Turbo Seca dyno results

We have a conservative Dynojet 250i; the Turbo pulled right at 90 h.p. This was with a non-stock low-pressure fuel pump and with the bike strapped down HARD to keep the original bowling ball-hard rear tire from blowing away. Not bad for a stock 30-year-old 650 pulling a shaft drive. This bike does have the Power-Up kit on it. To give you an idea of how impressive this is, the latest 600-class chaindrive sportbikes typically pull 105-ish on this dyno.

Now that the bike has a healthy stock fuel pump we'll run it again to see how the on-boost torque curve compares with the modern 600s, maybe after we get some decent rubber on it so we won't have to strap it down. I think we're going to be impressed again.

Again, free XJ dyno runs for anybody on this website.

 

damn if i was local ide wanna dyno!

 

Put your location info (at least the general area) into your profile! We don't know where "local" is...

And those are impressive RWHP numbers indeed, for a shaft-driven anything 30 years old. Please put a new tire on it before you hurt it.

Way cool.

 

Bigfitz, we have a one-owner, '71 Ducati R/T 450 in the shop right now. Completely original including the chain, sprockets, tires, paint, etc.

YELLOW!!!

 

I owned a Metro once upon a time...that had 89 horsepower...and wasn't nearly as cool as a Turbo


quote="motorcyclespecs.co.za"

Yamaha XJ 650 Turbo

Year
1982

Engine
Air-cooled, four stroke transverse four cylinder. turbocharged. DOHC, 2 valves per cylinder,

Capacity
653

Bore x Stroke
63 Ñ… 52.4 mm

Compression Ratio
8.2:1

Induction
4x 30mm pressurized Mikuni CVs

Ignition / Starting
CDI / electric

Max Power
90 hp @ 9000 rpm

Pretty cool that it has the same horsepower 30 years after the factory put out 90HP brand new.

 

I'm not sure about this, but I believe that the 90 h.p. figure they published was for the original low-boost version at the crank.

 

Im not trying to say its not making 90 hp. But best 1/4 mile times i have seen out of a stocker is low mid 12s. New 600cc sport bikes run low to mid 10s. I had a built v max tnt performance did the carb work took 40 dyno runs to get 124 hp at the rear wheel. stock it made 106 rwhp. You need to ask jeff how his compares to his h2s Jeff is running almost 20lbs of boost with his. If you have a dyno sheet post it can compare it to mine. Here is a link to what mine sounded like definitely not stock. http://s1237.photobucket.com/albums/ff4 ... ction=view¤t=121907006-1.mp4

If it is making 90 rwhp your making about 15 hp more then a stock bike. Yamaha claims 90 thats at the crank. They claim factory v max made 145 hp. They claim a seca 900 has 90 maxim x 85. Heck my virago was rated at 60. The beast of the turbo bikes in the 80s was the gpz750 turbo. I think it was making about 100hp and it was competing with ninja 900s gpz 1100. The seca turbo was not even as fast as the honda v twin turbo cx series. So if your dyno numbers are correct you have an exceptional runner

 

This is a long response so skip it if you aren't nice and comfortable<LOL>


A little background on the times first:

We all have guessed that the official numbers back then were optimistic to say the least. This was a time of pure "WAR" between the big four and sheers numbers meant everything. They all had to balance "optimistic numbers"(ie: lies) with the possibility that someone would catch them...."being optimistic" (lying). I honestly believe that they would have measured further up the drive train to get bigger numbers if they could have!

Oilhead is right from what all my initial reseach indicted. The "90HP" figure was for the original '82 and of course was measured at the crank. I also believe that it was rounded up from the only official factory # I've ever seen which was 88.943 @ 56.53KP(8.2PSI) done in Japan in early 1981. You would not believe how many emails it took to get that number but it came from someone who worked for Yamaha back then who worked on the turbo pjt. who is also the source of the failure testing numbers that I have quoted before. This would drop to 73 or so at the rear wheel taking into account driveline losses(of 18%).

Yamaha thought at the time that this would be sufficient to take the lead in the turbo wars. As Dave mentioned, it was not. When Honda increased the cc's of the CX turbo, it retook the lead. so the following year Yamaha sent out the "powerup kit" which basically changed the safety from the waste gate to the pressure relief valve or as many people cal it, the blow off valve. This worked but it also was a cheap and incorrect way to regulate the boost but since the decision had already been made to eliminate the turbo from the lineup, it was the cheapest, easiest way to gain the much needed hp. In effect, they were causing turbo-stall every time the valve was activated and over time, it can be very damaging to the turbo but again, that wasn't Yamaha's primary concern.

This was the basis for me deciding to run a full 18psi...it wouldn't hurt the engine and it could be safely done.

I have tried to compare my turbo to my other bikes in the same league, my Vstrom 1000, a '75 fully stock H2 and a very heavily modified '74 H2 but each bike is so different that it's very hard to draw a conclusion even riding them back to back.

I never rode my turbo at the original 8psi but i have ridden it when it wasn't producing boost.....ANY of the above bikes would have killed it and my built up GT550 would have also beat it as well. However, when it's running as it is now, the only one that has even a chance is the 74 H2. My guess on the 74 is right around 110-120hp. It was built OVER the Denco specs of the era which claimed it would produce well over 120hp with those modifications but I believe them to again, be optimistic.

Rons turbo should be producing around 11-12psi so the 90 # at the rear wheel is pretty believable, maybe a bit optimistic to me if everything else is perfect. I say this because I recently saw dyno figures which showed about 3-5hp at the rear wheel for each increase in turbo boost for a 700cc engine. As most builders know......the first wad of power is easy....it's the last 10 hp that is by far the hardest to find. Simple things like ring pressure against the cylinder walls can cost you 2-3hp. cam chain tension can cost you.....etc.

Maybe one day I'll dyno mine but I really don't want to. Dyno'ing a bike is so hard on the engine and frankly, there really isn't any compelling reason other then a very slight curiosity but my "official" guess would be right around 110-115 at 18psi.

Really doesn't matter though.....its a cool power delivery and a very fun bike to ride....which is why I like it so much....

jeff

 

As I mentioned before, my '79 CBX runs about 85 h.p. on the same dyno, and the CBX runs GOOD. Now there's no way the Seca would take it in a dragrace due to the very different power and torque CURVES (not just the peaks, which really don't mean a great deal). But the way the Turbo pulls makes me almost certain that it's putting out an actual 90 hp at the back wheel. It's also possible that somebody played with it way back when and it's putting out more boost than it should even with the Power-Up kit on it. I don't have any way to know. I just know that this thing screams when 6k comes up on the tach!!!

Another thing to consider about the original Seca Turbo tests, I read somewhere that the early '82s had sagging wastegate springs that would drop the max boost down to about 3-4 psi after not too many miles at all. True?? I don't know.

I helped do an article for Sport Rider several years ago where I developed a formula that used actual dyno curves to determine the driving force at the rear tire at any given rpm in any given gear. Might run it on the Turbo when/if I find some time.

P.S. I saw an 87 h.p. Dynojet run on a 72k kilometer Seca with the stock Power-Up kit somewhere on the internet the other day.

P.S. #2 , my bike has less than 6,000 total miles on it, and the motor seems extremely fresh.

AM I ever going to shut up?? I've had a lot of bikes over the years, but one that comes to mind now is my '81 Honda CB750F, purchased new. It wouldn't have stood a chance against the Seca.

 

Hey Ron,

A cheap Sun Boost gage costs 20 bucks and the boost controller I use cost another 18 or so off of fleabay. I mounted my gage on the leftside flat black fairing panel next to the gas tank with the controller located inside the fairing right below the gage.....then I'll show you how to SAFELY increase the boost, (not by using the BOV) and you won't believe the increase as the gage swings past 14-16 on its way to 18.....You will probably be as surprised as I was that your engine could make that much power!!

Then you can re dyno it for both of us and see how close I am<LOL>!!!

jeff

 

Sounds good to me. I wish there were some locals on here with XJs to play on the dyno, especially Turbos, of course. But as far as I know, slowboattohell ( ) and I have the only Turbo Secas in North Alabama. (Probably not true, but I have never seen another one in YEARS around here.) Actually, our buddy down the road has a rough but fairly complete one out in his salvage yard, but that's the only one around that I know of.

 

Man, you guys are getting me wound up! I have a ways to go yet.
Some stuff I've been doing:


The fuel pump was stuck but some light tapping on it and it came to life.

 

That's great nes Devo !! .....have you started the carbs yet? I had a BEAR of a time getting them off the rack, had to use 420 channel locks they were so tight. I used new screws to reassemble and this is important....to be sure they are nice and lined up, reassemble the rack on a glass table. It will keep them from mis-aligning and causing premature seal failure along with a host of other issues.


I went out for a ride yesterday. The bedroom thermometer said 41 but the sensor sits attached to the house. It def felt into the 30's. Tell you what....the turbo LOVES cold weather!! I was able to run steady on about 13-17 lbs of boost as I attacked a set of esses with the rpms between 5.5-8.5K in 2nd, 3rd and 4th. I found it's sweet spot and was able to keep it there, or very close for a couple of miles. No waiting for boost, instant power on tap and with the temps fairly low, NO DROP in power!! None! I sure was frozen by the time I got back home though. Turbopig loves cold weather, jeff not so much!!


jeff

 

Devo1, a light tap on the fuel pump started it up, AND you have what looks like an original fuse box in fine shape??? Do you have a direct connection to the Almighty or what?? What is that washer/shim you're holding in your hand???

Jeff, as many bikes as I've been fortunate enough to own, I have never owned a Kawa Triple. Ridden all of them, but never had one to call my own. Two of the sweetest models I had the pleasure to ride were the 350 and the 250. Preferred both of them to the single 400 I rode, supposedly the nicest Kawa triple (but this was admittedly a questionable example).

BTW, I owned a stock cherry '73 GT550 back in the 70s. Very sweet bike. It would pull my highschool buddy's stock '73 CB750 up to about 60 mph, then WHOOSH. :cry: :lol:

P.S. For you other oldsters like me, do you remember the very first Mach III and/or CB750 you heard going through the gears?? I do, both were '69 models and they sounded like nothing else.

 

How many previously-owned bikes can you put in your signature or whatever it's called?? I'm starting a list. 8)

 

Stop bragging.

 

Don't be sad just because your Turbo is the slowest color ever.

 

Not as many as you Jet-I Master.

 

Yo OHR,
The washer increases the spring pressure on the surge tank safety pop off valve. Stock, it opens at 15psi. That way when I bypass the wastegate and/or install a boost controller, it will be ready. Someday or year I'll be a bad ass as Jeff! :?:

 

It is the slowest period at the moment.