Standard Spec YPVS 350 Barrels

General forum on engines, transmissions, gearing and modifications to each

Moderator: rztom

Message
Author
Headcoats
Posts: 848
Joined: Sun Apr 04, 2010 6:13 am
Location: Pig On The wall Country

Standard Spec YPVS 350 Barrels

#1 Post by Headcoats » Fri Sep 29, 2017 4:04 am

Where is the choke point/restriction on standard barrels ?
Looking at my tuned barrels (UK) the inlet windows are really opened up but after having to go up 3 sizes on the rebore due to wear, I feel I don't want the inlets made into Swiss cheese again !

So what is a good compromise to get a decent jump in power and not go to over the top, or you can't have both !
Last edited by Headcoats on Sat Sep 30, 2017 10:24 am, edited 1 time in total.
Cryin' In The Beer Of A Drunk Man

hondaror
Posts: 2828
Joined: Mon Mar 03, 2014 8:44 pm
Location: Alberta, Canada

Re: Standar Spec YPVS 350 Barrels

#2 Post by hondaror » Fri Sep 29, 2017 10:55 pm

Pipes ad K&N pods, big increase. Leave the porting alone. You gain huge power and still have reliability.
Rory
2 1984 RZ350s
1985 RZ350
9 1986-1990 RZ350s
2000 ST2
2005 749
2005 749 with 999 engine

Headcoats
Posts: 848
Joined: Sun Apr 04, 2010 6:13 am
Location: Pig On The wall Country

Re: Standar Spec YPVS 350 Barrels

#3 Post by Headcoats » Sat Sep 30, 2017 4:28 am

I have some standard barrels and after the premature wear on my tuned "swiss cheese" barrels , I'm now more inclined to have something not so radical but was just wondering if the barrels could maybe have a light clean up?
Cryin' In The Beer Of A Drunk Man

User avatar
OldTZracer
Posts: 240
Joined: Thu Aug 05, 2010 2:21 am
Location: Alberta Canada

Re: Standard Spec YPVS 350 Barrels

#4 Post by OldTZracer » Sat Sep 30, 2017 10:23 pm

As Rory said, leave the porting alone - just clean them up...
"...its a 2-stroke ya twit - Its supposed to smoke..."

evan_calgary
Posts: 1368
Joined: Tue Nov 12, 2013 2:34 am

Re: Standard Spec YPVS 350 Barrels

#5 Post by evan_calgary » Mon Oct 02, 2017 3:45 am

Would have to agree as well. Also don't polish anything on the intake side. So many barrels get destroyed with amateur tuning. The 2-stroke tuner handbook is a good resource if you do move forward.

User avatar
T.RexRacing
Posts: 1318
Joined: Fri Nov 01, 2013 8:34 pm
Location: back in the hills

Re: Standard Spec YPVS 350 Barrels

#6 Post by T.RexRacing » Mon Oct 02, 2017 10:24 am

If ya want it ported let someone do it that's done the work to make it a worthwhile addition.
There is only one difference between a madman and me. The madman thinks he is sane. I know I am mad.
Salvador Dali

Headcoats
Posts: 848
Joined: Sun Apr 04, 2010 6:13 am
Location: Pig On The wall Country

Re: Standard Spec YPVS 350 Barrels

#7 Post by Headcoats » Mon Oct 02, 2017 12:05 pm

I will if I decide going down that road again but the answer I'm after is how important is it that the inlets are opened right out ?
Cryin' In The Beer Of A Drunk Man

User avatar
Questo vecchio rz
Posts: 1116
Joined: Sun Aug 16, 2015 5:55 pm
Location: Reconquista of California

Re: Standard Spec YPVS 350 Barrels

#8 Post by Questo vecchio rz » Mon Oct 02, 2017 1:04 pm

You have several great tuners in the UK.

Why do you not just send them to Stan ? It's kind of a no brainier. :smt017
Banshee (Baja) race bike,+ 2 A Arms,L.E.Ds, Toomey, +4 stroker IMS tank, run flats.
96 GSXR SRAD, Future Yoshimura rep.
85 custom Tri-Z
RZ/YZR bike(project)
86 VFR750 RC24 Merkel replica (project)
Royal Enfield Bullet 500

User avatar
T.RexRacing
Posts: 1318
Joined: Fri Nov 01, 2013 8:34 pm
Location: back in the hills

Re: Standard Spec YPVS 350 Barrels

#9 Post by T.RexRacing » Mon Oct 02, 2017 2:02 pm

It's my understanding the transfers require the most work so the inlet's likely secondary for mo powah.
There is only one difference between a madman and me. The madman thinks he is sane. I know I am mad.
Salvador Dali

User avatar
two-stroke-brit
-----
-----
Posts: 1701
Joined: Fri Nov 22, 2013 10:49 pm
Location: Houston texas

Re: Standard Spec YPVS 350 Barrels

#10 Post by two-stroke-brit » Mon Oct 02, 2017 2:06 pm

pipes,carbs and zeeltronic Iggy.
will give the biggest improvements
mark
350LC,Athena 392 big bore,stock porting,swiss cheese air box,stock reeds,spec11 pipes.(now TSA big bore pipes)
She might not be pretty but she will always be a fun ride


1982 YAMA RD350LC
98KDX 220R
1967 TRIUMPH TIGER
2001 TRIUMPH TT600

evan_calgary
Posts: 1368
Joined: Tue Nov 12, 2013 2:34 am

Re: Standard Spec YPVS 350 Barrels

#11 Post by evan_calgary » Mon Oct 02, 2017 6:16 pm

The transfers are the limiting factor on these barrels for flow. Thus why many of the aftermarket barrels can get substantially more power. Optimal transfer sizing. When you start messing with the size of the port windows you will majorly change power characteristics though.

I am on Rory's team when it comes to tuning. Bigger carbs are of no value on a stock motor. Throw on some pods and call it a day. Zeel may be worth some power but I didn't really see it. Of course if you have piles of tuning and dyno time then sure there are gains to be had. Stock carbs can even work on 396 granted they may cut a bit of top end.

User avatar
T.RexRacing
Posts: 1318
Joined: Fri Nov 01, 2013 8:34 pm
Location: back in the hills

Re: Standard Spec YPVS 350 Barrels

#12 Post by T.RexRacing » Mon Oct 02, 2017 7:22 pm

I have dyno access anytime as it's my office. However a bike I own hasn't seen a pull in 10 years. That may change when I get my GPL pipes......
dynocell.jpg
dynocell.jpg (86.11 KiB) Viewed 4025 times
There is only one difference between a madman and me. The madman thinks he is sane. I know I am mad.
Salvador Dali

hondaror
Posts: 2828
Joined: Mon Mar 03, 2014 8:44 pm
Location: Alberta, Canada

Re: Standard Spec YPVS 350 Barrels

#13 Post by hondaror » Mon Oct 02, 2017 8:25 pm

Very nice T! Very nice.
The dyno is the best way to tune. Porting should only be considered by an expert rider. The general public are not expert riders. There are so many sacrifices from porting, to get the big numbers. Ridability on the street goes out the window fast.
Everyone knows about "chicken strips". I had a track day about a month ago on a 2009 KLX250SF. Every street bike you look at, has chicken strips. Get on the track, and it's like magic, the strips are gone...even on the Kwacker 250. So, if you must port your bike, do us all a favour and track your bike first. Going fast, does not require porting. It requires corner speed, comfort with your bike and ease of operation. The RZ does that in spades. That's why they are so popular. Fun! Fun! Fun! Porting offers a very experienced rider other challenges.
Rory
2 1984 RZ350s
1985 RZ350
9 1986-1990 RZ350s
2000 ST2
2005 749
2005 749 with 999 engine

User avatar
T.RexRacing
Posts: 1318
Joined: Fri Nov 01, 2013 8:34 pm
Location: back in the hills

Re: Standard Spec YPVS 350 Barrels

#14 Post by T.RexRacing » Mon Oct 02, 2017 11:48 pm

Yeah but having the powah isn't about track daze or racing. Common sense has no place here dood. :smt003

Shit my Tuono doesn't really have any "chicken strips" and it's never been tracked. I know it's not acceptable to ride fast on the street but that's never stopped me. It's why I ride and always will be. I don't wheelie through town,there's a time and place for everything and in traffic ain't it. I live in the mountains and ride roads where 70 MPH is terrifying. Tight technical and tons o' fun.

The RZ is ported by Ed Erlenbach. Quite streetable and well behaved on pump gas. It's a matter of degree.
There is only one difference between a madman and me. The madman thinks he is sane. I know I am mad.
Salvador Dali

hondaror
Posts: 2828
Joined: Mon Mar 03, 2014 8:44 pm
Location: Alberta, Canada

Re: Standard Spec YPVS 350 Barrels

#15 Post by hondaror » Tue Oct 03, 2017 2:39 am

It sure is.
Rory
2 1984 RZ350s
1985 RZ350
9 1986-1990 RZ350s
2000 ST2
2005 749
2005 749 with 999 engine

Post Reply