Running lean
 

Hello guys,

I'm in need of some (technical) advice. I recently had my Tenere in for a service with a Yamaha dealer in London.
I had Kev's fuel and O2 mod installed and the bike rode very nicely. After getting the bike back and riding to work I noticed poor performance at low revs. I removed the seat and to my dismay, I discovered that the fuel mod had been removed and the wire into the temperature sensor soldered back together. :021:
I'm obviously livid and will take the bike to the dealer tomorrow but the real question is, will I have done any damage to the engine? I did about 170 miles without the mod and the stage 2 filter fitted.

Any technical/legal advice would be appreciated.

Cheers

Hi
It's very very unlikely you will have done any damage, in fact it won't have. It will just run a bit crap. But the big question is why did someone steal your mod from the shop that's bang out of order and I would be billing them for all sorts ,your time at �45 an hour, and any other cost. They had not right to take anything off your bike without your say so. And if it was just a service they had no right to do any other thing to your bike. I would go back to the shop and if you are not happy tell them you will call the police as it is theft and also tell them you will be putting what happened at there shop on YouTube and face book, trust me business will not want you to do that, and will do every thing to sort it out. Plus get the shop to tell you what member of staff did it, then ask him why as he had no right to do it Hope this helps.

Thanks bandit.

I went to the dealer today and explained what had happened. The mechanic, who's still learning English, thought he'd been instructed to take the mod out. They profusely apologised and reinstalled it. After asking if any damage had been done to the engine, their chief mechanic explained that the bike would have been running the factory mixture because the ECU would have compensated for the increased airflow. No idea if that is true or not. I remember reading something about the ECU only compensating for temperature change but I doubt there was serious damage done to the engine.
I guess these things can just happen.

Peace

Hi the ecu can't compensate or won't compensate when in open loop. So you have been running lean, in open loop the ecu don't read any feedback from the O2 sensor. It just do the calculated mixture from the info it gets from other sensors like intake air temp and coolant temp. It just rely on that nothing has changed from factory and uses the pree set mapping. It calculates how mutch air is pulled in to the engine by calculating pressure and temp to get the likely air density, this is because it doesn't have a air mass meter like cars do.

Tak Zipfer. I had a feeling it worked that way. I did 175 miles without the mod. In your honest opinion, would you have the engine checked out? I read about a guy in Australia how runs his Teneres without the snorkel and no fuelling adjustment. I gather they are pretty sturdy engines.

Running for a very few miles like that will not have done your valves any appreciable harm. Stop worrying

The 660 engine is a bullet proof engine. It's built for reliability, you feel it every time you use the throttle 😉 the lack of power but also the thousands of miles to go. I've seen the engine been manhandled in such ways that you can't believe without any visible damages. If it's a little lean don't worry it's only more heat and the cooling should work great. The low compression ratio should save it from any knocking.

Keep calm and carry on. Don't have sleepless nights about it - it'll be absolutely fine having after only 175 miles.

Thanks guys. Worry is like a rocking chair. It gives you something to do but doesn't get you anywhere.

Cheers

Here is something interesting then, I bought my Tenere in 2014 new from factory, have been running it from factory with DNA stage 2 filter for like since I got it without any mods. I am not sure how it works, What is a DNA stage 1 + 2 filter? It does have a rubber insert inside the filter like this? Does this mean, it has a DNA stage 2 filter with a kind of air constrictor?