Hi guys. I've got a 93 Suzuki DD51T with the 12valve 660cc engine and a 4 speed tranny. My question is about engine rpms. At 80km/hr I'm revving at 5300rpm. This seems too high to maintain for any length of time. I'd like to do at least 90km or preferably 100. Any ideas? Also, what rpm do you guys cruise at. And what would be my max rpm that I could maintain for say an hour? Thanks for any info you can give me. Happy whellin', Rosco.
I own a 1992 Suzuki DD51T 4 speed. It also has a multiple of the devils number on high gear. 666 rpm at 10Kms 1333 at 20Kms 2000 at 30Kms and 6666 at 100 KMs. I also felt that these numbers were high but apparently this engine is designed for high revs. But I still changed tires to a bigger size 185/65 R14 this gives me about an 8% reduction in RPM for same speed. I run mine at 80Kms/h for hours and it doesn't seem to strain at all. Now turning 4900 rpm instead of 5400 before. At 6700 rpm I'm now rolling around 108 Kms per hour instead of a 100.
Those revs are not high. Thats what they are built for. 100KMH will be fine all day long in a well maintained truck. I have driven WOT for hundreds and hundreds of kilometers with no problems. I am not saying that is always wise, but I havent burnt one up on the highway yet. (Although I know people who have) These engines are good for high rpm.
Thanks for the responce guys. I did some tests yesterday. At wot pedal to the floor I only got 92km/hr @5800rpm. Thats it! Any way to increase my engine rpms and get a little more speed out of it? Or do I just have to live with this? Thanks again, Rosco.
How many KM are on your truck? How long have you had it? How cold is it where you are? The fluids from Japan are TOO THICK for Canada. Make sure you change out your diff and trans fluids to synthetic 75/90. (From Japan, usually straight 90 weight!) Make sure you check your timing. What size of tires are you running? If you havent had your truck long, it will get better with some time. Seals and bearings need to essentially break in again in many cases.
Agree x10 with above...you are prob. losing a ton of power to super thick diff/tranny/and trans. case fluids....I've ridden atvs that wouldn't move in the winter beacuase the diffs were filled with too thick oil........Seafoam it...Ha...I know I beat someone to that....but it's true...the truck may have sat for some time since it's last use...so seafoam it as per the company video on youtube....
Oh, and check the stopper under your gas pedal. That is your speed limiter. Make sure the carb is actually opening up all the way. (Some will adjust the pedal stop so you cant actually get WOT)
i just bought a 92 carry with a 4 speed.. i'm about to have to buy a new set of tires for it sometime within the next week or so.. it has the 145r12's on it now.. should i get some 14in wheels and tires to put on it?? or is it better to stay with the stock ones.. i just figure if the 14in wheel and tire is a good idea, now would be the time to do it.. instead of spending the money on 4 new 12in tires then pulling them off 2 weeks later.. lol.. any info is appreciated.. thanks, john p.s. i'm in oklahoma and its tagged and insured so i drive it mainly on paved roads.. but everyonce in a while i like to hit a backroad that may be a little muddy, cause the roads around here suck.. just a little f.y.i. in case you have never been to oklahoma.. lol
Welcome B-nuTt...tons of tire threads here..but the latest discussion..http://www.minitrucktalk.com/showthread.php?t=3325
Thanks guys. MiniBrutes, to answer your questions. The truck has 10,000kms on it. I've had it 7 months. It's around 5 degreesC. The timing is spot on. Running 25" tires. And I don't think its the throttle stopper, the pedal itself actually hits the floor! In third gear I can push it to 6500rpm, but shift to fourth and I only get 5800rpm @ 92km/hr?? All tests are done with a gps. I'm starting to think its the oils in the cases as you mentioned, cause the engine itself runs so well, as the test in third shows. Once it stops raining (if ever lol) I'll change out the fluids and let you guys know the results....unless someone has any other ideas? Thanks again, and good wheelin' Rosco.
Cable at carburator OK, I had the same problem the first day I had mine. I found that somebody had actually pulled back the mechanical tiedown at the carburator( This was to stop delivery boys from drifting in the streets of Japan ) . You could still see the kink in the cable where it used to be from factory. I just re-attached the cable at this same spot and now I have full throttle at full pedal depression with some leeway for cable stretch with adjusment on floor. Because when pedal is to the floor butterfly in carburator should be full open. Unscrew pedal stop preferably before doing this adjustment...
Rosco - Its your tires. They are way too big for these little engines. Drop down to a stock size and the truck is MUCH peppier. With 25" tires you lose torque, acceleration and top speed. If you dont want to go down to stock size, a 23" tire is much more pleasant to drive on due to the improved power. Are you using a GPS to get your speed? Or the gauge? The speedo will be inaccurate in most cases, but will get worse with 25" tires.
My Little foot is shoed with 23.75" (185/65R14) and I still reach 108Kms (GPS) at 6700 rpm. It would do more but I don't want to push my luck. 80 Kms is comfort zone.
Thanks for all the responces guys. The throttle cable did have a little slop in it. I adjusted it so that when the pedal is on the floor, the carb is wide open. Changed all the vacuum lines aswell. What a mess of them too! It's better but I still cant get up to 100k. It may be the tires or the oils. Gonna try the seafoam trick too. I'll keep ya all posted. Thanks again, Rosco.
If the timing is "spot on", I would crank it up about 4 deg. Our fuel up here is MUCH better than the stuff coming out of the pumps south of the boarder. 4 more deg isn' t too much and will make a world of diff in the torque dept. This and the synth oils in the diffs and trans/transfer case should make a pretty big difference. Jon.
Can anyone please explane the Degrees thing I do not understand I first saw it it a few sigs like little foots. does it have to do with the cam angle, or the crank angle+ spark. I dont know much about working on cars but i am trying to learn quickly, I am getting a sweet Suzuki with a refer box on the back, cant wate thanks Clayton
Well where to start? OK, when somebody says he has timed his engine 4º ahead at 1000 RPM, it means that, the distributor position is 1/90th of a turn clockwise for piston #1 at topdead for this same piston. So this means you will have spark plug lightning just before piston hits full compression. By compressing the ignited fuel you get more power and better burn, but there is a limit. Because it is called timing this means at 2000 RPM you will need 8º and 12º at 3000 rpm since piston is moving faster. A set of centrifugical weights held by predetermined tension advances timing as RPM increase. Also there is Vacuum advance for when you floor it... When you lose vacuum spark is advanced to help tork and remove otherwise hesitation. Now this is as simple as I can get it, maybe someone else can throw in his 2 cents.
It's the ignition timing, the factory must look at the worst case sinario when determining the base and total timing on a vehicle with a fixed spark curve and base setting (like these vehicles). For the most part they usually under time the engine by at least 4 deg. to keep it out of detination while you are carrying the max load that the chassis is rated for in the hottest weather that they think you will drive in running the least octane fuel that is avail. in the area. In Japan's case the least octane that is there is about 90 PON (RON+MON/2) as they rate theirs at 95 RON (100 RON is their premium). The average temp in the Tokyo/Yokohama area is around 18 deg.C with a summer highs of about 25 deg.C. Our fuel being almost as good as the stuff in Japan (Mohawk has a 90 PON regular with a min of 5% Ethanol) and the fact that most seasons here are on average cooler than Japan you should be able to get away with at least a 4 deg. bump in timing. Torque is a product of many things, displacement (we haven't got much), stroke to bore ratio (these are just about square so no real advantage there) and peak cyl. pressure on the power stroke. The more pressure you can make the more torque you will have, to a point. It is possible to ignite too soon and start to go backwards in power production, or worse, initiate some wicked detonation. I will do a complete diagnosis on the spark curve of a Suzi 660 (F6A) once I get my hands on my dumper and give a full report. From what I have read though a 4 deg. bump in the ing. timing should be no problem for us Canadians. Jon.
I have 95 dd51t with f6a and 5 speed 2" lift 23 8 12 all trails on stock 12" rims . Cant use 5th gear max out 4th at 80 km h Shift to 5th and it slows down. Changed plugs air filter fuel filter most of vacuum lines not sure what else to do.
That's probably the limit. You have to think with only 45hp it just doesn't have the power to keep pushing the truck faster and faster. Probably gave up 5 gear with the increase in tire size. I run 25" on mine. It is only a 4 speed and there isn't really anything left my the time you get into 4th
