Squish Help
Moderator: rztom
- T.RexRacing
- Posts: 1318
- Joined: Fri Nov 01, 2013 8:34 pm
- Location: back in the hills
Re: Squish Help
Pre-ignition usually causes hole in the middle syndrome.
There is only one difference between a madman and me. The madman thinks he is sane. I know I am mad.
Salvador Dali
Salvador Dali
Re: Squish Help
Back to squish.
Yamaha designed the rz to be safe as houses. I doubt very much that burn and thermal gas insulation factor loss as a result of your squish being to big is even understandable in theory, let alone digestable to an engine builder of these moderate to simple engines.
My rough guess is if you have the original un modified head" which is rare" ( most have been shave or emery rubbed by the PO. Your compression will be around 120 standard( with new pistons rings).
Have the head shaved, or more to the point, re-flattened, aim for .9 to a 1.0 mm squish. Your compression will come up slightly, if you get over 130 I will be surprised. If it stays at 120 don't be worried, these things will operate quite well below 100 psi.
Ive successfully shaved/re flattened my own heads with emery paper, glass, water, regular measuring, patience, practice and a little luck.
An engineer with a decent bed mill could do the job in 10 minutes, but you need to be accurate in knowing how little the amount of material to be removed.
You need some room for rod expansion + big end play + little end play,+ slop, hence I've always been told don't come below .9 mm squish, just to be safe.
I think the TZ racers run down to .6.7 squish. But they are always running new bearings, tight tolerances, and special fuel.
I must say that every time i've shaved a head it does make a noticeable difference.
Holed piston, as previously mentioned, if its not an out of phase crank or someone hasen't fucked with the timing plate, Id be pointing the finger at excess air/ lean fuel( balance tube, vac line, reed boots, crank seal, fuel line, oil line, oil pump, float levels )
( a reason I like clear hoses for oil and fuel).
Yamaha designed the rz to be safe as houses. I doubt very much that burn and thermal gas insulation factor loss as a result of your squish being to big is even understandable in theory, let alone digestable to an engine builder of these moderate to simple engines.
My rough guess is if you have the original un modified head" which is rare" ( most have been shave or emery rubbed by the PO. Your compression will be around 120 standard( with new pistons rings).
Have the head shaved, or more to the point, re-flattened, aim for .9 to a 1.0 mm squish. Your compression will come up slightly, if you get over 130 I will be surprised. If it stays at 120 don't be worried, these things will operate quite well below 100 psi.
Ive successfully shaved/re flattened my own heads with emery paper, glass, water, regular measuring, patience, practice and a little luck.
An engineer with a decent bed mill could do the job in 10 minutes, but you need to be accurate in knowing how little the amount of material to be removed.
You need some room for rod expansion + big end play + little end play,+ slop, hence I've always been told don't come below .9 mm squish, just to be safe.
I think the TZ racers run down to .6.7 squish. But they are always running new bearings, tight tolerances, and special fuel.
I must say that every time i've shaved a head it does make a noticeable difference.
Holed piston, as previously mentioned, if its not an out of phase crank or someone hasen't fucked with the timing plate, Id be pointing the finger at excess air/ lean fuel( balance tube, vac line, reed boots, crank seal, fuel line, oil line, oil pump, float levels )
( a reason I like clear hoses for oil and fuel).
81 RD 250 LC Hybrid .Widened frame with Aprilia RS250 Back end & Front end, strokd RZ 421, Kennys TSA's, 31KVM26SS Carbs M-360 P-25 ALBA Ndl Pos 3, Air 1.3/4
81Rd350lc resto 2016
81 Rd250lc resto 2017
1999 ZRX 1100
81Rd350lc resto 2016
81 Rd250lc resto 2017
1999 ZRX 1100
- Evans Ward
- -----
- Posts: 1546
- Joined: Sun Jun 07, 2009 6:39 pm
- Location: Macon, GA
Re: Squish Help
What gauge solder works best with the stock RZ350 head in checking squish? I tried 3/32" but no squish noted on the solder strips. I'm doing this per Ron Black's (RB Designs) instructions prior to sending him my head for decking/ milling/ and setting for squish.
84 RZ350-Toomeys,SCR milled head, stk 26 carbs,300 M, 35 P, stock regrooved needles AS 2.5 turns out,stk air box,Banshee reeds Zeel non-progr CDI,TSRL Program YPVS,alum rad,R6 shock,GV emulators w/RT springs,fork brace,Shindy steering damper.
Re: Squish Help
Ive twisted 2 smaller pieces of solder together to make a thicker bit if the stuff I had on hand wasnt thick enough.
Dave
Dave
RZ 250 85 (Waiting)
RZ 250 85 (Parts)
RGV VJ21 250, Australian Speed Record Holder, MPS/G 250, 140.5 MPH
BMW R1100S 99 (Its Red)
BMW R1200GS (Its BIG)
http://www.dlra.org.au/index.htm" onclick="window.open(this.href);return false;
RZ 250 85 (Parts)
RGV VJ21 250, Australian Speed Record Holder, MPS/G 250, 140.5 MPH
BMW R1100S 99 (Its Red)
BMW R1200GS (Its BIG)
http://www.dlra.org.au/index.htm" onclick="window.open(this.href);return false;
Re: Squish Help
If your head is stock, squish was never a consideration of the factory, and that's why no reading. There is clearance in excess of what is considered optimum.
Rory
2 1984 RZ350s
1985 RZ350
9 1986-1990 RZ350s
2000 ST2
2005 749
2005 749 with 999 engine
2 1984 RZ350s
1985 RZ350
9 1986-1990 RZ350s
2000 ST2
2005 749
2005 749 with 999 engine
- Evans Ward
- -----
- Posts: 1546
- Joined: Sun Jun 07, 2009 6:39 pm
- Location: Macon, GA
Re: Squish Help
Thanks guys' Rory- yes head is stock. I'll contact Ron Black and ask what he wants me to do here.
Merry Christmas!
Merry Christmas!
84 RZ350-Toomeys,SCR milled head, stk 26 carbs,300 M, 35 P, stock regrooved needles AS 2.5 turns out,stk air box,Banshee reeds Zeel non-progr CDI,TSRL Program YPVS,alum rad,R6 shock,GV emulators w/RT springs,fork brace,Shindy steering damper.
- T.RexRacing
- Posts: 1318
- Joined: Fri Nov 01, 2013 8:34 pm
- Location: back in the hills
Re: Squish Help
I've found OEM squish is typically 1.77MM/.070" with stock gasket.
There is only one difference between a madman and me. The madman thinks he is sane. I know I am mad.
Salvador Dali
Salvador Dali
- Evans Ward
- -----
- Posts: 1546
- Joined: Sun Jun 07, 2009 6:39 pm
- Location: Macon, GA
Re: Squish Help
Heard back from Ron Black/ RB Designs- he no longer provides this service as he was only doing 1-2 per year.
Does anyone know a vendor for the milling/ setting squish for the stock RZ one piece head? As a last resort, I can contact some of the Banshee vendors.
Does anyone know a vendor for the milling/ setting squish for the stock RZ one piece head? As a last resort, I can contact some of the Banshee vendors.
84 RZ350-Toomeys,SCR milled head, stk 26 carbs,300 M, 35 P, stock regrooved needles AS 2.5 turns out,stk air box,Banshee reeds Zeel non-progr CDI,TSRL Program YPVS,alum rad,R6 shock,GV emulators w/RT springs,fork brace,Shindy steering damper.
Re: Squish Help
Scott Clough Racing in southern California. Don't have his website handy but a search will get you to it.
- Evans Ward
- -----
- Posts: 1546
- Joined: Sun Jun 07, 2009 6:39 pm
- Location: Macon, GA
Re: Squish Help
Thanks and have heard great things about his work!bjacobsen wrote:Scott Clough Racing in southern California. Don't have his website handy but a search will get you to it.
84 RZ350-Toomeys,SCR milled head, stk 26 carbs,300 M, 35 P, stock regrooved needles AS 2.5 turns out,stk air box,Banshee reeds Zeel non-progr CDI,TSRL Program YPVS,alum rad,R6 shock,GV emulators w/RT springs,fork brace,Shindy steering damper.