giddyuperic

Yes send it back and tell them all of the problems you have been having and they should be able to swap it out for a new one.

lsurber

I sent an email to Garen at VTX about my blown engine. They were very willing to help and a new engine is on it's way! So, don't get frustrated guys cause they are really doing a great job at addressing issues. It is a great car design with captured pins and all. You just can't beat the price for the quality that you get!

I think the original motors piston/sleeve were too tight from the factory! That is the only thing that could account for the high-temp issues people have had. Mine was sizzling hot but so rich it would coat my finger with oil(dripping) at idle if held in exhaust for just a few seconds!

I won't take any chances on the new motor when it arrives!

giddyuperic

Yes TEAM VTX Has one of the best support that I have seen and they are all about the racer or just the weekend basher. It is hard to find a company today that will stand behind their products like they do. So I would like the thank all of the people who work at TEAM VTX you are doing a stand up job, keep up the good work. Love my VTX ST-1. Eric

lsurber

Since I had motor problem I dropped in my ported mach 26 and having been thrashing my buggy hard! Not one single screw has come loose on a RTR, that is unheard of! When I got my LOSI everything was loose! The LST was my first ready to run vehicle and I never expected that LOSI would not loctite metal/metal stuff. I learned a good lesson with that.........don't trust any pre-built! So when I took a chance on this VTX I was kinda expecting more of the same!

j_blaze

How is the replacement engine? the 25. I got all the pieces of the 26 in a box ready to ship. Is the replacement engine doing better than the original? I got a 21 in for now and this thing still hauls. I can make all the long jumps still. I had another small problem though, my pipe got crushed on some pvc, its totally warped now and it rattles inside, it looks like one of the chambers cracked inside so I put on an old plastic pipe I had off my buggy and it still runs great. As far as a replacement, is there any pipe better than the JP3 out there?

lsurber

I haven't recieved my replacement yet but Greg emailed me Mon. and said it was shipping that day. I am still runnin with my Mach 26 which is pretty savage power-wise! Hope the new engine works out! If it doesn't I'm just gonna buy another Mach 26 for it. They are pretty inexpensive and have all the power needed to win any race, unless your running on some kind of sticky clay or pavement!

lsurber

Just got the new engine today at work. It was being unloaded as I was typing the last post! Will break it in tonight after work. It says 25 on the side and comes with pull-start, manifold gasket, carb, and flywheel cone.

giddyuperic

I hope you have good luck with it!!!! I would idle one whole tank threw it watching the temp and shutting it down when it get's no hotter then 230, Do this for the first tank only and then go from there. I still have that motor in the box as I run the ofna force 28 and love it!!!!!!! And I did the break in like that and have had no problems at all it idles like a dream and never gets hotter then 240 to 270. Let us know how it goes okay? Eric

lsurber

Well, I took it apart so as to do a very thorough job and leave no room for failures this time. On inspection I noticed a few things to point out. The pinch is not as tight (-.002 in) as the first motor so I don't believe overheating will be an issue if properly broke in. However, I did determine that the crank counterweight may contact the piston skirt when loaded at high rpm. So I would advise to remove some material from skirt to avoid a repeat engine failure. You want to match or exceed the radius of the crank counter-weight and allow about .030 in clearance between skirt and crank. This certainly accounts for my shattered piston skirt on the first engine! I see a ton of potential in this engine though! Great engine base for high output mods! Inexpensive!

j_blaze

Thats what I was planning, after a couple gallons of stock power I am going to port the 25 and use it for some big air at the track. I ported both my 21's and they sing now, I just had to use colder plugs and richen a bit, the power is sick. If the 25 is kickin', it will be great at our track. I love to put around with my ST1 against the mugens and 8's and keep up for the most part. Once I get some race tires and get my new body done I'll give the racing a shot.

j_blaze

230 on break in? I use a fan while breaking in o keep temps just above 200, 210 at the highest. I can use the trim to rev it up slightly then just slide the fan back and forth to a spot where the temps are right. Is this good or should I let the temps get higher for break in? This could be the cause for my current engines overheating now.

giddyuperic

Every body does it their way so you do what ever you feel right with. I have never had any problems at all with my motors when I break them in that way. So keep us posted on how it goes.

lsurber

Really check that piston skirt clearance and also the pinch on these motors! The pinch is what is causing the high temps and skirt clearance is what shatters the piston. I brake honed the sleeve, increased piston-skirt notch radius (for crank counter-weight clearance), direction notched the ports, carved and polished the block runners, and changed the crank-case pressurization timing. This thing runs like a raped ape with terpentine on its butt! LOL! My crank-case pressure timing trick got me 18:52 min. hard run-time on a single tank! Almost double the normal run-time with a 125cc tank! My idle temp is 195 and hard run is 228! I am happy now!

j_blaze

"crank-case pressure timing trick", explain...

giddyuperic

Hey blaze I thought you had you vertex 26 going and going good what happen? Is it still alive? Or are you going to do what the other guy did lsurbur it sounds like his is doing well for now I would like to see if it last I hope it does as I have a brand new one in my box and would love to trick it out like he did if it works? Let me know. Eric

lsurber

The trick I refer to has been hashed around in the engine section in thread called "Doubled my fuel mileage." I have since learned that it is called sub-piston induction. It involves notching the piston skirt on the exhaust side so you can see about a 2.5-3mm half moon shaped opening when the piston is at TDC. This is when viewed through the exhaust port. If you hone the sleeve to eliminate the extremely tight pinch, cut the piston skirt for adequate crank clearance, grind out the runners in the block, channel the ports, smooth the ports, and finally break in by heat cycling you will end up with one nice running engine with great fuel economy! If you cut the skirt so the radius is a little larger than the counter-weight radius and duplicate that cut on the exhaust side you will be in business! You will have to run the carb idle set screw all the way in to get the idle right though. Just don't go too far or you'll lock up the slider. Low idle is a product of the sub-piston induction cut. The bigger the opening the lower your idle rpm's go and could be difficult to keep running. It would be best to start small and slowly increase to be safe. I have a symetric piston where both intake and exhaust side cuts are equal and have no problems idling or stalling out. The engine is running great and I'm actually still pretty rich on the mixture!

j_blaze

You did this to the new 25 VTX sent you? That sounds awesome, but almost too good to be true. My vertex 21 is on its way out and has a bad bearing now, keeps sticking and making that buzz sound at mid to low rpm's, I'll try this on that engine and see how it goes. Just so I understand, you cut the same notch thats in the front of the sleeve for the crank shaft clearance on the rear of he sleeve. As the mostly used up fuel exits the exhaust it gets sucked back in under the piston on its way back up, right? Won't that add extra lubricant also?

lsurber

No, not the sleeve! I cut the piston skirt. If you pull the crank and place the rod/piston assembly on the crank to examine clearance you will notice that the crank counter-weight has a radius to it. The piston skirt is also radiused on the intake port side so it does not contact the crank counter-weight. The Go-Tech engines clearance was too small in that area! I increased it by cutting a larger radius in the piston skirt than what it came with from the factory. This avoids potential/inevitable destruction from crank counter-weight interference. I made it about .030 in clearance.

Now that you have the piston skirt radiused larger on the side closest to the crank counter-weight look at the side of the piston which faces the exhaust port. Cut the same/identical radius on that exhaust side. When the engine is assembled and the piston is at TDC look into the exhaust port. You should see a radiused opening on the bottom side sort of like looking into the carb when the slide is open a bit. It should be crescent shaped if you do it right. This will allow exhaust back pressure to fill the crank case just prior to pressurizing it from the piston down travel. This is called sub-piston induction and will increase fuel economy while not sacrificing power!

j_blaze

sorry I meant the piston skirt not the sleeve. The skirt on the 21 was already cracked during conrod detonation after porting. I put on a new conrod and fired it up and it has been running fine since. I just filed it down a bit so it would not crack more. I'll just do the same on the opposite side then, thanks. How much fuel economy would I get on a 21? 30 minutes?

I've seen some sleeves with the ports all the way to the bottom of the sleeve in one long continuous notch, is that better than the fangs?

lsurber

A venturi with rifle groove like a gun is the ideal kind of port for fuel mixture delivery. Just like that Tornado or Cyclone air filter insert for big cars that you have probably seen on TV infomercials! This is almost impossible to do though! With that in mind the fangs should be inverted from the way most people make them. They also should have a very sharp edge on the side closest to the combustion chamber and a shallow angle closest to the crank case.

So, the piston skirt was cracked in ur 21? I'll bet it was on the intake side where the crank counter-weight is!!!!!!!!!!

giddyuperic

Hey bud can you please post some photos of your mods please it would help alot of people to see what you are talking about please and thank you very much. Eric

lsurber

I would if I had taken any pictures of it! LOL! I had debated doing so and even had my digital camera out on my desk for it but my memory cards were full of data and I was too lazy to archive one of them! I am going to do another one very soon so I promise to photograph and document this time. Pretty much if you make the piston skirt look the same on both sides you have done it. The Go-Tech engines have a radius in there skirts where some others have a much flatter cut for counter-weight clearance.

j_blaze

It was cracked along the side where the piece of conrod snapped. The swinging conrod snapped the piston sleeve on the way down looks like. I think I'll try this tonight, just gotta unbolt the engine, back and head, I think I remember where I put the dremmel...

j_blaze

isurber you were right, the vtx 26 cracked on the side, this one did hit the weight. Heres pics of it after grinding, the first one is the cracked front side and the second is the modded rear side. I'll have it up and running in a few.

j_blaze

Great! first I have some grease in the HSN from just sealing it, so no fuel, then I got a bad bearing on the clutch! wheels turning on starter box! I'll take it apart and fix the bearing and try again. Its getting late though... It did fire up with throttle half way open, VVVRRROOOOOOMMM!