Par car slow all the time

[Tankercart]

It's a 91 par car. 2 stroke HD. I bought the cart from a guy who told me it was a project, and he wasn't kidding.

I've replaced the battery, starter generator brushes, voltage regulator, carb (chinese) , fuel pump, solenoid, ignition coil (3 ohm), cooling shroud, and replaced the air filter with a 2stoke 250cc cone air filter. She started right away, but full throttle she only went about 5 mph. I removed the gov cable and no difference. So I bought a compression tester, and decided to get serious. Sadly the compression topped out at 65 PSI. Can you get away with just replacing the rings or do you have to replaced the cylinder as well?

After reading a bunch of timing issues with this cart I decided to investigate it. I followed the ignition module sticky and it failed... the black wire to ground was open no matter how many times I spun the fan. That's weird because it gets spark. Should I replace with Ebay's pertronix module? I will be adding the ballast to increase the resistance from the coil. I read that's to protect the module, but how do you install it? Is it inline the blue wire coming from the module to the coil?

The muffler is pretty rusty and pitted. I've read if it's plugged up with carbon the engine will lose power. The gas in the tank was very dark when I bought it so I suspect it was ran with a very oil rich mixture. Red flag to those buying these old 2 stokes. haha. There are two holes in the muffler the size of a screw driver. I don't know if these are factory or if they were intentional... They do smoke a good bit once I quit running the cart. Any advice on this?

Last thing the secondary clutch doesn't expand very much. I can't tell if it's bad or the engine isn't strong enough to open it up all the way. The primary clutch moves and contracts pretty good. What makes a clutch go bad and can they be rebuilt? Can I sand/polish the belt surfaces and replace the spring? Is there anything I should lube?

Thank you very much for reading this very long thread.

[AGELE55]

Watching this thread... not sure how much help I can offer...lol

FYI, I have a Yamaha G1 and replaced the rings. I honed the cylinder while it was apart. It runs pretty well and I’m getting around 110-120 psi. For about $20+ it’s worth a shot and I’d start there.
As far as gas goes.. are you premixing or using the oil pump? I’m sure you swapped out the skanky gas, but check your premix ratio. I’m currently running premix at 1oz to 1 gallon ( yeah, a little heavy) with my oil pump output routed into a small plastic bottle. Once I get through a full tank of gas, I’ll measure the oil in the little bottle to verify oil pump output and hook it back up and run pure gasoline.
As a side note, my G1 received all the same parts you replaced because it was dependably undependable...lol. Only after I replaced the crank seals did it cease pissing me off on a daily basis.
Good luck and keep us posted. We just pulled an old gas Parcar from my neighbors barn and are beginning the process of putting it back into use.

[Tankercart]

Thank you for the response! I’m checking this thread fanatically. I ordered the rings I think your right couldn’t hurt to try before I shell out 200 bucks for the cylinder. I use a mix 1:85 1.5 oz oil per gallon of gas. I’ve read that’s what these Harley Davidson 2 stokes like.

I’ve been actuating the secondary clutch by prying to 2 screw drivers between the flanges. I squirted some graphite powder in there and it definitely helped. When I run the cart on jacks its expands a bit more. Still not to the point I have a feeling it should. I’m going to pull it off, wire brush all the rust off and reinstall it.

I took the muffler off and ran the cart as well.. it was loud but I don’t know if the wheels spun faster or not.. I didn’t like running it without the muffler so it was a short test.

I got to thinking about the ignition module.... it says to have the ignition switch to on... in this style cart the fwd rev switch is the on and there is no power to ignition coil or module until the accel switch in the foot pedal is activated. If I activate it the starter generator spins the engine and the voltmeter can’t read the volts going that fast... any advice on this? Also is there a simple way to time the module?

[AGELE55]

“If I activate it the starter generator spins the engine and the voltmeter can’t read the volts going that fast.“

Not sure I understand. I think you may be getting side tracked. If the cart starts and runs, it has spark, so the ignition is doing its thing.
The question becomes, why so slow? If your belt is slipping that would run you slow, even though the engine is going full speed. Maybe check the belt’s width? Maybe it’s worn too narrow?
Also- do you have full throttle response? Is the engine revving full throttle? I know the old Parcars had a governor... is it over governed?
I think I’d concentrate first on RPM. See if it’s hitting full rev. If it’s revving up, is it slipping?
I feel your frustration...been there, done that. Hang in and whoop it into shape.

[Tankercart]

Yeah. Sorry bout that testing the ignition module on this guy is hard to explain because of the key switch.. think I just need a jumper from the battery to the coil. But yes I am side tracked haha.

I’m glad you brought up the belt because it doesn’t look that old so I never questioned it.. however, the part number says it’s for a snowmobile and it’s over 1” longer than the correct size. I got a dayco HP2009 on order. I’ll let ya know how it turns out

[Lochlin]

Sorry, Tankercart. The forum doesn't get a ton of action in the winter and I don't check in as often as summer time.

If you are getting spark then your ignition module is fine. Who knows why the test is failing but for sure, spark = module good.

Your compression is way low for sure. I am surprised your cart is running at all 65 psi. These were pretty hardy motors though any will run with a low psi. For sure, though, 65 psi will kill your power and speed. You want to correct that before you do anything else.

Your motor may not need rings. Take the muffler off and rotate the piston down to the bottom if its rotation. You will be able to look into the muffler hole and see the piston / rings. If they are in place you may be ok. You could have blown the head gasket (where the cylinder head connects to the cylinder) or base gasket (where the cylinder connects to the case). As well, there is a specific bolt tightening sequence / torque for the head bolts. If the previous owner didn't follow those then those gaskets could fail. The manual is located here and will describe how the install the cylinder the right way:

https://www.buggiesgonewild.com/colu...UTILITRUCK.pdf


Regarding replacing just the rings or the cylinder too, it depends strictly on the condition of the cylinder. If your gaskets are ok, At 65 psi, you almost certainly have a broken ring if not both. If they broke "clean" then a new cylinder is not needed. If they broke and bounced around the cylinder until they were small enough to pass into the exhaust then your cylinder walls are probably scored pretty good.

Really, popping the cylinders off of these carts is a very simple task and takes all of 10 mins. You can go ahead and just replace the rings and see where that gets you. I would get a new piston too though. They don't cost all that much and, while you are there, you might as well do it. A couple of hints:

Rings are cheap. You may as well buy some spares. If one cracks during the install or something you'll have some on hand. Same thing with the gaskets. The head gasket is metal but the base gasket is heavy paper and easy to tear during installation.

I wouldn't mess with your clutch until you get that compression squared away. It's problem #1 for sure.

[raydhd]

I am with Lochlin at 65 psi surprised the engine runs at all. Point #2 is the muffler being blocked is another area that just a big issue with these engines.

[Tankercart]

Lochlin, Thank you for your response. Yeah I agree. The compression is surprisingly low for a running cart. I ran the cart for 2 minutes full throttle to see if warming the engine up would get a better compression. And it didn't, it got worse. It maxed out at 60 PSI... Having said that i did buy the cheapest compression tester on amazon for only 17 bucks so idk how accurate it is. Thank you for the torque reference and gasket information. I got a hone, rings, and gaskets on order as well as a new belt. I'll let you know as soon as get them.

One more thing about the ignition module... Where do I put the ballast to increase the coil resistance.. right now it's 3.2. Should I put in a 1ohm ballast?

[Tankercart]

Raydhd, Yeah the muffler is highly suspect. I mentioned it earlier. I think there may have been a powerloss because of carbon, and the last owner punctured two holes in it to alleviate the pressure. I'm not sure. I ran the motor without the muffler and did not notice anything strikingly different other and it's loud haha.

I'll take some pictures and post them soon.

[raydhd]

You will know pretty quickly after the cylinder work is done if the muffler is an issue. With a blocked muffler the cart will be slow and not respond to tuning.