What's Wrong With My Bike?

I’m continuing an older thread with a new problem…

I got my 1876 Batavus HS-50 running, but after parking it for 20 minutes, it wouldn’t start up again. About 30 minutes of trying got it running, but I don’t know why.

I’m wondering if there’s too much air getting in? Too much gas? When trying to get it started nothing happened unless I pulled the choke. As soon as I let go of the choke it stopped trying to start.

The bike used to start RIGHT up very easily every time. I checked the exhaust for build up, cleaned the carb well and put in a new spark plug. The insides of this bike are really clean. There don't seem to be any leaks from anywhere.

Also, there’s some hesitation now when accelerating…almost seems like the fuel and/or air supply isn’t consistent.

I took the clutch apart since it wasn't protected well and was really dirty, maybe causing it to not disengage when coming to a stop, even with a good idle.

Can clutch parts be cleaned with carb cleaner?


Re: What's Wrong With My Bike?

this is just a random guess, but maybe the engine itself needs to be decarbonized.

Re: What's Wrong With My Bike?

Carbon problems tend to come on slowly - not just suddenly make the bike stop running. However, it is possible that a big chunk of carbon came loose and plugged the exhaust.

I'd use brake & electrical parts cleaner to clean dry clutch parts. Less agressive than carb cleaner, and leaves no residue behind.

Re: What's Wrong With My Bike?

Jason Luther /

have you checked your ignition timing?

Re: What's Wrong With My Bike?

I dunno any specifics about that bike, but the carb might be leaking directly into the engine.. forming a puddle of liquid fuel in the crankcase. Then, when cranking, liquid fuel fouls the plug.

the leak could also account for what seems to be inconsistant fuel delivery .. actually it's way too rich, due to a overflowing float bowl or just a real high float level or similar..

the choke would lean the mix and might allow it to restart and run a bit.. but the puddle in the crankcae assures it won't run for long.

Some engines have a drain plug to quickly drain the crankcase (makes you wonder how much faith the manufacturer had in their engineering expertise) but you can purge it by closing off fuel supply, removing the spark plug and cranking the engine over for a couple minutes. The liquid fuel is expelled through the plug hole and exhaust port.

i'm not sure how to diagnose this directly .. Indirectly, maybe just shut off fuel supply while parked. And if the trouble only occurs when fuel supply is left ON, it's pretty likely there is a carb leak.

Re: What's Wrong With My Bike?

You know, there is a TON of carbon build up on the top of the piston, bottom of the head (where the spark plug enters) and in the exhaust.

What causes carbon build up and how can I prevent it in the future?

To decarbonize the engine, do I need to remove it from the bike? I have the header and cylinder off now so the crank arm is exposed. Would I need to take off ALL of it?

I put in a brand new spark plug, and after about 15 miles of riding there was a good amount of carbon on the outside ring surrounding the electrode.

How do I adjust the float?

I haven't adjusted the timing yet...seems like it's more complicated than piston rings.

How do I tell if fuel is leaking into the engine and how do I prevent that? My reed valve looks good from what I can tell, but it's also my first bike so I'm not super experienced.

Thanks again for your help!

Re: What's Wrong With My Bike?

the problem is it was made in 1876 which was a bad year in the netherlands

Re: What's Wrong With My Bike?

carbon buildup happens naturally when the engine burns fuel, especially in a two stroke where the oil is mixed in. i don't think it can completely be eliminated. decarbonizing usually covers the exhaust and inside of the cylinder head.

Re: What's Wrong With My Bike?

Leon Swarmer /

leave the engine in the bike . To decarbonize you just need to clean the top of the piston, The inside of the head and the exhaust port. use something soft (plastic scrapers). you are dealing with lightwieght materials. Try not to get the carbon into the crankcase.

adjusting timing should not be a very big deal

Re: What's Wrong With My Bike?

I find that synthetic oil reduces carbon ALOT :P

Re: What's Wrong With My Bike?


While parked do you leave your petcock open or closed?


Re: What's Wrong With My Bike?

No, I always close it.

Someone mentioned that my drive chain being too tight might have something to do with it too. I noticed that after tightened the chain a LITTLE, it was really tight when I pedaled it back home for 45 minutes. YAY! Maybe it tightened up during the ride and got so tight the engine gradually lost power wouldn't turn over again?

What is a good brand of synth oil and where do you get it? The best I've found in local auto shops is Valvoline 2-stroke oil for all 2-strokes (lawn mowers, outboards, etc.)

I'll try adjusting the timing too...this bike will be fantastic once I'm done...I hope.


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