Rumor has it that Luis Belaustegui #150 in the Dakar on a KTM 150 is running the APT Smart Carb this year. Seems to be frying a lot of pistons. Anyone have an idea why that might be happening? Is it a carb issue, or just the bike being too small for the job? P.S. don't recall him having that many piston issues in years past running the same bike.
A reliable source told me he thought APT might have issues with frying top ends without having the powerjet enricher for extended top end runs. Lectron has 30 plus years of testing and sells theirs with a adjustable powerjet (top end enricher) for a reason. In theory you could scale the rod up to pass enough fuel at wide open but it is far EZer and more safe to run a smaller rod and leaner settings for down low power and response and add the adjustable powerjet for making great top end power and running it as rich as you need to to keep top ends together. Also means you can just reach down and richen the top end when you hit the dunes or something. Thier is a reason after decades of tuning these metering rod carb Lectron chooses to sell theirs with the top end enricher. I am not saying this is a APT problem or why that dude is blowing up motors (as that can be lots of things) but after lengthy conversations about these carbs it might have something to do with it.
Air assisted forks. Not Air Spring forks. They have a light spring but need extra air pressure to work correctly. Makes them more adjustable.
Take the carb off and measure the hole on the spigot side of the carb. It should be 38mm. A Lectron 36 will be OK as they tend to flow about the same as a 2mm bigger standard carb.
I have found its adjustability quite cool. Fun to just spin an adjuster and see what it does to your top end. I got mine running fantastic. I don't run in the top end a lot but last ride was a lot of huge steep frozen snow covered hills chasing a WR250. I had no issues with roll on power (the 165 and Lectron are magic) and the top end was insane. Walt just found his Lectron allowed 1000 RPM more than his RB TMxx which used to be the top end king. All interesting stuff.
From what I have read I would say it's a KTM issue and not a SC issue. But my guess is just that.... a guess.
Blown up motors can be many many things. A simple leaking crank seal, plugged main-jet, lean carb, race gas and to much advance etc. So many variables. I think that KTM 150 was a little prone to blowing anyway was it not? i know they had major piston issues the first year. To be clear I was not blaming APT and was totally speculating. I did find it interesting I did hear that not having the top end enricher invites WFO issues and it makes sense.
Wrong tool for the job for sure. An 8000+km race with dunes the size of large mountains...and elevations from 0 to 15,000 ft...that thing would have to be wide open all day long in sand on alot of the stages. It's his 3rd Dakar try on a 150 and he has yet to finish it.
Not even close as the "show me your 4 stroke bike" is 148,481 at the moment and i have not even looked at other ones, might be bigger.
Darm tootin' A 150 in 20 ft sand dunes is not going to last WFO for 5,000 miles unless they took all the compression out of the motor and it made no power. Rich
I haven't gone that far in checking it out, but, I read that he changed the carb out, back to the original, on the first day. Apparently, little, to no testing was done with the APT, prior to the event. Corey, in one of his posts, postulated that perhaps the carb boot was blocking part of the pressurisation circuitry - at the top of the carb venturi, or just that it needed a different needle. He knew no more at that time. One report said that the bike lacked power with the Smart Carb, against the carb it was extensively developed with. Understandable, in a rush / rash change. Especially if part of the Smart Carbs main circuitry was being hindered, by other parts. When looking at the bike, it looked like, with the necessary huge tank, he / mechanics may not have been able to get to the adjustment dial on the top of the Smart Carb - it could have simply been that - not being easily adjusted, for lower running. Once again, WTF knows? I'll have to chase up more info on him/ his experiences this year In ADVs thread, a bloke that has had some involvement with Luis' previous attempts on the / a 150, said that this year, another bloke had been used for the build up of Louis' engines - and That was the reason for the blow ups / seizures. I think the commenter, had previously been the engine builder. So, blow ups seem to be Nothing to do with the Smart Carb, as it was removed during / after the first day. Just, rushed, inadequately tested - the Smart Carb- prior to the event. A 150 in the Dakar - yes it sounds a bit crazy, but it's Luis' decision. He, apparently, DID reach the finish, in last (?) place. Bravo, Louis! I'd love to see him make it easier on himself, and use a 300. I'm sure it would handle the event much, much easier. And, with the Smart Carb, with it's claimed improved economy / power / fuelling / oiling, would really help keep tank capacity required, down. Unbeknownst to many, a 2t in Rallies', does not necessarily mean having to have a huge tank, in comparison to a 4t. The lighter weight of the bike, and the comparatively much better torque and HP, and Lower revs, means they don't use as much fuel as you'd think. I worked at the OZ Maico distributors, a couple of times, many years ago and, and Ross, communicating with Herbert Scheck (sp? - I often get the great man's name spelling wrong, sorry), when he rode the 490 /500 Maico in support of his daughter in the Dakar, Herbert said they'd seriously over estimated the size of the tank required. They could have used much smaller capacity tanks.
I am reminded of an old saying "haste makes waste" change one item at a time and sort it out, this mechanic seems to be his problem, before you take an undersized motorcycle to an extremely tough event you should prove it first, the fact that they changed the carb on the first day tells me they were shooting from the hip, sounds like they did not do their due diligence in testing and proving their components, or in the case of cc's their theories of size
