More to come.
You took the plunge. Can't wait to see where this goes. :whoop:
Interesting ports. Is that a 40971? or later?
This is very exciting!
Quote from: teazer on June 05, 2021, 05:20:26 PM
Interesting ports. Is that a 40971? or later?
It's a 40971
Please explain those numbers..??
Very cool.
TZ barrels have a number cast into the rear that represents model # 409 and year/ variant
409-70 TZ750 A/B 64mm bore 700cc
409-71 is later 66.25mm full 750cc version and so on
Do you need a base gasket, Joe?
At some point I will need all gaskets and seals.
So for the uneducated this is half a tz750? :umm:
Quote from: Czakky on June 06, 2021, 07:14:46 AM
So for the uneducated this is half a tz750? :umm:
Yes.
:pop:
Quote from: teazer on June 05, 2021, 08:52:29 PM
TZ barrels have a number cast into the rear that represents model # 409 and year/ variant
409-70 TZ750 A/B 64mm bore 700cc
409-71 is later 66.25mm full 750cc version and so on
But still the version with 4 transfers, plus boost port? The later versions had 6 transfers, right?
I had a TZ750 cylinder block, and a head, plus a damaged cylinder block for maybe 30 years, but sold them to a guy restoring a TZ750 a couple of years ago. Just never got around to actually use the parts. Part of the reason was that I read somewhere that the TZ crank rotates opposite of an RD or TZ twin crank, and the short intake skirt of the TZ piston s are not really happy with the side loads when used in an RD. This may be of less consequence than I think, but anyway.
The 1981 TZ250H was the first countr-rotating TZ engine
Quote from: 85RZwade on June 10, 2021, 03:55:35 PM
Ther 1981 TZ250H was the first countr-rotating TZ engine
Yes, among the twins. But as far as i know, the 750 had a layshaft between transmission and crankshaft, so 4 shafts in total. And had opposite crankshaft rotation than RD and TZ twins.
Hmmm :science: :pop:
Correct, 750 motors run backwards.
I want to say that originally only the OW31 works motors had TZ350g (3g3 casting) 6 port but I read somewhere that they were standard on later monoshock production bikes. 409-70 and 409-71 share the same RD type 4 transfer ports plus boost port. Not sure what the later 6 port barrel casting number is but they may have been used on E and F models, but I have zero experience or documentation on those. If someone has a set of those or E/F parts book, that would be interesting.
According to the parts books 409-71 (4 ports) was introduced on the D model in production December 1976, so a 77 model as we would know them.
On a twin the intake port becomes imprinted on the piston skirt. OK for low mileages and race motors that are often apart, but not ideal for a daily driver.
But enough about part numbers, What is the project and when do we get to see a progress report?
If it's even half as good as your last one, it should be fantastic.
Honestly I've been watching this forum because of this.
Quote from: teazer on June 18, 2021, 12:19:26 PM
But enough about part numbers, What is the project and when do we get to see a progress report?
If it's even half as good as your last one, it should be fantastic.
I'm going to keep you in suspense for awhile but I'll post more pics once I pick up the rest of it. It's going to be a major undertaking but should be really cool. I will tell you this much, the motor will be pretty much the same as my other one except for the pipes. I talked to Gary Braun (Retrodyne) about making them for me this time.
:clap: finally, something to wrap our imagination around! Thanks Joe
Part 2
now we're talking. :whoop: :bacon:
Hi Joe,I have a sneaking suspesion you turning cyl-180 deg around so exhaust is to rear and carbs up front ,that would be better for piston life but hard to fit in front, amI close Joe
Quote from: preben54 on June 29, 2021, 10:17:01 AM
Hi Joe,I have a sneaking suspesion you turning cyl-180 deg around so exhaust is to rear and carbs up front ,that would be better for piston life but hard to fit in front, amI close Joe
I haven't put that much thought into it yet but now that you mention it.............................
Is that an FZR400 chassis Joe? Nice choice!! I like where your going!! I wouldn't go reverse cyl.. it's never proven to increase hp on our RD based case engines, TT saw it tried several times with guys using his cylinders and neither ever went faster. One of the reasons thought is that the later reverse cyl TZ's also had the crank rotating the opposite direction which may have aided the rev cyl intake flow, I've looked at it before but proper pipe length is an issue, and carb clearance and issues ect..
.
Rearward exhaust port sure makes packaging nice though.
It's never been preferred by OEM's because it's much easier to making a function airbox in the middle of the frame, where the intake is inherently protected.
I accidentally quoted myself somehow.
Quote from: EE on June 29, 2021, 12:18:46 PM
Is that an FZR400 chassis Joe? Nice choice!! I like where your going!! I wouldn't go reverse cyl.. it's never proven to increase hp on our RD based case engines, TT saw it tried several times with guys using his cylinders and neither ever went faster. One of the reasons thought is that the later reverse cyl TZ's also had the crank rotating the opposite direction which may have aided the rev cyl intake flow, I've looked at it before but proper pipe length is an issue, and carb clearance and issues ect..
.
Yes, it's an FZR400 chassis.........................as for the reverse cylinder idea, I don't really like how it looks anyway, so most likely NOT an option.
I'll be following this project! Nice choice Joe.
Excellent choice. We have an FZR in the garage. It sounds big and mean but only makes about the same HP as our RZ350.
Didn't Yamaha go to reverse cylinders specifically to reduce piston wear with large intake ports on the 250 models which ended up with huge intakes?
It's hard to get the pipes looking good on our old downward pointing exhaust ports. I had a set from a Kart motor years ago but they could not be fitted to a bike as you can see. On the reverse cylinder models, the exhaust ports are completely different exit angles.
I never thought about the angled exhaust ports. I won't be doing that anyway. Don't like the looks at all.
Not to sidetrack your thread Joe.. in 81 Yamaha reversed crankshaft rotation to allow for the still piston ported 250's growingly huge intake ports, by 85 they were on to case reedvalves so it wasn't an issue anymore by the time they got to the reverse cyl model in 88-90.
EE's right. Yamaha had issues with piston life on the 250G with it's cavernous intake ports.
Just thinking out loud, but since we are now off topic, might I suggest an RZ motor in that frame with say a stroker crank and CPI cylinder for about twice as much power as a TZ top end. :whistle:
Quote from: teazer on June 30, 2021, 09:48:37 AM
EE's right. Yamaha had issues with piston life on the 250G with it's cavernous intake ports.
Just thinking out loud, but since we are now off topic, might I suggest an RZ motor in that frame with say a stroker crank and CPI cylinder for about twice as much power as a TZ top end. :whistle:
Sounds like fun but I've already got the TZ top end and I've got an LC bottom end on the way to use with it. But....................mounting will be the same so I could always change my mind when I get to that point of completion. :metal:
I like the TZ route. CPI's have been so done..and redone..
:agree: stay the course
I know not feasible.. but, could re-line add intake bridge? just spitballing.
The problem wasn't the intake port size just look at the Portmap. The problem was the short skirt length and piston tech back then, Yamaha pistons were like teacups.. Joe I believe is running forged pistons he should be fine.. even if he replaces pistons slightly more often fun factory outweighs it to me. If his cyl needs a replate he could look at other single ring piston options before the replate n hone but I'd just run a good forged piston.
got it. not being familiar with it is why i asked makes sense.
It's not a bad idea mark just a lot of work for an arguable gain here. CPI runs a bridged cyl Reed intake BUT I think they gave up boost port efficiency by doing it because they bridged the boost port as well.. Honda is a great example of nicely shaped large cyl Reed intakes with an attached open boost port. Now if it were a piston port cyl I'd say yeah bridge it.
thanks for the explanation Ed. :clap:
Part 3
Cool!
Just for conversation, can you run a stroked RZ/Banshee crank in that bottom end?
I have an assortment of cylinder base spacers I will donate to anyone who wants them for the cost of shipping. 1.7, 2.0, 4.75, 6.7 mm thicknesses.
Mark
PM sent
Hey! I have a reinforced swing arm for that frame over in the for sale section!
Quote from: peaky on December 01, 2021, 09:29:34 PM
Hey! I have a reinforced swing arm for that frame over in the for sale section!
I saw that. I'm Thinking about buying it.