Antique Tractors Forum banner

1 - 8 of 8 Posts

·
Registered
Joined
·
4 Posts
Discussion Starter #1 (Edited)
Hello all,

Just wondering if anyone has come across this unit or a problem similar to mine and has some advice.

The (BV PowerSports) TrailMaster 300 XRX is a 300cc mini buggy that uses a Yamaha engine based off the Majesty scooter. BV PS bought up the 276cc engines and bored them to 300cc, then created this. Here is the engine label:



It came about 85% assembled last week. The engine/tranny/brakes/ignition/wires/cooling, all the big stuff was already done. We literally just bolted the wheels, roll cage and hooked the gas tank to the carb and manifold (vacuum based), changed coolant and oil, trickle charged the battery and was done. Or so we thought.

The buggy wouldn't start. We checked everything common on the engine and long story short, wires are the issue. Some of the cheap plastic connections were just bad and dielectric grease or bending the male/female connections didn't solve it. So the wires were stripped and crimped, no more issue with those.

That brings me to the wires entering the magnetor/flywheel assembly:

fw1.jpg

The wires going in were not all glued properly in their grommet (the whites weren't at all). Just touching the white wires would instantly stop the engine. We drained the oil and opened it up. It was immediately obvious the flywheel was hitting the wire bundle and this was the problem:

fw2.jpg

I can't believe there's no bracket holding the bundle back safely away from the flywheel but the damage speaks for itself. My small engine guy pushed the white (unglued) wires into the black grommet and noticed it bent the bundle away from the danger zone. That left us to believe that just pushing these wires in enough and gluing them into the grommet was actually their 'great idea' for how to handle this.

Since there's oil in there we couldn't think of a way to safely keep the wire back. Does it look like it's missing a bracket in there or has anyone seen anything like this before?

Just FWIW the buggy was purchased new. Amusingly BV PowerSports's site got hacked and has been down but the TrailMaster 300 XRX owners guide and parts guide (that shows assembly info) can be found by clicking here and looking for the proper model.

I already have them sending me a new flywheel assembly and a full backup wire harness for all the trouble. If we go put it in and it doesn't contain anything to keep this wire away from the flywheel I can only anticipate it's going to happen again.

Lastly, after we wire tied the white wires in deep enough where we knew it was bent away from danger, we tried driving the buggy after reassembling it. It drove perfectly fine (even jiggling wires) as long as the wire tie kept the bundle from hitting the flywheel. Although (sigh) after about a minute it ended up just dieing 100%. Previously it always used to at least turn the starter upon ignition, we just couldn't keep the engine running due to the wire issues. Now it's 100% dead and I know the battery is charged. Here is a really cruddy dark video of it driving down the dead end street (not that you can see it) and it coming back, trying to do a 3 point turn in the street. As soon as it's put in reverse, the tranny engages and starts to back up but the buggy dies immediately. Ignition does nothing. Any idea what would do that?

Thanks for any advice! I'm really in over my head..
 

·
Registered
Joined
·
4 Posts
Discussion Starter #2 (Edited)
Quite a lot of views without any replies. This is an ATV, I'm surprised. Anyhow just so other poor souls buying this buggy might find it useful I'll just respond here.

We have a new issue, the transmission is requiring insane RPMs to engage the clutch/gear, making it peel out. While I had fun in my younger years popping the clutch in mustangs, I know it leads to blown clutches, gears and trannies. But first, the magneto..

BV PowerSports 2nd day mailed me a new rear wire harness, magneto/flywheel assembly and paper gasket.

The engine dieing issue was a fuse blown directly from the battery to the damaged wires we were replacing. So that makes sense. The factory actually had a spare 15A in the plastic connector so once we replaced the magneto, it didn't blow anymore.

The new magneto is in and working great. Behind the magneto is actually a metal brace that we couldn't see before, holding the wire back. We bent it back just a bit more for safety. Threadlocked it all and it's working fine now:

newfwasm.jpg

Our transmission issue is the only one that remains.

In neutral we put it in drive and then need to almost push the gas all the way down to get the gear to engage. This makes the vehicle violently peel out and throw the passengers around. Reverse is even worse and sometimes it even jumps and bounces on the tires because of the crazy RPMs required to get the gear to engage.

My engine guy thinks it might just need an adjustment from the gear selector control to where ever it connects to on the engine. Otherwise does anyone have any idea what might make a small engine like this require such high RPMs to engage?

Thanks for any advice!

edit:

I should include that once in gear it drives just fine. Until you need to change gears and then, hold on to your helmets, *peelout*
 

·
Premium Member
Joined
·
1,009 Posts
i cant help ya none but i will thank you for tellin us about these. after seein how much trouble your havin with that one make a guy realize that i would never buy one of those!
 

·
Administrator
Joined
·
4,004 Posts
Wish I could help, but have no idea how those trannys work. Never had the need to work on one.
All I can do is wish you luck with getting it sorted out, and echo what Wizzard said, Thanks for the
warning about those specific dune buggies.
 

·
Registered
Joined
·
4 Posts
Discussion Starter #5
I have this posted here and buggynews specifically for that reason. To at least have something people can find in regards to information.

The latest is I had talked to a person who builds ATVs for a living in FL. He built his first TM 300 XRX just yesterday and called me. We discussed the unit and my specific problem. Since the gear lever does put the engine in the correct gear (forward or reverse) there's no issue with that.

What he said was because this is a Yamaha Majesty scooter engine there's a chance my variators weights are misaligned. He tried to explain what a variator was, something with weights on it that once spun, opens as it gets faster. Sometimes the 'weights' that pull it open get misaligned and will interfere with the transmission using lower gears.

He asked me if it felt like it had no low end torque and I had to give it a lot of gas to get going. I said yes that's exactly it. Both to get it in gear and to get it moving you really have to press the gas down too much, but once it's going it works fine. That's why it makes sense this could be the issue. Because in other words it's like starting a regular car in 3rd gear all the time. You need to get the RPMs up super high. I need to spin up the variator so much the lock problem goes away and I'm starting in a higher gear all the time. That makes me need to use high RPMs to get moving and also has the byproduct of being in high RPMs before the clutch engages the gear.

This video helped me understand what a variator looks like and it's exactly as he explained. I haven't figured out if this is my problem just yet but I'll post back just so there's information on the net about this.

Video of a scooter variator
 

·
Registered
Joined
·
459 Posts
Thats called a CVT (constant variable transmission). Basically it consists of two v-belt pulleys. The space between the two angled halves of each pulley varies to control your speed. The one on motor is open all the way while the engine idles so theres no friction between the pulley and the v-belt. The output pulleys two sides are together all the way so the belt rides on the rim of the rear pulley. As you give it gas the two halves of the front pulley pull together causing the friction to move the machine forward. As you give it more gas the pulley pulls together more and more forcing the belt to ride hire up on the pulley. The tension of the belt caused by the front pulley pulling together forces the two halves of the output pulley to move apart causing the v-belt to ride lower on the pulley. As you rev up the pulley's ratios are constantly changing giving you your "Constant variable transmission." I'm not familiar with that specific brand of CVT but It should be like all the rest. Them clutches are very common in snowmobiles.
https://www.youtube.com/watch?v=uCEvBGT8twM
 

·
Registered
Joined
·
4 Posts
Discussion Starter #7
I viewed a whole slew of videos from CAD transparent views to this really (for this thread) on-topic replacement of a clutch and variator:

https://www.youtube.com/watch?v=tZcoM7nUqAU

Thanks for your link, it was one of the best that I've seen. Just for their general audience I wish they pulled apart the variator to show how the weights push out when the pulley spins faster so the audience knew what force the variator was under. It does show a nice clean shot of the clutch spring (I'm scared to unbolt haha, or even rebolt).

I've seen the Yamaha Majesty variator and clutch assembly on the 400cc model and it was literally twice the size with a spring that required a clamp to work with. I'm hoping my assembly will be like the link I posted with just a couple bolts and a spring small enough for two people to handle, though I haven't really gotten that lucky with any part of this kart yet. We're going to open that pandoras box this weekend and are going to check if just replacing the variator is enough for now. Since this was a brand new kart it'd be nice to have a spare clutch anyhow.

Hope this helps anyone else dealing with one of their first few builds.

Thanks again!
 

·
Registered
Joined
·
1 Posts
long time and cold thread... but I have run into the same-ish problem. For me, the factory had routed the shift cables directly over top of the magneto wire harness, destroying the insulation in less than 100 hours use. Purely an incorrect assembly problem, from the factory in China no doubt. I am going to take the cover off to inspect inside also based on your post here.

Thanks for posting pictures and description. Very helpful, all these years later.
 
1 - 8 of 8 Posts
Top