January 2006

Pyromania

well I tried all my leads (vacuum inlet for tank, resprayed wd40 everywhere, almost set on fire!, also checked th drain plugs... you never know)... nothing slows down that beast.

it only happens when hot (hotter=higher idle) and ONLY if I whacked the throttle… goes higher and higher.... and stay there... 3 whacks =~1000 rpm more.

it does feel like there is SUCTION somewhere, but it ain't with the outside... it's as if there is a depression inside the motor. ie something that would suck air from a carb.

When i stopped it because of the smoke (WD40), i could hear coming from the RH carb (the one NOT hunting up, but not idling) gurgling sounds... freaky!! and if i opened the slide with my finger, the sounds got worse, almost like a boiling sounds ie bubbles.

To me it sounds as if this float bowl is getting sucked!

Soldier on

Did a few more tries today:

Sprayed the most potent carb cleaner druing tickover... F***all results
Switched slides
then carbs
F ALL!

out of rage, i took the 2 grottiest looking T250 26mm carbs I had lying around, didn't even wash them... and plugged them in.

Guess what?

same result!

So I guess the carbs aren't the prob, the motor is.

The only thing I haven't changed (for lack of funds) is the inner crank seals...

For you all experts out there, is it possible for bad inner seals to upset carburation at idle that much... I mean from 0-to 5k?

When bike is dead cold, it feels like you could adjust the idle (stays around 3k) but once warmed up, it just creeps higher to 5k No amount of tweaking will lower it. The idle screw does have an effect (say lower the idle to 3k) and the choke works... but the hotter it gets, the higher it goes.

Head scratching at its best

Followed Johnny's advice and let it rest for a week + it was too cold to work. SOOOO drumrolll...

Carbs cleaned and I tell ya they're clean

Iggy set up pedantically

All carb to jugs seal bettered wiv a dab of silicone... everything is air and oil tight.
Heads retorqued.
Changed the petcock, it flows well
Everything as per std specs.

Still revs at about 5k. MAkes you feel like you wnat to shut the throttle, but.. slides are as low as possible. It also doesn't cut th revs when you rev it up... goes slowly back to 5k... so throttle response NOT snappy.

MY plugs are a nice darkish milk choc color.
Except the LH one : has the same color but has a side of the porcelain where the color is still white original.

Could this indicate an air leak?

I pulled the rotor off and check if the bloody seals were the right way in... they are! I'll just shoot you a drawing of a detail that I'm not 100% sure about it but it looks OK though and couldn't cause the rising revs prob.

kinda disappointed here.. it would have been a good ending

Boy in 15 years of dabbling with bikes and scoots, I've never had something that obstrusive. Makes me really question my practice

So if the crank seals are allright, then it boils back to the carbs doesn't it?

Could the heads play tricks like that? say the plug hole .. I think I'd hear something, though...

Now what?

I decided to tackle this as two singles. Turns ou the LH side is the one hunting up, no idle but keeps revving its tits off and the RH isn't idling but runs from 3 to redline. If i let it go to the idle zone, it coughs up and usually dies, like rich. Plug this side black and wet.

I seem to remember i put the crank seals with the lip facing out... will check.... MY parts diagram isn't very clear about that.... Which way???

Trial and errors

I tried fitting the rubber boot just to see. it cracked (bloody workshop is wayyy to cold, -2C) but even put on had no effect on the idle. So I'll be going thruh the carbs again, I'm afraid.

I also def have a batt charging/stabilizing prob: this litlle bike eats bulbs for a living... Ah, the joy of restorations....I also def hav a batt charging/stabilizing prob: this litlle bike eats bulbs for a living... Ah, the joy of restorations....

Get your stuff together, stoopid

What could cause a motor to start and rev its tits off to 5k (and up) except a major air leak? I can't find any

The T250 is quite happy to go and stay in the red zone (8-9k) so 5k is like half-throttle setting?!!??

As far as I know the choke plunger can't be the culprit as it opens a fuel passage... it does work but at these revs not enough to choke the engine down. The idle (air) screw doesn't seem to have any effect.. but again at that range...

Just to make it clear: I usually make stoopid mistakes.

Progress? Ican't see any progress!

This thing is giving me fits!

It runs after swapping the leads... but is Huuuuunting up the rev range at idle... No Airleaks I can detect between carbs and jugs...heads plugs and rest torqued down...

Okay I'm not running an air filter nor are the rubber caps on top of the carbs, but that can really be enough to have an idle at 5000rpm and climbing.

Cutaways in the right direction
News seals left and right
Cleaned carbs (weren't that grotty)
etc...

Running t250II jugs and their 26 carbs

Could someone hint me in the right way before I set it on fire ?
Oh and battery's not charging... but that is (should) easy.

DUmb and Dumber than Dumbo

I've been checking the bugger yesterday and what I found goes along your lines:

LH Condenser is actually triggering RH Coil (white wire)... and I took great care making sure the leads DIDN'T cross Explains why I had to reset and adjust the points so much.

I s'pose that setting the LH point to open on the LHF mark with the RH COIL firing LH plug will do the trick...if you get my meaning... Switching the leads should achieve that.

The noise I heard sounded like the mixture was being ignited AFTER TDC

Checked the coils too (white type) and they're Okay, except they're a bit less than the other type (grey pair) Mine get 4.5 Ohm- 8Kohm and the grey type get 4.5-12K.

as I'm using T250R jugs and carbs (different porting, tad more power) should I put the "stronger" coils in?