Tbi / Premix conversion

The project consists of 2 parts – Converting the Tpi system to Tbi using Injectors Relocation Block and the second part of using premix instead of the original OI system.

Let’s start with the “why?” a question so many people asking. Those are my “why’s”, it might appeal to some might not to others.

1. It’s simpler. Less parts on the bike make me happy

2. It’s lighter*. By how much? 1.25 kg (2.8 Lbs). This weight does make a difference on handling as it’s seats very high in the frame

3. It’s more reliable (IMO). For one, less parts mean less things to go wrong or brake. For second, premix mean that if there is fuel there is lubrication – no intermediate to break that rule. Tbi mean cooler low end at the same time, which will add it own for long term reliability.


As part as light and “clean” as possible, I normally ride with number plate instead of head light, chop the rear black number plate support and remove the taillight, convert the dual cable throttle to single cable setup only and use AXP skid plate and CF pipe protectors as they are the lightest available.


The relocation block has been already discussed in many places and posts. Installation is basically straight forward, and I won’t add any new information here. Just worth second mention is that it is very advisable to add some oil (around 0.5%) to the gas when running Tbi. I’ll just say that I did not experience any stalling and / or any other weird behavior engine-wise. My bike have the Silber mapping and idle screw mod and run around 1700 RPM at idle.


Another thing worth re-mention and better be safe than sorry – Premix can be used solely after injectors relocation block is installed. Anyone which will try to run premix in Tpi bike will end up with destroyed engine.


So if you plan running premix and removing the OI system, do it while the throttle body and the injectors block is off the bike. Much easier access to the oil tank.

- Remove silencer, pipe and 2 top engine supports.

- lose all the connectors involved. (2) Injectors, CCP, TPS, ambient pressure and oil level sensor. Mark which one is which for easy re-connection.

- Loose throttle body clamps

- Remove 2 bottom sub frame bolts, loose the top bolts, and rotate the subframe upwards. Ones in position tight the top bolt to hold it.

- Disconnect oil line and remove throttle bod (you can hang it on the handlebar in the meantime, no need to disconnect the throttle cables)

- Take off the power valve vent hose (connected to the airbox on other end)

- Disconnect the black oil line that feed the oil pump and empty the oil tank. Prepare funnel and a can in advance. It will flow slowly out and can take 10-15 min to empty a full tank.

- Lose the 2 bolts that hold the oil tank. Pull it downward and loose the clamp holding the filling hose with screwdriver. Remove the sensor bracket from the oil tank

- With a screwdriver, press the tung that hold the filler neck and pull it out upward with the filling hose.


Now you need to be a bit creative making a bracket to hold the 2 pressure sensors in place. I used small L shape piece together with the sensor “pocket” I cut out of the original bracket. Once in place re-connect the CCP hose – I bought longer hose from AutoZone (5/32” ID fit great) as the original will be too short. If you do not want to re-use the long power valve vent hose, make a small cap to seal the airbox inlet. I used a small hose piece sealed with a bolt and RTV.

Oil level sensor stay disconnected, but oil pump connector needs to be re connected back to the oil pump or a dongle to imitate pump existence to the ECU.

Connect injector block and throttle body, tie nicely all wiring and you are done.

* As parts as the project cost, consider new sensors bracket (around 25$) and oil filler neck if you will ever want to re-install the system back.