Yamaha dt 50 . Tuning

[vmryanmv]

Hello there i have a Yamaha dt 50 1982 completely stock , i with thinking of putting the 60cc (kit) head and piston on it.
i was wondering what would i do about the carb ? and any suggestions. thanks Ryan.

[RhynoCZ]

Well, I would suggest not to touch it and leave it be, as it seems to be running just fine as is. But if you put the 60cc kit there, you can use the same carb, maybe rejet it afterwards. It's hard to tell without the dyno test.

I googled the 60cc kit, and it's not just the piston and the head I'm afraid. Anyway, the stock carb should fit.

https://i.ebayimg.com/images/g/gywAAOSwstxVZ~tj/s-l1600.jpg
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'87 Honda XBR 500, '96 Kawasaki ZX7R P1, '90 Honda CB-1, '88 Kawasaki GPz550, MZ 150 ETZ
'95 Mercedes-Benz w202 C200 CGI, '98 Mercedes-Benz w210 E200 Kompressor

[vmryanmv]

ok well could you tell me the restrictions on the bike due to it only goes 35 mph flat out , how could i increase the speed .

[RhynoCZ]

Take of the carburetor, check for any restrictions in the intake port/manifold. If there's nothing restricting the flow of air/fuel mixture, then it's time to face the reality. You have got an air-cooled, 2.3 kW, single cylinder two stroke with a 5 speed gearbox. I think 35 mph is about as good as it gets.

Now, trying to highly tune up such engine, it will take huge piles of money, the mpg will get terribly bad and the service intervals might not be thousands of miles as they are now, but hundreds of miles, maybe even less. Then you are going to get pissed because you blew a huge pile of money to get a couple of fun miles on it and then it was time to take it all apart again.

Getting a higher level licence to ride bigger bikes is the only reasonable thing to do here. If you still want to tune your motorcycle, you've got the wrong type of engine. A liquid cooled modern two stroke with 6 speed box would be better to start with.

I doubt anyone has got anything else to say here, search for DT forums for help, I suggest. More power and speed can be achieved, but at what cost? A tuned Aprilia RS50 is capable of 100kph/62mph+, for instance.
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'87 Honda XBR 500, '96 Kawasaki ZX7R P1, '90 Honda CB-1, '88 Kawasaki GPz550, MZ 150 ETZ
'95 Mercedes-Benz w202 C200 CGI, '98 Mercedes-Benz w210 E200 Kompressor

[vmryanmv]

Thanks for the reply , Thanks anyways

[RhynoCZ]

You might feel like I'm crushing your dreams, but I'm just trying to help.
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'87 Honda XBR 500, '96 Kawasaki ZX7R P1, '90 Honda CB-1, '88 Kawasaki GPz550, MZ 150 ETZ
'95 Mercedes-Benz w202 C200 CGI, '98 Mercedes-Benz w210 E200 Kompressor

[Teflon-Mike]

I built one of them once, twice, three times... I think I lost count after that.....

Mine was actually a '79 'E' model, the twin-shock one.. I acquired it in PX on a air-cooled RD250, and as it was related to the TY80's I'd cut my teeth on in School-boy trials, and had the full facilites of a pro work-shop at my disposal, 'we' thought t would be a chuckle to see what we could do with it... it was effectively 'free' after all!

Knackered 50cc barel, was replaced with the 60cc big-bore, 'cos it was cheaper, and offered faster... entire bottom end was rebuilt to take it and a lot of detail work and then current TZ and YZ 'race' know-how, went into it... With a Gianelli spanie, and the stock carb up jetted, we ran it over a measured quarter at a timed 60mph... one way.. wouldn't have got an FIM accreditation then... return run was made on the end of a rope! This was to become a common occurrence!

Crank-Case seal had 'popped'.

New seals were ordered.. clever bit of kit.. an adapted EZ-Out was used to remove the dodgy one without knocking the bottom end down..... new one fitted from the outside... AND it blew it again!

Oh-Kay..... have to kock it down and do it properly.... another set of new seals ftted, and loctited into place to be sure....

Blew again, and this time the bike nipped up, and snagged a ring... so yet aother barel kit was ordered... this one took it out to 65cc... crank-seals were again scrutinised and the bottom end knocked down to fit them.. BUT, with a retension plate to hold the bastards in the hole come what... oh!

STILL blew the fuckers!

Carbrettor sizing or jettg wasn't REALLY that much of an issue! Thing never seemed to hold onto its crank seals long enough to de-bug flat-spots!

It was a bit of fun... BUT.. things pushing forty years old! Let it have a little peace its dotage! Leave it standard!

Or just fit a DT/RD/TY80 engine! Drops straight in!
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My Webby'Tef's-tQ, loads of stuff about my bikes, my Land-Rovers, and the stuff I do with them!
Current Bikes:'Honda VF1000F' ;'CB750F2N' ;'CB125TD ( 6 3 of em!)'; 'Montesa Cota 248'. Learner FAQ's:= 'U want to Ride a Motorbike! Where Do U start?'

[bladerunner]

Before you bother with the big bore fit a new full exhaust! I had one back in the 80's and it would happily pull 50 on the flat. The dt,mt5 and ts50's of the time all seemed to gain most speed/£ this way as std pipes kill any power after 6k and something like a big one/gianelli will let it rev to 10k like it was supposed to. Then look at the big bore option and jetting.
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Current bikes...cbr929, KDX200's, Rd125lc mk2, RGV250's

[redeem ouzzer]

LC 125 engine can be made to fit (seen it done) and it's no more criminal than riding a tuned 50.

[picture_man36]

Try the big bore but make sure you get the carb jetting and oil pump set up correctly otherwise it'll run lean and may well seize....

You'll get it to do 50mph ish... I used to knock around with a few guys in the 80's that ran DT50's & ER50's and this was the easiest mod, but make sure you set it up correctly. It will benefit immensely from a new exhaust.. a Big One or Gianelli & a decent tail pipe.

If you can find one, drop the 80cc engine which will get you to 60-65mph ish and looks like the 50cc lump anyway.... (Honest officer I bought it like this....)
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'The Picture Man'

[stevo as b4]

[dangerousdave]

[redeem ouzzer]

[dangerousdave]

[RhynoCZ]

Well, it never occured me to fit another engine in (MOT fail if the engine VIN (type: DT50XXXXXXXX) does not match the paperwork, CZE though). Fitting a DT 80 engine would be actually alright I guess. I'd also fit the DT 80 front wheel/hub/brake if it's diferent. You do not want OP to get hurt boiling his brakes, yes even the drum brake can overheat.

Tuning a 50cc engine is still pointless though. If you ''need'' to tune an engine to get more power, you are doing it for the wrong reason. If you tune it for the fun of tuning it, that is alright, but then you also know you won't be riding it as you did before. The idea of tuning a everyday in use machine is just ridiculous. That, speaking of a road legal machine, race stuff is completely diffrent story and rebuild of the engine before every session is the esencial part of having a tuned racing machine.

TL; DR: I do not think OP's gonna be back any soon.
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'87 Honda XBR 500, '96 Kawasaki ZX7R P1, '90 Honda CB-1, '88 Kawasaki GPz550, MZ 150 ETZ
'95 Mercedes-Benz w202 C200 CGI, '98 Mercedes-Benz w210 E200 Kompressor

[redeem ouzzer]

[vmryanmv]

Could some one drop me a link or something to an exhaust, i have no clue what im looking at im sort of new to bikes , its a yamaha dt 50 1982

[dangerousdave]

[dangerousdave]

[dangerousdave]

[..]

[Pete.]

[picture_man36]

Not sure whether the DT50MX was sold in Europe or whether they just bought the 80cc (I do know someone who put a big bore on his 80cc - think they did a 90cc kit). I do know there were some 110cc big bore kits knocking about

I'm building an MT50 special. The UK spec bike was restricted down to something stupid and did 30 mph flat out... My then partner & I went to Corfu on holiday one year and we hired a EU spec MT50 and this thing went like shite off the proverbial shovel! 2 up it did close to 45-50 mph and this was in standard '50cc' trim... Having researched the model, to meet UK moped 50cc/16 year old legislation the manufacturers all had to restrict their 50's. With the exception of the 50cc 'Simpson' which was not restricted, some Garelli's and some Fizzers and SS50's they were all at about 30-35 mph. Yamaha, Suzuki, Kawasaki all did it with restrictors in the exhaust etc..

If you replace the exhaust with a decent pipe (the original with restrictors will be long gone anyway... change the tail pipe, and change the reeds your probably going to be close to 40 mph anyway. With say an 80cc carb you might make it to 45 mph in standard trim. Don't junk the airbox as its better that any POD filter.... thereafter it is a bigbore...

My MT50 was totally different matter - they restricted through the CDI so that don't rev, the ports on the barrel were also revised as well as the poxy 13mm carb and the exhaust front pipe. To derestrict the MT50 you need to engineer all of these out and the simplest way to do this is a 60 kit.. MT8 Carb, exhaust etc..

Will let you know how long mine goes before it self destructs... this said it'll not be going far and will end up more of a nostalgia ornament anyway !
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'The Picture Man'

[A100man]

[stevo as b4]

A stage 3 tuned RS125 run on chainsaw oil would still last longer though!