First timer carb balancing and camchain

[Schomosport]

Read up carb synchronisation and camchain adjustment using the many informative links in the forum and then settled to the task. Here is my tuppence worth of commentary.

I don't know if my camchain is noisy or not, don't think it is really but read the bit about turning the engine backwards half turn or so to make a sticky adjuster move to the next position. Bike on centre standard, select 6th gear with plugs in, tried to rotate rear wheel, ha ha, not it isn't going to budge (I am a weed). Parked it, we will come back to this after I have balanced the carbs and warmed the engine up a bit.

Off with the tank. Leave the rear bolt in loose so the tank doesn't skid off somewhere like the floor and prop the front up with a bit of wood at 45 degrees. (Helps if you have run it down to reserve first). You need to prop it unless you are have super dexterity in one hand to release the electrical connector to the fuel gauge. '98 manual downloaded from here shows 3 hoses, my 2001 only had the single fuel hose, turn of the tap and pull it off. Pull the bolt and put the tank on the floor and inspect what is to come. New to me bike a few months ago, now is a smart time to check the air filter. It's a good one, clearly been replaced very recently.

Oh goodness, those screws are tiny and I don't think I have a screwdriver that will get down there. Actually at this stage I can't see all 3 even with a torch because of the ignition coils and other assorted junk hanging of the cross-bar. Pick up phone, Ebay me a No. 1 Phillips x 250mm long, still think I am going to need it. Fortunately it is a hobby bike, not a commuter so a few days delay won't matter.

Remove the two bolts holding the cross bar and carefully pull the whole assembly up a few inches whilst trying not to stretch any of the wiring attached too much. Slackening off the harness cable ties helps no end. Slide thin bit of wood under crossbar and across top of frame tubes to support it out of the way. Back to the torch, twiddle throttle, ah now we can see all three adjustment screws. Rummage through tool box testing various screwdrivers, yeah might just get away with this. Wrap fuel tank loosely in blanket, put an old cushion on the seat and place fuel tank backwards on seat. Yes, fuel hose reaches back to the tap easily, no bother here. Run rope round fuel tank and chassis, pull tight and knot, I am quite clumsy and don't want a still in good condition tank bouncing off on to the floor. Start engine briefly to make sure I haven't pulled any hoses or wires off, all ok. Watch the loosely fitted black plastic elbow that allows the carb tops to breathe doesn't go walkabout.

The throttle cable had developed quite a lot of slack recently, now I can see why - one of the adjuster nuts is loose at the carb end. 10mm wrench to tighten, nigh on impossible to access with the coils in place, a doddle with them lifted up and out of the way per previous.

Assemble my new Morgan Carbtune. Last one of these I had, long since lost, used mercury. I am about to find out that the current version is much easier to read (and from memory responds more quickly) and yet the shim packs still have an uncanny resemblance to mercury columns shimmering (sorry) up and down.

Pinkies in between the carbs to remove the bungs and back in to fit the Carbtune. Start engine and let engine warm up until radiator too hot to touch. Its October, seems to take ages. Carbtune not fussed about a few blips to 6000 rpm to help the process, don't think you could get away with that in the mercury days.

Engine is warm, the columns aren't even so tweak the balance screws until they are. I haven't read deeply on this, the manual is on the computer which is inacessible right now, so I don't know if there is supposed to be a master reference carb or not. Doesn't seem to matter, we have 4 carbs and 3 adjustment screws and an idle adjuster to get it back to the right tickover speed, I will look it up later (now I have remembered, still to do!). All columns within Morgan's 2cm Hg recommendation, probably nearer to 1cm without any great difficulty. Few throttle blips, no meaningful variation, we are done.

With hindsight, yes I could have checked the balance without fuel tank removal, no I don't see any way on this earth you could make adjustments with the tank in situ although someone will probably tell me I am wrong. Engine seems a little smoother and more responsive, out for 60 miles today and yes it is nicer to ride, particularly when applying small throttle opening albeit fxing the throttle slack would have helped that no end.

Reassembled everything taking the opportunity to do a bit of HT cable and hose routing tidying along the way.

Back to the camchain adjuster. Engine is now nice and warm, put it in 6th gear, drop it off the centrestand and push the bike backwwards a couple of times. Yep, that's a scientific half turn backwards of the engine. Is it any quieter, not sure since I didn't record the noise before I started messing. Today's test ride appers to confirm that I haven't done anything too stupid since everything is beautiful. Aa are the trees along one particular part of my test route. All the same species, close to the road in two avenues for about a mile with leaves turning gold, magnificent, Not many more decent riding days left this year I fear, I am an old wuss now and 14C seems quite chilly.

Hopefully the above waffle is useful to someone, throw rocks at it as you will. Cheers all.

(Haven't touched the TPS, should I have?)

[RMT1983]

You could unplug the tps with the ignition on (engine off) plug it back in and if the rpm sits at 5K then its fine. if its anything other than 5k then it needs adjusting...

[Schomosport]

You could unplug the tps with the ignition on (engine off) plug it back in and if the rpm sits at 5K then its fine. if its anything other than 5k then it needs adjusting...

5250rpm so needs a tweak. Anyone know the code for a bit for those tamper proof screws please? Look like Torx so maybe I can grind the centre pip out with the Dremel or remove by some other means (flinches) and replace with socket heads.....

[RMT1983]

20 or 25... I think the 600 is 25 and the 1000 is 20...

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Can buy a selection from amazon for a couple of quid

[Gnasher]

Before you go moving everything. 

The master carb is the one with the TPS on, No 4 cylinder, this carb can't be adjusted the others are brought into balance with it.  The TPS has tamper proof screws for a reason, it's set to No 4 which is datum, in other words you're not supposed to move it!  The Yam manual like all Jap manufactures manuals is not that well written and from a stand point of the person using it has already been trained on the bike on a factor course and is qualified.   Now I'm not saying you're not capable or even possible not qualified, far from it.  But few have both boxes ticked of the previously stated, if you have you wouldn't be asking the questions   Haynes well lest said better but they're better than nothing   

No4 must be pulling between 230 - 250mmHG (as should all the others) with the idle set at 1150- 1250rpm. Carb tune are pretty accurate but unless they've been calibrated there's no way of knowing.  I see many a bike where the owners tell me they've balanced the carbs or dealer/other Mech has, only they're not as most don't calibrate and/or use crap equipment.  If No4 isn't pulling the above you need to start looking at firstly the mixture screw front bottom of the carb, this should be 2 turns out same applies to all the other carbs, once balanced. If you can't get it to pull the correct Hg with the screw at 2 turns out or very close each way, you need to start looking for dirty air screws and/or bleed passages.  The other very common possibility is were the carbs have been rebuild with crap pattern/aftermarket parts, many just replace jets, needles etc when they don't need to.  

No pattern/aftermarket part is going to be as good as OE, that's mainly why they cost more! And why change them if there's no need just a waste of money.    

When balancing get the engine warm is you can.  Start with bringing No 3 to match 4, then bring 1 & 2 into line, you may have to increase the idle speed depending how far out they are, then bring the two pairs 1- 2, 3-4 into line again you may have to adjust the idle speed.

Once you've got them all pulling within the range they're balanced and the idle speed is correct, then check the TPS it should read 5000.  If its not and the Hg, balance and idle are correct then and only then move the TPS.  

The chances of you TPS not being moved by now is unlikely, mainly because people don't understand it's a datum and start moving it with the crabs not set correctly as outlined above or it's been replaced (very common) with out checking all the specs, correcting any that are wrong before fitting the replacement.  

Setting up carbs isn't easy at times as it's made out to be. Everything depends on who's been there before you and what damaged, crap part/s have been installed and what tools used. Like everything in life it's easy when you know how, many on forums will tell you it's easy, it is but more often than not they're are doing wrong!

Cam chain noise is often out of balance carbs and/or the tensioner between teeth.  Providing it's not rattling loudly, get it warmed up and give the bike some stick in the lower gears to the red line for say a days riding out, to should pop the tensioner to the next tooth. If that doesn't work and you've got all the carbs balanced take out the tensioner and set it.   

These engines love to rev and they have very reliable cam chains and tensioners.

[Schomosport]

Before you go moving everything......

Thanks Gnasher for your detailed post. Glad I checked back to the forum before I went out to the garage and started fiddling.

There's a big element of if it ain't broke don't fix it here. Bike's a 2001 with 11,000 miles on it but new to me as of a few hundred miles ago so a bit at a time I am going though all the things I think need checking supplemented by info on here such as about the gearbox sprocket nut (done). By appearance it looks to have been loved and it isn't doing anything very much wrong when I ride it to think there is much wrong. But no service history (for what it is worth on a 24 year old bike) so reasonable assumption the carbs might not be properly balanced so I tooled up and got the Carbtune. Based on its output the carbs are now balanced better than before.

I completely get the bit about the TPS being synchronised to carb 4 and that with the Carbtune I don't actually know what vacuum it is pulling unless I tool up some more for a gauge and measure it. So maybe I actually have for maladjusted carbs that are reasonably well balanced at idle!

Anyway I take your point, silly to move the TPS at this stage so I will leave it alone. No one can read exactly 5000rpm on a tachometer dial and no one knows how accuarate the tachometer is so it would be helpful to know how close to 5000rpm is good enough since there is nothing in the manual.

If my understanding of engine control systems is correct, on a carbureted engine the ECU is only using the TPS to detect large throttle openings at low rpm so that it can retard the ignition to protect from pre-ignition and hence its setting is not super critical. If it were fuel injected then a different kettle of fish entirely. It may also show my understanding is flawed and I am talking carp, won't be the first time or last.

[RMT1983]

Yeah, it it aint broke dont fix it is always the first rule of bike club lol

Not knowing the history of the bike would suggest anything could have happened previously hence the suggestion of checking the tps. The checking process is also there for a reason.

Being 5250 id say its probably inline and doesn't need touching as you say how perfect can it be???

All of the above is bang on, however who's to say someone hasn't had the tps in a bathtub (I've seen it happen) or someone hasn't inadvertently knocked it, again it happens.

Definitely sounds like your on track for some good spannering!

Stay safe ?

[Gnasher]

11000 miles on a 01 bike that's a good find for sure, there's a good chance the TPS hasn't been moved, one way to check is there white paint on the bolts?  Not a absolute but a good indication. 

All the cylinders should be pulling the same spec range of Hg once correctly set and balanced.  Theoretically carbs only go out of balance due to slight bedding in and wear overtime and due to atmospheric conditions, the former is slight later is very slight, in reality what buggers the balance is mainly people messing about!  At 11000 there's a good chance all's well, unless I've missed something you don't say why you are doing a crab balance, is it too see if that effects your cam chain noise? 

As for the 5k on the tacho, it will only go into 3 positions 0, 5k or 10k as long as it's in the middle it's fine.  The TPS is pretty much as you think, it allows the ignition module to select one of three basic timing settings for a given throttle opening, the bike doesn't have an ECU, although many think it does, it doesn't.  They can be temperamental, that said in my experience (now watch the flood gates open) they only go that way when messed about with, or jet washed.  Most FZS600s these days have had several owners and many a hard life, even if they look clean and reasonably low milage, so they get played with and jet washed!

If you do have TPS troubles you'll find Yam OE are very expensive. But other bikes Yam bikes share same one as do some cars, off the top of my head it's Suzuki bikes and cars but can't remember which, it's been a good while since I've changed one. Someone will pop along with which I've no doubt or do a forum search or google search the part No or Yam bits for about £100 ish.

[b1k3rdude]

Lots of good on topic advice, nice one chaps.

[Schomosport]

...is there white paint on the bolts?  Not a absolute but a good indication.....

......you don't say why you are doing a crab balance, is it too see if that effects your cam chain noise?.........  

As for the 5k on the tacho, it will only go into 3 positions 0, 5k or 10k as long as it's in the middle it's fine.................

1. No paint plobs and have had a bit in them at some point but no skid marks on the plating beneather the washers either so who knows?

2. New bike, not had a Japanese 4 for 30+ years, just seemed sensible to check carbs were balanced. Haven't been near another bike so no real idea what sounds good or bad. The Honda 400/4 I had many years ago now that sounded and was bad. Nothing like that, seemed abit clanky hot day at traffic lights probably just an oversensitive and overworrying ear. Don't know why really, paid no more for the Yam than I have already spent in 12 months on my Norton. I will give it a hiding somethime soon - it goes well for a little one, not quite got used to red-line acceleration through the gears yet.

3.That's what I was hoping for.

On Ebay in June at 10,300 miles. Drove up to Manchester, looked and listened, chose not to test as no insurance, agreed £1850 and went back for it on the train week later and rode it back to Bedford. Prices dropping now the weather has turned but bought it to ride for pleasure not profit. Better than my Norton on every count but a Yamaha isn't a Norton, you would have to ride one to understand the difference. Truth be told I enjoy both and if I needed to go somewhere urgent and be there I know which I would take.

Thanks again.

[Gnasher]

What Norton? I've ridden a few.

[Schomosport]

What Norton?  I've ridden a few.

1972 850 Commando Interstate. A retirement replacement for the one I chucked down the road about 1988 and subsequently broke for spares. Could have bought 3 Fazers for the money I paid for it!

[Gnasher]

I had many an hour on a 1976 interstate but not in 76 it was in the 90s.  Great sound on full chat