Can’t Start Bullet Train

[Magicaldave]

hey Guys, Dave from OK here. Really hoping I can get some help as right now I’m hundreds of dollars in the hole on a really pretty brick.

Bought a bullet train and a handful of parts from bikeberry. Instant regret. But I figured I could make the hardware work. Since the build was complete it’s been **** to get it to start with either the electric or pull starts.

Intermittently, the engine will rev up just a bit and if I’m really careful I can get it to start. Once it does start it actually runs great, for the most part. It feels like it’s trying to give out more power than it’s actually able, like something is very wrong somewhere. Sometimes during operation, especially when going downhill, the engine will randomly stop and sputter out of life. When this happens it takes about an hour or so and it’ll start up with about the same amount of work as before.

I’ve tested, cleaned, and gapped multiple spark plugs. Pulling out the spark plug and testing on the engine reveals it sparks perfectly fine, but it SOUNDS like the problem when trying to get it to start is that there’s no spark. Not sure how to describe this.

Also checked for fuel flow and installed two carbs - one, the stock NT it came with and a “hi-performance” carb I bought as well. That thing is just a piece of trash.

As a bike it works fine but I cannot get it to start without putting way too much effort in. Plz halp. And thank you.

 

[Greg58]

Welcome to the forum, there’s been a couple of people asking the same thing. It sounds like a intermittent problem so check all connections of the wiring, since that engine hasn’t been around long we don’t have a lot of information on it.

 

[Magicaldave]

Thank you! It’s nice to have a place to hang out online for this sort of thing.

I realized I’d left my fuel lines open for however long it’s been since I last messed with it. That’s not helping anything. Left the line wide open and pulled the spark plug overnight, hopefully that helped.

I have some suspicions it’s a bad mag. Do you have any suggestions to test that?

 

[Magicaldave]

Think the real problem ended up being the carb. Figured the stock carb would work better and after leaving it overnight, she fires right up with either start method. Even sounds better at idle. Woot!

Will test a bit and see if it still does while riding.

Any suggestions for a carb that actually performs better than the stock one?

 

[Greg58]

The nt is a good choice for a stock engine, once you get it broken in and get the jet correct the nt is not bad.

 

[Greg58]

I have developed a routine of turning the fuel off while riding up to stop for any length of time.

 

[Magicaldave]

I have developed a routine of turning the fuel off while riding up to stop for any length of time.

Forgive me but I’m not quite sure what you mean by this.

You mean that you close your fuel lines while going uphill... so you can stop? I’m sorry if that seems dense!

My problem has been going downhill in particular, not uphill.

 

[Greg58]

No, I close the fuel shutoff at the tank and run the engine a while to make sure the carb bowl is not totally full.

 

[Magicaldave]

No, I close the fuel shutoff at the tank and run the engine a while to make sure the carb bowl is not totally full.

Ahhh. Normally that’s what I do, but when using the HP carb I had to do the opposite.

It wouldn’t deliver fuel properly and pooled up a lot in the air filter. I think that’s part of why I had to choke it to get it to start. Didn’t exactly figure that last part out until I removed it and gas came pouring out all over my hand, even with the line removed.

 

[Magicaldave]

Was going to post on here with more failure, but actual success this time!

Came back later and she started giving me the same trouble with starting as before. I guess clearing the lines helped a bit but even with them closed, a few hours on the porch did it right back in. When I DID get it to start it was weak and died after about 100 feet.

Swapped in the stock plug for farts and giggles... WOW. Ran so much faster I didn’t even feel comfortable running at full speed. Revealed a couple new but minor issues, like the vibration causing my tank to fall to one side. Some defect or another in my build caused me to lose my master link while going downhill - fun walk back home - but I think I can work that part out.

 

[Greg58]

The vibrating tank can happen when the top bar has a curve in it, one of my bikes did that, I ended up adding rubber at each mount and turning the bike upside down and using a caulking gun with silicone to fill all voids under the tank. I let it sit that way a few days and it solved the problem. As for the master link always point the open end of the clip opposite the way the chain travels.