Brian or Jimbo LO206 issue

Kj26

Kj26

Member
Ok here's the deal, the motor won't turn over 5500 rpms, no matter what gear combo I throw at it. The carb is clean and float adjusted weekly. It also constantly loses 3000 rpms in the corners every lap. Today I finally got a chance to listen to it close in the corner and it's sounds like popcorn popping, but it's fine on the straights. A few people said coil, but I'm wondering what you guys think. It only has about 20 races on it. Last week the motor shut off during the heat race, I unplugged the kill switch button and it fired up again. Replaced that this week.

It's not the setup, I put another motor on and it responded to the gear changes and only lost 700-900 rpms in the corners like normal.

Thanks,
Keith
 
Very good chance the kill switch wire to coil is grounded. Pull sheet metal shroud and black plate and check. Very common problem, they are often assembled improperly from factory. Sorry, it happens!
 
Flash I had all that off to check the wire, when I replaced the switch, the wire is in perfect shape.
Gonz, valves are good, already checked them.
 
I'm thinking coil or flywheel key like Greg suggested. It could be the valves were set wrong (in the overlap) - gonzari's suggestion for checking max lift would determine that.
Also look closely at the valve springs -- a broken one will make it sound like it's on the rev limiter also. Could even be the floats set wrong and running out of fuel in the corners / floats bouncing causing intermittent fuel delivery, etc.
Change one part at a time and go from there. I'd start by checking ignition timing for a sheared key - that costs nothing. Check and recheck, clean and re-clean the carb - that costs nothing. Recheck the valve max lift - costs nothing. THEN, after exhausting those possibilities, change the coil. :)



--
Thanks and God bless,
Brian Carlson
Carlson Racing Engines
Vector Cuts
www.CarlsonMotorsports.com
Celebrating 25 years of service to the karting industry
765-339-4407
bcarlson@CarlsonMotorsports.com
 
Just took it back over.
Valve lift is .250 intake, .251 exhaust. Both within legal parameters.
Valves are set to .002 like I have always done.
Key is in place.
I rechecked the float yesterday at the track. I just stripped the entire carb and cleaned it all out and checked the float again.

Now my question is can I run this on the kart stand and open it full throttle without blowing it up ? I could get mychron readings that way.
If so I could pull the coil off my other 206 which I know is good.

Thanks guys.
 
Kj26 said:
Now my question is can I run this on the kart stand and open it full throttle without blowing it up ? I could get mychron readings that way.
If so I could pull the coil off my other 206 which I know is good.

Thanks guys.
Click to expand...
Not unless you want to take the chance of ventilating the block... never run an engine at WOT without a proper load on it.
 
I just had a customer with a WF engine that would not run up to the rev limiter ( with proper gearing ). To complicate this it had no misfire sensations AND it would occasionally work properly. After checking everything over and over I finally changed coils and that was it. Was reluctant to change it as PLV coils have proven to be very dependable. Only seen one other failure and that was on a LO206. That was not a customer of mine ( at least not directly ) and I do know they had the coil gap very wide which I figured cause the failure from what I've been told. All in all they are very dependable but I think you should try to borrow one and test it.
I don't think running it to the limiter on a stand wiould be a good idea. It'll test the limiter but you really aren't loading the engine.
 
Thanks Flash, he can run his sisters 206, then after the races I pull the coil and try it in his. I'll write back after we run it.
 
Jamie,
I use Jimbos gauge, 1.052 and .860 if I remember correctly.
I have 2 lo206's, the one I'm having issues with has never seen over 5700rpms, as he's always run a plate. The other one runs 6000 or off the chip. I looked at all his Mychron data from last yr and it's all normal. This yr it's not even close.
 
Plate motors need a different float level.
What plate do you use?
 
The plate motors and long slide motors can have problems with too much fuel in the bowl if you set them at the same level as a motor with no plate or with the adult slide.
The smaller the plate the less fuel you need in the bowl. I'd make sure the float is not damaged or saturated and set the float level at .900"
 
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