97 TD resurrection, won't accelerate

[flyday58]

Hello again everyone, been awhile since I've posted. But I'm back with a problem on a 97 Royal Star Tour Deluxe that I'm attempting to get back roadworthy for a customer/friend. Bike sat at least four years after the PO passed on, not much history except what eyes reveal. Carbs were very clean though not pristine, but cleaned up easily with no petrified varnish to remove. Fuel tank was another story, so bad that I told the owner I wouldn't fool with it. A friend of his took it, pressure washed it and brought it back, along with a can of red goop that can be applied right over rust. I did it but told him no guarantees.

Once it all was back together it fired up on the second touch of the starter button and purred like a thing that purrs (right, Half-Pipe?!).  First shakedown cruise was when the problem appeared. No tach but it wouldn't rev above 3500 rpm or so except in idle. It doesn't act like a rev limiter, more like running out of gas. I found the #3 plug cap reading infinity; when I took it apart it was corroded inside so ordered a new one from Mother Yam. Everything else seemed okay.
TBC...

[flyday58]

Continuing...

Installed the new cap and went for a ride today. Bike now revs a bit more before acting the same way: more throttle results in a bog, with sputtering but no heavy popping, again like it's starving for gas. I could only go up mountain in 2nd gear, otherwise it lost so much power it threatened to stall. If I feathered the throttle it would run smooth, so long as I didn't ask too much of her. Going back down mountain I could get her to do 60 in 5th, no more.

When I resurrected the 83 XVZ years back it had similar symptoms; that turned out to be the ignitor/ECU, which was thoroughly corroded inside. This one is acting similarly. At idle it sounds like a Harley, but I've verified spark on all four coils and plugs. New fuel filter and S-hose, fresh non-corn gas. New float bowl gaskets but few other seals available from Yamaha. The float seats were all loose in their receptacles; I found two o-rings in my stash that worked but the other two are original. New intake boots, replaced the cone filters with an OEM unit and filter(maybe I should check the jet sizes since the PO had cones on it?). Fuel pump was clogged with varnish but I got it pretty clean, and it seems to be pumping gas.

One other thing, sometimes when I put the side stand down it'll quit, like it's in gear and the SS switch is sensing it. Today it refused to restart until I put the SS up, then it stayed running with multiple swings of the SS. When this happened, it would crank and fire but not run till I put the SS up.

Clutch switch is bypassed, fuel indication is bypassed, both at owner's request (lack of funds). That's the story, thanks for any insights.

Richard

[RDawson]

Check pipe temps at the heads? Running on all 4? 

[flyday58]

Yes, checked with my heat sensor. I had pulled the plugs after the first ride, brand new plugs, all were black and sooty. I'm pulling them now...

All sooty black again. I remembered one more thing. I did a speed sensor test and it failed. The manual says you should have continuity across the blue/yellow and white wires, I got zilch (open), even at the speedo itself. And the speedo doesn't come apart so I can't look to see what those wires go to. Anyone have a bike open so they can perform this test for me to see what they get? Thanks.

Edited July 29, 2022 by flyday58
add speed sensor info

[cowpuc]

"HALF PIPE" LOL!!  Hiya Flyboy, been a while,, how's the turbulence? I am not really qualified to offer advice on the 97 cause I really never touched one but until a real guru comes along we are, once again. stuck with each other LOL.. Common issues would be making sure the pipe(s) and air box(s) are open so she can breath. Speaking about it from a MK1 perspective I think I would take a close look at the carb slides/diaphram operations. Torn diaphrams and/or sticking slides are notorius for acting just as you describe. You should also double check those main jet metering rods hanging from the slides and slide springs. Another thing I would triple check is the timing advance module (if it has one). On the MK1  that puppy is mounted right beside the TCI and is vacuum operated. It could be as simple as a bad vacuum line so the timing is not advancing. Another thought you need to be aware of @flyday58,, those Royal Star Tourers were a different varmint than the MK1/MK2 and RSV's. They did not have a balance shaft, had smaller carbs and I am sure Mom Yam designed that motor to not spin up like the other V-4's she had produced. Maybe double check the OEM specs, drop a tach on it and see if its really only rapping out to 3500 R's. SOOO MUCH FUN brother,, I know you will figure out. By the way,, that red stuff you got your hands on for lining the tank is probably "Red Kote".. If it is you got your hands on the BEST stuff available for doing the job. I have coated many tanks thru the years and can verify, that stuff is AWESOME! 

Good to hear from you ya varmint!! Half-Pipe Puc

[flyday58]

Señor Puc, how's it hangin?! Figured you'd be along, good to "hear" your voice again! I'm still firmly earthbound since giving up the flying gig in 2018, enjoying running around on two wheels that don't (mostly) leave the ground. How's things in Musky Michigan?

Well-taken points you have there in your list. Pipes are open and I bought an OEM airbox to replace the cones the PPO had on it. Diaphragms passed the hold-up-to-the-light test so no tears or pinholes. They seem to return readily to the closed position after opening with my finger. One is a teeny bit sluggish on the return, another has a fairly deep gouge on the upper surface at the base, so exposed most of the time and not riding up in the bore. Metering rods are clean, return springs are in good shape. This baby is largely electronic so didn't see any vacuum advance on it. 

It won't accelerate uphill and I have to downshift to third then second to keep her going. I'm hoping someone will chime in on the speed sensor question

[flyday58]

As a note, this dude had what appears to be an identical problem to mine. No resolution, never been back. I'm leaning strongly toward an electrical gremlin. My speed sensor is failing the test noted above at the speedo, but not sure how to test that theory. Should have continuity between the blue/yellow and white wires on the harness side, I'm showing an open circuit. Ideas?

 

 

[flyday58]

Made a few test runs trying different things, none of which worked. I jumpered the L/Y and W wires together at the speedo connector, bypassed the faulty side stand switch, checked voltage running (14.1V at idle, 14.08 when revved). So electrical issue looking less likely. Looks like I'm taking the carbs off again!

[flyday58]

Pretty sure I found the problem. Clue was the cone filters installed by the owner prior to the current one, plus the sooty plugs, but I needed to check all the electrical stuff first before yanking the carbs again. As you might expect the jetting has been monkeyed with. Mains are 125s and pilots are 22.5s. We're in the mountains above 8000' (9000 at my house) so super-rich when coming on the mains above about half throttle, the third clue. Just a shame the bank has to be split to get at the float bowl screws. Jets on order from JetsRUs.com. This should do it; I'll follow up once she's all back together.

[flyday58]

That was it, big old jets to compensate for cone filters. Runs like it's aspose to now. Something to look for when acquiring an unknown history bike.

[cowpuc]

3 hours ago, flyday58 said:

That was it, big old jets to compensate for cone filters. Runs like it's aspose to now. Something to look for when acquiring an unknown history bike.

BANG SHANG ALANG you dah MAN brother!!! GOOD ON YA!!! Thanks for the update!! Puc