Need help with db30/predator 212

S

Stclair

New Member
#1
#1
Hey guys first post here. I got an old db30 a couple months ago and put a predator motor in it. I added a header pipe, non epa carb, air filter and included .038 jet. It has the stock rear sprocket and I put a 12t centrifugal clutch on it. Everything came from OldMiniBikes warehouse.

It starts up and runs well, but it vibrates hard during acceleration and doesn’t accelerate very quickly. It won’t wheelie even if given full throttle from a dead stop. I ordered a jet kit with an etube and a 36 and 37 jet but it hasn’t arrived yet and I’m not sure if that’s even the issue.

thanks

mike
 

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minibikin'

minibikin'

Sho-nuff
#2
#2
Welcome aboard. Rider weight and gearing go hand in hand. You can get the sprocket hub that accepts split sprockets and change your gearing easily and cheaply. If your looking for acceleration and wheelies combined with top end, I would upgrade to a 30 series TAV. Gives you the best of both worlds. The only way to tell if the engine is rich or lean is to read the spark plug....
 
S

Stclair

New Member
#4
#4
thanks for the quick reply’s I did pull the plug and it was a grey color not wet. Gearing is 12/70? Stock db rear sprocket. And I’m about 200 pounds. Talking with a friend of mine he said with that motor and gearing it should be hard to keep the front end down. That’s kind of what prompted this thread.

I neglected to oil the clutch before installing it. Didn’t know I had to with a brand new clutch. I put a little oil on the outside of it after the fact hoping it would work it’s way in but I’ll pull it apart this evening, oil it, and see if that helps. Is it common to need a 3 jaw puller to remove the clutch? I’ve seen videos where they slip right off the shaft.

thanks
 
minibikin'

minibikin'

Sho-nuff
#5
#5
Stclair said:
thanks for the quick reply’s I did pull the plug and it was a grey color not wet. Gearing is 12/70? Stock db rear sprocket. And I’m about 200 pounds. Talking with a friend of mine he said with that motor and gearing it should be hard to keep the front end down. That’s kind of what prompted this thread.

I neglected to oil the clutch before installing it. Didn’t know I had to with a brand new clutch. I put a little oil on the outside of it after the fact hoping it would work it’s way in but I’ll pull it apart this evening, oil it, and see if that helps. Is it common to need a 3 jaw puller to remove the clutch? I’ve seen videos where they slip right off the shaft.

thanks
Click to expand...
You shouldn't need a puller. I use a tiny bit of anti-seize before installing mine so they come off easily.
 
Triley41395

Triley41395

Well-Known Member
#6
#6
Stclair said:
thanks for the quick reply’s I did pull the plug and it was a grey color not wet. Gearing is 12/70? Stock db rear sprocket. And I’m about 200 pounds. Talking with a friend of mine he said with that motor and gearing it should be hard to keep the front end down. That’s kind of what prompted this thread.

I neglected to oil the clutch before installing it. Didn’t know I had to with a brand new clutch. I put a little oil on the outside of it after the fact hoping it would work it’s way in but I’ll pull it apart this evening, oil it, and see if that helps. Is it common to need a 3 jaw puller to remove the clutch? I’ve seen videos where they slip right off the shaft.

thanks
Click to expand...
I've not had to use a puller.
 
creia

creia

#8
#8
ALL of these Predator engines vibrate- some (much) more than others. What you might do (and what my son and I did on both of our DB-30s) is strengthen the engine mounting plate. The stock engine mounting plate on your bike is pretty wimpy (thin gauge)- remember, it was designed for an engine with less than 1/2 of the HP of what you have now! We bought new engine mounting plates that were already slotted and had them welded to the existing engine plates and it did help cut down the vibration. No way on having to use a puller on a clutch- take the clutch off and run the engine at idle while moving some 600 grit sandpaper back and forth on the rotating crank end. Take off just enough material so that the clutch slides on and off easily. Also, make sure that your crankshaft slotted key way and key are not bunged up- the key should slide along the key way easily.
Michael
 
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S

Stclair

New Member
#9
#9
The clutch slides nice on the shaft until it gets to the last 1/4” and then gets tight. I got it off and took it apart and oiled the bushing and it did seem to smooth it out a little. It’s probably the first 0-30% throttle shakes kind of hard and then it smooths out. If I’m already rolling and then give it throttle it’s a lot less noticeable. I really don’t have anything to compare it to though so it might just be normal?
 
ole4

ole4

#12
#12
These small engines do vibrate as there is no way to get rid of the primary and secondary imbalance inherent in a single cylinder engine without a balance shaft or other balance contraption. Due to their small size it should not cause any problems unless you modified the engine such that the reciprocating weight increases of you put on a out of balance flywheel or clutch Generally its not the engine causing a problem like you have. To isolate the problem you can remove the clutch from the engine, start it and rev it a bit and see if you feel excessive vibration. Also did it vibrate like that before you made the changes? If the engine by itself with clutch removed still vibrates the chassis then you need to check engine mounting plate for any cracks, bad welds etc. Adding a head steady has fixed some vibration issues but I'm not sure on a predator where to add one. Clutch chatter and poor engine tune can also cause stuttering that can be mistaken for vibration.
 
DaddyJohn

DaddyJohn

Well-Known Member
#13
#13
Stclair said:
The clutch slides nice on the shaft until it gets to the last 1/4” and then gets tight. I got it off and took it apart and oiled the bushing and it did seem to smooth it out a little. It’s probably the first 0-30% throttle shakes kind of hard and then it smooths out. If I’m already rolling and then give it throttle it’s a lot less noticeable. I really don’t have anything to compare it to though so it might just be normal?
Click to expand...
Like creia mentioned, these engines can vibrate to varying degrees, likely due to differences in manufacturing tolerances. I’ve had some that were reasonably smooth, and others that felt like a paint shaker. It’s possible you have one of the not-as-good ones.

On the clutch, you’ll find that the integral internal key gets thinner as you go across the bore, but you still have a little ridge all the way to the edge. If you use a grinding stone on your Dremel and get rid of the ridge to about 1/4” into the bore, the clutch should slide easily all the way over. If you look at the keyway on the crankshaft, there’s a little radius at the inside end, and that’s where the ridge in the clutch usually interferes.
 
Strigoi

Strigoi

#14
#14
toomanytoys said:
My predator shook my bike so bad. For some tilitson and ducar seem to shake less
Click to expand...
It depends on the engine. I have a DB30 that shook to the point it was almost unrideable with multiple setups in it (including a stock Ducar 212). It was either a very bad vibration while the clutch was engaging (tried multiple clutches) or a high frequency vibration in the bars that was actually painful when it had a torque converter installed. I currently have a stage 2 Predator 212 with a .272 cam, 24mm flat slide carb, flat top piston, billet parts and a regular Max Torque clutch in that frame with 12/70 gearing. Aside from running horribly rich right now, that bike is smooth and gets up pretty damn good. I can't wait to see how it runs once I get the jetting sorted as it should be good for 50mph or so. I was almost to at the point of selling it, but I'm glad I didn't now.

I was talking with a friend of mine a couple of weeks ago about carbs when I was over at his place doing some work on my drag bike. He had a kart and a minibike that ran the same size carbs. Neither quite right after lots of tuning, so for shits and giggles he swapped the carbs. Both engines had the same setup and the carbs were set up the same. Both ran great after the carb swaps. For some reasons those carbs just didn't work well with the engines they were originally on.

I don't get it, but that's just how it is sometimes.

Video of said DB30. You can hear it hating life a few times in the video.


I've had a few so I might have overshared a bit.
 
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P

Paul Kowalski

New Member
#15
#15
Stclair said:
Hey guys first post here. I got an old db30 a couple months ago and put a predator motor in it. I added a header pipe, non epa carb, air filter and included .038 jet. It has the stock rear sprocket and I put a 12t centrifugal clutch on it. Everything came from OldMiniBikes warehouse.

It starts up and runs well, but it vibrates hard during acceleration and doesn’t accelerate very quickly. It won’t wheelie even if given full throttle from a dead stop. I ordered a jet kit with an etube and a 36 and 37 jet but it hasn’t arrived yet and I’m not sure if that’s even the issue.

thanks

mike
Click to expand...
Are you still having problems ? check out this video on carbs by Pinky
 
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