907ie misfire - maybe a cure???

discussions specific to the 907IE
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Ducman
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model: 907 I.E.
year: 1992
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Post by Ducman »

Ask Dr. Bruce
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Laddie
Posts: 56
Joined: Fri Sep 21, 2007 12:00 am
model: 907 I.E.
year: 1991
Location: Australia

Post by Laddie »

Tamburinifan wrote:Laddie,
do you know if it`s OK f us regular farts/amateurs to to mail Duane?

Regards
I expect if it's for business or enquiry specific to products it would be OK.
I don't know how much time he can devote to tinkerers...lol
Laddie
907ie - for fun and frustration
900SS - for when the 907 won't go
XS1100 Yamaha - previous tourer
TZ253/350 A/B/E Yam - previous boy racer (DNF)
CB750K7
CB500Four
CB250
CB175
DT175 Yam
PE250 Suzuki
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Finnpaso
paso grand pooh-bah
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Post by Finnpaso »

Very many thanks to You, Laddie! :thumbup: :thumbup: :thumbup:
Antti http://www.youtube.com/watch?v=HeKOh3XoXPg&NR=1
KTM 990 Adventure -08 metal dark grey
Paso 750 -89 red/metal grey
907IE -91 red/metal grey
907IE -91 red
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Tamburinifan
paso grand pooh-bah
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model: 907 I.E.
year: 1991
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Post by Tamburinifan »

No reply from FIM yet. :thumbdown:


Anyway, more testing this evening. I guess our P7 like others have a "limp mode", meaning if a part or 2 of the sensors in the ECU system fails, the ECU has a map built in for that that will take us home.


I tried today:

I know I have good, if not perfect sync of throttle bodies but very close. Tried from that 0,5 & 1 full turn clockwise + the same anticlockwise: No difference at 3k RPM, still the stumble.

Unhooked MAPsensor: same.
W unhooked Map sensor, unhooked temp sensor: same.

Same meaning misfires 2,7k-4k RPM.

I cannot say why but I`m still suspicious about the ignition map at 0-11% thottle & low RPM`s.
Gert

907 I.E. -91
M900 -97
MTS 1100s -07
Rasser
Posts: 12
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Location: Denmark

Post by Rasser »

Hi Laddie,
Not on this forum too often, but good to hear that I am not alone with my troubles.
I have an 907 with 105.000KMs on it.
The exact same trouble have happened occasionally over the years since -98/26000KM when I got it from a dealer in Italy.
Modifications are Staintunes and FIM chip. Motor re-build at 98K-KM. Only one valve, two seats, 4 guides, piston rings and set of bearings, the rest looked just fine.
Sept-06 I did a Sunday ride (around Rome - was there for work) and it worked like a charm. Two days later, another leasure ride and it started playing up. Brought it back (in our work-van) and it troubled me the next months. First five minutes on my ride home, no broblems, after that I had to concentrate on gas and clutch to "catch" it when it shuttered. Then after much frustration I found that one of my five year old racing NGK leads had no connection. Late afternoon, so just bought what was available from a local shop and it worked the next month. Parked for the Winter. Spring came and started riding it - fine; total 2500KM to the WDW-2007 at Misano with lots of highway riding and high altitude mountain passes Back home a few shorter trips to Sweden, local rides; no problems at all.
Cured it - I thought.
Last month, weather fine, had to go to Rome (Italy) for work. Skipped going by plane and took the bike instead, but only after changing the poor quality leads to new NGK leads and fitted new NGK plugs.
Sunday morning, sunshine, all worked great. After 350KM or so, it all started again. Accelleration, even mild, will always work great, it just pulls. Idle is always great too. But if I put it to e.g. 3000 rpm it will come down to 1500 or 2000 sounding cramped not running free/loose and then go to 4000 and down again.
Next day, ran well til after some 400-500KM. Fast autobahn and countryroad riding. When I was climbing Grossglockner Hochalpenstrasse, up to 2500m, it started pretty bad and hairpin corners are not fun in conditions where you do not know it will lose its drive or pull hard. Hard work on the clutch.
Up the mountain or down it went away, maybe after a few steep, shut throttle, engine braking downhill kilometers.
Next day worked great, til some 200kms from my destination. Then I went straight for the Autostrade and keeping the throttle ON its manageable.
I felt the first day that it maybe started after rolling off on the throttle and when you open again it starts. Petrol delivery, regulator or.... Did check the delivery some time ago which seems ok at 3 bar although I remember it to go down to 2.5 when throttle is fully open and then slam shut.
I had a weekend off, drove into Rome with my Garmin, went on trips in the surroundings, went to the WSBK race at Vallelunga and it did fine up until my last ride when it started playing up realy, realy bad. Got tired of it, had no time to troubleshoot and let it rest in van on the trip back to Denmark.
Have had no time to check since I got back. I will make your mod to the air sensor, check my leads, my fuel pressure and leave it with that. Hope to get a few more rides before Winter sets in full time. Night frost - and salt on the roads - are coming.
As you also say its difficult to show the problem to anyone when its not constant. I have never had it when adjusting the bike.
I will keep you posted.

All from Denmark, for now.
Per
______________
907 I.E. -92, black
Earlier bikes
Aprilia RS250 (funniest and the only one missed!)
Hon VFR-92
Hon VF750S
Hon CX500C
Hon CB500
Laddie
Posts: 56
Joined: Fri Sep 21, 2007 12:00 am
model: 907 I.E.
year: 1991
Location: Australia

Post by Laddie »

thanks Rasser...

It's hard to believe but your problems in Denmark are almost identical here in Australia...lol.

I got sick (and very poor, too) of putting new parts on hoping that they would be the magic fix. I tested everything as much as possible.

The bastard 907 runs so well and then: *bump - boink...pop...
Some of the mechanics thought I was just being fussy - one guy rode it for 3 days (fairing off) - then finally it played up. We immediately thought coils or ignitors - but they were fine.
It might be possible they break down under load but they would usually do it consistantly, or not work at all...and why would they work under acceleration?

I haven't had much chance to ride it lately but intend to continue testing - hopefully to prove the theory. So far, so good.
Laddie
907ie - for fun and frustration
900SS - for when the 907 won't go
XS1100 Yamaha - previous tourer
TZ253/350 A/B/E Yam - previous boy racer (DNF)
CB750K7
CB500Four
CB250
CB175
DT175 Yam
PE250 Suzuki
blakduc1

Rasser's bike

Post by blakduc1 »

Rasser,

Interesting to see that someone has racked up some miles on a 907 as you have. They really are comfortable bikes and perform well if they run right and have better suspension. The problem you describe is a lot like what I have experienced with both my 907s. I have two black 1992 models like yours. You have used NGK spark plug leads? Did this help the bike run better? Might be something else I need to add to mine. Where did you find the correct wires?
Do you use the NGK equivalent plug for the Champion RA4HC? Or something different? Any other problems in that many miles?

Thanks for posting your comments.
dp
Tamburinifan
paso grand pooh-bah
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model: 907 I.E.
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Re: 907ie misfire - maybe a cure???

Post by Tamburinifan »

A possibility:
Check FIM`s FAQ, question 8: http://www.fuelinmoto.com.au/

Failing main bearings causing flywheel wobble, does not sound good....
Gert

907 I.E. -91
M900 -97
MTS 1100s -07
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Laddie907
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model: 907 I.E.
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Re: 907ie misfire - maybe a cure???

Post by Laddie907 »

this FIM FAQ / article was one of the first things i read about causes for misfires when I first got my 907 - over two years ago...
Yes, I was quite worried when I read it, too...

the article isn't quite correct - the 907ie sensors are on the crank and the jackshaft (like the later models referred to).

I think the amount of "wobble" on the crank to cause the sensors to bugger up would be very severe bottom end problems - I don't think I have these....yet.

The comment about gear backlash in the jackshaft is a possibility - but I have discounted this - my reasoning is that the motor (crank) is driving the valve gear and that friction in the desmo valve system will keep the gear teeth in contact - maybe the lash would be observed under deceleration...???

I'm not in a hurry to split my cases while the bike is still running OK.
I haven't had a lot of time to do more kms lately but the few rides that I have had since the ciggie butt I don't get the misfire anymore.
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Laddie907
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Re: 907ie misfire - maybe a cure???

Post by Laddie907 »

a few more hundred kms since the last post...the bike hasn't stuttered again at all...
a lot of this has been freeway cruise where the misfire was previously most noticeable.

my mate suggested I remove the line with the filter to see if the misfire comes back.
I was kinda frightened by that thought...
shat

Re: 907ie misfire - maybe a cure???

Post by shat »

How about fuel pressure? I just installed a replacement pump which put out a full 3 bar (44 psi) and the bike now runs without any slow speed hesitation whereas before the original pump went south completely, I was having the stumbling. Just a thought. If you remove the tank and place a direct reading pressure gauge on a T after the fuel rail but befor the fuel pressure regulator, thern replace the tank with the gauge and feed line out the left side, you should see the pump build to 40+ psi with just the key on (no start). When the relay times out (4-6 seconds) the pressure will of course drop off as the fuel returns to the tank. If you don't see this pressure, you may have a failing pump. Just a thought...
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Laddie907
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Re: 907ie misfire - maybe a cure???

Post by Laddie907 »

I did replace the fuel pump early on..
the original had a crack in the outlet in the tank
line pressure was still OK at 3 bar but I didn't want it to fail on me somewhere out in the sticks...

The 907 fuel injection system is a bit of a dinosaur and I expect it was about as refined as they could manage in 1991. It's all the same gear as Ford Cosworths and some other racing cars - so I can't be too critical...
I have some suspicions on various parts of the fuel delivery:
the regulator
pump duration timing
line types
anyway, at this stage my bike is running fine.
the whole hesitation / misfire issue went away when I put the cigarette butt in the line...
hondaboldor
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Location: Holland

Re: 907ie misfire - maybe a cure???

Post by hondaboldor »

Hi all,

I'd like to pose another posibility for our misfire problem;
I've had this problem for a couple of years now and recently I installed the "ciggie-butt tweak". Since then I encountered the misfire once when I rode on the highway.
Then I remembered a problem I had with a previous bike I owned; That bike also had a misfire problem due to a crappy exhaust system. What happened with this bike was that unburned fuel mixture ignited in the exhaust system while air entered the exhaust system at the place where the exhaust pipes were screwed to the cilinder head. When I replaced the exhaust system of that bike, the misfire went away. When I looked inside the old exhaust system of that bike, I saw white markings from the inner-exhaust combustion.
Now back to the 907; When I checked the clamps that mount the exhaust to the heads, each nut was kind of loose. I was able to retorque them; the nuts could be tightened more than half a turn! Since then I havened had any problems (yet....). Even while driving with 22 degrees Celcius....
So I recon the misfiring of our bikes could also be the problem of air leaking inside our exhaust systems.... Maybe someone who is encountering this misfiring problem could double check this by removing his exhaust system and check for white combustion marks inside of the pipes??? ;)

Hope this helps you guys solving your misfire problems....
greets,
Sebastiaan
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Laddie907
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model: 907 I.E.
year: 1991
Location: Australia

Re: 907ie misfire - maybe a cure???

Post by Laddie907 »

22 degrees celcius??? lol
I live in Queensland Australia - in summer it never gets BELOW 22 degrees for weeks...
we would regularly ride in 40+ degrees.

But Yes, temperature is an issue - it seems to only happen when the engine is hot (80+).

The exhaust sealing was one of the first mechanical things we looked for...
we didn't remove the exhaust but made sure the sealing was good.
the problem is a misfire - not a backfire...
if it was backfiring I'd be inclined to look for imbalance between the intakes (which there was, too...) or exhaust air leaks.

I'm sorry the ciggie butt didn't work for you...
How bad was the misfire before and was there any improvement?
It has to be TIGHT - not to seal it off, just to be very restrictive.
hondaboldor
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Re: 907ie misfire - maybe a cure???

Post by hondaboldor »

Hi Laddie,

Sorry for the late reply, but I was busy with study and finetuning the bike :lol:

But I think my problems are over. In the old situation (without the sig-butt) I had to increase the mixture in low-rev situations by turning the CO-screw kind of rich. Otherwise it was kind of a harsh ride below 3.000 rpm. In the new situation (with the sig-butt mod) I was able to turn the mixture down with 1 turn. It now runs beautifully from 2.000 rpm all the way to redline!
Thanks for your info; another pleased 907-rider here :D

Greets,
Sebastiaan
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