Friday, 13 July 2018

T-Max using my new sheave holding tool (and fitting a new belt)

This is essentially part 3 of a series

  1. identification of a problem
  2. replaced the major part


So this is sort of finishing off ...
When I did the work on my T-Max back a couple of weeks ago I didn't have a sheave holder to hold the sheave (pulley) but instead got it off with an 18v electric rattle gun. Now as I mentioned in that post I didn't know what the amount of torque that the rattle gun would be (although the maker says it's good for 215Nm (and the manual says 160).

So this post is about double checking that and providing a few observations missing from my previous post as well as some significant changes to my measured RPM.

New Sheave Tool

Normally I'd have "munged up" my own but after moving out of my old house I just don't have the workshop setup to do that right now so I decided to buy one. Having seen some ones on YouTube bend I was cautious, but I got this one off an eBay seller in Greece (not China) called f1sport (link to his profile) and while it worked out a bit for me (in Australia) I think the price is totally commensurate with the quality as its about US$83.

Here are some pictures I took of mine, its simply an amazingly high quality bit of steel


Basically all the bolts were in an included bag, and you need to assemble them ... given you're clearly mechanical buying anything like this the lack of instructions are more of a pat on the back of your intelligence than an omission.


The steel is impressively thick



Todays work

So with the variator held by the sheave tool tried using the torque wrench (set to 160Nm) to see if it tightened any, it didn't (setting off the small "click" in the head). So I loosened the nut, and then tightened it with the torque wrench and then tried to undo it with the rattle gun. Unlike last time, this time it did undo, it moved very slightly at first (if you weren't looking you'd be forgiven for thinking it wasn't moving, it took a few seconds of "rattling" before it was starting to move at a pace where I knew it'd spin off fast soon.

Basically I'm now confident on how much torque to put onto the nut with the basic electric rattle gun and have it pretty close to right (and lets face it the torque wrench isn't calibrated anyway, so there's bound to be error), which is what I did 2 weeks ago (and it seems I was on the money anyway).

So now I know.

The other purpose of todays exersize was to pull the belt off and put my new one on. I didn't do that last time because the surfaces of the new sheaves looked a bit rough (not polished) and so I was wanting to let the old belt "polish that in" for me before putting on my new belt.

This gave me the opportunity to have a look more carefully at the secondary sheave (which I didn't do last time) and see the extent of damage that may be there (as less was visible the way it was). While I didn't like what I saw, it wasn't as bad as the primary suffered.


Unlike the primary, the secondary suffered its impacts much closer to the center with just a few hits further out in the sheave ... this is consistent (in my view) with the "hard bit of shit" getting in there at highway speeds (where the wrap of the belt would be tight to the center at the rear and out on the perimeter on the front sheave.

Indeed a closer look makes it clear that some parts of the interior have not seen the belt yet as the dings are still rough and not filled with rubber dust.


The red arrow points to dings which seem to be sitting on the highest gear point of the belt, the green seems to have not seen the belt and I think the blue is the boundary.

I decided to put the new belt in and when I measured the older belt I was surprised to find it was significantly under spec. I'm sure that when I put the new sheave on that the old belt was 31mm, however when I measured it today it was 27, or at about 3mm below tolerance!

So I don't know if I did measure it properly or didn't ... vexing.

With the new belt installed (and knowing it was thicker) I took it out again for a ride and observed the rpm speeds with this new belt (and of course the installed 2 weeks back 19g standard weights). What I got makes me wonder if I indeed failed to measure the belt (or look properly at the vernier).

So now at 100km/h my tacho is showing (about, its not digital) 5,250rpm (more than 5200, less than 5300) which is actually much better, and closer to what my stock 2002 model was doing (which was 4830 and I had a digital tach fitted to that)

It goes like this now:
speed revs ratio



60 4000 66.67
70 4300 61.43
80 4500 56.25
90 4870 54.11
100 5250 52.50
110 5500 50.00
120 5870 48.92

With the "ratio" being how many revs per km/h, showing that the bike is now giving lower and lower revs per speed as gearing increases.

This data also shows that I clearly can't have measured that belt properly because

  1. its unlikely that it could have stripped off 3mm of belt in 2 weeks without there being a mess in there
  2. I further dropped the revs as I got it it was 5,800 @ 100km/h, after the weights it went to 5,600 and today with the new belt to 5,250

Consideration


This is the data for my old 2002 model (previously discussed)

speed revs ratio



60 3740 62.33
70 4080 58.29
80 4250 53.13
90 4520 50.22
100 4830 48.30
110 5340 48.55
120 5800 48.33

which now looks pretty close, although the older sheave seems to be fully engaged much sooner than the new one. I did a video today (forgot to do one on a fortnight ago) and interestingly my observation was that the weights overcome the spring to fully engage the front sheave at about this rpm.


As it happens I have a theory on why its later to engage. The answer can be found by looking a bit further around the fixed side of the secondary sheave at the spring


which is BLUE !

I'm pretty certain that Yamaha don't colour code their springs which means it (like the malossi weights) are after market.

Looking around on eBay  I see that there is indeed a company making blue springs, but its not Malossi as their springs seem to be Red (+30%), White (+13%), Yellow (+7%) and Green (-39%).
The company selling Blue is unclear about it because their kit also comes with some other adjusters to allow you to increase the spring tension  more.

This then is consistent with modders without a clue because putting light weights in with heavy springs will restrict the engine to a narrower rev range (never getting top gears) and be super revvy (when the engine was designed to be super torquey).

I guess that the next things on the agenda are:

  • keep an eye on the belt wear and see of those marks are causing it to wear faster (and the heavier spring won't be helping)
  • I still have no idea what caused the damage, so perhaps its pull apart the secondary sheave and have a good look. I'd have done that today but I didn't have a 27mm socket which would fit


Given that its got relatively high mileage and an unknown service history its probably a good idea just to pull that secondary apart and give it all a lube up...

Wednesday, 11 July 2018

Nut Bags

In Australia we call people who are crazy "nuts" ... thus those who are "as crazy as a bag of nuts" are often called Nut Bags.

The ancient Christians once used symbols on caves to mark their meeting places or declare themselves (usually a fish symbol), and here in Australia I've observed that Nut Bags are identifying themselves discretely with their own iconography:


Nut Bags may also associate with other merchandising

Friday, 29 June 2018

T-Max replaced primary Sheave

Since I got my T-Max I've been a bit concerned that its revving too high (compared to my last one). Its nothing I can be "sure isn't design" and its getting good fuel economy  ... but still 6000 RPM at 100kmh is too fukken much. So I decided to wait till the belt inspection interval.

In my last post about my T-Max I found something "amiss" when I went to check the belt (at the inspection time)


To save repeating myself I recommend reading that (short) post here.

Summary:

I think that the problem is that the weights are too light (and there is probably some misinformation about the standard roller / weight mass out there).

I think that the current situation (with the new parts) is pretty much "spec" but I can't actually know as a lot of this data isn't published.

Details:

So, in this post I wanted to just discuss some details about the work involved and to talk about outcomes.

Firstly for those who haven't done this, but are thinking of doing it, I'd say that its not difficult at all. Having had the earlier version (the differences I'll speak of in a minute) this newer system (which is about the same right through to the newest ones) makes the task of removing the weights (or rollers as the manual itself variously refers to them as) quite simple. The task of taking the primary sheave apart (making belt inspections a peach) is itself not hard.

There are a few points in the workshop manual (which I assume you have) that seemed more complex (perhaps only to me) than they were actually in fact.

The first point is the removal of the primary sheave, reading the manual (and some of the on line videos) makes it out to be a process which needs a special tool ... the sheave holder. If you have a decent "rattle gun" (or impact driver / wrench) then its actually totally un-needed to have the "sheave holder".

The trick is to not break the tension the secondary sheave has on the belt with the bolts as prescribed. The friction of the belt already in place (from the last time the motor was shut down) is entirely enough to allow the removal of the nut ... and thence pulling off the "right hand side" of the variator sheave to allow the belt to simply droop onto the axle of the primary sheave (which happens to be the engine crankshaft).

Its a peach.

The rattle gun I intended to use wasn't strong enough in practice (red rectangle) , but was in theory. I suspect that the previous mechanic put it on with too much tension. It should be tensioned to 160Nm torque and in theory my rattle gun is good for 215Nm ... it wouldn't budge so I borrowed this brute.


which undid it in about 2 seconds. My (smaller) rattle gun was used then to put the nut back on and (not knowing the exact tension it would deliver) just rattled it on "briefly" with the merest of "whacks" (NB not going spakko on it). I intend to check the tension later with a proper tool.

When you first start to pull the covers off the crankcase housing you'll see this:


This is actually the nut you'll take off and yes that's the crank (and yes mine looks like its been punished).

When you take the crank case cover off, you'll see it like this:



And its that spacer (or "collar" as it is mentioned in the manual) which takes that BT grease, the rest (only in a few places) takes "assembly lube"

As you can see that collar has holes (4 actually) and as well as the O-rings has a groove on the inside (which is obvious when its off) that you pack a little more of the BT grease into.

When you pull the crank case cover off you'll see that it has a bearing, which the "collar" sits in (and that's why it wasn't visible in the earlier shot).



This is the crank case cover removed and seen from the "back". The collar sits exactly inside this bearing. You can perhaps just see the two black lines where the O-rings rest inside the inner race. While the bearing is free to turn, the BT grease is just to ensure that the inner race of the bearing has a layer of lube between it and the crank "collar", and the O-rings ensure the lube doesn't get to the belt (a bad idea).

Now in the workshop manual its all a bit more confusing:



as well as all the instructions on what to lube and with what. 4 in the dotted lines there is here:



The weights I took out of my original variator were all within the diameter spec (25mm, min 24.5mm) given in the manual. However the manual doesn't specify weight. They weren't Yamaha ones quite clearly.


They were "Malossi" (and the previous owner swore it was all stock ... sigh) and while they had a few visible flat spots the should otherwise be good to go.


... except when I weighed them (on a scale that is only reading in grams) I found they were some 18g and some 17g ... when I weighed the bunch they were 143g (or 17.8g on average).

Interestingly the Yamana ones were on average 19.37g (or 155g for the lot) which as a whole mass acting on the variator is about 12g heavier ... which will mean that it takes a higher RPM for the mass of these to overcome the spring (in the secondary sheave) and mean a higher RPM before the "front" is fully engaged.

Taking a look again at the image of the primary sheave it was clear that the lighter mass resulted in the sheave never being fully in its highest gear:


as the red arrow is pointing to the maximum run out of the belt, and there is still a good centimeter of pulley left to occupy (again explained in the first post). This suggests that for those who favor weight changes to alter the power distribution in their T-Maxes it is akin to just riding around in a lower gear. Meaning your engine will be doing more revolutions per journey and thus wearing more.

So, with the new weights in the new sheaves I put the BT grease only onto  the thread, the back of the nut and inside the collar, reassembled it and took it out for a test ride.

This is where I found interesting things. I have (now) 4 data sets of RPM vs speed

  • my first T-Max
  • a fellow on the internet who sent me his 2009 T-Max data
  • this T-Max before changing weights
  • and this T-Max after changing weights
Here's what I found.
  • my 2002 T-Max was much higher geared, doing 4830 rpm @ 100kmh (I bought an external Tacho for it that worked off the spark plug lead because it didn't have one) and the gear ratios seemed fully engaged (biggest it got on the front, smallest on the back) by about 100Kmh (sensible)
  • the fellow with the 2009 model was doing 5100 rpm @ 60 mph (curse the USA for still being imperial) which is about 96kmh
  • my current (2006) T-Max was doing 5800 rpm @ 100kmh (which is a fair bit higher than either of the above)
  • after the rebuild of the variator it is now doing 5600 rpm @100kmh (which isn't much lower but is lower)

So where next?

Clearly I need to double check how much further the belt is coming out along the variator at higher RPM, is it making it all the way out? I also need to pull the rear sheave off and see if there is anything amiss there (and I still don't have any explanation for what caused all that damage to the inner sheave).

However I'm thinking that "perhaps its just different" ... I mean its getting good milage (4.5l/100km (or 52US miles / gallon)) and there are differences in the models. For instance:
  • the 2002 model developed peak torque at 5500 rpm (a bloody smart location really), while my model develops it at 6250 rpm (marketing wankers involved I'm sure). This means that to keep the cruising speed (assuming highway use) close to the peak torque they'd need to move the rev / gearing ratio. As it happens its almost at the 5500 revs of the older motor and probably within 90% of peak (its a not a steep curve) right now.
  • Opening the throttle sees the rpm rise quickly (faster response than my older bike) to over 6000 which is getting near to where this motor develops its peak power
  • Peak power has been moved from 7000 rpm on my 2002 bike to 7500 rpm on this (the 2006) bike
Its quite likely that the lack of publication of Yamaha weights has led people to perhaps measure the early model and then not double check that the parts haven't changed.

Perhaps too, the change from Carburetor to Fuel Injection (and some years of service experience) has led Yamaha to decide that slightly higher revvs isn't bad for the motor?

The older model

Having had both now (and serviced both now) I can say that one of the steps backwards to me is the variator. The older one was much more robust in design and was actually well lubricated (while this one is dry). Lets take a quick look at the older one from the manual:


Things to notice are:

  • heaps more sliders to stabilise the sheave to the cam (as the outer sheave is not actually attached to the crank and relies on the internals to prevent slippage)
  • the weight rollers are deeply embedded in a bath of BT grease, so really are massively protected. I never once had any problem in 160,000Km of daily riding (including traffic, dragging cars at the lights, mountain roads and touring)
  • the whole thing is easily kept into one piece when inspecting and changing belts, and indeed being a bit smaller I never needed to take it off to change a belt (unlike the newer one).
Note in the assembly instructions just how much grease is involved...

so as you can see even when you remove it, that sheave does not "fall apart" in your hands (as the newer one will when you remove it if you don't keep a good grip pressing the parts together).

Combined with the more relaxed rpm range of the older one I feel that Yamaha has bowed to the "wanker" set (I mean, they've got the money right?) and taken the T-Max from a practical and comfortable general purpose motorcycle towards a "wanker bike" when the reality is that it can never be an FZR-600 (and if you want one of them you should get one).

The removal of the fantastic and practical and discreet tie down straps from the passenger grab rail (I've loaded plenty of cartons of stuff onto the older one as a real work horse) and the increase in this direction of the newer models says that even more loudly.

Conclusion

So looking now at these numbers perhaps it really is all back to standard now.

Anyway, when my sheave holder arrives I'll need to pull the crank case off again and check that the rattle gun put the right tension on that nut (it was a guess, but it can't be more than 215Nm because  that's all its good for, and who knows how accurate any torque wrenches actually are anyway) and I'll be able to inspect (after run in) how far that belt is getting up along that sheave.

I'm impressed with just how reliable and robust the T-Max is, having done 160,000 on my first one (most of that being my mileage) and now having this one with 107,000 (and I've only done 13,000 of that) I see that belts last well, maintenance is straightforward and they can tolerate an amount of shit without breaking. I seldom got 20,000 km out of a "chain and sprockets" on my bikes, and with belts being less work and about the same price its quite encouraging.

more as it comes to hand ...

Tuesday, 19 June 2018

T-Max CVT issue

Back in about July last year I got myself another T-Max, and its been an interesting time with it so far. It's been quite reliable and hasn't missed a beat, but since getting it I've noted that it rev'ed higher than my older one for the same speed. I expected that there was something worn, but decided that as I was getting really good fuel economy I'd leave it alone till belt inspection light came on.

So the belt inspection light came on a little while back and I got around to pulling off the cover and having a look.

Well ... I'm sure there's a story to this:


I'm sure someone noticed that when it happened.

Interestingly when revved the outside of the belt doesn't get past that black line, and it should.

Here is a quick video showing that more clearly where that gets to:


So I've bought new front sheave sides and in anticipation of wear (or worse) new weights. The sliders looked good to go.

I'll keep you posted