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  #21  
Old 09-22-2019, 08:04 PM
MattB MattB is offline
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I'm following this thread closely as I have a Trailmaster that I've managed to get street legal. I'm running around 20hp and experimenting with my gearing. I'm running an authentic comet 30 with aluminium weights and white springs. I have a 60,54,46 and 38t sprocket. So far the 38t sprocket has performed the best running 55mph at 3800 rpms. I'm really inexperienced so interested to learn about these tavs.
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  #22  
Old 09-23-2019, 09:16 AM
onionfmr onionfmr is offline
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***FINAL UPDATE*** Made some spacers and installed the 9 tooth jackshaft sprocket over the weekend, everything else remained the same as my last previous update. Picked up approximately another 500 engine RPMs. The riding range for the mini bike improved markedly. I'll probably settle on this gearing and setup for the mini bike. Now, on to installing a genuine Comet TAV, fabricating and mounting a new real gas tank to replace the fake one, new modified exhaust with muffler, new fenders, adjustable engine plate, new 10" rear shocks, new seat setup, engine top plate. and new chain guard.

---------- Post added at 10:16 AM ---------- Previous post was at 10:01 AM ----------

Quote:
Originally Posted by MattB View Post
I'm following this thread closely as I have a Trailmaster that I've managed to get street legal. I'm running around 20hp and experimenting with my gearing. I'm running an authentic comet 30 with aluminium weights and white springs. I have a 60,54,46 and 38t sprocket. So far the 38t sprocket has performed the best running 55mph at 3800 rpms. I'm really inexperienced so interested to learn about these tavs.
Wow! 55 MPH is pretty good at 3800 RPMs. Whatever you are doing, sounds like you are doing it correctly! You have a very powerful engine! What exactly is it? Build specifications?

Maybe sid will chime in? Sid really knows this stuff! I'm no expert on any of this. However, I have tried a lot of different setups with engines and gearing. One thing that I have learned, it is pretty much trial and error to see what actually works! Your can make calculations and estimates. But, on these TrailMaster MB200-2 mini bikes, you don't always get what you think you are going to get.

Another thing that I've learned regarding the TAV, looks like you have already figured it out, is changing the garter springs, weights in the driver unit and position hole and tension of the driven unit spring can make a huge difference in performance!
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  #23  
Old 09-26-2019, 12:44 AM
MattB MattB is offline
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I ordered my engine from studzracing.com.
BSP Race Engine Level 5
24mm Mikuni Jetted Carb
290/260 CAM
Champion Rockers
37lb. Springs
22cc Full Race Port Head Milled
SS Valve 27mm Intake Exhuast
Billet Molly Push Rods
ARC Billet Rod .020
Flat Top Piston
ARC Billet Race Flywheel
APPROX.20hp

I'm going to try running a clutch with a jackshaft and see what kind of speeds I can come up with. I'll post my results in this thread
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  #24  
Old 10-04-2019, 08:06 AM
onionfmr onionfmr is offline
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Quote:
Originally Posted by MattB View Post
I ordered my engine from studzracing.com.
BSP Race Engine Level 5
24mm Mikuni Jetted Carb
290/260 CAM
Champion Rockers
37lb. Springs
22cc Full Race Port Head Milled
SS Valve 27mm Intake Exhuast
Billet Molly Push Rods
ARC Billet Rod .020
Flat Top Piston
ARC Billet Race Flywheel
APPROX.20hp

I'm going to try running a clutch with a jackshaft and see what kind of speeds I can come up with. I'll post my results in this thread
Would be cool if you could post a picture of your mini bike. What are you using for a gas tank?
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  #25  
Old 10-04-2019, 09:47 AM
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itsid itsid is offline
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Quote:
Originally Posted by MattB View Post
... I'm running around 20hp and experimenting with my gearing. I'm running an authentic comet 30 with aluminium weights and white springs. I have a 60,54,46 and 38t sprocket. So far the 38t sprocket has performed the best running 55mph at 3800 rpms. I'm really inexperienced so interested to learn about these tavs.
?! HOW..
with aluminium weights (148g) and white springs you raised engagement speed to 4000 rpm ..
which means @ 3800 rpm the clutch isn't even fully engaged yet
(and most power is turned to belt dust and heat)

and since the clutch isn't even fully engaged @3800
the overall ratio would be 10.2:1 soo you're travelling at maybe 20 mph

Sorry Matt, but something you said is clearly wrong..
I hope spring color and or flyweights..
also
IF 38T would be good gearing for your setup on a series 30..
and the TC would have had shifted up
you'd be travelling at 62.8 mph @3800 (8mph more than you claimed) btw

But with a stage 5 clone with 37lb valve springs
I think is fair to assume the engine is meant to run maybe TWICE those rpms.
(and forgive me but I doubt you can even push it to the theoretical max speed of 110 mph at all)

So no.. 38T is a terrible idea in my book.
let's just assume you would have all the power claimed
(20 horses...hardly.. but let's stick with that)
then your absolute max speed would still be just under 80mph
(just air drag alone would stop you going any faster)

And if we further assume the engine is meant to rev 7600 rpms peak
and since it's street legal you want to keep it ~10% below at all times
you'd dial in for max speed (79+some odds mph @ 7000 rpm)
and that'd be a 55 or better 56 T sprocket
if you want all the rpms for some reason you need even more teeth (62 to be precise)

Also studzracing CLEARLY states:
Quote:
(NOT FOR USE ON ANY EQUIPMENT, OFF ROAD, RECREATIONAL, OR EMISSIONS CONTROLLED. APPLICATIONS. DOING SO IS A VIOLATION OF FEDERAL LAW)
So yeah, you spent 1100 dollars on an engine that the seller clearly tells you must not be installed on road legal equipment... tight move!
and you still claim you made it somehow road legal ... tight claim!
with all the above and especially
since coincidentally your 55mph matches a miserably rounded result for
a cent clutch setup of 3.8:1 @3800 rpms...
I say you DO NOT travel 55mph on a road legal Trailmaster mini bike,
I even doubt you have a stage 5 engine!

Frankly Matt,
pics or it didn't happen!!

'sid
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  #26  
Old 10-07-2019, 12:42 AM
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landuse landuse is offline
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Quote:
Originally Posted by MattB View Post
I ordered my engine from studzracing.com.
BSP Race Engine Level 5
24mm Mikuni Jetted Carb
290/260 CAM
Champion Rockers
37lb. Springs
22cc Full Race Port Head Milled
SS Valve 27mm Intake Exhuast
Billet Molly Push Rods
ARC Billet Rod .020
Flat Top Piston
ARC Billet Race Flywheel
APPROX.20hp

I'm going to try running a clutch with a jackshaft and see what kind of speeds I can come up with. I'll post my results in this thread
Dang!!!! I think 99% of us DIY'ers would never spend $1100 on an engine. Even if it is fancy
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  #27  
Old 10-07-2019, 01:35 AM
MattB MattB is offline
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http://https://m.imgur.com/a/j30GqCV

---------- Post added at 01:55 AM ---------- Previous post was at 01:44 AM ----------

Aluminium weights, blue springs and the green spring on the #3 hole on the comet driven put me at 55 mph on flat land. I'm 270 lbs. I've ran a 60, 54, 46 and 38t sprocket. The 38 has given the best results.

---------- Post added at 02:16 AM ---------- Previous post was at 01:55 AM ----------

Quote:
Originally Posted by landuse View Post
Dang!!!! I think 99% of us DIY'ers would never spend $1100 on an engine. Even if it is fancy
Yeah, I've noticed most in the minibike community are working with tight budgets.

---------- Post added at 02:35 AM ---------- Previous post was at 02:16 AM ----------

This Sid guy seems like a straight up weirdo! Lol

If anyone has any real experience with Trailmaster gear ratios please chime in.
Quote:
Originally Posted by itsid View Post
?! HOW..
with aluminium weights (148g) and white springs you raised engagement speed to 4000 rpm ..
which means @ 3800 rpm the clutch isn't even fully engaged yet
(and most power is turned to belt dust and heat)

and since the clutch isn't even fully engaged @3800
the overall ratio would be 10.2:1 soo you're travelling at maybe 20 mph

Sorry Matt, but something you said is clearly wrong..
I hope spring color and or flyweights..
also
IF 38T would be good gearing for your setup on a series 30..
and the TC would have had shifted up
you'd be travelling at 62.8 mph @3800 (8mph more than you claimed) btw

But with a stage 5 clone with 37lb valve springs
I think is fair to assume the engine is meant to run maybe TWICE those rpms.
(and forgive me but I doubt you can even push it to the theoretical max speed of 110 mph at all)

So no.. 38T is a terrible idea in my book.
let's just assume you would have all the power claimed
(20 horses...hardly.. but let's stick with that)
then your absolute max speed would still be just under 80mph
(just air drag alone would stop you going any faster)

And if we further assume the engine is meant to rev 7600 rpms peak
and since it's street legal you want to keep it ~10% below at all times
you'd dial in for max speed (79+some odds mph @ 7000 rpm)
and that'd be a 55 or better 56 T sprocket
if you want all the rpms for some reason you need even more teeth (62 to be precise)

Also studzracing CLEARLY states:


So yeah, you spent 1100 dollars on an engine that the seller clearly tells you must not be installed on road legal equipment... tight move!
and you still claim you made it somehow road legal ... tight claim!
with all the above and especially
since coincidentally your 55mph matches a miserably rounded result for
a cent clutch setup of 3.8:1 @3800 rpms...
I say you DO NOT travel 55mph on a road legal Trailmaster mini bike,
I even doubt you have a stage 5 engine!

Frankly Matt,
pics or it didn't happen!!

'sid
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  #28  
Old 10-07-2019, 01:05 PM
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itsid itsid is offline
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Quote:
Originally Posted by MattB View Post
..I'm running an authentic comet 30 with aluminium weights and white springs. ..running 55mph at 3800 rpms...
he said
Quote:
Originally Posted by itsid View Post
?! HOW..
with aluminium weights (148g) and white springs you raised engagement speed to 4000 rpm ..
which means @ 3800 rpm the clutch isn't even fully engaged yet
(and most power is turned to belt dust and heat)

and since the clutch isn't even fully engaged @3800
the overall ratio would be 10.2:1 soo you're travelling at maybe 20 mph

Sorry Matt, but something you said is clearly wrong..
I hope spring color and or flyweights..
....
said I...

Quote:
Originally Posted by MattB View Post
...Aluminium weights, blue springs and the green spring on the #3 hole on the comet driven put me at 55 mph on flat land. I'm 270 lbs. I've ran a 60, 54, 46 and 38t sprocket. The 38 has given the best results....
great, now the garters turned blue.. good.. we finally have a fully engaged clutch in your TC,
and even enough oomph to get it to shift up a notch
~1:03:1 is close to 1:1 but still far from the possible 0.9:1 the TC is capable of
(that'd result in the aforementioned 60++mph)

And there's little room for reasoning I'm afraid:
the engine doesn't have enough power (TORQUE!)
to make it shift up further at that specific rpms. period!

With an engine allegedly hoarding 20 horses,
that can only mean ONE thing:
your gear ratio is terrible for your engine and setup.

Either the engine has far less power than claimed,
or the engine has a significant lack of torque up to 4k rpms
and only starts pushing above that threshold (like a 110° cam or so)

in both cases you need to gear lower in order to cross that dip.
since a stage 5 engine is far from being limited to just 3800 rpms
(very likely capable of passing 7k rpms with ease)
there is 100% no reason to not make use of the additional rpms that are at your disposal.

And that raises another issue with the terrible gear ratio you have:
you CANNOT reach the theroetical max speed with it!
you simply cannot break the laws of physics,
therefor your top speed will be limited to roundabout 80 mph
(at whatever rpms your peak hp is set to be)
And that suggests a 5.5:1 or lower gear ratio

I doubt your engine has a governor (all modifications of a stage 5 engine are rendered useless with one)

Sure you're far from being skinny and ridning a far from being lightweight bike.
and that combination isn't working in your favour at all
BUT if 55mph is all your engine is capable of,
then it has less than 8hp! (7.4hp to be precise ...a very mild stage 1 engine that'd be)

So yeah.. pick the flaw yourself..
(hint: engine power or gear ratio are BS.. maybe a combination!)

'sid

PS funny btw that you show us a pic of a SR hemi Tillotson 212 (10hp)
and not bsp 196 stage 5 (20hp) you claimed to have installed.. just a coincidence I think
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  #29  
Old 10-07-2019, 04:55 PM
MattB MattB is offline
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[URL="https://imgur.com/a/Tw7W6T3"]https://imgur.com/a/Tw7W6T3[/URL

It says 196r on the block. What do you suggest the gear ratio I run? I'll run it and see if your calculated results match up with the real world results. I'm new at this and trying to learn.

---------- Post added at 05:46 PM ---------- Previous post was at 04:56 PM ----------

https://imgur.com/a/Tw7W6T3

---------- Post added at 05:55 PM ---------- Previous post was at 05:46 PM ----------

https://imgur.com/a/Tw7W6T3
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  #30  
Old 10-07-2019, 08:18 PM
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itsid itsid is offline
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Thank you!

To me that valve cover looks like the dull hemi one from what little we can see of it,
but truth is.. should've noticed that the 196s have a different shroud than the 212s
my fault!

Now..

As I said you want to gear much lower, in order to find the sweet spot of your engine;
it should rev 7k++ rpms and that means it's peak torque is likely around 4500 or so rpms.
(ask studz if they can give you a better estimate)
And that is where the fat lady sings in this opera.
Something you surely do not want to miss out on.

I'd say upwards of 55 teeth is what you want (56, 57, 58 such)
since you have a 60T.. go with that!

And while it surely is slower at any given rpm up to 3800 rpms than the 38T,
it's what follows that will make a huge difference.
Not only you should be able to easily hit speeds above 70mph
(again with 20 horses nearly 80mph are doable)
you will also have the torque to get up to the rpms that are necessary to reach such speed.

let's just say 7k rpm.... 73mph is still a scary amount considering the mini bike thingy you sit on.

KartInfo by kartcalc.net:
Code:

KART
RW diameter: 19 in | 48.26 cm Total weight: 436.51 lbs | 198 kg
ENGINE
Original HP: 20 Asummed HP: ~20 Torque: 15.01 ft lbf | 20.35 Nm RPM: 7000
TRANSMISSION
Final ratio: 6:1 TC type: series 30 6" driven Lowest ratio: 16.2:1 Highest ratio: 5.4:1
PERFORMANCE
Max Wheel Torque: 243.15 ft lbf | 329.67 Nm Min Wheel Torque: 81.05 ft lbf | 109.89 Nm Acceleration: 12.86 ft/sē | 3.92 m/sē Top Speed: 73.27 mph | 117.92 km/h
5.7:1 @ 7200 rpms -> 79.3ish mph (very close to the limit!)
or if your engine does not rev that high (doubt it)
5.4:1 @ 6800 rpms -> 79.09 mph
5.2:1 @ 6500 rpms -> 78.5 mph

And yeah.. my point hasn't changed.. if all you can reach is 55mph, then all you have is 7.4horses
(I think that's about what you do have @3800 rpms tbh.. until the fat lady starts singing )

'sid
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  #31  
Old 10-07-2019, 08:29 PM
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Sounds good. I'll get back with this thread soon and let you know how it went!
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  #32  
Old 10-07-2019, 11:38 PM
MattB MattB is offline
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Sid, any idea what my driven setting should be on the comet 30? I have a green and a yellow spring , there are 3 holes marked #1, #2, #3.
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  #33  
Old 10-08-2019, 11:38 AM
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itsid itsid is offline
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I'd go for OEM (wich usually is red.. but I think the green one was on yours right?)
and put it in #2 (stock setting)
first.

IIRC the yellow one is stiffer, and more preload (hole #3) is the "torque" setting.
holding the TC back from shifting up as long as possible.

I'd go with stock first and let the butt be the judge..
if it feels like there's a hair of torque missing (hole #3 and then yellow in #1, #2 and finally #3)
but I thinnk it should be fine keeping the driven in stock config.
since yeah.. you don't actually could complain about your engine not having enough oomph, could you

'sid
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