ESE's works engine tuner

[FastFred]

... has anyone installed roller bearings on the banshee style crankshaft that originally used ballbearings?

Look at the Yamaha TZ's from the 70's they have a similar (cruder) crank to the RZ, the TZ used roller brgs on the outside and ball races for the inner two brgs, some factory race bikes I think used rollers all round. The outer roller TZ brgs had brass cages and groves on the outside of the race which were located by half circlips to keep the outer shell in the right place. The inner ball brgs had plastic cages and there was a labyrinth seal between them and half clips each side between the seal and brg, these located the crank central in the crankcase. All the brgs had little dowels to stop them spinning in the case, all the half circlip groves were in the bottom case half.

I have seen TeeZee grove std roller brg outer shells by spinning them in a lathe and using a 4" angle grinder and a very thin cutoff blade.

Road RD cases were converted to racing TZ ones by mounting the lower case against a lathe face plate and with a suitable parting tool in the end of a boring bar. TeeZee would swing the lower crankcase half back and forth by hand and carefully wind the the cross slide in to cut a very nice half circlip grove. To stop the brgs spinning in the cases he cut a second set of smaller half circlip groves for pieces of 1.5mm O ring, these griped the brg and held it firmly enough to stop the outer race spinning.

There you are, some of the best kept race prep secrets from the 70's.

If you ask me very nicely I will tell you what he did to TZ cylinders to make them Fast Reliable and above all, Easy to Ride without that all or nothing light switch effect out that of the box TZ's were known for.

[peewee]

hey wob the only thing i find on the nj305EW is its just a nj305 with one piece steel cage. maybe theres a missing letter. nj305EWN perhaps ? the letters EW seem to be specific to NSk but im not finding a nj305EW with clip groove on their site.

[wobbly]

Ive got plenty of them, send a PM.

[peewee]

If you ask me very nicely I will tell you what he did to TZ cylinders to make them Fast Reliable and above all, Easy to Ride without the light switch effect out of the box TZ's were known for.

i wouldnt mind some more info on that crankshaft in the pic . never seen one like that before

[FastFred]

i wouldnt mind some more info on that crankshaft in the pic . never seen one like that before

Google TZ350 crank

TZ cranks are old technology dating from the very beginning of racing 2T's, and invariably cracked and/or spread the big end pin holes. RZ cranks with their forged pins are much better ...

[Dutch Fisher]

Calculated, 1 cylinder. Two cylinders with 90° combustion separation run much smoother. With 180° separation they only sound smoother but the torque fluctuation is almost as bad as in a single.
Attachment 310115Attachment 310116Attachment 310117Attachment 310118

Calculated ! I'm intrigued

If you don't mind a bit of peer review Frits, pls feel free to publish your variables and their values.

[Frits Overmars]

Pete used to tap the original pin into the piston so it didn't interfere with the ring and then drill another hole in the new position and insert a pin he'd retrieved from an old piston. You just have to make a hole with the desired press fit for the pin, OR, do like others do and press it in from on top into a 2nd larger hole below the ring land and bend the end of the pin so it can't come out. Depending on the method you will need to get the right rings.

Pressing the pin in from above and then bending the lower end is the tried-and-trusted Yamaha method. But it requires a rather soft steel for the pin, or the bending force might cause loss of press fit in the vertical bore.


Emot recently developed a variation on the theme: the pin is pressed in from above, after which the top of the vertical bore is closed by welding.

[husaberg]

Google TZ350 crank

TZ cranks are old technology dating from the very beginning of racing 2T's, and invariably cracked and/or spread the big end pin holes. RZ cranks with their forged pins are much better ...

Best place to see the TZ and RD crank stuff is here I have posted it before. Wob has mentioned before the old RD cranks are better balanced that the later stuff.
Certainly more rebuildable that the LC stuff to. They do also have different bore centres.
http://www.t20suzuki.com/racing.htm#TZcrank.
this is interesting
http://www.2strokeworld.com/forum/in...?topic=3262.15

[Frits Overmars]

looking at the B port/passage, it just gets me wondering if the complex twisting of the passage is a product of having to work around the existing crankcase stud spacing pattern. The cylinder entry is strongly influenced by the casting wall thickness surrounding the ring spanner clearance for the cylinder nut. The final entry to the cylinder is in fact almost on the stud centre....Is it time to review the traditional stud spacing and number thereof?

I think so, Ken. Stud spacing is the very last thing that should be established when designing a cylinder.

Funnily enough, if one duplicated the exhaust port plan over the suggested B & the C ports, it would start to look like another scavenging system. Frits, I am sure that this must give you a warm and fossy feeling. NOTE: fossy is probably Kiwi for fuzzy.

A warm and fossy feeling as in wetting your pants?
Anyway, duplicating the exhaust plan reminds me of a cylinder constructed by a certain Ken Seeber...

[fatbastd]

Minor additions to the TZ crank discussion above: the crank pictured (not in the cases) is a 350G - male thread on the ignition end, which removed the problems associated with the female thread being very close to the rotor keyway, sometimes resulting in the end of the crank braking off...

The TZ250/350 cases of that generation also had rubber forward engine mounts, which th RD's did not.

Standing by, FastFee, for your words of wisdom on how to make an old TZ 'fast and reliable' and 'easy to ride'. The 6 port 350 F/G cylinders (no reed valves) were much better in both these respects than the the twinshock sh!tters that I suspect TeeZee was fiddling with..

Ling the dream..living in the past!

[wobbly]

Another thing to add on the RD/TZ cranks is that the aftermarket RZ cranks that are rebuildable can easily be made to fit into
the TZ cases, with some web machining and an offset retaining clip.
Even the 115 long rods will fit to increase the case volume.

[twotempi]

Pressing the pin in from above and then bending the lower end is the tried-and-trusted Yamaha method. But it requires a rather soft steel for the pin, or the bending force might cause loss of press fit in the vertical bore.


Emot recently developed a variation on the theme: the pin is pressed in from above, after which the top of the vertical bore is closed by welding.

I have relocated pins without problems. I used the same method as EMOT. Just ensure that the top end of the pin is 1- 2 mm below the piston crown.

The pin was a needle 1.5mm dia out of a little end bearing into a 1.45mm ish hole. You may need to use a mill file to dress off the outside of the piston at the position of the pin after fitting the pin .

[Frits Overmars]

The pin was a needle 1.5mm dia out of a little end bearing.

No need to demolish bearings or old pistons in order to obtain pins. One piano or guitar string will provide you with hundreds of pins in any diameter you want.

[peewee]

heres my next question. the yamaha bearings use a small nub on the circumference of the bearing to keep it from spinning. most aftermarket cranks use a oringed bearing to accomplish the same. if roller bearings with a clip in the lower case half are used instead of ballbearings, will the clip and clamping pressure of the cases be enough to keep the bearing from spinning or would each bearing need a clip and a oring ? all my experience has been with single cylinders that use interference fit of the bearing and case. these horizontaly split cases are new to me

[wobbly]

Simple answer is that its easy to fit the clip in the lower half, and a cut O ring piece in the top - problem solved.
Its not so much outer race rotation, its the case fretting caused by cranks that are not dead true that cause all the problems.
If you are not under 0.015mm on all the bearing journals then the crank is a shitter, and should not be used in a race engine.
Over 90% of RD/RZ cases are shagged on the main tunnels due to ( shop ) wankers rebuilding the cranks.
Now you know why Honda refused to sell crank parts for two strokes.