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Hello everyone. This is a Go Cart and not a typical "ATV" but it has an engine so I'm hoping someone can help me. It's a Helix FTX with a Manco 150cc engine. The engine will start and idle for awhile, but will not take even a small touch of throttle. Stalls. It seems to take throttle and rev up when you first start it cold, but in just a minute, it will not take any throttle. I've replaced the Fuel valve/Pump on the fuel tank with no joy. It's a nice little cart, but without a workable engine, it's a boat anchor. I'm not dumb when it comes to small engines, but this one has me stumped. I'm running out of options. I'll mention that while it is idling, it will sort of "cough" every 6 or 8 seconds and then recover and idle again. Eventually one of those "coughs" causes it to stall. It will start back up pretty easily, but as I said, it absolutely will not take any throttle and then it will cough and stall a minute later. I thought it could be timing, but there is no "adjustment" for timing on this engine. I downloaded the user manual and it mentions nothing about timing and is pretty much useless as a service guide. It just shows the basics. I'm attaching the manual so you can get an idea of the machine I'm dealing with. Any input would be greatly appreciated. Kind regards, Don Manco-Helix-6150-150cc-Owners-Manual.pdf

in this thread, I want to discuss how 4-cycle atv engines work- what the different types are... how they are set up and which you prefer. To start off, are the cams on ALL atv 4-strokes powered by a cam chain? I know that on say a lawn mower or logsplitter engine, the cam is turned by the tappet, pushrods, and valve rockers. Which is better and why? Chain-driven cams or pushrod-driven cams? Are the pushrods just an old version and everything is transforming to chains or the other way around...or not at all? Just looking for some explanation, history, and downsides/upsides...

Problem: The ATV starts and runs at idle perfectly. But as soon as I open the throttle, the engine starts to slow down until it stops. On the attached video you can hear the sound of how it works: see video below Prehistory: there is a Polaris Sportsman 500 1998, which for about 1.5 years stood in repair, including also replacing CDI with one taken from the same ATV. Finally, the vehicles were on wheels, traveled several kilometers and overheated - forgot to fill the antifreeze Came back home in small moves. The next trip started well, but after 10 km there was a feeling of a small drop in power (even as the vehicle got warm completely) but still drives. Next trip - the situation is repeated. The next test of ATV through time and a huge loss of power from the very beginning. The engine sneezes, does not want to go more than 5 mph. What has been done: the carburetor has been replaced with a new one (inexpensive, $ 40), a new spark plug, a new ignition coil, the engine head has been removed, the piston is in good condition, valves were corrected - but the problem was definitely not in them. Ignition control unit is suspected. Who faced similar? Please help in solving the problem. Thanks in advance.

Hey people Question for all, just picked a 1986 bayou 300 thinking of going synthetic any thoughts ?

Can I use an old snowblower engine in my 90cc quad? The old one blew up. Thanks for the help.

I have not been able to start my 300ex that I just got off a guy. I was able to getting it running once, then never again. After a week of trying to make it run I got a compression tester and it is saying about 30 psi. Is this definitely the rings just worn out or can it be something elses? I can't even make it pop when I spray stater fluid in it.

I have been trying to get my 300ex to start for sometime. a few days i got it to start over and over and then the next day it wont start. I do the value lash and keep the covers off. I was (prob exhaust) smoke coming out of the covers with for the valves. I also noticed that the crank position marker had smoke also coming out, but i just thought it was from the head and it being in the cold. The hole for the position marker also has air come out when it turns over, but it is very light of air flow.

Hello. New here. Just picked up a used 350 motor out of a 1991 big bear. Going to put into my 1986 350 moto 4. From what I've read the engines are the same. The only difference so far I've notice is I have to change out transfer case. The moto 4 isn't 4x4. Has anyone done the same swap and any advice before I tackle it.

Looking for someone reasonable ,HONEST and experienced to rebuild a 2002 Yamaha big bear 400 2 wd

I need a good used bottom end or complete engine that is compatible with the 2003 Honda TRX250ES Recon. I prefer the electric shift model. I believe that several model years will fit.

Ive been trying to identify this engine. Bought this buggy from a friend. It has a Quadzilla stamp on it, and here are the numbers underneath: LH152QMI *1K27205* Any help would be appreciated, about at my wits end trying to figure this out.

I have a 2002 cannondale cannibal 440 with the 450 kit. Recently I was riding it and it seemed to backfire out of the airbox then stalled? I started it back up got it back to the house, noticed my airbox boot had a tear in it and some of it was sitting on the throttle body. Now my cannibal wont turn over, what could be wrong with it? could rubber that fell into the throttle body be removed ? thanks

Have you guys ever had an issue where your wheeler runs great the first 10-15 minutes of the ride up and down hills, slow and fast speeds, and then it just peters out? It starts cutting out real bad and not making the RPM's like its supposed to? Well if so, help a brotha out cause that is what mine is doing. What would cause it to just quit after it is thoroughly warmed up like that?

Quad with a Ferrari engine Quad with a Ferrari engine

Radial Engine Motorcycles Radial Engine Motorcycles

Motorcycle with a Viper V10 Engine Swap Motorcycle with a Viper V10 Engine Swap and Weird Motorcycle Helmets Weird Motorcycle Helmets

I purchased a used 2001 Yamaha Warrior, and the owner stated all it needed was a starter (friend of a friend type deal). I installed the starter and it turns over, however, during starting there is a loud knocking sound. The sound goes away after it starts. I removed the side cover to review the gears, and they all appear okay, with no missing teeth on the gears, and nothing visably loose. Any ideas? Appreciate any help.

Hopefully someone here can help me out. I am getting ready to build a pulling tractor using an ATV engine and need some advice. These are garden tractors that are converted for pulling a sled just like the big tractors do. The class I am interested in allows the use of an ATV/three wheeler engine. It can be up to 400cc, but has to be a single cylinder, four stroke engine. We are allowed to modify them, but they have to be run on gasoline, and are not allowed to use any form of supercharging or nitrous. We can start out with a smaller engine and use a big bore kit, but the final size must be 400 or less. My question is, which engine would have the most power potential for something like this? I am not concerned about brand loyalty or anything like that. Any help would be appreciated.

Looking for a good used or rebuilt 650 H1 my 07 siezed at crank. Any direction would be great!

Hi All, I will start by saying I am real new to ATV's but not to wrenching. I just completed a complete fluid change on my 1990 Big bear 350. The owners manual recommends 20w40 for the engine oil but I see nearly everywhere people using 10w30 or 10w40. I actually was unable to find 20w40 so I used 20w50 that I did find at Walmart. My questions are: 1) What is the Statndard that is OK? 2) Is regular oil for Automobile OK to use? 3) Whats the difference in Auto oil vs Motorcycle oil vs ATV oil? Is there any? Thanks!

I need an engine for a 2005 ltz400. My engine case has a leak and I'm afraid the damage may be deeper so To save money I need a compatible engine. I have searched Craigslist and had no luck. I won't downgrade but if it will fit on the frame I wouldnt mind upgrading. Any help would be much appreciated. Even if all that's done is a point in the direction of one.

I have a 50CC kids ATV with 2 cycle engine. It starts fine but quickly loses all power when throttling. Any idea what to look for when I dig into it? (I've never worked on a 2 cycle engine before)

HI I have a Raptor 660 2003.. I'm having a problem of the engine staling out when i Ride it.. I turn it on and it sounds fine now when I take it out and rev it up it starts choking and starts dieing on me...It doesn't do this all the time. I got to ride it for five mins then it starts to choke.. the carb has been rebuilt about 6 months ago....is there a oil pressure switch on this model?? Thanks for your help..