter. Few got that far. |
|
Title: Re: REV LIMITER???? Post by KNOCKDOLIAN on 03/02/10 at 13:53:32 Thanks for the fast reply. Thats put my mind at rest. I was only hammering it to check carb having changed jets and exhaust. Am I right in thinking that with stock jets and exhaust it would be difficult to hit the limiter? |
|
Title: Re: REV LIMITER???? Post by LANCER on 03/02/10 at 16:34:08 on a bike with stock engine it MAY be possible to hit 6500 in 4th gear; in 5th gear (or 4th gear on an 80's model) you will not come near redline at wide open throttle. |
|
Title: Re: REV LIMITER???? Post by verslagen1 on 03/02/10 at 16:54:05 oldfeller put that myth to rest. There is no limiter on our bikes. It's by design that you can't reach above 6500 rpm's. |
|
Title: Re: REV LIMITER???? Post by Oldfeller on 03/02/10 at 17:11:18 But Verslagen, nobody has ever blown up an engine. Not me, Not Lancer, Not you. ........... Nobody. Something is keeping us from fatal RPMs .... I don't think we know yet what it is. We have a black box, But it is on a cruiser engine. We had limits in the head exhaust passage -- some have removed that. We had a cam limit -- some have removed that. Some have wicked it on up pretty high .... ... but no blown up engine yet. Why? I dunno ... |
|
Title: Re: REV LIMITER???? Post by verslagen1 on 03/02/10 at 17:35:14 That's true, but until you uncorked it, there were some around here said you can't even reach 6500. Until someone definitely got a tach and rev'd it up till it cut out, it don't got one and might as well stop talking about it like it was there hopin' to find it on some wild and crazy down hill run. |
|
Title: Re: REV LIMITER???? Post by Digger on 03/02/10 at 19:23:50 FWIW.... The old Road Rider magazine had a test of the Savage back in the mid-to-late 80's. The author talked of bouncing off the rev limiter. |
|
Title: Re: REV LIMITER???? Post by Oldfeller on 03/06/10 at 02:28:55 OK, I'm up for a technical challenge. We can even make a foot race out of it if you want a little competitive thrill in your life. We have no collective answer after literally years of internal consideration -- so LET'S ASK SUZUKI .... (not generally what we do around here as a first choice, I know). If they get inundated with the question, then by golly the one person who speaks and writes Japanese might get off their duff and ask the people in Nippon who do really know -- the designers of the black box in question. ================= IF YOU HAVE A CUSTOMER SERVICE INQUIRY: 1) Use the Dealer Locator tool to locate your nearest Suzuki Dealer or 2) Should you have a situation that you believe requires American Suzuki's immediate assistance you may call Customer Service at 714-572-1490. Customer service representatives are available from 8:30AM to 5 PM PST. or 3) Put your inquiry in a letter, including copies of all relevant documents (service records, etc.). Include the 17-digit vehicle identification number (VIN), your full name, mailing address, and day/evening phone numbers. Send via U.S. mail to: American Suzuki MC/ATV Customer Service P.O. BOX 1100 Brea, CA 92822 Customer service inquiries for Suzuki Motor Vehicles usually involve documents which cannot be handled effectively via e-mail. Therefore, inquires which cannot be answered by your local dealer, should be submitted via U.S. mail. |
|
Title: Re: REV LIMITER???? Post by dasch on 03/06/10 at 05:29:33 just by watching this: http://www.youtube.com/watch?v=npNRWgi2jsA Ok, after he gets it going... at around 1:55... it seems it does have a limiter. You can tell it does a brraaap braaap braaap when it reaches max rpm. |
|
Title: Re: REV LIMITER???? Post by Oldfeller on 03/06/10 at 07:36:49 I used to be the "I think we have one" guy, but I had to admit we do not KNOW for sure. That guy in the video has a stock cam and other stock items and he may just be riding the flat spot. Our bikes have a built in top end flat spot ... this IS known. A Lancer stage 2 unlocks the flat spot and you can spin it up a lot more. Trouble is, now that flat spot is gone, what is keeping the engine from blowing up? Back to "I dunno" .... cause we don't know. |
|
Title: Re: REV LIMITER???? Post by KNOCKDOLIAN on 03/06/10 at 12:05:25 Well im not so sure now. I changed the 55 idle jet for the 52.5 and it now seems to rev as hard as I dear. It must have been fueling problem but cant work it out. Why does the idle jet affect full throttle? |
|
Title: Re: REV LIMITER???? Post by LANCER on 03/06/10 at 19:41:42 Keep in mind that the symptom of a too rich main jet circuit will cause the engine to stumble at wide open throttle. |
|
Title: Re: REV LIMITER???? Post by jef.savage on 03/19/10 at 02:04:00 I don't have a lot of mechanical experience but this sounds very similar to a problem I ran into with my '66 Dodge Charger. With the stock valve springs the engine would not rev past about 5600 rpm even though the tach showed a 6500 red line. The springs just didn't have enough tension to close the valves any faster so they would "float", just staying open. When I had the heads milled and replaced the cam I also replaced the springs with a competition set that had dual inner and outer springs like our bikes. With the new springs the car would easily rev to it's red line and beyond, even in high gear. I'm thinking with stiffer springs these engines may rev higher and even allow you to blow one up if that's your goal. |
|
Title: Re: REV LIMITER???? Post by Yonuh Adisi on 03/19/10 at 11:59:38 424D4E065B4B475E4144444D280 wrote:
You know, that makes pretty good sense. We should have thought of that before. |
|
Title: Re: REV LIMITER???? Post by PipJones on 03/19/10 at 14:18:59 6D626129746468716E6B6B62070 wrote:
I really hope blowing one of these things up isn't acutally someone's goal. But if it is, give me a call... I'd love to be there |
|
Title: Re: REV LIMITER???? Post by Oldfeller on 03/21/10 at 03:41:23 It's not a goal, just an observation .... Do you really think it is spring pressure? We have 4 valves (relatively small valves) and dual springs on those small valves. Plus, if the valves floated regularly don't you think there might be some popped or bent tulip heads or certainly quite a few burned exhaust valves would have been seen as a consequence? (VERY occasionally we do pop a valve head off around here but it is not been noted as being an over-rev situation per se -- it just happens when rolling down the road) |
|
Title: Re: REV LIMITER???? Post by Oldfeller on 03/23/10 at 08:55:03 Megan at Suzuki America is working on it. Surprise -- this isn't an easy question for American Suzuki to answer. It is not listed in a feature list anywhere and the black box does not list all its functions as some of the control is based on PROGRAMMABLE (burn once) E-prom chips and you are actually asking about the details of an old prom burn program located at a vendor that is like 10+ years old. "I dunno" seems to be the current answer still .... But she's working on it. I'm going to draft a letter asking the same question, just to see if it gets routed a different path to a different answer. |
|
Title: Re: REV LIMITER???? Post by Oldfeller on 04/27/10 at 03:06:31 There has been no further reply to either telephone calls or written letters. Suzuki America does not know .... or Japan won't be bothered to look, take your pick. So, the mystery continues |
|
Title: Re: REV LIMITER???? Post by Charon on 05/22/10 at 12:24:11 I wonder - over on the Rubber Side Up there has been posted a torque curve going up to 7000. Yet some say there is a 6500 rev limiter. Others have remarked that there is a difference between the early and later ignition boxes. Perhaps the older ones had the rev limiter and the newer ones do not? |
|
Title: Re: REV LIMITER???? Post by verslagen1 on 05/22/10 at 12:49:23 Only way to prove or disprove it since you won't except the statements from the few that have modified their engines to be high rev engines. send the CDI to a known high roller and do a before and after dyno run. oh, wait... you'll still question if the numbers can be believed. |
|
Title: Re: REV LIMITER???? Post by Serowbot on 05/22/10 at 13:24:10 There's no need for a limiter,... so there is no limiter... She runs out piss before she gets there... :-?... If you do over-rev intentionally,.. you may feel what could be perceived as a rev limiter,... that's when the valves go into float, you'll loose compression and she'll fall back... it's a "law of physics" limiter... but by then, she's been screaming to be shifted for more than a thousand rpm's,... probably 7500 or 8000 revs... |
|
Title: Re: REV LIMITER???? Post by Charon on 05/22/10 at 14:39:20 As a matter of interest, yesterday May 22, 2010, I took my box stock '07 S40 out with the idea of seeing whether I could hit a rev limiter. Note that I have no tach on the bike. After riding it for plenty long enough to be sure it was warm, I put it in second and wound it up till it would go no faster. There was no sound of break-up as one would expect from an on-off rev limiter. It topped at 60 mph, which if Suzuki's table on Page 4-2 of the Owner's Manual is correct, corresponds to 7150 rpm (slide-rule accuracy). I repeated the run using first gear, but quite frankly I am unsure of my own measurements, since I didn't write them down immediately. I think I remember seeing 47 mph in first, which would be about 8700 rpm and which I do not believe. If on the other hand I saw 37 mph the rpm would have been just under 7000. I would expect the rpm in 1st to be higher because there is less aerodynamic drag at the lower speed, but not that much higher. It is easy to misread a speedometer, and I may well have done so. If anyone cares, I was using 87 octane fuel (with Sta-Bil) from last fall when I put the bike away for the winter. Shell Rotella 15W-40 oil. Bike has about 6200 miles. Temperature about 70 degrees, altitude about 1800 feet. Suzuki gives the following speeds at 6500 rpm. 1st, 35 mph. 2nd, 55 mph. 3rd, 75 mph. 4th, 90 mph. 5th, 100 mph. There is some rounding, as both the Metric and English speeds are given to the nearest 5, and the Metric and English speeds as given are not exactly equivalent. Because of that rounding my rpm calculations are necessarily inexact. Okay, people. Since I seem to have a reputation for questioning the methodology of others, here's your chance to question mine. |
|
Title: Re: REV LIMITER???? Post by Serowbot on 05/22/10 at 15:04:37 I like it,... I'm with ya'!... Pretty darn gutsy too!... ;)... Savage pistons are made from Unexplodium... ;D... |
|
Title: Re: REV LIMITER???? Post by Charon on 05/24/10 at 19:50:16 Even with a tach and a dynamometer, the only way to find out whether an engine has a rev limiter is to wind it up until the rev limiter operates. If the rev limiter doesn't operate, or isn't present, you have to keep increasing engine speed until some other limit is reached. You can do it with the engine unloaded, for example in Neutral. Or you can do it with the engine loaded either on a dynamometer or the road. If someone has a different or better idea, speak up. Now, as it happens, I spent my working career as an electronics tech. Given a little more test equipment than I have, I would test the ignition box electronically. On the bike, I'd just unplug the wiring from the pulse generator coil in the stator and use an electronic pulse generator to trigger the ignition box. I would then vary the pulse generator frequency to simulate different engine speeds, and observe the spark output with a 'scope. With a little more work, that procedure could also "map" ignition timing at different engine speeds. If I were going to design a rev limiter for a carbureted engine, given present EPA rules, I would not design a system that worked by interrupting the ignition. That's because the interrupted ignition allows unburned hydrocarbons into the exhaust. Instead, I would start retarding the timing as the engine approached redline. The timing could be retarded even to the point that the spark fired just before exhaust valve opening. The rider would never realize the limiter was working, but would just feel the engine going flat and revving no higher. Fuel-injected systems do it by interrupting the injectors, but a carbureted engine doesn't have that option. |
|
Title: Re: REV LIMITER???? Post by Oldfeller on 05/25/10 at 08:54:16 OK, we can pretty much say we don't have an ignition cut off type of rev limiter. We may have a spark retard electronic only version of rev limiter, but apparently it will still let you go way up past the official 6,500 rpm red line. Construction of the engine is apparently fairly explosion resistant just from the natural construction of the motor. Unexplodium piston, indeed !! Question answered well enough for me -- jest run it !! |
|
Title: Re: REV LIMITER???? Post by ratz on 05/25/10 at 10:44:13 78535A4954553B0 wrote:
Hmm,you may have come up with my next project!I do have a pulse generator and a O'scope.I'm thinking a square wave for the pulse. I guess if you put the CDI input on Ch.1,and the output on Ch.2,it would more or less show the advance curve and how it behaves as the revs go up. The Savage fires twice per revolution,doesn't it? As an aside,I have a '91 Suzuki Bandit(carbureted)that definitely does use the cut-off type of limiter.Breaks up really well at 13,500 RPMs! Of course,you did say CURRENT EPA regs,so that doesn't say much. |
|
Title: Re: REV LIMITER???? Post by JohnBoy on 05/27/10 at 11:26:24 67444C4E4D44444D5A280 wrote:
could it be a long stroke, and a low compression ratio? |
|
Title: Re: REV LIMITER???? Post by Oldfeller on 05/27/10 at 14:55:13 Johnboy, it isn't a long stroke -- it is perfectly square or equal ratio which used to mean a performance engine. Long stroke engines have strokes longer than their bore diameters. Ours does not have that at all. 8.5 to 1 compression ratio isn't a high compression ratio to modern standards -- that starts at over 9 to 1 and is generally around 10 to 1. But it isn't a slug either. It means it is an engine intended to burn regular gasoline. |
|
Title: Re: REV LIMITER???? Post by Serowbot on 05/27/10 at 19:07:48 584B5E50444C584B4D442A0 wrote:
I believe it's once per revolution,... twice per 4 cycle... :-?... but,.. that's what you meant... |
|
Title: Re: REV LIMITER???? Post by ratz on 05/27/10 at 19:53:37 Yeah,that's what I meant!(It's not what I said,but.....) :) It does wasted spark on the exhaust stroke,no reason to make a new single cylinder box if a twin cylinder box will do,huh? Good thing is,the frequency of the pulses I feed it equal the number of pulses out,so I don't have to remember to multiply by 2 on the output. (Yeah,I know,dealing with these complex numbers like 2,real hard,huh? ;)) I want to try it a couple of more times to be sure of what it seems to be doing.I'm playing with the CDI on my '96. My first try showed an advance curve that ramped up fairly quickly from 2000 RPM through 5000 RPM,then kind of leveled out from there to 7000 RPM. I didn't see the timing retard,as was referred to earlier in this thread,it just didn't advance much at that point. I didn't try anything above 7000 RPM,think I might on the next couple of tries,just for giggles. |
|
Title: Re: REV LIMITER???? Post by Charon on 05/29/10 at 04:47:12 Ratz, a couple of things more might be of interest, if you think to check them. There is a wire from the START system to the ignition box, which might be a start signal and which might retard the spark during cranking to prevent kickback. Might be interesting to put 12 volts on that and see what it does. It is also said the ignition system is rather sensitive to low battery voltage. It might be fun to vary its input voltage to find the threshhold. Reason I mention the START signal is that there are a number of threads on the difficulty of push starting the S40/Savage. I think it is possible the absence of the START signal causes the engine to fire before TDC (normal spark advance) and "kick back" instead of turning over. |
|
Title: Re: REV LIMITER???? Post by ratz on 05/29/10 at 05:36:42 Those are a couple of good ideas! It's going to be a few days before I get to play with this again,but I will definitely try out both of those,just to see. |
|
Title: Re: REV LIMITER???? Post by verslagen1 on 05/29/10 at 08:14:51 If you can, take some measurements and I'll make a curve for it. |
|
Title: Re: REV LIMITER???? Post by Truckinduc on 05/30/10 at 11:12:19 I might hook up my acewell gauge that reads the signal through the plug wire. Its pretty accurate and ill see what my bike will rev to. its nice it has a max rpm recall feature. Seems like it will reach close to the 10k my ducati will. Im not sure how credible it will be as the motor isnt stock, but we are still looking for an electronic limiter correct? |
|
Title: Re: REV LIMITER???? Post by Oldfeller on 05/30/10 at 11:47:12 The more we learn, the more we know. |
|
Title: Re: REV LIMITER???? Post by ratz on 06/01/10 at 21:28:57 68434A5944452B0 wrote:
I got around to checking that.The signal from the START circuit does indeed retard the spark timing,looks to be about 4-6 degrees.Hard to say exactly,I'm having to do a guesstimate with an OLD o'scope and a timing light! As far as voltage,the CDI seems to get rather unhappy below 10 volts,on mine anyway. Verslagen,as I mentioned I'm playing with this with some old equipment,but I'll see if I can't come up with some usable info. Also,I ran it up to 10,000 RPM this time,advance seems minimal from 7000 to there.Doesn't cut out,doesn't retard,just doesn't do much.Guess Suzuki didn't see a need for much to happen past 7000 RPM on this engine. |
|
Title: Re: REV LIMITER???? Post by Oldfeller on 06/01/10 at 21:39:40 So, we have no rev limiter function, neither by cutting out nor by retarding the ignition. We should be able to rev up to destruction, but we don't because internal motor friction or valve float or something generally stops the rev up somewhere around 7,000 rpm ..... (on a stockish bike anyway) Am I getting all the info provided so far? |
|
Title: Re: REV LIMITER???? Post by ratz on 06/01/10 at 21:47:15 Like I said,it didn't cut out or retard,but I do have to say it didn't seem to have much advance from 7000 on.Of course,at those RPM's,you probably don't need much advance,but that MIGHT kind of keep things down. That said though it didn't seem to have an out-and-out limiter. |
|
Title: Re: REV LIMITER???? Post by verslagen1 on 06/03/10 at 17:29:02 Hey ratz, wonder if you can do one more thing... At what voltage does the ignition crap out? Is it the CDI or the coil? |
|
Title: Re: REV LIMITER???? Post by ratz on 06/05/10 at 13:46:41 Starts misfiring at 10 volts,pretty well loses output at 9.5 volts.This was at 1500 RPM,not sure if it would be different at cranking speeds or not. That's at the CDI.I've been measuring at the CDI output(or input to the coil,if you will.) Haven't been able to find my high voltage probe for my o'scope.Of course,I haven't used that since the last time I worked on a TV.(Shudder!!!) |
|
Title: Re: REV LIMITER???? Post by verslagen1 on 06/05/10 at 13:57:14 Thanks ratz. Now we know, if you got less than 10v cranking, it ain't gonna start. |
|
Title: Re: REV LIMITER???? Post by ratz on 06/05/10 at 15:16:07 You're welcome,verslagen.I've gotten so much good information from this site,I'm glad I can give back in some small way. With the old equipment I'm using(I've been working with electronics a LONG time!) I'm afraid I won't be able to get accurate,repeatable measurements for you to do a curve from. I haven't given up yet,I just need to try to refine it somewhat. |
|
Title: Re: REV LIMITER???? Post by genejohnson on 06/05/10 at 17:24:47 The rev limiter everyone feels exists could be the ignition advance topping out for the rpm it was designed to turn. If you stop and think about it, our bike has nothing more than the mechanical advance that is built in. It can be retarded to make starting easier but there is no way to make something happen earlier, electrically, than it happens!! Therefore the advance remains the same throughout the rpm range until saturation. Gene |
|
Title: Re: REV LIMITER???? Post by ratz on 06/06/10 at 10:17:24 A lot of engines with electronic ignition have no mechanical advance.As far as I can find looking at the microfiche,this one doesn't either. That said,you are correct in that it doesn't cause the spark to occur earlier,but rather less late. The pickup coil is at max advance in relation to the crankshaft(mechanically).The CDI retards the signal(in relation to the crankshaft) throughout it's curve until the top of the curve where it's firing at the pickup coils timing.So,as RPM's increase,the signal is retarded less and less until a max value.By what I've seen,that seems to happen pretty well from 7000 RPM up. Therefore,as I stated in a previous post,that might be the limit. I believe a couple of people on here have found ways to relocate the pickups position to increased advance,I'd be interested to hear how much effect that had. |
|
Title: Re: REV LIMITER???? Post by phantom on 09/03/11 at 13:10:06 Rev limiter: a little old but good topic, I was wondering myself. Here is my input for what its worth. My 2005 Suzuki Savage LS40 650 Thumper has 6,500 miles then converted to a RYCA (not a purest) cafe racer. Elevation Sea level. Carb. jet needle: removed white spacerand installed three washers provided by RYCA. main jet 155. pilot jet 55. pilot screw 1.5 turns out. Air filter k&n. Muffler Harley Dyna. New Elec. Tach. Speedo. Direct drive. Fifth gear 60 mph turning 4 thousand rpm. She sounds great so I cut her loose . First gear 7,500 rpm no stamer. Second gear 7,500 no stamer. She was still climbing and I backed out!. So, I would say if there is a rev. limiter it's way up there. Hope this helps out. Have fun! Phantom |
|
SuzukiSavage.com » Powered by YaBB 2.2! YaBB © 2000-2007. All Rights Reserved. |