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New Mac .28 Hyper 7 Break in issues

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Joined: 02 Mar 2011
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PostPosted: Wed Mar 02, 2011 5:40 pm    Post subject: New Mac .28 Hyper 7 Break in issues Reply with quote

I'm new to Nitro buggies, thought getting an RTR would be pretty painless, I guess I was wrong. Ofna really needs to consider creating a quick start guide for radio setup and engine starting / break in.

Anyway, I can get the motor to start, but not idle for more than a minute. Or if I increase the idle screw, one the engine warms up a little, it starts trying to engage the clutch. Any tips for getting the setup right?

Also, should I leave the glow plug ignitor on the engine after it starts during break in? That is, if I can get the engine to idle to break it in.
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Joined: 23 Aug 2009
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Location: Western, PA

PostPosted: Wed Mar 02, 2011 11:28 pm    Post subject: Reply with quote

Start with setting up the Idle air gap in the carb. Set the gap to around .6 to .8mm is like the thickness of a credit card, but because you are braking in the engine set the idle gap to around 1mm, I will explain.

2. Set up the LSN(low side needle) and HSN(high side needle) needles to stock setting, if you dont have the stock setting just put the needles flush with the housing.

3. If you are in a weather with less than 50deg. try to used a hot plug.

4. Warm up the engine with a heat gun or a hair dryer, until the block get very warm, if you have a temp gauge try to get the engine at 150-175deg.

5. Start the engine, should start very easy. Once is running try set a steady idle using the LSN. Once you have a steady idle you can start brake in the engine.

a. 2 or 3 tanks in idle, bleep the TH (touch the gas in the transmitter real quick to clear the pipe from fuel and unload the engine) Make sure the engine reach at least 200deg. if not and just 1hr or 2 in the HSN.

b. Tank 3,4 and 5. Adjust the Idle gap from 1mm to aprox .8mm.You migh have to adjust the LHS to get a steady adle again. In this 3 tanks you will drive the car in a smal place do some figures 8 do net let the car run out of fuel during this 3tanks. This will be at 1/4 of a TH runs.

c. Tank 6,7 and 8. Without touching the needles( as long the engine is steady) run the car doing the same thing but in a bigger area with 1/4 TH and 1 or 2 straights a round 50meter at 1/2 th. I mean do a few figures 8 and 1 straight, a few figures 8 and 1 straight.

d. Tank 9,10 and 11. Adjust the Idle gap to approx .6mm is like the thickness of a credit card. Adjust the LHS to get a medium low idle( engine will be kinda low but not too low that will engage the clutch)
At this point with the idle set you drive the car in approx 50meters or so straight, will apply 50% TH with a few runs at 75%TH. At this point is when the engine should start to get loose, again do net let the engine run out of fuel and try to get the temp to a 220-240deg but must important you should see a stream of smoke, at this point you should have plenty.

e. Tank 12, 13 and 14. At this point you do not need to touch or play with the idle gap for nothing I mean NOTHING. If you need to adjust the engine you will use the LSN and/or HSN. Lets lean the HSN 1hr, if the idle get High you just need to Rich the LSN, this mean that you will turn the needle until you get a steady iddle again. Once is done no need to touch. Same thing as step D but drive the car with a few straights between 50 and 75%TH and 1 at full TH. Make sure that you monitored the temp or make sure that you have a steam of smoke.

By now you should have at least half gallon or more trough the engine, so you should be very close for good set up. Once you are done make sure you set the piston in the lower section, you can do this by hand rotate the flywheel until you feel is free, if you fell presion just back up half turn. Why? once the piston sleeve cool down will shrink, that is why I said in the bigining to warm up the engine so the sleeve expand and make it easier to the piston move. In the very first gallon try to warm up the engine before start, will be tight in his first gallon of life.

One more thing so you understand how to adjust the carb. The fuel will pass through the HSN first then LSN. If you close(lean) the HSN you wil feel the idle raise what you do rich the LSN to bring it back down. Why this happen? because you ar limiting the fuel in the HSN(where the fuel first get in to the engine, means the less fuel will get in to the LSN, that is why you need to rich the LSN) Now, If you adjust the LSN will not affect the HSN and no need to be adjusted.

In any engine always adjust the idle gap first, this is one or the must important step when tunin an engine, as bigger is the gap that is how much fuel will suck and will make it difficult to control, smaller gap will use less fuel and better performance. I seen as small as a .4mm but this is in racing tune in a racing engine.

I hope this help, if you have any questions just send me a PM.

Make it simple. HSN will affect LSN, but LSN will not affect HSN.
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