Triumph Rat Motorcycle Forums banner
261 - 274 of 274 Posts

·
Registered
Joined
·
135 Posts
Discussion Starter · #261 ·
I just measured shoulder to base on PRT. I'm getting an average of 3.427" on the intake and 3.417" on the exhaust. It would be nice if they were identical, huh? And it varies a bit around the circumference. I suppose that makes it close enough to be equivalent to the 71-2576 at 3.415"?
 

·
Super Moderator
Joined
·
10,318 Posts
Hi Daryl,
shoulder to base on PRT
average of 3.427" on the intake and 3.417" on the exhaust
varies a bit around the circumference
nice if they were identical
Obviously not MIL-TFD-F1 ...

close enough to be equivalent to the 71-2576 at 3.415"?
Wonder if "varies a bit around the circumference" makes 'em more or less oil-tight in certain positions ...

Regards, :rolleyes:
 

·
Registered
Joined
·
135 Posts
Discussion Starter · #263 ·
I've decided there's too many variables as it sits. I really need to install the tappet blocks to literally get a good base line.

What I learned from installing just a top o-ring on the PRT is that you have to do that by installing the o-ring in the head, not the o-ring on the PRT. When it came apart, the o-ring stayed up in the head. If installed the other way, the o-ring doesn't necessarily get pushed into it's recess in the head. There's two "steps" in the recess and putting the o-ring in the deepest step puts it where it should be. If it ends up on the lower step, it's less snug in the gap. The correct result allows for a lot of vertical possibilities for the PRT. It goes into that o-ring as far as it gets shoved into it, but not necessarily to the shoulder of the PRT unless the lower bit takes up enough space. So, the blocks will go in and will reassess the gaps.

Just for information purposes, the PRT o-rings I removed are in vastly different condition. I'm not sure I would know the cleaned up intake o-rings were not new. The leaking exhaust top one is hard, black, and crumbling and the other is slightly better but also obviously past it's use by date. The discrepancy is astounding.

For the tappet block install I am planning on: oil on the block before installing, rubber lube (p-80) on the o-ring, triple check the alignment is square to the bores while install. Anything I'm missing or strong opinions to the contrary? 🙏
 

·
Super Moderator
Joined
·
10,318 Posts
Hi Daryl,
For the tappet block install I am planning on: oil on the block before installing, rubber lube (p-80) on the o-ring, triple check the alignment is square to the bores while install. Anything I'm missing or strong opinions to the contrary?
Couple of thoughts:-

. If the tappet block O-rings are Viton (they should be), they're by definition oil-resistant, so special rubber lube isn't necessary - the oil (or grease?) and P80 are going to get mixed anyway, so imho save the P80 for jobs that need it?

. "alignment is square to the bores" - you mean each tappet guide block is square to its bore in the cylinder block, not the cylinder bores?

:sneaky: There are a couple of other factors that could be considered when installing TGB:-

. either the centre of the hole for the locking screw is perpendicular to a line through the centres of the two tappet holes;

. or the 'twist' an off-perpendicular hole imparts to the TGB matches the difference between the centrelines of the two cam lobes, which aren't necessarily at exactly 180 degrees to each other ...

... :whistle:

Hth.

Regards,
 

·
Registered
Joined
·
135 Posts
Discussion Starter · #265 ·
That's very helpful. By square to the bores, I was implying aligning a line across the tappet holes centers with the cylinder bores centers. I had not really thought that a 'twist' could be desirable. There are wear marks on the tappet shafts that I will look at to see if I can figure out where the "middle" is or should be.
 

·
Registered
Joined
·
135 Posts
Discussion Starter · #266 ·
I have installed the tappet guide blocks without any drama.

I'm totally fascinated by how everything is lining up now that they are in place. With the old intake o-rings to mock it up, the PRT/o-ring piece has the latitude to move up and down between the TGB and the head. The top o-ring stays up in the head and the bottom is in it's recess in the PRT. And the whole thing, with the old head gasket in place, has about 0.04" (that is on the outside, probably less of a gap inboard) of space to move in. Where it was previously, and where it would end up regardless of where it started, is with the chrome bottom of the PRT resting on the TGB and therefore the top o-ring about 0.04" above the collar of the PRT.

From what I can tell from the in situ pics I took before disassembling (not definitive as the grime gets in the way), it looks like that's where it was previously. One of the takeaways from this is that the PRTs should not be putting any pressure on the head/cylinder as they are floating between the two on the o-rings.
 

·
Registered
Joined
·
135 Posts
Discussion Starter · #268 ·
"Trillian, is this sort of thing going to happen every time we use the Infinite Improbability drive? Very probably, I'm afraid."

I have been diligently working the kinks out, so to speak. Hopefully, I can remember all the details so this recap makes sense. It may help someone in the future (who has the bike that came of right before or right after mine on the line ;))

After much deliberation, reading and rereading, a post by Rudie in this thread on triumphtalk got me to a decision. https://www.triumphtalk.com/threads/1972-triumph-daytona-part-3-and.55633/
Semi-related, a book called The Perfectionists, by Siimon Winchester, feels like it's talking about this kind of situation. Engineers come up with a plan. The plan is fine, except the precision in the machining is not up to the allowable tolerances. So the machining gaps add up and pretty soon the gap is navigable by the oil and the customers complain. So the company has to come up with a band-aid. SB 324, the cushions and the wedding bands, is the attempt at closing the gaps. However, what if the gaps don't amount to a full cushion? This is where my particular bike is. Thankfully, I am able to stand on the many who have experimented before me.

I decided to put in the cushions, but to cut the cushions. I had the gasket set and it came with 4 white cushions, 0.100 thick. If one is inclined, it is possible to put the cushions on a socket of appropriate thickness and cut them to size. My sockets have a groove so the cushion stays more or less in place while xactoing it. I measured the stack gap without the cushions to get the crush sorted out and ended up needing a bit more than a half of a cushion. Then I sanded the cushions to get it as close to 0.030 crush as I could.

The wedding bands. I thought this part would be simple, but ...... SB 324 says tight fit and glue if necessary. Forums say bands tend to be loose nowadays. The bands I received were very tight. I had to sand the ID to get them to fit. The fun bit is that it is not possible on my bike to assemble the thing with the band on the PRT. The band won't clear the cooling fins when it's on the PRT. So the band on mine has to go on the guide block first, then the cushion, then the head with the PRTs.

At the point where I had it all back together, more or less, there was a lengthy delay because I am special. I lost track of one of the rubber bands that holds the wiring to the frame. You know the one right above the engine. I have a picture of it before the head came off, and I know I thought about it at one point (hey, I should put that somewhere else). And then it disappeared. I cleaned a rather large portion of my garage in an attempt to locate it. Stuff that hadn't seen the light of day for 10 years was sorted out, but I did not locate the band. Hmmm. Where could it be? I am not one to cross off something just because it is virtually impossible. No fair jumping ahead. Could it be in the engine? Very unlikely. But, not impossible. I have a borescope, so I drained the crankcase and looked up inside. I couldn't see the entirety, but I also couldn't see the band. So, off with everything. Guess what? Not in there. To this day, I have no idea where it went. And I don't throw anything away. Must have walked off by itself.

Back to the main plot. Eventually got to starting it up. From the get go it seemed a bit off. Fine but not fine. Definitely different than before. When it was warm I had to screw one of the carb air screws (carb was removed, but not touched beyond that) all the way in and the other was mostly in. And it won't rev past 5500 rpm. ??? I decided to replace the orings and phenolic spacers (one of the few "original" seals left). While waiting for that to arrive, I realized that the baffles in the mufflers (aftermarket cocktail shaker things) had migrated to the rear and the other had migrated toward the rear. So I'm thinking I've got this sorted out. Air leak and more restrictive exhaust. Yeah, whatever.

Beta test. Air screw not all the way in, but still pretty close. And the float bowls seem to be overflowing at the top, sometimes. :confused: Then I see that one of the float bowl gaskets has torn and a section of gasket is literally vibrating in and out of the gap while the bike is running. Float bowl screws were not tight. So, remove the carbs and tear them apart. One of the fun (literally) things about all this R&R is that I can see if anything is changing from one rebuild to the next. In this case, the floats were exactly where i left them (I marked the height inside the bowl), the main jet passage was spotless. The whole thing was really clean, tbt. I ordered the appropriate drill bit and confirmed the idle jet was clear. Still not positive if that removed anything. i think it did, but not much if it did. As an aside, I put bowls with drains on them so I wouldn't end up with fuel crap left in there if I had to do work on anything. Anyhow, double checked everything and put it all back together.

Try it again. Everything seems to be working. Except still not going over 5500 rpm. I chased my tail on that one for days. I checked every electrical component. Checked the points, the gap, the timing (good idea as they were all a bit off). Double checked valve clearances. Battery voltage. Not a thing wrong but won't go over 5500. Then it dawned on my stupid brain that if I could ride the bike at normal speeds in normal gears, it must be going over 5500. Turns out the tach has decided to run at 80%. I still haven't delved into that one. It spins freely, newish cable, cable spins freely, cable spins. The speedo is something I tore apart to free up. The tach is not. I managed to turn the adjusting screw (through the light hole in the bottom), but it did not correct the issue. Something for another day.

That's not all, naturally. I went out a couple of weeks ago. At some point I felt more vibrations through the handlebars than usual. I really should just pull over when that happens, but it seems to not be in my nature. So I keep going and as I'm going to upshift from 1st to second, I can't. My foot is telling me there is no such thing as a gear selector. I look down and the right side air filter is sitting on the gearshift, so my foot is resting on the flat of the filter housing. No problem. Merge across 3 lanes of traffic with the clutch pulled in and pull into a random parking lot to address it. How it didn't just fly off, I'll never know. Bonus, when I had put the filter housings back on, I know they tend to come loose so I snugged them down with emphasis. I literally couldn't push it back in place without loosening the screw. Good lord.
I make it home, check for loose bits as I still have this vibration thing, and find the muffler baffles have again come loose and gone rearward. It really hates being baffled I guess. When I put the baffles back where they belonged and tightened the bolts, the screws (both sides) snapped off. I really don't know what's going on there. I never had an issue with that previous to this escapade. Now there's new hardware and I keep rechecking it so hopefully it stays put.

So that's where I'm up to. Took a ride today and nothing fell off or seemed any worse for wear than when I started.

Oh, one question. I am slowly eradicating oil leaks. It seems there's one where the oil feed pipes come out. Problem is, I can't get a socket on the nut. Or a wrench. Should I be able to? Not sure if the pipes have been whacked to get in the way or if I'm missing something.

Thanks again for everyone's help. 🙏
 

·
Super Moderator
Joined
·
10,318 Posts
Hi Daryl,
"Trillian, is this sort of thing going to happen every time we use the Infinite Improbability drive? Very probably, I'm afraid."
😄

diligently working the kinks out
Took a ride today and nothing fell off or seemed any worse for wear than when I started.
(y)

oil leaks. It seems there's one where the oil feed pipes come out. Problem is, I can't get a socket on the nut. Or a wrench. Should I be able to?
The stud is 5/16"-24. However, the listed "S1908" Nut should be 'small hex.' - 7/16" AF instead of standard 1/2" AF - I can get a 7/16" AF ring wrench or 1/4"-drive socket on my bike's.

right side air filter is sitting on the gearshift,
How it didn't just fly off,
Consider a cable tie through a couple of holes on each filter? Might not stop one coming off but at least it won't go far?

The wedding bands.
If you ever need to cut new "cushions", consider using 70-4746 - a cup washer that simply fits around the tappet guide block, the side of the "cup" retains the "cushion"; used by all triples and pre-'69 twins to retain the bottom "cushions". (y) Reason I say, "If you ever need to cut new "cushions"" is their thickness would then need to take account of the thickness of the bottom of the cup washers.

Hth.

Regards,
 

·
Registered
Joined
·
135 Posts
Discussion Starter · #270 ·
Hi Stuart,

Thanks.
The stud is 5/16"-24. However, the listed "S1908" Nut should be 'small hex.' - 7/16" AF instead of standard 1/2" AF - I can get a 7/16" AF ring wrench or 1/4"-drive socket on my bike's.
Yes, I can barely get the open end on it endways. I'll try the 1/4". The 3/8" socket I have is pretty thin, but it's the gap between the case cover and the pipe that's the issue. That's where the socket body gets in the way.

Regarding the air cleaners. Not the first time one's come loose. It was the first time one traveled away from the carb. In the past, it's just got wedged in the middle. Thanks for the tip. Although, I am getting better at understanding what the preflight check should include.:)
 

·
Super Moderator
Joined
·
10,318 Posts
Hi Daryl,
air cleaners. Not the first time one's come loose.
I'm actually contemplating replacing the Triumph one with a K&N - I've had K&N's on at least one of my T160 since the early 1980's, no problems at all. That'd also get rid of the sleeve that screws on the carb., that the Triumph filter clamps on; the K&N will just clamp around the threads on the carb. (y) K&N RC0170 if you want to give 'em a go.

Hth.

Regards,
 

·
Registered
Joined
·
135 Posts
Discussion Starter · #272 ·
Thanks for the suggestion. I looked at the K&N filter and had an idea. As an experiment, I've put a rubber band between the clamp and the housing. I only did one side. We'll see which side lets loose first.

Also, I tried the 1/4" sockets and no bueno. I'm not exactly sure if one of the pipes has been bent so as to interfere or if I should have know to deal with this when the cover was off. :rolleyes: Just to get a socket past the cover and pipe is a challenge. To do that far enough from the nut to fit into the socket is impossible. I don't want to try bending the pipes as I'm afraid of making a slow leak a fast leak.
Automotive tire Motor vehicle Wood Vehicle Automotive exterior
 

·
Super Moderator
Joined
·
10,318 Posts
Hi Daryl,
tried the 1/4" sockets and no bueno. I'm not exactly sure if one of the pipes has been bent so as to interfere
:( Mine takes some fiddling, the socket is quite short, I push that on the nut first then the extension will slide into the socket, even though it isn't quite straight.

Fwiw, afaict from your photo, the pipe obscures about the same amount of the nut and stud as on my bike. Looks like it might be luck whether or not a given socket and extension can be wiggled in to tighten the nut. :( Given also 1/4"-drive sockets/extensions/wrenches - if they existed at all in the late 1960's - would've been an expensive and exotic rarity, I suspect the pipes were bolted to the crankcase before the timing cover was fitted, so a more-common ring wrench could be used to tighten the nut?

Hth.

Regards,
 
261 - 274 of 274 Posts
Top