Another live axle conversion

[SpiderSpartan]

Here's a few shots of the wiring cleaned up. I still need to figure out some kind of remote choke control.

 

[chancer]

Something like this I think will work
http://www.ebay.com/itm/Replacement...f36b7e6&pid=100338&rk=1&rkt=8&sd=161261318354

 

[SpiderSpartan]

I have a new problem now. I adjusted the throttle and I'm getting good throttle response now, but apparently this engine's top speed is 1800 RPM. The torque converter is supposed to fully engage at 2200 RPM. Is there a lighter replacement spring I could get that reduces the engagement speed?

 

[Hellion]

Surgery? De-governor-ate it.

Just a note on the kart's "patina". The rust on the floorpan and the gas tank.... looks kinda neat that way.

 

[SpiderSpartan]

I've adjusted the governor to the max setting, but I really don't want to fully remove it. I've seen what can happen when you do and it makes me too nervous.

What I've dug up is the pink garter springs change the engagement to 1800 RPM. The only place I've been able to find them so far though is ombwarehouse.com. Anyone ever buy from there or know anywhere else I could get them?

 

[Poboy kartman]

I've adjusted the governor to the max setting, but I really don't want to fully remove it. I've seen what can happen when you do and it makes me too nervous.

What I've dug up is the pink garter springs change the engagement to 1800 RPM. The only place I've been able to find them so far though is ombwarehouse.com. Anyone ever buy from there or know anywhere else I could get them?

You sir...are completely ignorant and WRONG! Go for it....(and save your money for a new engine.)

Do you think we are idiots...spending our time trying to help people?

 

[SpiderSpartan]

Please don't mistake my fear as a sign that I'm unappreciative for the help you guys provide. If I can adjust the clutch with parts designed to meet the same specs as the engine's original design I'd rather do that than modify engine internals.

---------- Post added at 12:52 AM ---------- Previous post was at 12:29 AM ----------

It's been one of those days. I just checked the engine manual again and it says the max RPM is 3800, not 1800.

Now I'm at a loss for what might be going on. The engine is going full throttle when I floor the gas, but the drive clutch is not fully engaging. Even on the jack stand, where the wheels can spin free it just doesn't engage the drive clutch completely.

 

[SpiderSpartan]

I cleaned and lubed the drive clutch last night. That seemed to help a little, but I'm still not getting to full engagement while driving. I did go full throttle with it up on the jack stand and it fully engaged, so I'm thinking maybe I have it geared too low for the weight. The engine itself weighs almost 90 pounds. I figure about 150 pounds for the kart+engine and another 250 for me and a passenger for a total of about 400 lbs.

Right now I have the following gears, 10 tooth driven->10 tooth js input->10 tooth js output->54 tooth axle for a ratio of 5.4.

I'm thinking of going 10 tooth driven->12 tooth js input->10 tooth js output->54 tooth axle for a ratio of 6.48. This should put me down to a top speed of about 20 mph, but maybe I'll actually be able to get there.

Do you think 6.48 is high enough, or should I go higher?

 

[SpiderSpartan]

Anyone know what kind of max speed I should be expecting from this thing? I've found a couple reference sites and the one formula has me worried.

www.engineersedge.com explains HP=Force (in lbs) x Velocity (in ft/min)/33,000. Reworking this for V in my case gives V=12.5hp x 33,000/400 lbs. = 1031.25 ft/min = 11.7MPH

www.Wallaceracing.com has a 1/4 mile calculator based on weight and hp. It comes up with a speed of 73MPH.

Is my kart too heavy for this engine?

 

[chancer]

Use this calculator. Just put in the 5.4 an 1 instead of tooth counts.
http://www.diygokarts.com/speed-calculator.html

 

[SpiderSpartan]

Use this calculator. Just put in the 5.4 an 1 instead of tooth counts.
http://www.diygokarts.com/speed-calculator.html

Thanks Chancer. I'm familiar with that calculator and with 13 inch wheels, 3800 RPM, and 5.4 ratio I should be getting 27 MPH.

What I'm really wondering is, will 12.5 hp get me there with 400 pounds of kart and passenger?

 

[chancer]

Oh. Ok then Yes probably. A typical Finished Kart is 150ish and Driver 150ish. So 300 lbs and Typical or 6.5 HP. I would *guess* 12.5Hp and 400lbs No problem.

 

[SpiderSpartan]

Anyone ever use bike brake calipers on a kart? Just wondering as I start to look at covering this thing to disc brakes, because 2 bike calipers are about 1/3 the price of a kart caliper.

 

[mckutzy]

No... Don't cheap out on brakes... They make you stop... Or who ever stop...
Take it from me(I have a few threads on brakes) don't... Get the right kind the first time...

Edit:are we talking "bike" as in bicycle... Or "bike" as in motorcycle???? Big difference...

 

[SpiderSpartan]

Thanks for talking some sense into me. I was looking at bike as in bicycle brakes. After I posted the question I found a thread where sid explained how much smaller bicycle brakes are than kart brakes. I've been on the road the last couple days and it's kind of hard to search the forum on my phone. Maybe I'll call around to some local junk yards to get pricing on motorcycle brakes.

 

[mckutzy]

Check the rear size tire dia... That will dictate what size rotors you can use...
Get the whole brake system... All the brake parts... From the donor bike..

 

[SpiderSpartan]

I got the choke control hooked up and changed the jackshaft input sprocket from 10 tooth to 12 over the weekend. I now have full control from the drivers seat without having to reach behind me. I ended up using an Arnold Universal Throttle Control Kit from Tractor Supply since I could grab it locally and it has a few different control arms.

I also got a laser tachometer and checked the engine RPM. On the jack stand I'm idling at 1200 and hitting 3800 at full throttle. It doesn't look like the tc is getting to overdrive at full throttle on the jack stand. When driving I'm not getting out of Intermediate Range. I'm wondering if my tc came with the silver springs rated at 3600 RPM. I've got some blue and pink spring sets coming to try and get me accelerating in the peak torque range for the engine.

With a 398cc 12.5hp engine, the driven spring set to off road, and functioning throttle and choke controls I'm not sure what else the problem could be.

 

[SpiderSpartan]

So I finally found a thread online where people are discussing what sounds like the same problem I'm having. http://www.oldminibikes.com/forum
They say the tc is shifting too early, keeping the engine from reaching full RPM. So I changed my order to a set of pink springs (1800 RPM) and white springs (3100 RPM). I'll let you know how it works out.

 

[SpiderSpartan]

Springs showed up today and I'm glad I went high and low. Put the white springs on first and engagement/ top end got worse. Threw the pink springs on and the thing flew. Made me glad I adjusted the brake band mount yesterday.

I still need to

1. mount the ignition key
2. mount the choke control
3. add some kind of battery bracket
4. take everything apart to clean and paint
5. convert to disc brakes
6. add seat belts

Thanks for all the help on this guys!

 

[mckutzy]

If you are going to use a rod for actuation of your brakes...you will need to reposition the band and rod for proper braking...
Ex.. Kartfab..