Sinnis Shuttle EFI Hot start problem

Hi fellow forum members
I am looking for some help with my Sinnis Shuttle 125 with fuel injection. I bought it a few days ago and on paper it looks great. 2020 model, 5k miles, 12 months MOT, one owner etc. It wasn't quite so good when i went to see it, a few marks, corrosion and news that it had a full top end rebuild(alarm bells should have rang) but it started ok and ticked over quite nicely. I had a quick run around the block and all seemed fine. So £1000 lighter i came away with a scooter in the back of the van.

On getting it home it started ok and ran fine for a few miles. When i tried to re-start it after the engine was warm it wouldn't re-start. I jump started it from the van battery and after much engine spinning it eventually started. There is no way it would have started again just using the bikes battery.

So the problem is hot starting and i started investigating and spending money. So far i have bought a new battery(just to be on the safe side), air filter and spark plug. Still no joy.

Further investigation revealed the fuel injector splurting out enough fuel to power a GPZ1000 at 100mph so the mixture is definately rich. I then noticed that the exhaust didn't have a o2 sensor and infact there was no place to fit one. Also i have taken the cooling shroud off the engine and there is no temperature sensor and no tapped hole that I can see to fit one in. Looking at the loom there are 2 locations where somebody has soldered 2 wires together and covered them in blue heat shrink. They stick out like a sore thumb and it obvious that this is not standard.

So my conclusion is the former owner probably didn't run the engine in and knackered the top end. They sent it to a mechanic who fitted a standard carburated cylinder/head and therefore couldn't refit the temperature sender. The mechanic then tried to eliminate the need for sensors by joining the wires from the temp sender together and then they must have found they needed to join the wires from the o2 sensor together as well to get it to run. Mechanic then informs owner all fixed but neglects to mention that the the ECU doesn't know what the engine is doing and probably thinks it is permanently starting from cold and hence throwing loads of fuel into the cylinder.

Sorry for very long description but now i will get onto my plan for repairing the problem and hopefully you will give me some feedback.

So the plan is to buy a new temperature sensor, i cant find anywhere in the top part of the engine that is designed to accept a threaded senser but i am thinking it might go in one of the threaded holes for the EGR blanking plate. For the o2 sensor i don't really want to take the exhaust off, drill a hole then weld on a nut to take the sensor. So my plan is to fit a rheostat between the 2 wires that would have gone to the sensor. Then I can adjust it until i get a decent fuel/air mixture or if someone on here knows what resistance the sensor should be at normal running condition then i would fit an appropriate resistor.

So thats my plan and hoping it should work as long as it wasn't the ECU that was the problem in the first place. Hopefully there will be some people on here who can advise me on the error of my ways and maybe come up with better advise. If not i will go ahead and let you know how it works out.

 

Thanks for the advice Mark, not very encouraging but yes I have definitely bought a LEMON. Buying a cheap scooter is bad enough but to buy one with complicated electronics and no possibility of getting a workshop manual I don't know what I was thinking. I'll spend a few more pounds on it and see what happens, to be honest I quite enjoy the challenge. Ill keep the thread updated, it might help somebody in the future and avoid them making the same mistake.

 

Hi all. Just to close this topic. I fitted the temperature sender into one of the holes for the EGR blanking plate. It was only M6 so I tapped it out to M10 to fit the sender. I had problems identifying which wires I should connect to it but managed to find the "Delphi Small Engine manual" on line. This was really helpful and worth a look if you have Delphi fuel injection. The scooters worked great since. I've checked the spark plug a few times and it shows mainly the correct straw colour, maybe running a little rich and I'm thinking in the future I might fit an O2 sensor into the exhaust. So all's well that ends well except I would probably have been better spending a bit more money on a Honda PCX.

 

Has it got an aftermarket exhaust ? with no fitting on the down pipe for the co2 sensor? And on another point, check valve clearance as factory settings are to tight.

 

It's got a Sinnis exhaust off a carburated engine. The scooters going quite well now. It's starts really easy, I can even start it with the crappy Kickstarter. Top speeds about 50mph so far but it's been windy and I always seem to be going into a head wind. I don't think the fuel economy is very good because I keep having to fill it up but I'm only putting about 4 litres in because I don't trust the fuel gauge yet.
In future I might drill a hole in the exhaust and weld a nut on to take an O2 sensor but then again I might buy a new one. I've seen one from Torro that looks good and is quite cheap. I hadn't thought of checking the valve clearance, I think I should do that in the near future.

 

Get O2 sensor fitted in downpipe asap, 50mph +/- is about right for top speed on these.