mt pro with obr motor

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lefnut

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i got mt pro with the 30.5 obr motor and just put on belt drive from rcdad and im not liking the power seems real boggy trid messing with the carb but still boggy let me know what to do got abouit six tanks through the engine it still don t come alive until mid range to top end no at all i also got a ddm pipe.
 
Do you have a higher RPM clutch spring? That helps loads for the launch. Are you running the MT tires? You can shave like 5lbs of rotating mass by going to a different wheel/tire combo. The MT pro is a heavy girl!
 
what tire wheel combo would you go with by the way rcdad belt drive cover didn t stay on for 5 min no big dell do i need that belt drive cover and if i do how do you keep it on.
 
I run mine with out the cover. I run trencher rears on all 4s. I am still running the stock engine with a 990 and jetpro pipe using a 8k clutck spring and the belt drive. Runs great for the stock engine. Low end is good, however being the stock engine, it runs out of breath on the top end. With my custom cage my MT is around 35lbs.
 
Sounds like a tuning issue. I've got an ESP 30.5 Champ port and it moves my MT without hesitation, and I'm running the stock tires. What carb are you running? Are you running the stock Zen clutch?
 
stock clutch with 8000 spring and a 660 or 680 carb got the carb and motor from obr.
 
lefnut said:
i got mt pro with the 30.5 obr motor and just put on belt drive from rcdad and im not liking the power seems real boggy trid messing with the carb but still boggy let me know what to do got abouit six tanks through the engine it still don t come alive until mid range to top end no at all i also got a ddm pipe.
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Did you buy the torque motor or the regular 30.5 modd motor,cause you shouid have went with the torquemotor and a 8000 ior 9500 clutch spring,will defantley make a huge diffrence.
 
whittron said:
Did you buy the torque motor or the regular 30.5 modd motor,cause you shouid have went with the torquemotor and a 8000 ior 9500 clutch spring,will defantley make a huge diffrence.
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A stock 30.5 has plenty of torque for the MT. So, it should haul ass either way. And 9500 is overkill, in my opinion. Highest I'd go is 8000.
 
The 8000 rpm spring is perfect. The 9500 is a drivetrain killer. Like stated, the 990 is better. The 668 has a bit of a bog in the low end.
 
Deluge said:
If it's a 668, that's your issue. Get a 990.
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+1

im running stock engine, mt tyres and baja rears(on other MT), 8k spring, and 5T cann on both of my MTs, and they both haul ass :)

my onroad MT boggs a little bit on the bottom end, but thats because im running steep gearing

the onb engine should have noo troubles
 
the guy at obr told me the 668 was just right for the motor i was getting and the 990 was to big and i do get the bogg in the lowend mid to top end is ok. need lower end
 
Your not going to notice that much of a diffrence switching carbs,your going to notice a bigger diffrence switching clutch springs.
 
whittron said:
Your not going to notice that much of a diffrence switching carbs,your going to notice a bigger diffrence switching clutch springs.
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hes alrdy running a 8k spring, if you switch to any higher ur asking for problems.

and

unless you want a snatchy madman, a 8k spring is plenty of punch of the line even for an MT with stock tyres/wheels

Deluge said:
Yep. 668's are known for low end lag. The 990 doesn't have that issue.
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+1 on the carb, as deluge stated, the 668 has a reputation for low end bogg.
 
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Hey guys,

I just ordered a prostock 30.5 and added a stuffed crank for more torque as well as a 668 carb. Dan at OBR told me the 668 is better for torque, he mentioned the 668 and 990 are the same bore but because the 668 has a choke, that area in front of the carb the choke blocks helps accelerate air flow which draws the fuel in quicker and helps throttle response and torque.

I beleive him and it makes sense but why two opposite views on the 668 carb. I am only going on what i was told but you guys seem to be certain on your opinion as well.

Any one have any more info as i will call OBR tommorow to ask again.

Mike
 
whittron said:
Your not going to notice that much of a diffrence switching carbs,your going to notice a bigger diffrence switching clutch springs.
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You will notice a great difference of the 990 over the 668 the 990 has no low end bog at all just takes off. I agree the 9500 clutch is to high of rev your car does not take off smooth if you gun the throttle it more of a jerk off wich is drivtrain issues as stated.
 
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