Author Topic: GTR giving me a hard time backfiring and stuttering  (Read 21014 times)

Offline mitcheman

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GTR giving me a hard time backfiring and stuttering
« on: June 28, 2015, 05:12:55 AM »
He guys,

I hope you can help me. I have got myself a kawa gtr 1000 '93. And it is giving me a hard time.

Can anybody tell me the correct way to setup the carbs. Because out of all the bikes I have/had this one is killing me.

When I bought it the numb 4. carb was missing some parts...main jet and needle. So after replacing that i'd try to set it up. Now sparks 1 2 3 are almost brown and numb 4 is black.

When I give it some throttle round 3 4000 rpm I can hear it stutter and cough with some small backfire bangs. When I turn down it starts to bang very loud couple a time. And only on the right side (carb 3 and 4). I have power enough it rockets to 120 kph no problem. But it stutters and coughs doing it.

I have synced the carbs with my gauges and they are in sync. But it looks to me that 1 2 3 are to lean and number 4 is rich. How do I tackle this?

Thanks in advance!

Gr. Mitcheman

Offline George R. Young

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Re: GTR giving me a hard time backfiring and stuttering
« Reply #1 on: June 28, 2015, 02:01:50 PM »
If all the parts are stock and correct, a rich condition might be caused by a too-high float level.

However, as you say, carb #4 was missing some parts. Maybe it's missing a pilot jet.
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Offline MAN OF BLUES

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Re: GTR giving me a hard time backfiring and stuttering
« Reply #2 on: June 29, 2015, 01:37:00 AM »
water

46 YEARS OF KAW.....  47 years of DEVO..

Offline mitcheman

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Re: GTR giving me a hard time backfiring and stuttering
« Reply #3 on: June 29, 2015, 02:08:31 AM »
I'm going to check the number 4 carb again. Float etc.

Man of Blues what do you mean with water?

Offline DC Concours

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Re: GTR giving me a hard time backfiring and stuttering
« Reply #4 on: June 29, 2015, 08:49:44 AM »
water in the tank, condensation, etc. drain carb bowels and run some fresh fuel.

Offline connie_rider

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Re: GTR giving me a hard time backfiring and stuttering
« Reply #5 on: June 29, 2015, 11:29:56 AM »
Sounds like high float level making #4 rich.
But DO,,,, Check the spark plug caps and wires.

As you are in Netherlands, look up GCE (Gtr Club of Europe) members that live near you.
They may be able to assist.

NOTE:
A GCE Rally is planned in Breda Netherlands Aug 1-5. (try to be there)

Ride safe, Ted

Offline mitcheman

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Re: GTR giving me a hard time backfiring and stuttering
« Reply #6 on: June 29, 2015, 12:48:47 PM »
He guys,

Well this is the lower side of my carb. Looks complete not?




How can I adjust the float level? And to what level?

thnx!

Offline MAN OF BLUES

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Re: GTR giving me a hard time backfiring and stuttering
« Reply #7 on: June 29, 2015, 02:29:12 PM »
first step
obtain a factory service manual, to see if you assembled the carb correctly.
it will also show correct procedure for setting float.
there are parts not visible internally from just these photos alone.
its sounding to me like the actual slid needle main pilot jet was not installed correctly, it should be installed from below, under that metering jet and emulsion tube (the one with the hex)
compare the bore of all 4 carbs visually, where the slid needle goes thru that projection sticking up from the bottom.
they should all look the same. shoot and post a picture looking in from the rear of the bore.
it is virtually impossible to analyze and explain all this, with so little to go on, not having the assembly in front of us.

the water comment was concerning contaminated fuel, and it causes blockages in the primary low speed idle circuit...

46 YEARS OF KAW.....  47 years of DEVO..

Offline mitcheman

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Re: GTR giving me a hard time backfiring and stuttering
« Reply #8 on: July 01, 2015, 02:43:43 AM »
Well i'm gonna pull the carbs this weekend. And check all the valves.

Does any know the height of the float?

Thnx!

Offline MAN OF BLUES

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Re: GTR giving me a hard time backfiring and stuttering
« Reply #9 on: July 01, 2015, 09:24:45 AM »
17mm measured like this

46 YEARS OF KAW.....  47 years of DEVO..

Offline SteveJ.

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Re: GTR giving me a hard time backfiring and stuttering
« Reply #10 on: July 01, 2015, 07:29:23 PM »
Just an obvervation here, but IMHO, you should not be messing around in your carbruetors if you have to ask how to adjust a float. There are some very expensive, sensitive parts in there that can get ruined by not knowing what you are doing. I.e., each slide is something like $115 $US.

A good choice for knowledge is to join COG and get access to an excellent article from MOB on "Carbs, It Ain't a Diet Thing"(I think I got that right). It goes into amazing detail on the workings and repair of carbbies. Worth the $37US just for that, but he also did a bang up article on the cooling system, among others.

If nothing else, hook up with  https://sites.google.com/site/shoodabenengineering/intake-and-exhaust and ship the carbbies over the pond. This is probably the best, most economical and definitely least stressful way to go.

Thanks, Rich, for doing those when you were more than "just a memba".
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Offline MAN OF BLUES

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Re: GTR giving me a hard time backfiring and stuttering
« Reply #11 on: July 02, 2015, 01:15:09 AM »
you are more than welcome... it was my labor of love, and my passion to assist.
tough to do via the internet tho, especialy when you can't see the things that may be wrong...

46 YEARS OF KAW.....  47 years of DEVO..

Offline connie_rider

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Re: GTR giving me a hard time backfiring and stuttering
« Reply #12 on: July 02, 2015, 06:45:22 AM »
Mitcheman seems to be pretty knowledgeable.
Synced the carbs etc...
MOB has supplied the info he needs.. Hopefully he doesn't have to spend the big $$ it requires to ship to Steve and back to Europe..(Ain't cheap)

Mitcheman, did you check into GCE Club?

Ride safe, Ted

Offline Mettler1

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Re: GTR giving me a hard time backfiring and stuttering
« Reply #13 on: July 02, 2015, 08:02:15 AM »
Mitcheman seems to be pretty knowledgeable.
Synced the carbs etc...
MOB has supplied the info he needs.. Hopefully he doesn't have to spend the big $$ it requires to ship to Steve and back to Europe..(Ain't cheap)

Mitcheman, did you check into GCE Club?

Ride safe, Ted

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Offline connie_rider

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Re: GTR giving me a hard time backfiring and stuttering
« Reply #14 on: July 02, 2015, 08:15:45 AM »
Thanks Mettler1.
I forgot to attach that.

Ride safe, Ted

Offline Steve in Sunny Fla

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Re: GTR giving me a hard time backfiring and stuttering
« Reply #15 on: July 06, 2015, 11:16:40 AM »
I think you're also missing the main needle jet. Steve

Offline MAN OF BLUES

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Re: GTR giving me a hard time backfiring and stuttering
« Reply #16 on: July 06, 2015, 11:45:54 AM »
first step
obtain a factory service manual, to see if you assembled the carb correctly.
it will also show correct procedure for setting float.
there are parts not visible internally from just these photos alone.
its sounding to me like the actual slid needle main pilot jet was not installed correctly, it should be installed from below, under that metering jet and emulsion tube (the one with the hex)
compare the bore of all 4 carbs visually, where the slid needle goes thru that projection sticking up from the bottom.
they should all look the same. shoot and post a picture looking in from the rear of the bore.
it is virtually impossible to analyze and explain all this, with so little to go on, not having the assembly in front of us.


the water comment was concerning contaminated fuel, and it causes blockages in the primary low speed idle circuit...

Steve, you talking about what I noted above?

my thoughts exactly... kind like the same thing Jen did...and the symptoms....




item 5 below


should look like the bore on the left carb in this photo...

46 YEARS OF KAW.....  47 years of DEVO..

Offline MAN OF BLUES

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Re: GTR giving me a hard time backfiring and stuttering
« Reply #17 on: July 09, 2015, 10:19:47 PM »
 :popcorn:

46 YEARS OF KAW.....  47 years of DEVO..

Offline mitcheman

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Re: GTR giving me a hard time backfiring and stuttering
« Reply #18 on: July 10, 2015, 11:57:10 AM »
He guys,

Looks like I found he culprit...number 4 had no....needle guide.

Yesterday i've adjusted the valves and swaped float 4 with 1. Still the same issue. Now today I pulled the carbs I looked into them and then I saw it. No needle guide in number 4.

Lucky me I had one spare given to me by the seller. Popped it installed the carbs. Connected my carbtune to snyc her, started her up and no more loud bangs!

So I think we can say issues fixed! And topic closed.

Thnx for the help!

PS. found an easy way to pull the carbs. In a nutshell:

open up airbox, pull the airboots back and you can take the carb out no problem.

to install:
place the carbs connect the cables etc.
cook the airboots in hot water.
and stick them back in via the airbox :-).
they will go in with no problems at all.

Offline connie_rider

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Re: GTR giving me a hard time backfiring and stuttering
« Reply #19 on: July 10, 2015, 12:38:39 PM »
The needle guide is what Steve and MOB thought could be the problem.

PS. found an easy way to pull the carbs. In a nutshell:  open up airbox, pull the airboots back and you can take the carb out no problem.

I don't think anyone here has ever mentioned that. Sounds like a good idea to try when I next pull my carbs.

Ride safe, Ted

PS: Are you going to meet us in Breda NL?