Yoshimura Pipes. Pics? Experience?

[Highside]

I just bought what the owner claimed was the last NOS Yoshi pipe for the XS650. Unfortunately, my camera is down for now so the pics will ave to wait a little. The headpipe dia is 1 5/8 and the collector dia is 2.5. To me this seems a bit big, head pipe dia for this application should be 1.375-1.5.

I was wondering who else has this pipe and what their experience has been. I someone has pics of their pipe already installed, that would be cool too.

 

[angus67]

2.5 iirc, is for inline fours, like 1k bikes. I think that guy was putting you on. thats a huge difference in pipe diameter to be designated for a two cyl. 650. Does it sound ok?
I was trying to get my hands on a honda(82) 4-650, A friend has a yoshi pipe that he was gonna give me if I turned it into a cafe. didnt get the bike.

 

[Highside]

2.5 iirc, is for inline fours, like 1k bikes. I think that guy was putting you on.

That isn't what he told me, that's what I measured.

thats a huge difference in pipe diameter to be designated for a two cyl. 650. Does it sound ok?

I got the engine apart right now so I won't know how it sounds for a bit. I'm more concerned that it won't have good mid-range power, than how it sounds.

It would seem to me that the ideal 650 pipe would start out 1.375" for about 8", then step up to 1.5" for 7", then step up to 1.625 for 7", then have a 2.125 collector.

 

[jay760]

I had a pipe that was like that once, one of the best 2-1 I've had, made the mistake of cutting the tail pipe off and welding a supertrap silencer on

 

[jay760]

Tried to find a picture, only have one of after the supertrap was put on, they're not Yoshimura but they are of a similar size to the ones you have, these were adapted from a Norton I think, that's why they don't really follow the lines of the bike.

 

[Highside]

Tried to find a picture, only have one of after the supertrap was put on, they're not Yoshimura but they are of a similar size to the ones you have, these were adapted from a Norton I think, that's why they don't really follow the lines of the bike.

Yeah, i'm starting to think that this pipe was meant for a big bore engine.

I might have to buy a MikesXS pipe for the time being, since it's 1 1/2".

 

[jay760]

Mine was fitted to a standard 650 engine to begin with, just with dellorto's fitted, the front pipes are 1 3/4" with a 2.5" tail pipe. I would fit them first before buying another set, even if it's just to see what they are like when fitted.

 

[Highside]

Mine was fitted to a standard 650 engine to begin with, just with dellorto's fitted, the front pipes are 1 3/4" with a 2.5" tail pipe. I would fit them first before buying another set, even if it's just to see what they are like when fitted.

1 3/4!! WOW!! I'm suprised that you had any bottom-end or midrange power at all.

Looking at the whole xs650 exaust track, I'm kinda puzzled. It ALL seems too big.

The intake valve is approx 1.625", which should make the exhaust valve 1.2". instead, it's ~ 1.375.

With proper porting you should be able to shrink the exhaust valve and port, while still maintaining proper flow numbers.

 

[5twins]

You can use inserts at the head to reduce the diameter. This fools the engine into thinking it has small headpipes, the kind it likes. I made my own from the ends of stock headpipes .....

This adresses a couple other problems with the pipe and port. It nicely seals and centers the pipe, and it fills that step in the port (with the addition of a filler ring) .....

 

[Highside]

You can use inserts at the head to reduce the diameter. This fools the engine into thinking it has small headpipes, the kind it likes. I made my own from the ends of stock headpipes .....

This adresses a couple other problems with the pipe and port. It nicely seals and centers the pipe, and it fills that step in the port (with the addition of a filler ring) .....

That's a good band-aid fix to large pipes, but smaller pipes should make better power, especially if you step them up to a larger diameter after about 12" or so.

 

[STLFSTJ]

I want to see pics of your exhaust highside...

the XS I bought came with 1 and I'm wondering that if these belong on the XS? either way I'll use em... All they need is some clean up.