'84 Tecate Crank Stuffing and Rebuild w/ pics

[barnett468]

I have not seen it done that way before. I can't see it well but it looks like there are some lines going in both directions near the crankcase. It almost looks like knurling in stead of directinal wedges. Wonder why they only put it on one crank half.

[atc007]

Wow Mik.. I have seen a lot of "Turbo Whirling" we called it around here lol. MUCH Like Bens. YOURS,,,,,WOW, That thing would damn near diesel itself for 6 revolutions on it's own once up to RPM. That thing is just,wow. Are you sure they don't have that crank interlocked with another set of gears down in there!! lol. I honestly don't see any advantage to that deal lol. Pretty cool though. Great thread 81 R !

[MIK6]

I dont know how it works either.. lol
im not a motor builder, never claimed to be. I wish someone could tell me more about it..
All I can say is that it runs good! Alot if people have ridden that trike shes definitely a runner! Most guys that hace ridden it cant believe the Rs it turns, another member at TF said hed never ridden a trike that likes to be held wide open and shifted w/o lifting like it does.
I picked that crank up w a new rod pressed in for $50 and a rod kit. So I figured id have more than that into rebuilding my crank. And I didnt have shop turnaround time. If it works I am all set, if not id rebuildtmy stock crank and swap it on next rebuild.
so far the only downfall has been low end lugging thru trails.. but w all the miles I have on that old T3 im use to that! Lmao

[barnett468]

Wow Mik.. I have seen a lot of "Turbo Whirling" we called it around here lol. MUCH Like Bens. YOURS,,,,,WOW, That thing would damn near diesel itself for 6 revolutions on it's own once up to RPM.

The first one I saw in 76 was about half as deep as Mk's dual saw blade model but it was all away across on both halves.

Since the transfer ports are on the outer parts of the crank i would think that if anything at least do it there. Perhaps mk's turbo fins are actually connecting rod coiling fins?

Inner piston cooling fins?

An additional gear for the trans?

Certainly looks nasty and pretty cool to me at the very least.

[just ben]

I have not seen it done that way before. I can't see it well but it looks like there are some lines going in both directions near the crankcase. It almost looks like knurling in stead of directinal wedges. Wonder why they only put it on one crank half.

all the lines go the same way, looks like knurling but without the crossed lines. It is done on both halves but the lines aren't as deep on one half.I have seen several done this way and was the only way I have seen it done until I seen mikes pic.

[barnett468]

Here's 2 photos in the link below of a totally different approach to turbo veining. It is done on mini 2 stroke engines designed for rc toys etc.

http://www.beatyourtruck.com/prodreview-SUREFIRE32.html

http://www.scooterinvasion.net/forum...6f89cf9300f007

[Xowner]

This is another version of the turbo crank

[JasonB]

really interesting thread, this is all new info for me. I went through the crank stuffing idea with the 250/500 honda motors. I have seen people swear up and down that putting a big bore top end on a 250r bottom end merritts pulling the tin cans off the crank to increase crank case volume for better operation. I have seen people swear that removing those will increase turbulence in the cases and decrease power. Interesting concept overall, nice work with the install of your nylon filler thanks for the detailed write up on your work. pretty neat

[El Camexican]

It's hard to see but both crank halves are veined but they are alot smaller on the one half.Also a pic of the aluminum slugs in the crank.I tried to show how the rod is modified also.Attachment 185020Attachment 185021Attachment 185022Attachment 185023

That crank looks like it is meant to give the throws more surface area to pick up pooled oil and throw it back up to where it could drip into the crank bearing holes. Never heard of that before, but what else could it be?

[just ben]

That crank looks like it is meant to give the throws more surface area to pick up pooled oil and throw it back up to where it could drip into the crank bearing holes. Never heard of that before, but what else could it be?

I was thinking mik6's looked more like oil slingers. Although I am 98% sure who the engine builder was there is NO way to contact him to pick his brain for the reasons they modded these engines the way they did.

[El Camexican]

I was thinking mik6's looked more like oil slingers. Although I am 98% sure who the engine builder was there is NO way to contact him to pick his brain for the reasons they modded these engines the way they did.

I’ve seen photos of one like Mik6’s before (I don’t remember where) and seem to recall reading that the idea was that you got a lighter crank that created more turbulence in the cases. I guess if you were curious enough you could send a photo to these guys http://www.faliconcranks.com/ and ask them if they might know what the theory behind yours is. As far as I know Falicon is the be all end all of motorcycle cranks (at least for 4cyl engines) and they’ve got some guys working there that have been around a long time.

I typed “2-stroke turbo crankshaft” into Google images and a lot of wild looking cranks come up, but nothing like yours, thats a keeper!

[just ben]

I know Raffa's 490 was/is running a crank that looks just like mine. I'm sure there is a build thread on here for that bike maybe there is a pic showing the crank. I have also seen this in a air cooled R engine.

[barnett468]

Just found the following online, thought it might be interesting for some.


“I've been going back to some old Dirtwheels mags and came across an interesting article on a Factory Honda 250r for Stadium cross... Dean Sundahls Atc. Anyway, here's what was interesting:


Excerpt from article in Dirt Wheels, Oct 1982."

"...after the crankcases are matched, RPM (Racing Products for Motocross in Toledo Ohio) cuts a small boost port into the front transfers. This allows the fuel/air charge to start its trip to the top a little sooner..."

The crankshaft receives RPM's unique "turbo" modification. The crank is full-circled, stuffed, and balanced. With this balancing, the 250r counter balancer can be removed, allowing the engine to rev move freely because it has less weight to turn."

Special "veining" is then cut into the outer circumference of the flywheels. This machining, when used with the small boost port (from above) cut into the cases, actually forces the charge into the transfer ports and up to the combustion chamber, giving the engine a sort of "two-stroke turbo" effect, as well as fully atomizing the fuel/air mix for better burn. This is the most expensive mod done by RPM, as well as, being an exclusive in the engine-building field."



CYLINDER HEAD “TURBO” CUTTING

“Trinity tried to think outside the box for a while with cranks and their heads as well.....They still to this day turbo cut the head. I have a head on my bench that is an early model done by JD i believe when they were doing the R&D.

In THEORY it was to create a funnel reaction that would focus the fuel to the spark plug.....Notice how the cuts turn and angle to the plug. Trinity still does this I believe but they have perfected it by using the CNC or another type of non-human method.”

[TecateDan]

This is good as I'm just about to build a new motor for my tecate.

[81Rmachine]

x

Well, it sounds to me, that for any age, you are an extremely sharp guy that thinks about a lot of different angles/possibilities and knows a lot of stuff. Considering you think this way and know so much, at what an old guy would consider a "young" age, I think you should do very well.

Thank you for the kind words, I sure appreciate it! I try to do as much R&D and flow testing as the boss will possibly let me get away with, but in reality you have to get engines out the door to make money. I have a passion for 2-strokes even more so and being able to talk with gurus such as the guys in this thread is very interesting to me!

atc007, Thanks, Im sure glad this thread got the attention I was hoping for. Anytime you post some of your own work on a forum you always suspect some criticism which is expected and constructive criticism, such as it all has been so far, can be very helpful. Of course some other forums are full of guys that just love to tear your work apart and I'm glad to be able to talk with you guys who are open minded and were around when they were actually making 3-wheelers yet and not too young like me LOL! This thread has been full of interesting pics and I've learned alot already so thanks to everyone who has contributed and KEEP POSTING!!