What the foc???blocked jet???

[mars696]

Hi again focs!


I have a low rev stuttering.beneath 3000 rpm,starts from idle.
If i hold the throtle steady at these rpm it stutter,but if i open the throtle,it accelarates with no prob...
Second time,i took the carbs out for a more comprehensive clean this time.
Nothing change....
I saw something weird to me...
At the jets near down to the needle jet,i couldnt see through... ,the same thing with the four of them.
Now even i spray carb cleaner and compressed air.
Is this normal???
I thing these are the "slow jets".Are these little flat screws(just to make my self clear...i think..)
Thanks guys...

[peteski]

I'd still put good money on a blocked pilot jet. I had the exact same problem you describe two years ago and spend weeks searching for an electrical fault. When you start the engine from cold and leave on tickover, is one of the downpipes run colder than the others? If so this might narrow down your fault. It took two attempts to find this blocked jet on mine, mainly because I didn't know which screws were jets and which were just plugs.



The blue arrow is the pilot screw for sure, you can leave this be. IIRC the green is the pilot jet and there should be a small hole running through the middle.

[darrsi]

This sounds very similar to what my bike is doing at the moment, around the 2500rpm mark, although mine is fine at idle, and acceleration is spot on.
I've just ordered a K&N air filter as i was wondering if it was a breathing issue, but the bugger has been lost in the post for a week so i'm still waiting for confirmation of a replacement, so still none the wiser? 

[mars696]

Petski,i have exactly what you said.
When i start the engine,the downpipe of cyl 1,run colder than the others....
The jet i'm talking about,is where is the yellow arrow i draw...(see pic pls).At my carbs these  jets are completly blind..and i dont know if it sould be this way or not...i cant even find it at the Yam manual.


Darsi,for me k&n air filter and exhaust didnt make any difference at all...

[bozboz]

I had a similar problem with on an old cb500 work bike. Spent days taking the carbs apart cleaning, refiting, mucking about with the float levels, etc, etc! Always one downpipe was running cooler with low speed stuttering/hesitating but accerated fine and the heat came through with the acceration. My problem in that case turned out to be solved with new HT leads!
If that fails my friend Dave at TSR may be able to solve your problem, he can clean the carbs ultrasonically and vapour blast them -very thorough come back looking new!!! This may clean an internal part that the carb cleaner just cant shift?
Heres a link, hope it helps:
http://www.tsrvapourblasting.co.uk/carb_cleaning.html
 
Cheers BozBoz 

[darrsi]

New HT leads means new coils then......

[peteski]

Petski,i have exactly what you said. When i start the engine,the downpipe of cyl 1,run colder than the others.... The jet i'm talking about,is where is the yellow arrow i draw...(see pic pls).At my carbs these  jets are completly blind..and i dont know if it sould be this way or not...i cant even find it at the Yam manual.

You now know where to be looking then, cyl 1. Please note that the photo shows the jets removed. I'm not 100 percent sure but I think the yellow arrow points to a plug which does not have any hole. It was two years ago since I did it so memory is not that fresh. I have a fully working set of carbs in the garage at home. I'll take the bowl off one tonight.

A blocked airfilter won't cause problems as described here, no harm fitting a K&N though!! A faulty HT lead, spark cap or plug can. The way you can rule this out is to move the sparkplugs (put 1 in 2, 2 in 3 etc) and see if the problem moves (feel the downpipes again). You can also swap the wiring on the coils. One coil fires cyl 1 and 4 and the other 2 and 3. Eg: There's no harm putting lead 2 on plug three and vise-versa. Just swap them over and again, see if the problem moves.

[peteski]

I can confirm the screw indicated by your yellow arrow does not have any hole in it.


This one is the pilot jet. take it out and hold it up to the sky. There should be a clean hole running through the middle.

[mars696]

Thanks a lot for your time and help peteski!
All of my pilot jets are absolutely fine....i am allmost sure that its not a carb problem anymore...
I follow your instructions today,about the spark plugs etc...
I swap the cyl1 spark plug to cyl2,now i think that the downpipes get hot all together,still no so sure though.
But the problem its still there.
I also check the coils resistance,first and secondary,tps and all are in specs.
I have allready change the spark plug caps to ngk sd05f(no diffrence),but as i saw today they are 5k resistance,and yams are 10k.
I dont know if this cause any further problem,but nothing have change after all these changes and checks...
I am starting to think valve clearence...

[darrsi]

Keep talking people, you have my attention......

[peteski]

Thanks a lot for your time and help peteski!
All of my pilot jets are absolutely fine....i am allmost sure that its not a carb problem anymore...
I follow your instructions today,about the spark plugs etc...
I swap the cyl1 spark plug to cyl2,now i think that the downpipes get hot all together,still no so sure though.
But the problem its still there.
I also check the coils resistance,first and secondary,tps and all are in specs.
I have allready change the spark plug caps to ngk sd05f(no diffrence),but as i saw today they are 5k resistance,and yams are 10k.
I dont know if this cause any further problem,but nothing have change after all these changes and checks...
I am starting to think valve clearence...

It sounds like you're checking all the right things. I've been in your shoes so know what it feels like chasing a problem such as this. I wouldn't rule out carbs just yet. One tiny flake of crud stuck in a passage will stop the whole thing working. It needs to be scrupulously clean inside there. And if you've got a spark on all four plugs then it's unlikely to be electrical.

I'm not saying it isn't but the valves on the FZS/Thundercat tend to be pretty bulletproof. The bucket and shim design means the wear on the valve seat is compensated by the wear on the bucket. You'd have to be unlucky.

[mars696]

ok,lets see all the things until now...


What problems and syptoms i have:
-Erattic idle.
-difficult start.
-Low rev stuttering,bellow 3k with steady throttle[size=78%],[/size]no prob when accelerating..

Things i have done so far:
-Two times carbs off and cleaned.
-every day carb sync
-mixture adjust,2,  2 1/4,  2 1/2.
-spark plug change.
-check spark plugs.
-check resistances in everything.
-no air leaks
and others little checks...


nothing solve the prob,nothing out of specs.


i am out of ideas.... i will go to my mechanic for more check i think...
Any ideas are allways welcome focers



PS: I just remember now that one year back,when i once tried to turn on the engine something blow out with smoke,from the back of the seat.
Back then i didint search it more(my bad,i know) but the problems i have, were allready there,before this.
Anyway everything works the same.Still try to guess what the foc was that

[mars696]

So just an update.                                                                 I find out that my ht leads arcing.                                   Is there any way to fix this,exept from buying new coils? Anyway to seal them or just to replace ht leads only? I know that they are moulted in to the coils but there has to be a way for this...                       

[red98]

you can buy a connector for the ht leads... cut the lead on your coil and fit a new lead........however this will create a join which will attract moisture and the problem is most likly to be within the coil itself.....best bet is used coils....try ebay or something similar 

[SteveH41]

Not related to the Fazer but I had a ford focus 2007 model which had the same kind of fault, numerous trips to the garage but could not find the fault as it presented no error codes in the ECU, got pee'd off with all the running about so got myself some brand new coils, changed them over myself and all was well. Then sold the car for a Ford Kuga

[red98]

when you  checked the plugs,did you re-gap them  ....should be 0.7 i think 

[darrsi]

Plugs are between 0.7 and 0.8, i did mine last week. 
 

[red98]

Plugs are between 0.7 and 0.8, i did mine last week. 

did it make any difference 

[darrsi]

To be honest they didn't really need adjusting at all.
I spent ages at work with a vernier hunting for a washer that's 0.75mm so i can keep it in my wallet for future though. 
My K&N air filter has just turned up at work, finally, 11 days after ordering, so i'll pop that in tomorrow   

[red98]

To be honest they didn't really need adjusting at all.
I spent ages at work with a vernier hunting for a washer that's 0.75mm so i can keep it in my wallet for future though. 
My K&N air filter has just turned up at work, finally, 11 days after ordering, so i'll pop that in tomorrow 

 
11 days  ....who did you order with 

[darrsi]

It was off Flebay, the first one got lost in the post  
Genuine part, and only £30 delivered (eventually), i think they're about £68 on the K&N website!
The firm communicated with me though, and also offered a refund if i wanted it, so i won't hold it against them.

[Dead Eye]

Bit off topic but, strangely that happened to me as well...

I got my K&N from eBay and the company emailed me a couple of days after purchasing saying that their warehouse had been broken in to by use of a mini digger and that my shipment would be late :s Was a rather odd email but I received my filter in the end :P

[darrsi]

Maybe that's why i got mine for only £30 then 






"Know anyone who wants to buy an air filter? Going cheap, last you a million miles....." 

[Dead Eye]

I actually got mine for just under £30 delivered as well :P Coincidence?

[darrsi]

Sounds like some sort of devious scam, it wasn't a Scottish company perchance was it?