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Art, i assume you know that when an engine blows up in the lower end that it needs to be trued if the crank is out of alignment. I think what he means by its better then factory is that its in the minium set requirements. I saw one guy not true his crank after a lower end, and lets say this, it blew up a lot more.
Marc:
I didnt think of the bottom end problem, but most of the time wouldn’t the crank need to be replaced anyway, so why the need for machining? I don’t think I would trust a crank to turn 14000+ after it had went through a bottom end failure.
I don’t want it to look like I am singling out this kart or driver or machine shop. I just wanted to know if machining box stock motors is the norm or the exception before I buy something. I would rather go with the ultra fast shifters, but the budget won’t let me. The budget will let me run a box stock class, if this actually is one.Art
You cannot machine the crankshaft on any TAG engine and be legal. It is common to rebuild the crankshaft with a new rod, crank pin and bearing. Then the crank is reassembled and trued. Most factory cranks are trued to within .001″ runout, we try to true cranks to .0003″.
Blink:
That answers part of my questions. Thanks. The rest of my questions will come out in time.Couldberacin,
I see the concern you have about our class, and your right, it most definetly is a STOCK class. I didn’t think about it when i posted that my crank had been trued to run within 1/4 thou. Marc is right; I did a bottom end rebuild after blowing the main bearings and replaced the rod bearing and pin, main bearings and case seals. When the crank was reassembled, my motor builder was able to true the crank within a 1/4 of a thou. which turns out to be better than stock. There was no “machining” to the crank to achieve this runout, it was simply a replacement of broken parts with OEM parts.
Hope this clears it up for you and we’d love to have you racing here in CO!What are the pros/cons between the Sonik and Leopard motors? The sonik looks like is a much quicker motor, and Im thinking about switching over.
@streets2trackracer wrote:
What are the pros/cons between the Sonik and Leopard motors? The sonik looks like is a much quicker motor, and Im thinking about switching over.
I don’t run a sonik, so I don’t have any personal experience with them but they do seem to blow up “quicker” 😉
Art,
I love my Sonik. It twists fast, has low end power and is easy to tune. I have had a problem with my chain getting to tight and ruining the bottom end. Once I started using the proper chain lube, This probelm went away. So far, I have had no problems this whole year. The motors are great for a “heavy” (185lb.+) driver.
$.02 worth.
JimI’d be interested in switching over if i knew the Sonik was pretty reliable. How many hours do you get between rebuilds? Would it be that big of a difference to me (i weigh 150lbs)? Just want something that can compete at IMI, as well as Bandi….as it seems Rotaxes win at IMI pretty much regardless.
I go about 6-9 hours before I do a top end on my Sonik. As for the bottom end, I won’t go past 400 miles because it let go once at 560 miles. It took me a few bills before I got the hang of it but now it is just as reliable as any other engine along as you take care of it like you would change the oil on your car.
Dane, you wouldn’t be talking about me now would you? 😆
I thought that the TAG rules were no mods on engines all u have to do is take it out of the box and bolt it on but it sounds like to me that people/ teams have been blue printing their engines to perfect factory specs or even better than perfect factory specs. Thats a shame because i got a TAG kart so i could just race so i didnt have to worry about sending off my engine to get it blue printed and spending $ on the engine.
correct me if im wrong
Kyle,
Your not wrong in the sense that the TaG class is a stock class. This is still true. Modifications are NOT allowed, but when something happens to your engine like blowing the bottom end then there is a need to rebuild it (with OEM parts, not aftermarket bearings, etc…). You have to disassemble the crank to replace a rod bearing and put it back together (as in my case). It is impossible to return the crank back to that exact spec that it came from the factory with after you reassemble it. You simply want the crank to run as true as possible. Making a crank run true has nothing to do with modifications, there is no modifying involved, it is just rebuilding it so it doesn’t wobble and come apart at 18,000 rpm. Wobble could also blow your main bearings again and you’d have to start the whole process over again.TaG shouldn’t be about which engines faster, it should be about driving skill and chassis tuning. Just my .2 cents.
Blueprinted motors and drivers should be DQed regardless of the excuse. TaG is driver and chassis, making it more expensive will kill the class. BTW you do have to true a crank when they blow, you just cant modify it.
TaG is about driving skill Ben. That’s why your leopard has to weigh in at 355 lbs and my Sonik weighs in at 375 lbs. Sanctioning bodies with alot more info and skills than we could ever muster have dynoed all the TaG engines and made weight adjustments accordingly. In my mind, all the engines in the class are equals at the end of the day because the higher HP engines carry more weight and the lower HP engines carry a little less.
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