Carb to filter rubber

[declan]

@Calum I think he means other 2 strokes didn’t fit them

[Calum]

@declan probably because it was patented technology. Other manufacturers didn't use YPVS. They had to make do with their own derived systems.

There is a big difference between the RAVE system on my RS and the YPVS system on my DTR.

[declan]

@Calum nah that’s not the case many tuned 2 strokes still use the bottles they just don’t seem to come stock

[Calum]

Yeah I don't know.

[SpookDog]

Cheers guys.

Anyone of one for grabs or sale? Never seen one anywhere...

[markus.w]

@SpookDog
Yamaha DT125R Boost bottle yeis chamber 2 DTR DT125 DTR125 YPVS TZR GPR SC125

[Nottsbiker]

@markus-w said in Carb to filter rubber:

@SpookDog
Yamaha DT125R Boost bottle yeis chamber 2 DTR DT125 DTR125 YPVS TZR GPR SC125

The YEIS chamber sits on the inlet manifold above the reed block

The chamber on the side was only fitted to the later models and I'd assume was some kind of intake silencer rather than a performance related part

[GeirA]

@Calum as you know, DTR was first released in 1988 and even though YEIS has been a part of the intake system on the DTR throughout the years doesn't mean it did very much for the performance in either way. And because YEIS wasn't implemented in any newer two-stroke models from Yamaha may confirm that. YEIS might also have been more of a marketing strategy to keep two-strokes popular in a time when four-stroke engines began to take bigger market shares.
Yes, Yamaha could have removed it, but that cost resources and money. So why change something that probably just doesn't matter either way? Yamaha is also a company that are reluctant to change motorcycle models that still sell well, like the DTR. Yamaha YZF ThunderCat was another motorcycle that was sold for many years virtually unchanged. In Asia and South-America there are models designed in the 70s that still are produced and still sell well in those markets. They aren't even manufactured in Japan. Actually, Yamaha has a lot of factories around the world that produce the same models year after year, and models we will never see in Europe or the US. Even the design of some models is done outside Japan. I know for sure that Yamaha DTR 50 was designed and produced by MBK in France, not Japan.

[Darty]

@GeirA What’s your point? lots of 2strokes in the 1980s used ‘boost bottles’ - YEIS was used on big bore IT’s and YZs from the early 1980’s.

It was deemed an improvement on engines that are now over 30years old in design.

2strokes were still being understood well into the 1990s,

The second YEIS bottle was added to the DTR for the 2000 model year ,

[Nottsbiker]

Yamaha just refer to both of them as Air Chamber on the parts diagram's - I still say its not a performance item and its just a bolt on for emissions / silencing etc.