125-200cc how to deal with new ECU and carb mods

Hi
I just picked up an SM125 from 2012

As we know these engines are considerably different in set up yet everything from a WR engine fits on or into it

i was happy to see that this later type of SM 125 has the same power valve actuation as the WR/CR

I do have a 125 Fast by Ferracci cylinder on the shelf (yes it will end up on it)

the only thing that is intimidating me is the following

the engine is equipped with a 28 delorto carb

I would like to have a lectron on it yet this delorto carb is equipped with a throttle position sensor

the ecu (responsible for the spark) takes signals from this sensor but also air temp engine temp and controls the oil pump but also an air valve

Is there somebody here on the forum that did this change of carb on a SM or WRE on a bike younger then 2011?

Robert-Jan

I had an 11 plate rs 125 with the same 28mm del carb with tps etc

I upgraded this too a 34mm without tps

I simply left the tps plugged in and tied to one side

The bike ran spot on for over 8k miles like this, the tps seemed to have no effect on the bikes running or performance

If assume it would be very similar on the sms

Btw I also have an sms and will be grabbing ac cr carb and manifold too give it a go, so il let you know but dony expect a reply quick I take ages haha

Do you run still with an oil pump connected?

Would changing out the ignition pack for wr one an option?

The coils can power up the the ecu and the ignition is indipendend system .
Yet there is one pick up sensor not in that set up thats feed into ecu.

I am a bit afraid it will mess up other functions like the oil pump control

Robert-Jan

I only have experiance of my r's which had a mechanical oil pump and not an electric one

I'm sure I have seen many people have fitted larger carbs, I think the Thread about the guy with the fmf on his 2007 has a larger one fitted

They make aftermarket tps boxes you could put before the lectron.

If like to know what else the tps controls? It can't effext the actual throtel as this is manual carb and cable

So either it can advance and retard ignition or advance oil pump

I may have to phone my husky dealer as I remeber years ago when I looked at a new one they had a power parts book with a carb kit in there

I think its only affecting the oil pump actuation as the ignition is an RPM controlled system regardless if the throttle is open or closed (in case of an air leak in the manifold, the ignition timing would still be controlled on the actual speed of the crankshaft)

the older types that have a mechanical oil pump did not have a TPS and the electronic power valve control was controlled by the CDI that gets its command from a RPM sensor

I do more and more lean to the Idea to change out the ignition coil set and have the WR ignition that has its independent ignition circuit
the power coils can still power up the ECU fro the other functions

the only ?? I have is the pick up sensor feeds in the ECU if that one is not present any more it will for sure not give a ignition pulse (not a problem as it is taken care by the WR ignition) yet does it shut down other systems like the oil pump?

the TPS can not be mounted on a lectron and I suspect that this sensor is used for the amount of actuation of the oil pump

I would like to maintain the oil pump feature (don't get me wrong I will abolish it if it is to much hassle to make it work with a lectron)

The more I am thinking the more it will be that the FBF cylinder will become a 165 (same as the WR) then only the tranny is different (better for the street) but still doing the wheelies with an easy of a throttle twist

Robert-Jan

Also looking into a 165 for my sms

just need to figure out wether thr oil pump will continur to work without the tps

if it does im throwing on a wr carb 8-)

Does anyone have a spare sms stator for sale 2012?