Author Topic: RD350 Track Bike build  (Read 45777 times)

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Offline Drehmoment

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Re: RD350 Track Bike build
« Reply #450 on: October 18, 2021, 05:30:47 PM »

Yes, I think that was Gordon Jones' comment.  I think he mean't the TZ and Aircooled RD Cranks will all fit.  As you say, the LC is too long at the waterpump drive.


Ok, that makes sense. Thanks for clarifying.

I am currently rebuilding my RD 250 which I raced about 15 years ago. And now got it working for my first race in years, but unfortunately ruined the engine with my stupidity. ( I did only open one petcock before entering the track for practice)

Now I look into some options for the rebuild and have some questions.

Would you mind posting them here or should i create a new thread?

Here is my german thread on the bike rebuild: http://caferacer-forum.de/viewtopic.php?t=29875


Offline 5port

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Re: RD350 Track Bike build
« Reply #451 on: October 18, 2021, 07:10:05 PM »

I am currently rebuilding my RD 250 which I raced about 15 years ago. And now got it working for my first race in years, but unfortunately ruined the engine with my stupidity. ( I did only open one petcock before entering the track for practice)

Now I look into some options for the rebuild and have some questions.

Would you mind posting them here or should i create a new thread?

Here is my german thread on the bike rebuild: http://caferacer-forum.de/viewtopic.php?t=29875


Can I suggest you go for a new thread on your bike?  I think you will get a better response to your questions about your bike from many people if you ask on a separate thread and, it keeps the subject of the thread less complicated.  ;)
I will certainly try to reply on your thread.  However, specific questions about my RD350 Track Bike are still best on my thread.

Cheers

5port
5port

Offline Drehmoment

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Re: RD350 Track Bike build
« Reply #452 on: October 19, 2021, 12:42:00 PM »
Sounds good to me :)
I will open a new thread.

Offline 5port

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Re: RD350 Track Bike build
« Reply #453 on: November 15, 2021, 09:09:53 AM »
So, here is my recent post about TZ Crankshafts.  I now have an original copy of the 1976 TZ250/350C parts list:  ;)

So, looking at the parts lists, there is obviously some discrepancies in the updated listing of the TZ crankshaft and it's parts.  This is the trouble with updated online lists, you can't always trace the original components.  ???
Looking at the TZ cranks, they are all now listed back to the '72 TD3/TR3 as the 3G2-Y1140-00.  Of course, the 3G2 is the '79 TZ250F and I don't think Yamaha were planning that in '72!  :D
The cranks did change though, not least in the rods, and other specialists do claim different Yamaha TZ250/350 balance, over the years.  ???
The '72 TR350 was model 328 and if you look at the modern parts lists you see the 4 crank webs are still listed as 328 parts, the No1 web is listed as 328-11412-02, the other webs are 422, 432 and 442.  So, that is alright then?  Well sort of but, the last suffix -02 shows the story, these are the 3rd type of those webs!  There was an original -00, then the -01 before the final -02.  Also, the whole crank did have earlier numbers.  Originally, the TR3 crankshaft was the 328-11400-00. There was probably a 383 (TZ350) code crank, possibly a 430 (TZ250) crank but, unfortunately we do not know.  Only the original series of parts lists would show the detail, the updated parts lists only show the final '79 TZ250/350 version.  ???


The '76 partslist shows the crank assy as.. 1H3-11400-00!  :)  Yes, the 1H3 is the TZ250C MTC (Model Type Code) with frame numbers 430, 1H4 is the TZ350C MTC, with frame numbers 383. 
So.. the '76 crank was remodeled as a TZ250C part.  The crank webs were still 328 (TR3) numbers but, with the -01 suffix ( so, 2nd version).
This would tend to indicate that the '76 crank assy was primarily designed for the 250. The partslist shows the same crank fitted to both the TZ250/350C.
Has anyone got an original 1973 TZ250/350A/B partslist to prove the original TZ crank details? 
Cheers

5port
5port

Offline G Jones

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Re: RD350 Track Bike build
« Reply #454 on: November 16, 2021, 12:22:21 PM »
Good luck finding the original parts book for the 1973 TZ250/350A/B....
I can't say for sure how the changes in  parts list formats were handled - but - I am guessing - something like this:
Early 70's were all in paper format.
Late 70's / early 80's paper & microfiche.
(Microfiche libraries included a lot of the early 70's bikes)
I'm guessing now - but at some point after this - the parts lists
would have been fully digitized on to computer disc.
I would also guess - that as many of the earlier parts had been
either dropped or superceded - any parts no longer available would
have had the latest currently available part number used in the parts
list - Yamaha obviously thought it was not relevant to use old numbers
for parts that were in any case not available when they moved to computer
based files.
Most people these days will be using the PDF copies of the "digitized"
"updated" parts lists.
I do have an extensive collection of Microfiche up to mid 80's - but I no longer
have a microfiche reader (other than a small portable unit - not use for years)
It's very rare to need anything more than the widely available parts lists - I do
also have a part number database - which matches numbers to models - so
that helps sometimes.
101322-0
I doubt you'd find anyone disagree that the cranks (of all TZ250/350) were
essentially the same - and probably built / designed originally for TZ250.
The only 250 / 350 specific cranks I have seen are the Hoeckle - which had
different balance holes - whether it matters or made a difference - couldn't
say - I have 2 engines I currently use - one with 250 crank - other with 350
crank - can't say I notice too much difference on the track (both Hoeckle)
The early parts lists (the ones I have access to) did not list a "complete crank"
only the separate flywheels...
101324-1



Offline 5port

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Re: RD350 Track Bike build
« Reply #455 on: November 16, 2021, 03:56:07 PM »
Hi Gordon,
Thanks for your info.  I have an original '76 paper partslist for the TZ250/350C.  I agree with your thoughts about the paper/microfiche and digital list progression, backed-up with what we see to buy sometimes today.
It might not be very important but, I am interested how these cranks changed.  Firstly, we now know that there were 3 listed different versions of the 4 328type webs listed (00, 01 and 02) and that they show those backwards compatible to the TD/TR3, with the 02 type webs and the complete Crank now listed as 3G2. 
We know that there were different versions of rods.
We also know that there were at least 3 different listings for the complete crank, 328 (TR3), 1H3 (TZ250C) and 3G2 (TZ250F).
Without the original TZ250/350A/B parts list, it is not possible to be certain of that early TZ crank but, I am tending to suspect it was the same as the TR3, ie the 328 numbered part, probably still with the 00 webs.    ;)
Cheers

5port
5port

Offline G Jones

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Re: RD350 Track Bike build
« Reply #456 on: November 16, 2021, 04:23:46 PM »
It might not be very important but, I am interested how these cranks changed.  Firstly, we now know that there were 3 listed different versions of the 4 328type webs listed (00, 01 and 02) and that they show those backwards compatible to the TD/TR3, with the 02 type webs and the complete Crank now listed as 3G2. 
Well - I guess it depends what your interest is...
If you have the interest - certainly spend the time - although it will always be difficult due to the number of years that have passed & the changes in format over those years - you could add to that - Yamaha were probably not particularly fastidious in how the bikes were built or in the recording of any relevant data at the time...
I would take a bet - Yamaha never intended these bikes to last more than a few years - in fact - probably not even that long - they were built for winning races - which they did - as soon as they were not capable of winning races - they were effectively abandoned & the next model created.
I guess the factory made a few quid out of spares - but once the numbers dwindled - they moved on...
My only interest is in keeping these bikes running reliably - and improving where we can with small adjustments...
There are several ways to go with the cranks - I think we probably covered that before - there are certainly reliable proven ways to have a good crankshaft - none of them cheap - but I guess that's the nature of our hobby....
Most of the original cranks are worn out now anyway - only suitable as door stops or paperweights...

Offline DaveHunter

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Re: RD350 Track Bike build
« Reply #457 on: December 26, 2021, 11:12:14 PM »
101546-0
 Great thread 5port, I’ve been reading sections at a time & really enjoying the discussion. Attached is a picture out of the ‘71 product brochure of Yamahas new test track.

Online NivagRD

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Re: RD350 Track Bike build
« Reply #458 on: March 24, 2022, 08:19:08 AM »
Hello 5port, I have enjoyed reading your comprehensive and well written thread whilst recovering from Covid. You have done a lot of detailed research. Re crank balance, have you looked at how other big motorcycle makers have achieved that on 2T race engines with the same bore, stroke and rod length to stroke ratio? 
I look forward to further updates to you thread as the bike evolves. Best, Gavin
1973 LS2, 1980 RD200DX, 2019 CB650R.

Offline 5port

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Re: RD350 Track Bike build
« Reply #459 on: March 25, 2022, 09:01:08 AM »
Hi Gavin,
Thanks for the positive feedback!   :)
The RD crank balance subject is, I think, sorted.  The trouble is that although the principles are understood, it still requires some experiment to get the solution that you want with rebalancing the 2R8 crank.  Unfortunately, experiment is not cheap.  ??? 
Overall, the RD and TZ250/350 situation is also sorted really, the road RD's will continue with rebuilt cranks for years.  Racing TZ's have already moved-on to new-built cranks as many of the original race cranks are now rebuilt to death. The RD/TZ re-engineered version is great and will be used as long as good RD Lead balanced cranks are available for modification to TZ copy.
Unfortunately, the 2R8 rebalance to 350 hi-rev standard seems to be a niche problem.  I certainly believe that I know what needs to be done but, it would need a fair bit of money to prove.  I estimate around £700 at least and, it is unproven. For that money you can have a proven RD/TZ crank.
The specifics of the 2R8 re balance are 2 options.  First option is extra lightening holes.  Unfortunately, the standard 2R8 holes are not in a perfect position for simply recreating a TZ balance so, this would be experiment.  Second option is use of tungsten balance weights.  These would be fitted opposite the crankpins. Unfortunately, this would also be experiment and, the overall crank weight would be increased a little.
For me, I would like to try the simple lightening hole mods on a 2R8. I have tried to find the most cost effective tuning on the whole project.  Of course, this is not hugely expensive in racing terms but, all the £££ jobs soon add up to a ££,£££ bike!

Cheers

5port       
5port

Offline 5port

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Re: RD350 Track Bike build
« Reply #460 on: April 03, 2022, 04:38:53 PM »
Hi everyone,
I managed to get a brake disc cut down for my front brake.  The width of the braking surface has been reduced to 5.5mm from the 7mm original.  This is a weight reduction measure and, the thinning has taken off over 400g, nearly a pound.  This makes a useful reduction to overall weight, a good reduction to front unsprung weight and a reduction of rotating mass. 
I know that further gains would be possible with a modern high-spec brake but, this is my attempt to optimise the original part.  So, a useful gain.  :)
Cheers

5port
     
5port

Offline german

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Re: RD350 Track Bike build
« Reply #461 on: April 03, 2022, 09:38:05 PM »
Hi Chris,
these 400gr lost on the brake disc are more to feel as 5kg on the whole bike. We even go down to 5mm on the disc.
Regards Uwe
Classic Racers do not hide the ashes, they keep the fire burning
Yamaha DS7, RD250, RD400, Yapol TZ250B, Daspa TZ350, TZ250A, FZ750/1000, Honda RS125, Jackson Special 250, Höpfner-TD3, Hejira TM250, Siroko TZ250, Tomic 200, Bakker TZ350B