I am having some problem with my new XTM 457 Pro engine. I am running this in a Savage 25 LE. When the truck is about to hit the 2nd gear shift point is bogs seriously. You get the "wa wa wup, wa wa wup" sound, and if you keep on the throttle it WILL stall. The truck also does not idle very well. It has a high idle sounds and slowly starts dropping and will eventually stall. If you go from idle to Wide open throttle, you get the "wa wa wup" stalling type sounds and if you keep on it, it will stall. This is also for a rolling Wide open throttle transition.

There is LOTS of smoke coming from the exhast, and the low end seems to be ok. I have set the carbs back to facotry setting and tried re-tuning from there. Still nothing. The engine has about 1 to 1.5 liters of fuel through it - this includes the break-in process. I am using Trinity Horsepower 20% nitro 12% oil content. Currently the carbs are set at: High Speed about 1/2 turn lean from factory. Low Speed Factory setting.

I have replaced the glow plug still nothing. There also seems to be ALOT of oil on the back plate and the pull start. Also, the problems really start appearing once the truck gets to about 200 F or so. Could there be an air leak robbing the truck of power at Wide open? Is it possible that there is a leak on the back plate and that would account for all the excess oil on the back plate?

Break-In procedure and truck upgrades:
Did the Heat-Cycle method for about a total of 45 mins run time. Replaced the glow plug.
Running with a 47t/17t gear setting. Will be switching back to 49t/19t tonight.
3 shoe Aluminun clutch.
Standard sized Proline Maxx Mashers on fake bead-lock rims. I forget the manufacture on these.
Hump pack

ANY help would be greatly appreciated!! If I missed any important details, let me know and I will try and get the answers.

usually when the truck sputters and almost stalls when it's about to switch gears it means that the high speed needle is to lean. go on youtube.com and serch for nitro engine tuning

i would put it up on blocks and floor it, check the temp. if the temps are low under 200 lean out the hsn a little if it gets worse and stalls sooner then richen it up. if its idling badly do the pinch test just pinch the fuel line, it should stays idling for at least 4 to 5 seconds. i would half to agree with benzzyo5, it sounds too lean on both needles.

Ok thanks. I will try richening both the highspeed and lowspeed needles. The last time I ran the truck I pinched it to kill it. It ran for about 3-4 seconds then the rpms went really high for 2-3 seconds. Doesn't this usually mean a rich condition? I only ask because there is LOTS of smoke when the truck is running and there is a "splatter" mark when the truck is idling for a bit in one sopt. Also, there is LOTS of oil on the back plate and pull start. Should I be concerned with this or is that just something pull starts do? Does the XTM 457 Pro usually want a rich condition for optimum operation? Thanks for the help so far!!

I run the 457 in my X, i keep it alittle rich and she treats me right.

No..... I would look to the gasket between the engine and header that it is in good condition and making a good seal. That can be leaking and cause a lean condition when there is not enough pressure in your fuel tank. Also there should not be that much oil on the pull starter and back plate.

Dennis

If your engine sputters and slowly idles down till its about to die its loading up and probably to rich. The first problem is 2 fold, you have an engine now that has a lot more top end power curve than your old engine. The transmission will need to be adjusted to shift at a higher speed. After that you can trim out the engine for preformance. The XTM specs for that engine is about 4k higher than your stock engine. Or at least it sounds at least that much higher.........good luck m8[:-]

I took the engine out this morning and had a look at where the exhaust header meets the engine. In my opinion it was quite loose. It did not feel to me that it was making a seal of any form. Also, the purple silcone coupler from the header to the tuned pipe seemed loose to me as well. How tight of a seal should things be?

I also changed the gearing to 49t/15t. Will this be to much torque with this engine?

With this gearing, will I need to make it shift later then factory setting or sooner? From 1st to second, and from second to thrid?

Thanks for all the help/suggestions so far!!

with the xtm i'd use 17/49 definitly. and those zip ties and the purple coupler should be nice and tight so no ar leaks out of there and causes pressure problems with the fuel system

I just checked the gasket on the XTM engine to the one that is from my HPI S-25. The one from HPI is thicker. This made a much more snig fit on the exhast manifold. I am using all my old HPI Savage 25 LE exhaust system - HPI Tuned Polished Pipe, header and couplers. I would assume that is why the XTM gasket was not fitting properly? I will have to stop at my local hobby shop and pick up a 17t bell and try that.

Also, I was thinking of changing the exhast system. I was looking at the Jammin Pipes JP-2 setup. How much of a difference will this be over the stock Savae 25 LE exhaust system? Does ALL the mounting hardware/gaskets/spring/set screws/manifold come with the pipe? If not what other items will I need? I like how the pipe is connected to the manifold. No more of that purple silicone coupler. Thanks again for all the help!!!