Triumphrat

IrlMike · 02-09-2008

Can't seem to get a tickover lower than 1400 rpm & revs tend to 'hang' a little after blipping the throttle. I've just fitted a K&N into the stock airbox, dynojet kit, & fitted a Thunderbike 3-1 pipe.
It did this before I made these changes tho' the rev 'hang' is a bit better than before.

Not taken it for a ride yet, just trying to get a good balance & tickover.....not sure I totally trust the tachometer but it seemed to read before as expected per top gear road speeds ?

Bike is 98 Tbird with 22k miles

Set up:
Stock pilot jets (40), screws about 2 1/4 turns out
Main jets 98 (dynojet also provided 94s)
Needles 2nd from top
(this is as per dynojet instructions)
float heights 14.0mm, 0.5 richer than stock

Balancing gauge flutters a bit on #2 cylinder, others pretty steady (only have a twin set tho', so have to stop & swop nos. 1 & 3 about & compare with #2 cyl)

Turning the pilot screws out (richer) seems to increase tickover speed....any further in & get 'hunting' & zorst pops a bit....
plug check on #3 (new iridium '8's) shows +very+ clean plug

Plan to take it out on the road tomorrow & see how it runs at running throttle & revs...

Any thoughts on the tickover / basic balance set up gratefully recieved....

Should I be going richer on the pilot screws & trying again with the balance screws to get lower tickover ?

Should I change any other settings ?

Just to give the full picture, I worked the inlet rubbers +slightly+ (keeping well away from the 2 'indents')
also 'tweaked' the ignition pick up to give ~ 2deg advance (gap to rotor set at 25 thou)

Thanks,
Mike

gregp · 02-09-2008

First and foremost, Check your valve clearances! You may have a tight valve that is giving you these symptoms. Your bike has plenty of miles to warrant this check, and it may need adjustment.
I have the same jet kit (it just arrived last week, and I have yet to install it), but my bike ('96 Adventurer w/Mikuni's) currently idles and runs great. I have read the instructions and everything that you have described sounds to be spot on as per the instructions.
BTW- The Dynojet jet numbers mean nothing when comparing them to standard Mikuni jets. They do this deliberately.
Other than the valves, you might adjust the fuel screws out just a bit more, to 2 1/2 turns or so. Your description indicates a lean condition at idle, so check the air boots for cracks or leaks, and make sure that the K&N filter is properly oiled, and seated correctly.
I see in the instuctions that you can call Dynojet and explain your problem to them for help with diagnosis and there is a symptom sheet that you should fill out first, before you call.

jimmyj900 · 02-09-2008

Good reply from gregp!

Also, check that your idle is at 1000 rpm. If it's too high or low that can also cause hesitation.

Jim

Kiwi Tiger · 02-09-2008

I assume you know when you change a pipe or air filter it will effect the mixture delivered. The 4 most important things ( in my humble opinion ) are the pilot jets, the main jets, the needle taper and the needle height. To get it running at the best possible mixture you need to put it on a Dyno and see what it is doing at every 000 revs. Then you make your changes and do it again. I have done this on my Speedy. We got it right on the 5th run. Runs like a Top. Whats right for 1 bike ( same make and year ) may not be right for the next bike. Book a Dyno afternoon and enjoy future riding knowing its running at its optimum.

IrlMike · 02-10-2008

Many thanks for the replies -

Just done the valve clearances - all bang on now - couple of inlets were tight ~ 1 thou

One thing re leaks, the boots between the carbs & airbox have an inner circlip type thing at the airbox end, - one was missing, didn't have, so middle cylinder without (tho the rubber 'double flange' is still a good fit) - know leaks are critical on inlet side, not sure about filter side ? all looks ok otherwise.....but that middle cylinder is hopping a bit on the balance gauge....will get clip ordered tomorrow & at least rule it out

very difficult to actually get tickover down below 1400 - after backing off the outer carbs to start, then bringing them up again to get a balance, the tickover ends up high - I have been balancing at no throttle, tho' when opening the throttle, the balance seems consistent ?

going to have another go.....& maybe try on road...will post later with results

point taken re the dyno time - not sure if such exists in county cork tho !.....that said, according to thunderbike, the dynojet kit should be fine as i'm not that far from stock

cheers all,
Mike

jimmyj900 · 02-10-2008

Quote:

Originally Posted by IrlMike

One thing re leaks, the boots between the carbs & airbox have an inner circlip type thing at the airbox end, - one was missing, didn't have, so middle cylinder without (tho the rubber 'double flange' is still a good fit) - know leaks are critical on inlet side, not sure about filter side ? all looks ok otherwise.....but that middle cylinder is hopping a bit on the balance gauge....will get clip ordered tomorrow & at least rule it out

It doesn't matter much on the inlet side of the carbs, so that's not a worry as long as the inlet rubber is in place.

Quote:

very difficult to actually get tickover down below 1400 - after backing off the outer carbs to start, then bringing them up again to get a balance, the tickover ends up high - I have been balancing at no throttle, tho' when opening the throttle, the balance seems consistent ?

An idle that high indicates either a vacuum leak on the outlet side of the carbs (carb rubbers or vacuum takeoff caps faulty) or that you've taken a wrong turn on the carb balancing.

The purpose of balancing is to get all three cylinders producing the same power at an idle since carb balance has progressively less effect as the throttle butterfly is opened. At full throttle the carb balance at idle has virtually no effect.

To balance the carbs requires interactive adjustment of the idle speed and balance adjustments to keep the idle at 1000 rpm and an equal vacuum on each of the carbs.

Since you only have a two gauge balancer, be sure the vacuum port you're not using is capped when you're balancing the other two carbs.

The method is to set the idle to 1000 with the idle adjustment knob and then match the outboard carbs to the center carb using your gauges and the balance adjust screws on the linkage. When the idle changes, you reset it to 1000 and then rebalance until the vacuums match at idle.

Set your mixture screws (at the bottom rear of the carbs) to 2-1/2 turns as a baseline, start the engine and then redo the carb balance while slowly turning the idle down to 1000 rpm.

If you have no air leaks on the outlet side of the carbs (check the rubbers and vacuum takeoff caps) you should be able to get things sorted out.

Let us know how it goes.

Jim

IrlMike · 02-10-2008

Many thanks for that, Jim, you've put my mind at rest re the airbox side of things - after a bit more fiddling & junking the gauges (beginning to suspect them!) I'm down to a nice even 1200 rpm & have it picking up sweetly & dropping back nicely too on a sharp blip - your 2 1/2 turns out seems bang on, that's where i'm set now, tried more & not good.

One thing I've noticed is that the (wind-up - poss in more than one sense!) return spring att to centre carb seems a bit weak - I could put a small bit of pressure on the cable pull lever & drop the tickover down - plenty of cable slack, so not that... spring looked a bit gummed up with corrosion, so dropped a bit of oil on - some improvement...

going to try her on the road now - i/2 hr of daylight left..

i'll post a bit later with results....

cheers, mike

IrlMike · 02-10-2008

well....the results....

WOW !....the triple flies

!

pulls like a train from 2k to 8k+....what a torque monster & i'm on a 19 tooth drive sprocket !....up to 95 ish & still pulling strong...
she's quite happy pootling in civilised (quiet -ish!) mode at 2k or a bit less in any gear with good smooth pick-up...

thunderbike pipe has gorgeous rorty sound, fairly loud, possibly a bit nearer to a 'pull' (even by ireland's laid back standards) than i would like, but, hey, memories of 'slippery sam' roaring away at Mallory Park back in...hmmm....a while ago

!

only minor quirk is the 'popping' on decel, esp backing off from very light throttle - not too bad & i remember the the thunderbike dyno video was similar....

not sure, but maybe should i take the needles a notch richer, they're 2 down from the top at present (out of 6) ?

high revs & low revs (at wide throttle) are definitely good - if i'm being picky, mid range is slightly less so....

might be nice to get tickover down to 1000rpm, tho' the indicated 1200 +feels+ low & is smooth...apart from the usual bag-of-spanners-in-a-bucket of course

thanks again for your input guys

mike

jimmyj900 · 02-10-2008

Oil the throttle cable and see if your return spring stiffens up a bit.

I use engine oil on mine. I put it in the top end until it drips out the bottom, but then I figure the extra oil helps prevent corrosion.

Jim

IrlMike · 02-10-2008

Jim,

Yeah....you're right....my guilt feelings have returned for putting that (rather dry) cable lubing job further down the list...

(Maybe not that guilty as bike is new to me & pretty well everything needed doing!)

But, hey, this is cool - I'm learning ! Carb butterfly springs do lots more than just bounce that cable back

Cheers Jim, bang on again !