I have a MACH 28. I have completed break in per manufactures directions and decided to tune it for some power. The Mach manual states that the needles should be set to 2 turns from closed for LSN and 3.5 turns from closed for HSN. Within minutes into the 1st "Tune for Power" run after reseting the needles the engine climbed to 300 degrees which of course caused me to immediately stop the engine not to mention it did sound a little lean. Now the out-of-box settings for this engine were 3.5 turns for LSN and 4 turns for HSN. I also assume that "fully closed" is when turning the needle clockwise slight resistance is felt, making this my starting point. So my questions for the MACH owners are what are you settings? is this a typo in the manufactures documentation? what temps do you normally see?

And to answer some of the questions:
1. No Apparent Air leaks
2. New glow plug (MC-59)
3. In a savage before mid tank temp hit 300

One more question is fully closed for the LSN dependant on the idle screw??? Since this does prevent the slide from entering the carb some amount.

Thanks in advance for your help!

Richen your low end and little on the top end. Go at 1/8th of a turn at a time and let the motor run for atleast 60 seconds before touching your needles again.

See if that helps and get back to me.

I'm having some serious tuning probs with mine! When I barely touch the throttle on my controller it gets moving pretty quick. As soon as I start adding more throttle it bogs down. It seems to run it's best when the tank hits about half way down. It also seems to make a snap crackle pop sound some times as well. Is that normal? It's all stock and the car in question is a hyper7 pbs.

havent read much and i know yewr problem, its a mach .28 . theyre impossible to get power oout of without hitting temps like that, during a race last year mine (it was only an engine to train with) got up to such a temp that the temp guages just said error. lool

everytime one of my cars has made a crackle-pop sound is when there was an air leak somewhere. Make sure your carb is sealed good to the block. I pull all my carbs and put silicone sealant on the o-ring and then reinstall them. Another notorious place for leaks, your backplate: make sure your backplate screws behind the pullstart are tight. The backplate screws can rattle loose so it's not a too uncommon problem. The entire crankcase of these engines is under vacuum when running so you don't want air getting in. If either of these locations aren't sealed well you're going to have severe tuning problems guaranteed.

Also, make sure your head screws are nice and tight. Loss of compression due to a weak seal makes it hard to tune as well.

Dave

Thanks Dave! I sealed it up last nite and ran it this afternoon. HUGE difference! Idling is way more consistant and it runs much better. I'm still having a wee problem getting it tuned correctly as it'll bog at about 3/4 throttle and stall when I apply braking to turn from almost full rev. No more snap crackle pop either.
Travis

glad to hear that it's better. If it's stalling when you go from full throttle to braking, most likely the low end isn't set right. Both of mine have the screw flush with the endbell of the carb.

I'm no engine expert, but I've had many nitros over the last 15 years. Of all the engines I've had, this engine is on the top of the list for most touchy. I love it though, bought both of mine on ebay cheap ($100). I run one in my mammoth ST and the other in my ravager.

It sounds like your running a little rich, get a temp gun it help curb the learn curve assosiated with tuning

I've had the same problems with mach .28. And inconsistent running, dying for no apparent reason, and so on. The best thing I ever did for that motor was put x carb on it. It runs cool, more responsive, no more dying after half tank, and holds a good tune.

It runs like a rocket now. Too bad I already ordered a couple of other engines. A used VSPEC and a MIT modified GO Tech.21 race engine!

What's this X carb you're talking about? Never heard of it.

poorwboy what is an 'x carb' or more importantly where can I get it ?? Because as it is my mach 28 is a DOG !!
I think I'll look into checking the seals as well, who knows it mite be a whole new engine.

I also have a GO TECH 21 5 port and it absolutely smashes the mach 28

It's a great motor isn't it? A bit touchy in tuning, but when you find the sweet spot it does very well. I love the sound of it too. You gun it and it's instantly screaming like a banshee

Funny that I've talked to alot of people about the mach 28 and NO ONE has EVER called it a great motor!

Must admit though, I liked it alot before it went up against some decent motors .... [sm=disappointed.gif]

eh, to each his own, I bash every weekend and it has never let me down, always puts a smile on my face. I drive an 86 fiero with a modded 3.4pr in it (about 240hp/250tq at flywheel). Is it faster than a corvette? No. But the fact is, it doesn't have to be, it flies and is fun as hell to drive. Same goes for the mach 28

there may be something better, but it doesn't mean what you have isn't great

Sigh.......you guys, for so many years and you still wont learn.


Forget the Mach 28! Get a Mach 3 Turbo!!! THose things give you the closest turns! Comes with micro-power technology, and three progressive aligned blades for the best cooling. The Powerglide series comes with more lubrication as well as single point loading. So ya, get one of those babies.Heck, you wont even need to replace them, just add some after-run cream and they'd stay sharp forever....

Totally random BTW. Mach 3 Turbo is an awesome shaving razor for those of you who dont have beards or mustaches, or dont shave for that matter.

Sorry Its the carb off of the stock savage 4.1.

Funny that but my son has one (as do some of his mates) and it's at least as quick as any of the others in racing. Dead reliable, easy to start and tune and not a sign of any wear although it's only got about 6 litres through it so far. He doesn't even use nitro in the fuel, it's just an 80/20 all castor mix but the compression is much higher than standard.

Downunder,

Love the Emu dude!!!!

Whats in your fuel ? I would be interested to try something similar...


Kyosho GXR28 BMW3, I've got a new GO TECH 21 5 Port for my bug and it's awesome,

It leaves the mach 28 for DEAD.

Actually I also have a vertex 21 from my..... ahem HSP Tornado and although the mach 28 has it on bottom end, the vertex kills it up top ..

rckal

The fuel is just home blend methanol/castor the same as we use in our planes. He ran in his engine using it then started racing but it was a bit down in power compared to the others using 25% nitro so we took out the head shim then machined a fair bit off the head button to get the compression up around 13:1 and now it's at least equal to the 25% nitro cars. The fuel is way cheaper and he gets 8 minutes per tank compared to 6 for the others so less pit stops.

Hey thanks man