Try not to be so narrow minded that you think you must have a jawa to get 80 hp I guarantee you any 450 to date is very capable of that for similar or less money than a jawa and parts are probably much cheaper and easier to get and we haven't even began to talk about fuel injection and power programmers that have 10 different curves, did someone say nitrous or turbo?! I've heard of low compression very mildly built 450s on gasoline with a turbo putting 70hp down to the rear wheels! Mx engines are getting more powerful from the factory every year and they are very plentiful and easy to obtain, we have way more techs available to build them than jawas so just open your eyes a little wider. All that power doesn't mean anything if you don't have a little luck and a great tire program to go with it.
has anyone tried running a pair of 125cc sudans
- Thread starter ttownwideglider
- Start date
ttownwideglider
New member
All that needs to be done to the 450s is lots of high performance parts to become available. But the problem is the laws of supply and demand. Just don't think that the demand for kart racing will be enough to see this happen. Plus theres that pesky transmission that has to be reworked, and then bulky cases and extra weight. That's why the Jawa is such a good fit for karts. I has been refined for many years to race mainly dirt ovals some asphalt. Its got no tranny and through pure simplicity it is very dependable. The easiest cross over to karts of any engine that wasn't originally made for them because it was developed for the same type racing. Iam very disappointed Jawamaster would not join the thread and offer some basic info. Guess he thinks if he doesn't join in it will help spur his engine business, don't know. But as with everything racing related the info will be made aviable, maybe not the super secret tricks which are going to be very minimal, but the general stuff. As more of us get into the engines all that will happen. These engines are to simple and there are to many good mechanics here on Bobs. That is whats nice about Bobs lots of guys will share info with everyone. This is not nascar or formula 1, mostly good fun and bragging rights, not much money involved. Think how expensive the axiro50 is 5,000$. You can get the top of the line Jawa with cnc ported head for the same price brand new,add carb and exhaust and its ready to rock and roll. I haven't been able to see if there are different cam set ups yet but that is about all a guy could change to gain any extra torque or hp. With the cnc head this is a very simple engine to dial in, no intake or exhaust track work, no valve work, no head work. There is the possibility of fuel injection, but coming from a old carburetor guy all ya get with F.I. is a little quicker throttle response, if the carbs set up right. I love the two strokes but without the extra cc the 4 is the only way to go nowdays. As I said earlier the 2 stroke has lost a lot of its advantage because the 4 have came so far in technology over the last few years.
FOURTOGO
Member
All that needs to be done to the 450s is lots of high performance parts to become available ?. Honda CRF450 you can buy hot rod parts all day long 24/7/365. FlattrackRacers have been running them a while. Jawa a great engine Just about any MX-er engine a solid piece also. . Honda head work piston crank . What other Hot Rod Parts do you need. The Jawa was built to do one thing REV HIGH make torque. MX-er engine run down low mid range top end . Advantage
MX-er can pick up phone and buy all over town and the net. - Jawa Make a phone call to the dealers at hand parts are a bit more pricey. Con Jawa built just for racing longer uses between rebuilds than MX-er. Cost a new Jawa $3500, Honda show bike engine $2200-2600 with EFI . Engine mounts on the market now QRC . KTM is also a great unit Yamaha . I am sure the folks running the Jawa want to prove that they are Bad To The Bone as they should. If you want more CC's talk to the people running to UAS.
MX-er can pick up phone and buy all over town and the net. - Jawa Make a phone call to the dealers at hand parts are a bit more pricey. Con Jawa built just for racing longer uses between rebuilds than MX-er. Cost a new Jawa $3500, Honda show bike engine $2200-2600 with EFI . Engine mounts on the market now QRC . KTM is also a great unit Yamaha . I am sure the folks running the Jawa want to prove that they are Bad To The Bone as they should. If you want more CC's talk to the people running to UAS.
Any decent 4 stroke builder should be able to design and grind up whatever cam is needed. If they cant then I'd find another builder because they dont know enough about racing engines. Granted you're not going to get it perfect but you can get somewhere close enough to know what you need. And valves, well there's so many around I'm sure if you speak with the valve manufacturers they will have something on there database that can be made to fit.
Its not easy at the start but its going to be great.
I'm not to keen on the EFI thing though. I think that will get expensive. Maybe there needs to be a spec EFI system or something that reduces the extreme costs that can come with EFI and TC. You can't police TC if electronics are involved. Even F1 had to go to a spec control module and spec recorder so that jumper boxes could not be used to get in the backdoor of the EFI/TC control.
Tim has some 4 stroke cases coming soon and hopefully he designs the bare cases to accomodate a wide variety of crank strokes. That way there will be plenty of room for people to play with engine design without having to spend a fortune on billet bottom ends.
Its not easy at the start but its going to be great.
I'm not to keen on the EFI thing though. I think that will get expensive. Maybe there needs to be a spec EFI system or something that reduces the extreme costs that can come with EFI and TC. You can't police TC if electronics are involved. Even F1 had to go to a spec control module and spec recorder so that jumper boxes could not be used to get in the backdoor of the EFI/TC control.
Tim has some 4 stroke cases coming soon and hopefully he designs the bare cases to accomodate a wide variety of crank strokes. That way there will be plenty of room for people to play with engine design without having to spend a fortune on billet bottom ends.
JawaMaster09
New member
Sorry I didn't get back to you the other day my family ask me to stay away from answering anything on here. I'm not real sure what the stock carb flows I could not find much info on the net about it. I was not really interested in it at all because I wanted to but my FI that my father and I had built for another project on it and see how it would preform, The FI did so well at the Dyno that a carb was out of the question ( as we expected it would)... IMO the Fuel Injection if set up correctly will out run the carbureted engine every time. Jawa made a lot of different cam grinds for these engines, However JAWA as a company has just changed hands in the last year, I'm not sure if they will continue to offer different cams. Both the engines I have do not have any port work done to them they are stock, I have not yet felt the need for more HP in the UAS this is a stand by for me when they get a little closer on power then I will go there.. All the HP numbers you will find about the JAWA are by using a 34mm carb witch is what they have to run at most speedway events, Bill Cody told me he built one years ago using a 38mm and made his most power that he has ever made out of a JAWA but he also said he had not dynode the one he built with FI on it but said it was a lot faster.... IMO this engine has so much more left in it racing it stock other that the injection has really proven it's the best engine to buy everything it has raced against has been built to the hilt 450's, BRC's,250's ect. I like the JAWA because it was different than everybody eas going in the UAS at the time when I built it I got on the internet to find a CRF450 and found the JAWA did some reading and knew it would win UAS races in a heart beat....with a lot of tire and setup work a great driver is a must as well..
Taft Racing
Member
I have a 15 degree angle built into the cases for the average racer to use bolt on and go. But I have no problem making a new design to lay the engine down at 65 degrees. The 450 65mm stroke crank has virtually the same dimensions as the 2 cycle 72mm stroke crank. It wouldn't take much to convert a crank to be used in a 4 stroke. Its a wide open market lots of innovation to be had. The 250 2 stroke is a wild ride stock. Open the exhaust Build a pipe for a wide high rpm band wick them up and they'll run with any 4 stroke any where.
The external crank dimensions are nearly the same because the crank pins are much bigger in the short stroke 450's. If the stroke was to be increased on the 450 then it will need a bigger dia crank wheel so that the crank pin still has sufficient material around the crank outer dia of the pin area. So the cases would require thick wall that could be machined to allow for the clearance if someone wanted to run the bigger crank. The crank case bolts would need to have enough PCD to allow all this to happen. I dont have a problem with a 450 crank in a 2cycle 250 but I wouldn't put a 250 2cycle crank in a 450/500 4cycle. I mean you might be able to if you fitted a bigger pin but you would sacrifice stroke because you would have to shift the pin further inward to keep the pin bore tight at high rpm. Maybe take a look at the Jawa crank and use that as a reference to work with. Also depends on crank web thickness as well.
Of course it all depends on how hard you push the engine too.
Taft Racing
Member
Longer stroke you'll drop rpm. The 250 pin is pretty stout i doubt you could shear one .just saying. Allot easier to make custom rods
ttownwideglider
New member
Hey Jawamaster thanks for the addition of info. Have been involved in racing and engines for many years. Just wondering how the F.I. makes the engine that much faster if a carb is set up right. I understand the F.I. controller sets the Fuel -air ratio at a optimum amount designed to fit the injectors. The computer also controls the pulse length but the timing also has to be altered to compensate for the fuel changes. This requires a very complex controller like a Power Commander for a Harley with a lap top to remap it all the time and a lot of dyno time to see which maps work best under what conditions. This also requires a climate controlled environment so you can change all the variables, humidity, bar pressure, temp, altitude very complex. What I have found on the Harleys is mainly a small increase in the throttle response not in overall performance. That's why Nascar engines didn't increase in power when they shifted to F.I. just a little bit quicker on and off throttle input. Iam not much of a computer genius so a carb is the way for me. To the 450 people, You Guys astound me you talk about expense of the Jawa then go right into making all these custom parts for the 450. Lets look at what you are saying first 2,000 engine, custom crank, custom rod, custom cams, custom cases, custom pistons. Plus look at all the work involved. Every rebuild will be a lot of custom parts too, not cheap either. the Jawas longevity should be very because the 889 model 90mm bore and 77.6mm stroke. That's a very short stroke for that bore and makes its power at 8,500-9,000.Thats a very tolerable range for the longevity of a racing thoroughbred engine. Hope everyone had a merry Christmas.
JawaMaster09
New member
My JAWA is not an EFI engine it is a manual fuel injection engine it is set using fuel pump pressure, barrel valve, and popet valves length of stack height and injector placement high speed return popet no computer at all this is set up just like a sprint car injection
is setup. A lot of things can be accomplished with this setup over a carburetor.
Taft Racing
Member
Used 450 500.00- 1500.00. Any where USA. 500cc stroker kit 750.00. Titanium valves come stock. A current ever expanding line of aftermarket parts. Thousands of engine builders + motorcycle dealers across the country for easy access and sponsor potential. House hold name recognition for increased popularity for the sport.
ttownwideglider
New member
Hey Jawamster I went to Codys site and noticed that the newer style engines are 4valve that seems like a great performance improvement. A lot better flow ratio and fuel placement in the chamber. I also noticed the for the newer engines there are 3 different cam set up so they are a little more tunable. Are you running the short stroke and big bore engine? Know there has to be a difference in the low end torque rate between the two models. It also seems strange that the longer stroke (square) engine turns turns a lot higher rpms. This is not logical in my terms of engine performance. Longer stroke normally is lower rpms. I like the mechanical F.I. but are you running a small 12volts motorcycle battery to operate a electric fuel pump. My brother used to race a 410 Sprint with a westmar engine and we fought the pills a lot of the time. Is this giving you any problems, getting to lean. The rebuilds don't seem that expensive either. The rods are kinda steep but everything else is reasonably priced. Like resleeveable cylinders, can keep to the max cc displacement easily. Thanks for you input Jawamaster greatly appreciated. Sorry about the brain fart forgot we were talking ohc engines. Tried to change the post but got copied to quick. Getting oldtimers disease I guess.Lol Don't get me wrong Mr. Taft I like Jap 4 and 2 strokes . Have a 250 Yamaha on my Z21 Ranger, race a little methanol Kt in Yamaha. They are of very good quality. But buy the time you buy a 450, rebuild with stroker kit and all the other parts that need to be customized youll have close to the same amount of cash in it, maybe a little cheaper. Just doesn't seem worth all the trouble to me when there is a engine that requires very little mods to install on a kart.
JawaMaster09
New member
I have a 2004 884 long stoke and a 2012 889 short stroke engine the short stroke revs a lot quicker and turns 10,500 RPM were the long stroke engine I have only ever turned it 9,500 RPM both have big torque numbers. I have the injection setup very conservative I don't have to mess much with the pills, I did this on purpose) I'm leaving about 8hp on the table by doing this I have dynode it this way and know 8hp is a good number) I have not yet needed to put it on kill and risk a piston to win a race tires were more important to me. I do not run a electric fuel pump my pump is ran off of the crankshaft and is the same type of pump that is used by sprint car engine builders. The 2012 engine I have has a NiSi cylinder and will not need to be resleeved for some time.
ttownwideglider
New member
Cody must have the numbers on his site backwards he has the 889-10-006 at 8500rpm and the 884-6 at 11,000. But what you say makes much more sense. Is the 884 a 4valve set up like the 889? Can you tell me the difference in low end torque from 3000 to about 7500, just the basics. Don't expect any fine details just want to know which way to lean towards for out of corner acceleration. What does the rebuild schedule seem to be, about how many racing hours can a guy get out of them.
Taft Racing
Member
Check on your engine weights also. Just saying Jerry's driver is kart size yet they were pushing 500lbs. I cut the tranny off a 08 rmz 450 and ran it for 2 years w jackshaft sudam style. It was less than 10 lbs heavier than my sudam. My 250 converted engines are 5lbs heavier. Just a note. Not that the engines even care about how much weight you pile on but the chassis tires and corner speed may
JawaMaster09
New member
I would get the 889 short stroke bigger bore engine I'm not sure if they still make the 884 as a new engine.... they both have almost identical torque curves with 889 being higher on the chart. But a lot of that could just be from us playing with the FI I wanted about the same curve just more torque and power we were able to get this over a 1200 RPM longer range. The UAS has not seen this engine run yet I had a small issue at the only race I tool it off the kart stand for and I had to run the 884 because of time.
FWIW, short or long stroke ratios have nothing to do with rpm obtainable. Its only a longevity thing. Any engine will make power and rev to whatever providing the breathing and ignition allow it to. But the internal parts will suffer drastically reduced life span. Thats why the conrods are always pricey. They are a very stressed part and the bigger cranks on a single cylinder gets tossed around with the extra counter weights it becomes a recipe for eating itself alive. The piston suffers massive g-force loads too so its just simply safer to design the engine to breath at its optimum at a lower rpm range.
GeorgeHenry
New member
Zoommmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmmm JAWA 500cc model 889 bad to the bone 0 to 60 in 2.7 seconds over 80 hp stock, no brakes , no gears over 125 mph on dirt whole bike weights 170 lbs. Watch the speedway video from around the world nationals they do wheelie down the straight and slde wide open on corners. 3 bikes going wide in the corners, man just imagine the thrill when in a wedge go kart with this 500 cc 889 short stroke on F.I . Remember that Mullis won the Grand National at the THUNDER at Carnesville, GA just last week ago he lap the field was on a smaller motor the old 500cc 884 model when his carb came lose on turn 4 as he was approaching the checkerflag and still won.
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