Tillotson 212 seems to be cutting out around 6000 rpm and not revving further

vegetable

Active Member
#3
It may help if you tell us the specifics of what was done to the engine, what gearing and tire size, and top speed.
Billet rod&flywheel
Tillotson flat-top piston
HOT265 cam
stock valve springs (24lb in tillotson motors)
24mm geninue mikuni (130 main, 20 pilot)
CDI ignition

13" tires
12t on driven pulley
74t on axle
tested and hit 38mph but the issue in the video prevents me from going faster even though i should be able to
 

River Rat Ron

Well-Known Member
#4
Those springs rule out floating the lifters. If I remember right that cam should pull nicely up to 7500.
Is it popping at the exhaust ? If so my guess is a fuel supply issue. Leaning out…
Are you running a pulse pump or just gravity fed.
Gearing seems good for that setup, plenty of carb.
Run the snot out of it WFO for a few minutes then kill it and pull the plug. If the porcelain is white you’re lean.
 
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vegetable

Active Member
#5
Those springs rule out floating the lifters. If I remember right that cam should pull nicely up to 7500.
Is it popping at the exhaust ? If so my guess is a fuel supply issue. Leaning out…
Are you running a pulse pump or just gravity fed.
Gearing seems good for that setup, plenty of carb.
Run the snot out of it WFO for a few minutes then kill it and pull the plug. If the porcelain is white you’re lean.
it pops only with the muffler off and when i let off
im running gravity fed
Ill run it and check tomorrow, last time i pulled the plug it was black with hints of brown but I dont think i was running the snot out of it

i do have a 135 and 140 jet in my garage but will check with the 130 inside
 

vegetable

Active Member
#6
Those springs rule out floating the lifters. If I remember right that cam should pull nicely up to 7500.
Is it popping at the exhaust ? If so my guess is a fuel supply issue. Leaning out…
Are you running a pulse pump or just gravity fed.
Gearing seems good for that setup, plenty of carb.
Run the snot out of it WFO for a few minutes then kill it and pull the plug. If the porcelain is white you’re lean.
it looks like this, i think i need to go up a jet size
 

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River Rat Ron

Well-Known Member
#7
For your set up that 24mm should be running fat ( rich )
I’m a fan for trying the cheapest, easiest things first.
If it does it again after re jetting you’ll know you need a fuel pump…
One thing I failed to mention as I’m not terribly familiar with Tillison is the coil.
They make a rev limiter coil and I’m not familiar if they are standard or after market.
 
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#8
What do you mean by CDI ignition? The stock coil is a CDI so did you replace it with a aftermarket coil? What Flywheel? The location of the flywheel magnet relative to the keyway determines the timing, if it is a arc flywheel then timing should be 32 degrees BTDC but if you are using a non stock coil I'm not sure. I do not hear any sounds that do not seem normal in your video Engine seems to pull great till your tach says 5000 or so. What tach are you using? Just curious. Make sure throttle raises the slide all the way when you have the throttle open. Check the back of the slide not the front. Engine sounds great to me just seems like it is not at full throttle.
 

vegetable

Active Member
#9
For your set up that 24mm should be running fat ( rich )
I’m a fan for trying the cheapest, easiest things first.
If it does it again you’ll know you need a fuel pump…
One thing I failed to mention as I’m not terribly familiar with Tillison is the coil.
They make a rev limiter coil and I’m not familiar if they are standard or after market.
did another run today, it seems like it is breaking up around 6000 (this time it was more obvious, as it was sputtering and staying)
What do you mean by CDI ignition? The stock coil is a CDI so did you replace it with a aftermarket coil? What Flywheel? The location of the flywheel magnet relative to the keyway determines the timing, if it is a arc flywheel then timing should be 32 degrees BTDC but if you are using a non stock coil I'm not sure. I do not hear any sounds that do not seem normal in your video Engine seems to pull great till your tach says 5000 or so. What tach are you using? Just curious. Make sure throttle raises the slide all the way when you have the throttle open. Check the back of the slide not the front. Engine sounds great to me just seems like it is not at full throttle.
cdi as in electronic igniton (found on mopeds and other, a guy in canada makes these kits for predators and other engines) ill check the slide and make sure it is going. swapping out the main jet tonight then will be testing it tomorrow. as for the tach it is one of those autozone tachometers (iEquus 8068)
 

River Rat Ron

Well-Known Member
#17
I was afraid of that. I would invest in a fuel pump. Once installed you’ll probably be running very rich…try it.
More than likely you’ll have to jet it down ( leaner ) than it was initially. It’s sucking the bowl dry is my guess
Drill and tap your intake manifold for a clean pulse. You can pull it from a pcv line but you risk oil vapor in your pump.
 
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#20
thank you, but i might have to wait a couple days. my fuel filter decided it was a good time to break, and i dont have any others on hand at the moment
Try running it without the fuel filter, it may be too restrictive. There are inline fuel filters for pressurized systems and there are inline fuel filters for gravity fed systems. They look basically the same, it's what's inside that's different. The pressurized filters have a finer medium (block smaller particles) making them more restrictive, possibly too restrictive for gravity feed depending on application (flow requirement). If you replace the filter, get a filter made for gravity feed.
 
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