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Old 10-04-2007, 08:27 AM   #31
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I think a better investment over a modded motor is to learn how to drive! If you can cut consistent lap times and make the show (AMain) on a regular basis then your ready to take it to the next level.

Most all of the fast guys I know go fast on stock motors, master that and you can justify the additional cost of a mod. If your not in contention to win at the end of the day then whats the point in buying a mod to go faster or run longer?

At club races and even state series races I have seen good drivers take a stock motor and even tune it a little fat and still lap the field.

If your not a good wheelman then buying the $400 mod motor is just a novelty! Buy a stock motor and take the money you saved and buy clutches, tires and fuel and go practice more!
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Old 10-04-2007, 11:28 AM   #32
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Originally Posted by HookaMega View Post
I think a better investment over a modded motor is to learn how to drive! If you can cut consistent lap times and make the show (AMain) on a regular basis then your ready to take it to the next level.

Most all of the fast guys I know go fast on stock motors, master that and you can justify the additional cost of a mod. If your not in contention to win at the end of the day then whats the point in buying a mod to go faster or run longer?

At club races and even state series races I have seen good drivers take a stock motor and even tune it a little fat and still lap the field.

If your not a good wheelman then buying the $400 mod motor is just a novelty! Buy a stock motor and take the money you saved and buy clutches, tires and fuel and go practice more!
i agree, also if you spean alot of money on a race engine i would also invest into a elcheapo good engine to club race with. (thundertiger pro 21b-r, novarossi 21 bf, os vg, rb s3II ,dynamite platinum......) to get more practical runs in and to get cleaner lap times. would also reduce engine wear on the more expensive engine.
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Old 10-04-2007, 12:02 PM   #33
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yeah most mid range engines can be ran for about 10 gallons before they need a new piston and sleeve. thats a lot of racing! ok, they won't go as well, but they will still go pretty good.
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Old 10-04-2007, 02:47 PM   #34
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Good point. Rotax (Karting) motors are a little more refined out of the box than most nitro motors I have taken apart.

I am guilty of the heavy throttle finger more often than not, despite what I think is an incredible pipe / engine / clutch combo from the beginning.

Here is another thing to keep in mind, IF you do decide to have a motor sent in for modification, pick one of the companies that has a dyno rig, flow bench etc. Technology behind the theory so to speak.

I personally have had a motor modded by a reputable individual, and it was terrible. Having taken it apart and compared with the motor my friend got from him there was a great deal of variance (due to the hand modding process) between them on the porting and crankwork. I suppose thats what you get when something that has to be done so precisely is done with a $3 metal file / dremel rather than a CNC or at least a jig to make them consistent.

BTW I am not flaming anyone, just adding in my input, given that I have been touched by this debate. there is a lot of good information in this thread.. both for and against.
I have to disagree with you regarding you said the Rotax Motor is more refine out of the box. I have been racing rotaxmax since 2003 and I have seen many motor had botton end problem, the rotax is no where near as reliable as any .12 and .21 engine I ever owned. The 2006/2007 rotax motor are better, but it still has its fair share of problem ( plastic gear broke on a new motor with 2 hours )

I have a few mod motors and all of them tune as easy as any stocker and my current JP B5 is no exception.
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Old 10-08-2007, 12:53 AM   #35
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Default Depends on the mod

If you do a little flow work and balance work on a motor it makes it more tractable and easier to drive in my opinion. Most mod motors you see on the market are just mildly ported and balanced. I say they are more tractable because by smoothing out the flow you also eliminate peaks and valleys in the power output. A good mod will also have much better balance and less friction in the crank assembly. This gets you two advantages. A well balanced motor will last longer given proper care. Less vibration means the top and bottom of the rod will stay rounder longer and also won't make the tolerances bigger in the crank bearings by hammering them thousands of times a minute with uneven forces. Keeping everything nice and lined up without slop. However having said this if you are thinking about buying a modded motor just because you think the added power will put you on the top step of the podium you are barking up the wrong tree. As one of the other posters said you'll gain much more by learning to drive with more finesse and throttle control. A mod motor is useful after you get those skills because its more predictable and that allows you to even get more precise with your driving. I do have some experience with the what I call 'full modded' nitro motors having used them in top fuel and extreme class dragsters. The sleaves of those motors look like a tree trunk they have so many cuts in them. Different head buttons. Shaved backplates to cut down on friction. Taking one of the balls out of each crank bearing to get less friction and precision fitting the crank to the bearings so its not too tight and not too loose. Going as far as taking a pair of tweezsers and pulling the coil of the glowplug down towards the exhaust port to get more power. All of which is totally useless on dirt as the power is too abrupt. Nothing wrong with modded motors but like most things they have their place.

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