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Bog from start to mid

  • Thread starter Thread starter mjime714
  • Start date Start date
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mjime714

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Whats up everyone, I have a Yokomo GT4 with a RB X12T 5 port and I have a weird problem with when I punch the throttle from a stand still. it bogs from the start to about mid. I have to blip the throttle a few times until it gets up to higher rpms for the car run normal. I took the motor apart to inspect it, but there were no problems. Do you think it may be the clutch or 2 speed? I played with the tune and it is consistant throughout.

Thanks for your help peeps.
 
Were I a betting man, I'd say it is set too lean for the ambient conditions. Odds are it is colder outside than when you typically run the engine, this requires you to richen the mix.

I am thinking it is a fuel flow issue vice a tranny or clutch issue.
 
The weather out here in socal has been hovering between 70s to the mid 80s. There was a time from when I got the engine where it was running really good, but sometimes it is just acts up even if I do richen it up. I still get the bog at breakin settings.
 
When you adjust the mixture try adjusting the LSN (Low Speed Needle.) thats the one on the side of the carb.
Go 1/16th of a turn, run the car for a few laps and make more adjustments as needed.
 
originally posted by FastEddy
When you adjust the mixture try adjusting the LSN (Low Speed Needle.) thats the one on the side of the carb.
Go 1/16th of a turn, run the car for a few laps and make more adjustments as needed. [/QUOTE]

Thanks FastEddy. That's how I tune my cars already. Do you think I need to go at less than a 16th?

I talked to Rody Roem of RB Concepts and he thinks it might be something else. What would it sound like if the clutch were slipping?

thanks
 
It almost seems like something is stopping the shaft to spin until it is moving fast enough to get past whatever is binding it.

HMMMMMMMMM. I dont know. I have been playing with the tuning of the engine for a while now and I am almost convinced that it is not that.

Thanks Maxxcrazy88.
 
What temp are you running at? I would tune it 1/12 of a turn, 1/16 might be too little. Roll your car around, make sure the drive train is running smoothly. If your running centax, ajust the engaging point to engage at a lower rpm. If it's a 3 shoe, then allow the engine to warm up, then slowly take off, and I mean real slow.:smoke: Some clutch are design to engage at a higher rpm.
 
I always adjust my car to run at a top temp of 220. It usueally hovers around the 200 mark.

The car rolls smooth, and I checked it for any binding.

I have a 3 shoe clutch and I am waiting on the centax to arrive at my LHS. As for the clutch engaging at higher RPM, I have to keep reving the engine to bring it up to a higher RPM for it to run normal. Any way to adjust this? Springs for the clutch shoes?

Thanks Akina'sMtx-2
 
I still think the issue is with the LSN and or overall tuning.
Your running a Performance racing engine. The RB needs to be leaned out to the point it preforms well. Tuning by temperature alone isn't a good way to get your RB to work properly.

The RB LOVES higher RPM.
Try leaning it out on both the top and the bottom until it runs properly.

Once this is done then check the operating temps and make any minor adjustments as needed to reduce the heat.

The proper all around temp for the rb should be around 260-280. Temps of 300-320 even up to 330 would be acceptable after an all out 4 minute race.
Its amazing that you can even get it started with settings that give you a 200 degrees operating temp.

Your not dealing with an engine designed for kids in the park, its a racing engine and a new way of thinking is needed to get it to run properly.
 
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8-0 260-330 for a 4 min race? This is my first RB and I absolutely love it... when it runs right which is 40% of the time.

One question about tuning. Do you adjust the LSN first then the main needle or vise versa? I read in a number of magazines that you should tune the low first then adjust the main. Am I correct when I say that the main needle does affect the low end. So if I lean out the main, I need to slightly richen the LSN?
 
mjime, 200ish is still too cool for that engine. 260 is pushing it, and 280 is really pushing it. My friend got the same engine, but not the 5 port turbo. He is running at 240-250 on a normal 80 degree day. Yes they will run better at operating temp. Tune with your ears, and moderate the temp. I agree with fasteddy, just need to tune you lsn and see how it run, it sound like its bogging because it's too rich.
 

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