Joined the (RZ) Chernobyl Club

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Gus the crank guy
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Joined: Sat May 19, 2018 12:02 am

Re: Joined the (RZ) Chernobyl Club

#16 Post by Gus the crank guy » Sun May 20, 2018 2:34 pm

.0025 is way too tight, wiseco had problems years ago with cilicone content being wrong, they have a good piston now but that is too tight, I'd run it .0035 to .004 and let it rip

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kenny
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Location: Worcestershire UK

Re: Joined the (RZ) Chernobyl Club

#17 Post by kenny » Mon May 21, 2018 5:27 am

If you shut the throttle after a long blast and your idle screw/pilot jet is wrong ie to weak it will lock solid at those temps. Pilot jets flow all the time not just at low throttle openings. So you may have gone from good mixture to lean in a split second. EGT is a mine field as the probe has to be fitted with the bike in perfect setup then that is the EGT for that bike and that bike only.
Wossner is another forged piston supplier and have a very good track record.

Gus the crank guy
Posts: 36
Joined: Sat May 19, 2018 12:02 am

Re: Joined the (RZ) Chernobyl Club

#18 Post by Gus the crank guy » Tue May 22, 2018 4:46 pm

I am surprised as rich as that motor is the egt's were that high, you said the head is cut, what is your squish clearance?

concours
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Re: Joined the (RZ) Chernobyl Club

#19 Post by concours » Sat Jul 02, 2022 1:55 pm

WFO for 45 years
1984 RZ350
1973 Yamaha TX750
1975 Yamaha DT400
1974 Norton Commando 850
Triumph Tiger 1050
Triumph Rocket III

concours
Posts: 95
Joined: Fri Aug 30, 2013 10:45 pm
Location: Kensington, New Hampshire, USA

Re: Joined the (RZ) Chernobyl Club

#20 Post by concours » Sat Jul 02, 2022 1:56 pm

Since all sorted out & running well. The plating on cast iron was not reliable. 3 failed attempts.
WFO for 45 years
1984 RZ350
1973 Yamaha TX750
1975 Yamaha DT400
1974 Norton Commando 850
Triumph Tiger 1050
Triumph Rocket III

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Redline Junkie
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Posts: 624
Joined: Tue Dec 25, 2012 12:55 pm
Location: Halifax, Nova Scotia Canada

Re: Joined the (RZ) Chernobyl Club

#21 Post by Redline Junkie » Sat Jul 09, 2022 9:56 pm

concours wrote: Sat Sep 03, 2016 9:17 am
RuZty wrote:
concours wrote: E) Piston clearance set at .0025", RH side lived just fine, despite a pegged temperature reading.
I think Wiseco call for .003-.004" for a 66mm bore. How did you measure it? RHS might have not been far behind, it had to start somewhere. Are you sure you had no air leaks?

As sure as I can be no air leak. I meticulously assembled, new crank seals, Yamabond cases, reed blocks cleaned, inspected, gasketed (included Loctite 518)
Did you pressure and vacuum test the engine once assembled? I do it every time I have the top end apart.
1985 RZ350F being restored now!
1987 RZ350 Stock
1985 RZ350F basket case
1985 RZ500 Stock

concours
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Re: Joined the (RZ) Chernobyl Club

#22 Post by concours » Sun Jul 31, 2022 1:06 pm

Gus the crank guy wrote: Tue May 22, 2018 4:46 pm I am surprised as rich as that motor is the egt's were that high, you said the head is cut, what is your squish clearance?
2mm, IIRC
WFO for 45 years
1984 RZ350
1973 Yamaha TX750
1975 Yamaha DT400
1974 Norton Commando 850
Triumph Tiger 1050
Triumph Rocket III

(F5)
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Location: Wellington New Zealand

Re: Joined the (RZ) Chernobyl Club

#23 Post by (F5) » Mon Aug 01, 2022 4:22 am

concours wrote: Sat Jul 02, 2022 1:56 pm Since all sorted out & running well. The plating on cast iron was not reliable. 3 failed attempts.
Didn't see this mentioned. I had that done on a small bore 50cc road racebike. Came off in first race. Then I sent it to US Chrome. Lasted 10 yrs of abuse to 14,000 rpm and had worn after lots and lots of hours, a bit, used with say 20 single rings and 4 pistons, but never flaked.
496 Cheetah. TSS PVs, PWK35s, Ignitech, RGV(ish) chassis

concours
Posts: 95
Joined: Fri Aug 30, 2013 10:45 pm
Location: Kensington, New Hampshire, USA

Re: Joined the (RZ) Chernobyl Club

#24 Post by concours » Tue Aug 16, 2022 3:15 pm

kenny wrote: Mon May 21, 2018 5:27 am If you shut the throttle after a long blast and your idle screw/pilot jet is wrong ie to weak it will lock solid at those temps. Pilot jets flow all the time not just at low throttle openings. So you may have gone from good mixture to lean in a split second. EGT is a mine field as the probe has to be fitted with the bike in perfect setup then that is the EGT for that bike and that bike only.
Wossner is another forged piston supplier and have a very good track record.
I have the KOSO with rapid response probes. I located them 6" from the bore, per their instruction. Any comments?
WFO for 45 years
1984 RZ350
1973 Yamaha TX750
1975 Yamaha DT400
1974 Norton Commando 850
Triumph Tiger 1050
Triumph Rocket III

RZtuner
Posts: 152
Joined: Sun Sep 17, 2006 10:28 pm

Re: Joined the (RZ) Chernobyl Club

#25 Post by RZtuner » Wed Aug 17, 2022 2:14 pm

Concours wrote: [resealed the crank, repaired the bores, added EGT's and observed reasonable temps, around 1200F at WOT short pulls. BUT, the coolant temp was always high. After 350 miles I cranked on it, redlined 3rd, 4th, 5th... resulting in coolant temp pegged, coolant overflowing the reservoir, and a light seizure. EGT max temp logged at 1450, obviously China Syndrome.]

Most aluminum alloys melt at around 1220 degrees F. so 1200 degrees is far from reasonable, it's on the edge of melt down!
66mm bores makes the liners really thin and more heat transfer to the coolant and possibility of overheating.
350 Prod. SCTA Bonneville World Landspeed record holder
500 Prod. SCTA Bonneville World record holder
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concours
Posts: 95
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Re: Joined the (RZ) Chernobyl Club

#26 Post by concours » Thu Aug 25, 2022 9:08 pm

RZtuner wrote: Wed Aug 17, 2022 2:14 pm Concours wrote: [resealed the crank, repaired the bores, added EGT's and observed reasonable temps, around 1200F at WOT short pulls. BUT, the coolant temp was always high. After 350 miles I cranked on it, redlined 3rd, 4th, 5th... resulting in coolant temp pegged, coolant overflowing the reservoir, and a light seizure. EGT max temp logged at 1450, obviously China Syndrome.]

Most aluminum alloys melt at around 1220 degrees F. so 1200 degrees is far from reasonable, it's on the edge of melt down!
66mm bores makes the liners really thin and more heat transfer to the coolant and possibility of overheating.
I am having doubts about the vacuum petcock. Performs as designed as far as I know. BUT, I theorize, under low vacuum (WOT) it closes or restricts flow. Any users ever able to prove/disprove this theory?
WFO for 45 years
1984 RZ350
1973 Yamaha TX750
1975 Yamaha DT400
1974 Norton Commando 850
Triumph Tiger 1050
Triumph Rocket III

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