'84 Tecate Crank Stuffing and Rebuild w/ pics

[MIK6]

My 87 has a sprock 300 topend and a turbo cut crank.. its an animal on the top end!
w the weight reduction it is harder to ride on the lowend, got to keep the Rs up. But I have never been on a trike that likes to be held wide open like it does! When im running thru the gears I dont lift!

[just ben]

My 87 has a sprock 300 topend and a turbo cut crank.. its an animal on the top end!
w the weight reduction it is harder to ride on the lowend, got to keep the Rs up.

That's the silly little kx flywheel that you run LOL. I got rid of my kx ignitions because of that. I still have a motoplat that uses an even smaller flywheel but It will be used on the engine with the modded crank. since it only has a 60.5mm stroke it should work better than it did on a stock engine. I hope anyway

[xrider]

RPM out of Toledo used to stuff cranks back in the 80's. They were known for their "Turbo Cranks". There is a dirtwheels project 82 250r where they had RPM balance and stuff the crank and perform the turbo modifications.

Ben, thats pretty interesting, I wasn't aware anyone did any stuffing before dirt bikes had it done factory except for old vintage sleds I guess.
Well I just got it running here this past weekend, and I can say it did make a noticeable difference. It didn't seem to make any difference in the lower end, I can lug it and it pulls just as hard as it did before, no worse, no better, but it made a pretty positive difference on the upper end. This engine didn't exactly have a light switch powerband from the factory, It pretty much surged into the powerband like a good powervalve engine does. Now it gets up to the powerband and really hits, I like it alot, It makes it so much more exciting to ride. Its not that its peaky or all top end like alot of engines are with abrupt powerbands, it just gained enough on top that when it does hit the powerband it pulls that much harder and makes it feel more like hitting a switch.
In conclusion, I would definitely recommend it! If you have the time and the ambition go ahead and try it for yourself, I had very good results from it and had fun building the engine, It was a learning experience! I'll have to get some vids of it soon and post them if anyone is interested, Nick.

[81Rmachine]

barnett468, Thanks for posting those links. I've heard of "turbo veining" just haven't heard it called that until now and honestly when I heard someone mention it I had to laugh at the idea, I guess the only thing I could see it doing is creating windage in the crancase. Those works bike pics had me wondering why they spent so much time polishing connecting rods. On a 4 stroke V8, just for example, rod failures are fairly common compared to motorcycles and the two main reasons for polishing or the term I'm more familiar with is "beaming" rods, is that it removes any stress risers to eliminate the formation of cracks, and it reduces crankcase windage by reducing wind resistance and by shedding oil from the rod. However any rod failure I've seen at work happens at the big end of a rod with through bolts instead of cap screws and on an application requiring a less than adequate rod by rules and even in that application we dont polish any rods as it wouldn't keep the rod from breaking at the big end anyway. Motorcycle engines are just a bit different, especially 2-strokes. While 4 strokes benefit from running a vacuum pump or a dry sump oil system that pulls vacuum on the crankcase a 2-stroke is pressurizing air for the induction phase. I can't say I've ever seen a 1-piece motorcycle rod ever break either. Seems like alot of work for nothing. Its kind of funny how much theory has changed in engine building. I have a friend that builds factory Arctic Cat Snocross engines and im sure if veining worked they would be doing it.

[barnett468]

Hello 81Rmachine;


I figured you were a car guy after reading your first post. I’ve done a lot of old Ford 289's, 390's, Boss's, CJ’s and Chev’s, like Z28’s etc., and I too have seen a lot of those 2 piece rods you mentioned, lol. Most guys I know simply shot peen them instead of polish them. I always stuff in ARP cap screws.

You might have heard of the latest fad/technology called “chryo freezing” for engine parts. Below is a link in case you haven’t. I’ve never had it done simply because I buy rods I know will work for my app, like Chinese Eagles, Crowers or of course Carillo’s etc.. I also know very little about the process.

http://www.300below.com/motorsports/


TURBO VEINING – Your “windage” comment brought up something I forgot to mention. The turbulence created by the veining will atomize the fuel better, which as you probably know, makes it burn better which creates a more powerful explosion in the combustion process which in turns creates more power.

Since as Just Ben mentioned, there is some talk about this process possibly “starving” the rod bearing of oil, if I had a turbo veined bike, I would simply run a rich oil/fuel mix. This will at least help compensate for any potential loss of oil to the bearing created by the veining process.

If one runs at high rpm’s frequently, it would be beneficial to run a rich mix anyway due to the increased rate of oil migration created by the higher rpm’s.


As far as motorcycle rods go you must be young, lol. There were plenty of snapped 2 stroke rods back in the 70’s, especially on the 125’s, and especially on the pro bikes like DG and FMF etc. I have also read several threads about ATC250r’s breaking rods. Not being there, there is no way to tell why. The rod breaking issue seemed to be much less prevalent after the 70’s.

As far as 4 stroke bikes go, yes I too have seen fewer rod failures with them, however [short irrelevant story], while I was at Kawi, Rob Muzzy was testing a Super Bike [1000 cc road race engine] on the dyno. The dyno was 75 feet from me. He spun it up to max rpm at which point it literally shook the concrete floor a little, then after around 20 seconds, it grenaded, which sounded like a bomb going off and I could hear Muzzy mutter some colorful words as he turned and slowly walked away from the carnage.

I don’t remember if Kawi polished the rods on the works bikes. All I can say is that race wins and season championships were their only goal despite the costs back then, so if they simply thought it was added insurance against breakage or that it might gain a rider half a second at the end of a 30 minute race, they would do it irregardless of the cost.

From Steve Wise interview.

“The Daytona 200 - I rode the 1982 200 on a 1981, in-line, four-stroke, while my Honda teammates Freddie Spencer and Mike Baldwin got the new V-4 FWS. That bike [the FWS] was a huge deal because Honda quietly told all of us that it was a true $1 million dollar motorcycle.”

http://www.motorsportretro.com/2010/...ds-steve-wise/

[81Rmachine]

barnett468,
I have heard of cyrofreezing as you mentioned, there seems to be a few companies every year at PRI and IMIS advertising cryogenic freezing for everything from valve guides to, as you mentioned, connecting rods. Mondellos promotes cyro freezing as well as stress relief shaking for any part most specifically blocks because of how much the bores can shift from relieving residual stress. This process is basically a shortcut and perhaps a more effective means of "seasoning" a block from repeated heating cycles as im sure your familiar with. While I was working for Brzezinski's just last year we were contemplating using these processes to eliminate premature guide wear in iron guides near the top from the old non roller stamped rockers required by many circle track rules, but ended up using liners with very good results. I see many different brands of rods with the company im with now. Eagle, Scat, Carrilo, Crower, Oliver, and Callies are a few of them we use in engines all with pretty good success and no freezing.

The turbo cut cranks make much more sense in creating turbulence to promote mixture motion as you mentioned over the theory I was told. Keep in mind I've never seen a crank like this in person, but someone had told me it was to act like a fan and throw air and fuel into the transfers which I didn't buy because the only way that would work is if the air and fuel entered at the center of the crank, which who knows maybe that theory might work on a rotary valve then??

As far as your assumption of me being young... You hit the nail on the head LOL I haven't heard or seen many motorcycle rods break in my lifetime, but then I've only been around since '91! I can see the additional expense for a little added insurance as you mentioned, it certainly can't hurt!

[MIK6]

Here is the only pict of my crank I could find.. I forgot to take before picts.. lol
I added green arrows to point out the cutting..

[MIK6]

I run 40/1 klots in 110 octane fuel.. the motor has 40 or so hours on it mostly wide open.. lol
idk about changing fuel mixture.. she runs great!!
I let anyone that looks at it at TF take it for a rip! Makes me smile to hear what people think of the old girl!

[86T3]

Ben, do you have a pic of your crank? Idk why but i think i remember the veins being much more subtle on ben's crank. I love this thread btw, maybe ill do a little stuffin sin im planning on tearing apart my show motor

[barnett468]

Here is the only pict of my crank I could find.. I forgot to take before picts.. lol
I added green arrows to point out the cutting..

Wow, cool photo. Looks like they only did the inside 1/3rd of the crank. The crank I saw in 76 was done the full width of the flywheel surface. This was before CNC machines or computer operated mills were on virtually every street corner. On the crank I saw, the guy likely cut the crank on a mill with a rotary table. Had to take a long time, lol.

Also, as Just Ben implied, changing the weight of the crank and/or ign flywheel will affect the engines characterics.

I have done quite a bit of this type of testing. In 76, I had a Paul Nyland, pro ported Bultaco 250. The Tacos had two or three different interchangeable bolt on flywheel weights. It came with the heaviest one and I installed the lightest one. Well, it basically gave it the feel of a 125 on steroids with around 50 hp, lol. It would stall easy while braking in gear, and just spun the tire wildly under hard acceleration unless the track was super sticky, in which case, you better hold on to your hats cause you're goin fer a ride.

[barnett468]

barnett468,

I have heard of cyrofreezing as you mentioned, there seems to be a few companies every year at PRI and IMIS advertising cryogenic freezing for everything from valve guides to, as you mentioned, connecting rods.

I wonder how its working for ole' Walt Disney? This might be before your time though, lol.

The turbo cut cranks make much more sense in creating turbulence to promote mixture motion as you mentioned over the theory I was told. Keep in mind I've never seen a crank like this in person, but someone had told me it was to act like a fan and throw air and fuel into the transfers which I didn't buy because the only way that would work is if the air and fuel entered at the center of the crank, which who knows maybe that theory might work on a rotary valve then??

Well, dynos don't lie providing one is using the same dyno under the same weather conditions. Some dynos are in climate controlled rooms. It's very simple to do a back to back test with and without a turbo veined crank.

One could also easily compensate for any difference in perf caused by the different weight of both cranks by simply calculating how much weight they needed and add it to the ignition flywheel in the form of a press on outer ring to the turboed crank eng.

I would love to see this because I love testing and hard "factual" numbers.

I also know from my previous testing, that the biggest dyno numbers are not always going to give the best overall perf. This is easy to see of one watches pro funny cars etc., drag racing on tv. They actually have too much hp, so they have to reduce it some so the car hooks up better. Around 1000 hp per cylinder, insane.

While I was doing the development testing on the 86' T3 prototype at Kawi, one of the tests we did was an ex pipe test. We tested around 4 different ones and we said "not good enough", so the engine engineers went back to the drawing board, made some new pipes, dynoed them and gave them to us. Well, the pipe that had the most mid range on the dyno lost, mainly because it had so much that all it did was spin the tires when it came on the pipe, but it was also a bit short on peak rpm as well.

When we told the engineers that we wanted the pipe with "less" power, they didn't understand why until we explained it. I actually felt bad for them because they worked very hard on these designs and testing and I'm sure they were a bit disappointed to some degree. The consolation for them was that the other new pipe they designed was the one that was used on the production bike.

If one simply installs a bigger Mikuni, and throws away the stock "silencer"/muffler and installs ANY non spark arrester type, the 86 T3 will be WAY faster than it already is for around $100.00 in used parts.

As far as your assumption of me being young... You hit the nail on the head LOL I haven't heard or seen many motorcycle rods break in my lifetime, but then I've only been around since '91! I can see the additional expense for a little added insurance as you mentioned, it certainly can't hurt!

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.

[just ben]

Here is the only pict of my crank I could find.. I forgot to take before picts.. lol
I added green arrows to point out the cutting..

my crank looks nothing like that. I will try to dig up a pic but I have been having issues posting pics lately.

[barnett468]

my crank looks nothing like that. I will try to dig up a pic but I have been having issues posting pics lately.

Hello Just Ben;

I am FAR from a computer expert, however, I think if you turn the photo into a URL and then put [IMG] in front and [/QUOTE] in the back, it should work. Include the “brackets”. I think this MIGHT bypass the systems auto feature, however, I could be very WRONG, lol.

[just ben]

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.

[MIK6]

Wow ben.. that is alot different!
I got a smoking deal on mine, thats why im running it.. lol
I got it w a new rod for less than I could have had a new rod pressed into my crank.