Need Help with Tillotson 212 Engine Binding Issue

4 Stroke Kart Engine Forum
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Hello all!
I will apologize for the length of this post as well as any posting etiquette issues that I am guilty of. I am new to the forum and new to Mini biking.
I decided to remove the governor on my Tillotson engine and ran into some issues. From what I’ve read, the stock Tillotson flywheel, rods, and valve springs should be strong enough to handle higher RPMs.

Flywheel Removal Trouble
I tried removing the flywheel using the method where you apply pressure behind it with a large screwdriver or pry bar while gently tapping the shaft to shock-load it. No luck. I then attempted using a three-jaw gear puller, but the flywheel still wouldn’t budge.

Crankshaft Play and Governor Removal
During the process, the camshaft and one of the lifter pushrods came out. I reinstalled them, making sure the timing marks were aligned. However, I noticed that the crankshaft had quite a bit of lateral play—almost like the bearing’s inner diameter was too large for the crankshaft. I wasn’t sure if that was normal but continued working.

Since the flywheel wouldn’t come off, I left it in place and proceeded to remove the governor by taking off the retaining ring and governor arm shaft. Once that was done, I tried rotating the crankshaft by hand, but it would only move a few inches before binding up. I checked for any misaligned gears or obstructions but didn’t see anything obvious. I did notice the crankshaft gear sat about 3mm forward of the camshaft gear, which I assumed was just because the crankcase cover wasn’t installed.

I pushed the crankshaft back into alignment with the camshaft gear and tried again. It still bound up after about a quarter turn. I removed the camshaft and tested rotation again—same issue. This led me to believe the crankshaft shifting forward might be causing the piston to bind in the cylinder.

After reinstalling the camshaft (double-checking the timing marks), I also made sure that the crankshaft gear was no longer extended past the camshaft gear. At this point, the crankshaft rotated smoothly with only normal resistance from piston compression. Thinking I had fixed the issue, I put the crankcase cover back on, refilled the oil, and tried starting the engine.

Recoil Starter Binding
When I pulled the recoil starter, the cord would only extend about five inches before binding up. If I let it retract and pulled again, it would extend fully but felt much harder to pull. The next pull would be short and bind up again.

I drained the oil, removed the crankcase cover, and checked everything again. Nothing seemed out of place, except the crankshaft gear was once again sitting about 3mm forward of the camshaft gear. Assuming this was because the crankcase cover was off, I pushed the crankshaft back into place and tried rotating it—it seemed fine. But after putting everything back together, the recoil starter issue persisted.

At this point, I’m out of ideas and hoping someone here might have some insight.

Questions:
Any ideas on what could be causing this binding issue?
Is it normal for the crankshaft to have some lateral movement in the bearing?
Should the crankshaft gear be sitting farther forward than the camshaft gear? If not, could that misalignment be causing the piston to bind?
Can the stock rods, flywheel, and valve springs handle higher RPMs? I plan to use the throttle screw as a limiter to keep it from revving too high.
What’s the best way to remove the flywheel if I need to replace the crankcase bearing?
Any help would be greatly appreciated!

Thanks

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Easiest way to help you diagnose will be with video. Unfortunately words will only get you so far.

Was this a brand new engine? Governor is there for a reason. Do you have any sort of tachometer to know what revs you were turning?

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Any ideas on what could be causing this binding issue?

Check the valve lash on the exhaust valve. The tight feeling is compression. When you pull through the first time, that’s the compression release or ez-spin bleeding off some of that compression, but when it’s tight again, that’s the compression after the compression release closes. Your valve lash may be loose. It should be less than .003 or as close as possible to 0 without pre-loading it.

Is it normal for the crankshaft to have some lateral movement in the bearing?

Yes, this is a normal tolerance for oil around the shaft; that is why we have oil seals. Once the side cover is on, it shouldn’t cause bind problems.

Should the crankshaft gear be sitting farther forward than the camshaft gear? If not, could that misalignment be causing the piston to bind?

The camshaft gear is narrower than the crank gear. About the helical gear used by the Honda-based engines, as it rotates, it wants to move laterally, and without the crankcase cover on the engine, it wants to separate, which can cause it to bind. Once the side cover is on the engine, its a non-issue

Can the stock rods, flywheel, and valve springs handle higher RPMs? I plan to use the throttle screw as a limiter to keep it from revving too high.

In karting, the 196cc engines have turned a little over 7000rpms with a stock rod. However, the most common failure is the rod dipper failing. Most use the MARS brand rod because the dipper holds up better, but it’s still a stock rod that gets replaced fairly often.

The flywheel is dangerous at higher rpms. The Tillotson 212E flywheel has been falsely advertised to handle up to 10,000 rpms. It’s no different than what comes on the Predator or any other stock Honda clone engine, but it’s been marketed that way to sell you on the engine. You should have bought a Ducar 212, which has the same engine but comes with a die-cast aluminum flywheel. It wouldn’t need to be replaced and cost less than the Tillotson 212E.

For mini bike use, I suggest using a cast aluminum flywheel with a 6200rpm rev limited coil at a minimum unless you decide to put a billet rod in the engine.

What’s the best way to remove the flywheel if I need to replace the crankcase bearing?

Use a flywheel knocker, and don’t be gently hitting it; it should come off.

1 Like
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Wow Mark Thank you for all this great information! I figured it out, it was the rod that goes up to the rocker was not seated so it wouldnt start. It’s funny you mentioned the flywheel because when I took the cover off, I was like this looks exactly like the flywheel on my Coleman 196cc which i know is not rated for much past 3500 rpms. I am going to take your advice and get the cast aluminum one. Yeah I am very disappointed in the Tillotson. When I got it I followed the break in procedures put it on my Mini-Bike and was surprised the acceleration was slower than my stock motor. So my wife and I raced she was on her coleman b200 with the stock motor. We did a 1/4 mile and she beat me by 5 bike lengths. My top speed with the stock 196 was 39 mph, with the stock Tillotson it was 31mph talk about frustrated! Thats how I ended up here!
Again Thanks for the information!!

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Clayton,
I appreciate the response, if I hadn’t got lucky and figured it out I was going to put up a video. Now I am stuck trying to figure out why it either smokes or won’t stay running unless it is choked… What a debacle! I wished I had asked people’s thoughts on here before buying this turd!

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Trust me, I understand your frustration. We’ve been working with Tillotson for 40 years and have helped build a good reputation for it, but these newer companies handling their products are overzealous in their marketing and lack experience. We have to deal with many of their shortcomings and have worked to correct their mistakes.

The 212 engine should make more than 1hp(the 2121E isn’t 9-10hp as advertised) than the 196 at around 5000rpms. Still, below 3600, there isn’t enough power difference, so any difference in the gear ratio(including tire circumference), load, or parasitic losses will quickly negate any power difference, which may be the difference in your race.

The smoking or stalling issue with the engine could be the issue with the vents on the fuel tank. If the tank isn’t venting well, carburetor tuning issues can occur. It could also be debris clogging the jets for fuel circuits. Also, check the fuel cut-off that it’s completely open, we’ve had customers have it partiallly closed without realizing it. Last could be the jets are on the small size or the air bleed on the larger side of their factory tolerance. Considering the EPA regulations, these stock engines barely run as is. If you are using the factory air box and exhaust, you may need a .030-.032 main jet, and if you replace the exhaust and air box, you may need .036-.038. The bigger jets should help the engine start and run a little better.

I would also do a leak down on the cylinder head; if it’s not sealing well(you may try lapping the valve)or if you preloaded the lash adjustment, it will be harder to start and run poorly.