mach23

I just got an MGT 8.0 on saturday. so far i have only ran about 8 tanks through it and i am haveing a bit of a problem. When i have it full throttle it dosnt really respond well, it wont die down but it kind of sputters and wont really turn on like it should. I have adjusted the high speed a little bit maybe almost 1 full turn in and it still does it. Like i said i wont slow down or anything it just isnt turning on like it should. Also haw fast does this thing need to be going for it to shift? i havent been able to get it to shift yet except when i put it on a stand it will but it takes a while. This isnt my first truck so i am familiar with them but this one has me wondering. My temp right now is around 245 too. Thanks for any help

Dale Gribble

My Feedback: (4)

When it cuts out at full throttle, it is either too rich or too lean. It's either loading up or starving for fuel- both can cause that issue. Since your temps are 245, my guess is that your HSN is too lean when you go full throttle. I would richen your HSN up 1/2 turn.

So, a 2-speed relies on the engine being able to reach a certain RPM that causes the 2nd gear centrifugal clutch to grab. If the RPMs aren't reached or the 2-speed clutch is set improperly, it won't engage. Since you are cutting out at WOT, your truck isn't hitting the correct RPM resulting in no shifting.

Richen the mixture up a bit and see what happens.

mach23

yea i just richened the HSN up and it seems to be alot better, but the temps are still staying at 245-255 and its only 50* outside. I am still getting really good smoke from the exhaust though. If the temp stays this high will it hurt it or should i be ok? Also will it help to cut a hole in the front to get more air? Thanks for you help i appreciate it.

Dale Gribble

My Feedback: (4)

Your temps are good. You could even richen a tiny bit more to get your temps around 230-240. What fuel are you running?

I would cut a hole in the body; most folks cut a square or round hole in the body's windshield to get more cool air across the cooling head.

mach23

i am running odonnel RTR 20%. I will cut i hole in the windshield, i have also been looking at the nova heads.

Dale Gribble

My Feedback: (4)

Don't get the Nova head now... They can help reduce temps, but a standard cooling head is ok with a proper tune. An aftermarket cooling head is kind of a band aid if that makes sense.

BChiz

Hi Mach. I also have a new 8.0 that I have not started up yet to breakin. I have heard that the needle settings for both low and high needles in the manual are to rich. When you first started yours, did you leave them where they were from the factory or did you have to lean the high speed needle in some? Let me know how you started your breakin. Thanks.

mach23

I did break mine in with the stock settings and yes it was very rich but if you follow the directions you start to lean it out on tanks 3-4 if i remember right. even with the factory settings it will stand right up straight.

bigdogkanicsar

if you have good smoke at top end aand it still seams sluggish it could be that it is loading up with fuel at idle or low speed.
if it's rich at both idle and high speed , it may not be cleaning out properly.

mach23

thanks for all the help, i seem to have it alot better now. i am going to cut a hole in the windshield to give it a little more air...

TTMT

My 8.0 has always run hot - 275+.  I have been out to Associated and had one of their engine guys tune it for me.  He even replaced the original carburator.  I've concluded that my particular engine just runs hot.  It doesn't seem to be running too hot when I've had the technician work on it, though.

My temp gauge is good.  I've used it to measure other temperatures and it seems to be fine.

I suppose I should try to slightly richen the high needle and see what the temp does.  Overall, it runs very nicely, so I don't want to foul-up the performance.

I agree with the shifting issue.  Sounds like mach23's engine was not reaching high enough rpms.

Mclovin350z

Try some fuel with less oil content. Maybe some O'donnell race blend 20% or Byron 20-30%. They have 14, 12 and 11% oil content. That O'donnell rtr stuf is either 16 or 18%, I can't remember, but that's too much. Also instead of and ugly hole in the windshield you can try 'scoops'. Kind of like a hood scoop ormoonroof cut. Sometimes I even flare out the fenders behind the front wheels. In my opinion that looks much better than a big goofy hole in the windshield, and keeps the body more rigid for crashes.

Mclovin350z

Another thing to keep in mind is the size of the 8.0. Many people don't realize how long it takes for that huge engine to fully warm up, making it tricky to tune.

TTMT

I thought you wanted higher oil content to better lube the parts and keep friction (heat) down. I'm running Trinity Monster blend 20%- recommended by my LHS. Do you know what the oil content is in the Trinity blend? I think you want a blend with caster oil instead of synthetic lubricants too, correct? Iunderstand the the Sidewinder blends are extremely good too.

What is the effect of having too much oil content in the blend?

Mclovin350z

I'm going to be general here....Too much oil can actually create more heat. Less oil means more methanol. Methanol cools as it's drawn into the engine. Castor / synthetic blend is the best. I think most are about 20% castor and 80% syn, but no one really seems to know because most fuel companies won't give that info. Most engines only need (and are recommended to run on) about 10-12% oil torun well forthe usual 6-10 gallons. The reason why traxxas and other companies say to use high oil % is because that gives you a safety net on tuning......traxxas warranties ALOT of engines.Funny thing is, for example, Byron 20% with 12% oil is far easier to tune vsany 16% oil content fuel. It's also better to run lower oil because you won't be chasing so many one way bearing issues like you normally would with higher oil content. When I switched from O'donnell race blend (which isexcellent fuel, with14% oil), to Byron I noticed a dramatic change in temps and tune-ability. On average my engines will run about 15 degrees cooler, make more power, and tune easy. Keep in mind you always want to be at 230 or higher on a broken in engine. I'm pretty sure the monster fuel is 16% oil.