i don’t believe your tuner messed with timing did he? And you weren’t experiencing this after tune i don’t believe? if tuner didnt change timing it’s probably not knock due to fuel after all this time since tune, im sure you use 93 or whatever the high grade is. driveline somewhere you hooligan, give you a 200hp toy and look at ya, tearing stuff up :cool: You the man, tear up repair and ride like an alien in them mountains, nothin but a thang.
 
@warp9.9 mentioned the torsional bearing and @Speedy chimed in on another post where I first mentioned this and brought that up too. If that's it, I'm afraid to ask, what's involved in changing that out?

Here is what he had to say....
The barometric pressure sensor, located on the top corner of the airbox under the seat, and the intake air temp sensor allow the ECU to adjust mixture for both altitude and temperature changes, albeit they both have limits and are subject to non-linearity and manufacturing variations. As you go up in altitude the absolute pressure drops so the ECU adjusts and injects less fuel to maintain AFR. The result is that with 20% less air, and fuel, the bike produces 20% less power and likely even less. Why: because the intake and exhaust tracts are designed, or tuned, as is cam timing, for air density near or at sea level. Denser air conducts sound faster than thinner air so the farther away from sea level the less in tune those systems become. The result is even greater power loss than just the change in air pressure would indicate.

The position of the air temp sensor is critical. If it gets much heat from the radiator, or engine itself, it will result in a leaner running motor. So when climbing a mountain, the engine makes less power the higher you go, has to work harder due to the grade and creates more heat for the radiator to dissipate and the engine to radiate. Slow down to drive through a town and the bike can run like crap if the temps sensor is getting heat other than from the air flow in the intake system. Even when properly placed, the air flow through the intake is so low at near idle throttle openings that the whole air cleaner gets heat soaked. (This statement is made under the supposition that the O2 sensor is not active. The O2 sensor can compensate for this heating affect so long as it remains with the scope of the O2 sensor operating range.)

As to the thump: Did the driveshaft universal joint get inspected when the bevel box was changed? A bad u-joint can bind at a given rotational position and induce a vibration into the drive system. Is the thump episodic or is it constant and rhythmic? Does it change under different loads? Test the load condition by riding the brake; does the vibration change at all? A failing torsional bearing may exhibit episodic vibration whereas a failing u-joint would be prone to rhythmic vibration.
 
@warp9.9 mentioned the torsional bearing and @Speedy chimed in on another post where I first mentioned this and brought that up too. If that's it, I'm afraid to ask, what's involved in changing that out?

Here is what he had to say....
Ya lift the tail and pull it. The triumph way is drop the motor roll ot over. I say no matter which way drop the sump and clean it first do not use fuzzy rags the lint will clog the sump screens. Its work but I'm sure you're a qualified Rocket Scientist and could handle the wrenching easily!!
 
Ya lift the tail and pull it. The triumph way is drop the motor roll ot over. I say no matter which way drop the sump and clean it first do not use fuzzy rags the lint will clog the sump screens. Its work but I'm sure you're a qualified Rocket Scientist and could handle the wrenching easily!!
Reading some old posts where you chimed in. One was Doc Roc mentioning a sound (not the same) but at 3k rpm! Turned out it was his timing chain adjuster. I have one of Neville's. I checked the adjustment recently and believe it's OK. Another post mentioned clutch cable play. Lots of things to check out. I saved the sump gasket I removed when I did the rebuild and installed a new one. If it's not torn and looks good can I reuse, or do I need a new on every time since it's a dry fit? Not trying to be cheap, it's just I can move faster without waiting for parts and the bike is my primary means of transportation.
 
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Ya lift the tail and pull it. The triumph way is drop the motor roll ot over. I say no matter which way drop the sump and clean it first do not use fuzzy rags the lint will clog the sump screens. Its work but I'm sure you're a qualified Rocket Scientist and could handle the wrenching easily!!

@warp9.9 Torsional Bearing. OK, read up on it- dang, THAT looks like a ton o' fun! I'll need to buy a press and special swingarm removal socket. I'll ask later how to make that tool. I no longer have a shed, just a portable tent/shed over gravel shared with lawn mowers, etc. and just enough room for the bike.... Hoping it's something else, but you have good instincts so I'm preparing myself for the possibility. Today I reached down and held my hand where the drive shaft comes into the torsional damper. I didn't feel anything there when I felt it in my foot. Hoping that's a good sign that it's something else, and not anything worse.

@R-III-R Turbo pulling the clutch in slightly doesn't seem to affect it. Also, I checked my cable play this morning and it was OK. I noticed I could NOT get it to do it in 4th gear going downhill this morning. I couldn't test 5th because that stretch of interstate is a 55 mph speed trap. On most roads the surface is too rough to notice what I'm feeling. It has to be smooth like interstate. More tests on the way home to confirm, but seems like only 4th and 5th on flat or uphill, not down- What does that suggest? You said earlier, "Increased load is increased risk of knock." I need to get that octane boost or just buy some more.

@Speedy " A failing torsional bearing may exhibit episodic vibration whereas a failing u-joint would be prone to rhythmic vibration."
It's more of a thump, like hitting a rock or crack in the road, than a vibration but it does feel random and it's hard to hold it exactly at that position to keep it going.

@Kevin frazier No, the tuner didn't mess with the timing and I am using 93 fuel. "give you a 200hp toy and look at ya, tearing stuff up..."
I thought they were oversized sport bikes and should be ridden appropriately or they get soft, fat, and lazy like those other big bikes I see lots of out there - aren't they?
 
I removed my good luck charm bell. A bit worried that after all this that it was that banging back and forth, but NO. Back to other more complicated theories. On way back from work I confirmed that it does not present when going downhill and holding at 3K in 4th.
 
Well there's a clue. If it's a randomish thumping only in 4th and 5th, at 2900-3000rpm, and while engine is under some load.

Is it any worse when going up a hill, than when on the flat?
Is there any difference between how it feels in 4th and 5th?
 
Well there's a clue. If it's a randomish thumping only in 4th and 5th, at 2900-3000rpm, and while engine is under some load.

Is it any worse when going up a hill, than when on the flat?
Is there any difference between how it feels in 4th and 5th?

First of all, I just looked it up, but yeah, you're the guy- your "how to" videos on things like setting the timing were a huge help to me when I (complete newbie) did a Lush cam and piston upgrade. I think Lush was equally afraid that I'd blow up my bike due to inexperience- got lucky.

If you didn't see my shout out to you in my

DIY Beginner Upgrades Cams & Pistons - Lives To Tell The Tale

post, let me thank you again here.

Your questions- so, you'd probably pick up on those differences right away, but it's harder for me to say. Kinda like how my ex-wife would make me take fish oil supplements and then ask me if my joints felt better.. "uh, I think so..." Seriously, I think 4th and 5th are similar and probably about the same uphill as on flats. Sometimes I think I may have felt it in 3rd, but then not sure if that was a bump in the road- if so, definitely less frequently. One thing I noticed today and, I may need to repeat to make sure, is that it seems to happen when moving up to 3k, whereas easing down to 3K doesn't produce it. Let me make sure of that though.

I just got some Lucas Octane boost and poured about 1/3 bottle in (treats 25 gallons) with my low fuel light just starting to flash. I plan on filling up about 1/2 way tomorrow so I don't dilute it too much and seeing if it makes a difference.

Thanks
 
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