DT125R ARCHIVE

NorDt · Guru

Different barrels and Tops ? difference ?

the only way is YAMAHA DTR · Guru

4dl barrels are the best

NorDt · Guru

Please explain why ? whats the difference from a 4dl barrel and a 3mb barrel ?. And what dts came with the 4dl barrel stock ?

NORFE · DTR Trusted Engine Builder

id assume its all to do with porting/locations/durations as thats all that makes or breaks 2 strokes

have a read for the basics

http://www.2-stroke-porting.com/Port_Work.html

can get very complicated confuse

NorDt · Guru

ive read books like that earlier. And i get the basics.

Do you know what model dts came with a 4dl barrel ?. Do you have any experience with it norfe ?

the only way is YAMAHA DTR · Guru

http://www.dt125.de/Forum/thread.php?postid=1263066

4dl have boost ports, and larger ports and different timing, compression and i think nickle plated also use oring gaskets

NorDt · Guru

Okay, I dont understand german.
THanks. But do you know what dts came stock with this barrel ?

the only way is YAMAHA DTR · Guru

tzr 125 rr 4dl

NorDt · Guru

What about the sachs zz 125 ? is it possible that it came with the 4dl ? have a friend that claims he had a zz 125 which was much faster than my friends dtx

the only way is YAMAHA DTR · Guru

no only the tzr 4dl belgarda had it, people have fitted wr200 topends with lots of work like changing the crank shaft and ignition timing etc

the only way is YAMAHA DTR · Guru

http://dt125r.activeboard.com/t43277535/dt200-wr200-big-bore/

http://dt125r.activeboard.com/t44907362/4dl00-zylinders/

NorDt · Guru

didnt know the wr200 came as 2 stroke.

So the 4dl is the best barrel. But they never came on dts ?. do you know which one of the dt barrels are the best then ? and what heads ? Is it the 3mb head thats the best ?

the only way is YAMAHA DTR · Guru

well i know the 3mb head has higher compression, theres also all sorts of tzr ones that fit like 4fl and 4fu,

also the dt 230 lanza is very similar

NorDt · Guru

yeah but the dt 125cc came with different barrels too didnt they ? 3mb and 3nb and stuff ?. Are there any noticable change on any of theese barrels ?. i once tried a 1999 dtr with a dep pipe fitted. It felt rubbish compared to mine, It wouldnt wheelie properly in any other gears than first. And it didnt pull nearly as good as my dt 125 re 04 mod.

the only way is YAMAHA DTR · Guru

was the power valve working, i dont know much about the 3bn barrell apart from its plated

NorDt · Guru

I dont know if the powervalve was working.

the only way is YAMAHA DTR · Guru

1999 didn't come fitted with YPVS in england and where restricted shut

NEV · Guru

97 & 98 3 wire servo, 99 0nwards 5 wire servo.

Check electrical 2 on this link

http://www.yamahamotorcyclespares.co.uk/spares/modelImage.asp?modelID=9130&uID=0

NorDt · Guru

The powervalve was proboably pegged then.

NorDt · Guru

Hehe. Too much hazzle

the only way is YAMAHA DTR · Guru

biggrin lol that post was on the wrong thread

NorDt · Guru

Thought it was a bit weird, but i though maybe u ment i should try getting hold of the owners of those bikes to ask them what barrels where on them xD

2T_Toe · DTR Respected Member

There's another head with no name or numbers on the casting that has a larger squish band/gives higher compression than the 3MB head. I know it comes fitted to the TDR Belgarda, not sure what else.

The 4DL's ive looked at have had 3MB barrels but the porting may be different than standard as i never had a look inside. I'll have to check whats fitted to my TDR Belgarda and check the porting.

I've been looking stroker kits available for the Blaster Quad that shares the bottom end with the DT but i'm not sure if the small end will take a DT piston, i'll have to look into it.

the only way is YAMAHA DTR · Guru

the 4dl barrels had boost ports and oring gaskets http://dt125r.activeboard.com/t44907362/4dl00-zylinders/

2T_Toe · DTR Respected Member

From what i can gather there, regular road going 4DL bikes have lightly modded 3MB barrels, only the SP's have the 4DL plated barrel with the boost ports and o-ring gaskets.

I think i've actually got one of the modded 3MB barrels as a spare when i bought my bike, the '3MB00' is part of the casting and the 'P' following it is stamped in afterwards. Another one i'll have to check when i get chance...

the only way is YAMAHA DTR · Guru

might be worth a few quid

2T_Toe · DTR Respected Member

I've been doing a litle digging, Blaster stroker kits should work as the small end shares the same dimensions as the DT, though gains wouldnt be huge cc wise. One of the spare cylinders i have is a Belgarda one, does look a little different from the other spare i have but i'll have to do a sided by side comparison when i get the chance.

the only way is YAMAHA DTR · Guru

blasters cylinders arnt crank inducted, and are air cooled

2T_Toe · DTR Respected Member

I think you're thinking of big bore kits bud, stroker kits have a longer stroke crank and a spacer to go under the cylinder to compensate, nothing to do with the cylinder itself, though i'm guessing you'll need port work as this will be off once the kit is fitted.

NorDt · Guru

So you add a spacer underneath the cyllinder and add a long stroker crank ?. Would this gain any effect at all ? wouldnt this just make the bike slower ?. I think the chineese calculates CC only after the piston has passed the exhaust port and is going upwards. Makes sense. Theres no compression before the piston has passed the exhaust port.

So. correct me if im totally off. But with a spacer underneath the barrel. wouldnt it just make the time the piston uses on going down after igniting. And back up and then start compressing fuel after its passed the exhaust port. just slower ?

I can see one positive effect from a spacer underneath the barrel. You get more fuel sucked in there and then pushed back up to the top of the barrel and wich is compressed and ignited. So maybe this evens it out. Since theres more fuel to be compressed i mean. But this would be harder on the piston and crank right ?. Maybe even for the top end ?.