Jetting Help

[yamaboy]

Hello all.

Please help me with this .....bike. I have taken the carbs off about 6 times and I'm lost. Thanks

I've slapped on a 110 Main Jet ,needle is at the 2nd position , carb floats at 23mm and idle screws at about 2 1/2 turns out. The kit is a Factory Pro and I still have the stock emulsion tubes with 13k miles on them(They don't look that bad..I've ordered some from Factory Pro but it is taking forever) . Stock 52.5 starter jet.

I am currently having issues with idling right and after checking header temps with an Infra Red gun at IDLE , #1,2, and 4 are around 350-400F degrees . #3 is only 170. Seems that the Idle Screw does not help . I have allmost turned it back in(screwed in from 2 1/2 turns)

Is it the float height for carb #3? Too rich?
Not firing properly? Too weak of a spark?



P.S Have changed the Voltage Regulator because it wasn't putting out 13.7-14V at 3000 Rpms.
Have synched/cleaned the carbs
Spark Plugs do not look that bad and only have about 1500 miles on them. Have also cleaned them.
Have checked for spark for all 4 wires. Seems ok.


What is the screw do in this picture? Also is the Starter Jet just for starting?



What about #33. The Pilot Air Jet(132.5) What is this do and how to adjust?



Note: Do not take credit for the pics. Just borrowed them and will delete if necessary. Thanks

[thatkid]

The screw in the first photo "What does this do" That will be the Pilot jet, or #32 Jet, pilot in the second photo.

The Pilot Air Jet #33, and the Pilot Jet #32, both work with the Idle Mixture. I wouldn't go messing with the Pilot Air Jets, the only adjustment would be jets of a different size.

The Starter Jet is only in use when the choke is on, so yes it's only used for starting.

I've said this is in previous threads, If all 4 cylinders are not running close to 100% no amount of Carb tuning will solve the underlining issue. Before messing with the carbs.

Check the cylinder compressions, (in your case #3 could be low). Tight valve clearances can course low compression and poor/rough idling. Could also have vacuum leak's on the intake's.

The coils should deliver a spark capable of jumping 1/4" or 6mm, and be of a nice blue colour. I use a Phillips screwdriver inserted into the plug caps. With the metal screwdriver shaft held 1/4" from the cylinder head, start the engine (it should run on 3 cylinders) and check for a nice blue spark, an orange spark is a weak spark. If the spark won't jump 1/4" then it is to weak.

DON'T touch any metal part of the screwdriver, the voltage will be in the region of 10,000 volts and you will get one hell of a belt/shock, If you suffer from any Heart problems, or serious health problem, DON'T carry out the above Spark Test.

DISCLAIMER.
Iv'e carried out the test many times, You do it at your own risk. If your not comfortable, either don't do it, or buy/construct a spark testing tool, details are in many Haynes Manuals.

[yamaha_george]

+5K on the advice, Mawler I am looking forward to retiring very soon as "that english geezer with the answers "

[thatkid]

+5K on the advice, Mawler I am looking forward to retiring very soon as "that english geezer with the answers "

Retire, Yeah dream on, that's not in your nature. The advice i can provide is what i know about the 600 (only had her 13 months) and my experience gained since i was 14, when i started fixing bikes, went on to work in a Ford franchise @ 16.

Your experience/expertise is motorcycles, looking @ your photo that's gota be a lot longer than my experience ya got 14 years on me.

[yamaboy]

The screw in the first photo "What does this do" That will be the Pilot jet, or #32 Jet, pilot in the second photo.

The Pilot Air Jet #33, and the Pilot Jet #32, both work with the Idle Mixture. I wouldn't go messing with the Pilot Air Jets, the only adjustment would be jets of a different size.

The Starter Jet is only in use when the choke is on, so yes it's only used for starting.

I've said this is in previous threads, If all 4 cylinders are not running close to 100% no amount of Carb tuning will solve the underlining issue. Before messing with the carbs.

Check the cylinder compressions, (in your case #3 could be low). Tight valve clearances can course low compression and poor/rough idling. Could also have vacuum leak's on the intake's.

The coils should deliver a spark capable of jumping 1/4" or 6mm, and be of a nice blue colour. I use a Phillips screwdriver inserted into the plug caps. With the metal screwdriver shaft held 1/4" from the cylinder head, start the engine (it should run on 3 cylinders) and check for a nice blue spark, an orange spark is a weak spark. If the spark won't jump 1/4" then it is to weak.

DON'T touch any metal part of the screwdriver, the voltage will be in the region of 10,000 volts and you will get one hell of a belt/shock, If you suffer from any Heart problems, or serious health problem, DON'T carry out the above Spark Test.

DISCLAIMER.
Iv'e carried out the test many times, You do it at your own risk. If your not comfortable, either don't do it, or buy/construct a spark testing tool, details are in many Haynes Manuals.

YOU ROCK

I hope it's the #3 plastic cap(I had a resistance of 12 ohms) or I believe I didn't sit the float "holder" all the way in its slot. Therefore too much fuel escapes through it. I did not do a compression test yet and the valves are about due for an inspection. 14k miles.

I did the spark test by removing 1 wire at the time and by inserting an older NGK plug ,held next to the head. The spark looked blue for all wires. So the Phillips screwdriver test into the plug caps with the spark plugs detached is to test just the wires , right?

Before messing with the carbs , it idled fine and ran great. No stumbling or anything. The resistance for 2 of my plug caps was over the 10k limit.
Today ,I bought some NGK "spark plug resistor covers" or plug caps which are rated at 5K ohms. (IN the manual the specs are 10k ohms)

Will I be fine with running lower resistance plug caps or will I risk breaking the Ignition Module or the Ignition Coils?

Thanks

[thatkid]

If you haven't seated the #3 float correctly you could have damaged the rubber o-ring seal, rendering the float needle useless. If so that carb should be leaking fuel out of the overflow tube. Quick test but not fool proof.

Turn on the ignition (don't fire up the engine) the fuel pump should prime for a few seconds then cut off. If it keeps pumping and/or fuel leaks then maybe the seal is damaged. Turn the run stop switch off then on, the fuel pump should prime again (mine does) Repeat the process (run stop switch on/off) until you are satisfied there are no fuel leaks.

I use the screwdriver merely to obtain a 1/4 inch or 6mm gap, to check if the spark has the correct intensity to jump 1/4 inch. It's nothing more than a cheap alternative to expensive Oscilloscope's Testing equipment E.T.C. It only identifies weather or not the spark is strong enough, not the cause of a weak spark. If the spark cant jump 1/4 there is a problem.

To my knowledge the spark plug caps or plug leads have resistance, to comply with FCC regulations, to reduce radio interference.

If the different resistance of the new caps will, damage anything

I wrongly assumed you jetted the carbs because of running/idling issues. My Bad.

If you do remove the carbs again, maybe use a air line to clear the pilot jets.

[yamaboy]

If you haven't seated the #3 float correctly you could have damaged the rubber o-ring seal, rendering the float needle useless. If so that carb should be leaking fuel out of the overflow tube. Quick test but not fool proof.

Turn on the ignition (don't fire up the engine) the fuel pump should prime for a few seconds then cut off. If it keeps pumping and/or fuel leaks then maybe the seal is damaged. Turn the run stop switch off then on, the fuel pump should prime again (mine does) Repeat the process (run stop switch on/off) until you are satisfied there are no fuel leaks.

I use the screwdriver merely to obtain a 1/4 inch or 6mm gap, to check if the spark has the correct intensity to jump 1/4 inch. It's nothing more than a cheap alternative to expensive Oscilloscope's Testing equipment E.T.C. It only identifies weather or not the spark is strong enough, not the cause of a weak spark. If the spark cant jump 1/4 there is a problem.

To my knowledge the spark plug caps or plug leads have resistance, to comply with FCC regulations, to reduce radio interference.

If the different resistance of the new caps will, damage anything

I wrongly assumed you jetted the carbs because of running/idling issues. My Bad.

If you do remove the carbs again, maybe use a air line to clear the pilot jets.

I guess I'll have to take the carbs apart.(carbs are squeaky clean as of 2-3 days ago)
And no , you did not wrongly assume that I jetted my carbs. I'm still messing with my carbs. You can see in my signature what I currently have done with the carbs. Before jetting it , it ran great but still didn't sound good while idling. So I decided to check my ignition system .

Found VR was only putting out 12.7V at 3k therefore I've changed it. Now it's 13.7 at 3k rpm. Moreover, I found a cap plug which had a rusted spring inside and bad looking resistor. It read 50K ohms. This could have contributed to killing my VR... The other 2 plug caps are about 9.8K ohms and the last one was about 11-12k ohms. I believe this 11-12k ohm one was plugged into #3. Secondary resistance for 1 coil is 13k ohm and the other is 13.2k ohm which falls in the manual specs.

So before messing with the carbs anymore , I want to make sure that my ignition system is out of the way.

The pump primes and stops really quick . I have done this about 4-5 times and there are no leaks. Only way to know for sure is to disconnect the carbs again. This is prob. about the 10th time disconnecting them. Ha ha.. By the way I'm takling about the float valve "plastic holder"(one that supports the floats) not being seated well. You are prob. thinking about the little o-ring on the side with the rubber diaphragm.

Ok boss ,let me know if you have any more ideas. I'll check for spark before messing with the carbs with the new NGK plug caps and tell you what I come across.

P.S I guess I'm still a noob and confused about the screwdriver approach VS a spark plug inserted into a plug cap. Wouldn't it be the same thing to insert a spark plug and hold it 6mm away from the head?

[thatkid]

Using an old plug, could prevent the spark jumping 1/4 inch. The plug could be faulty, Plug types for the 600 is CR9E or CR8E, i believe the "R" indicates a resistor plug.

EDIT.

just re-read your last post.

"By the way I'm takling about the float valve "plastic holder"(one that supports the floats) not being seated well. You are prob. thinking about the little o-ring on the side with the rubber diaphragm."

The plastic float holder has a rubber o-ring seal roughly 13mm diameter where it seats in the carb body, and will leak fuel if damaged. Ask me how i know

[thatkid]

Another thing, if memory serves me correct. I think the float bowl actually firmly seats and holds the float holder in place when its refitted to the carb. Otherwise the fuel pressure would blow the float holder out of it's seat.

[yamaboy]

+5K on the advice, Mawler I am looking forward to retiring very soon as "that english geezer with the answers "

I hope you're not serious! You'll always be "that english geezer with the answers "

[yamaboy]

Another thing, if memory serves me correct. I think the float bowl actually firmly seats and holds the float holder in place when its refitted to the carb. Otherwise the fuel pressure would blow the float holder out of it's seat.

I always wondered about that . So I guess I've eliminated that possibility of fuel leaking through there. Also turns out that #3 spark plug resistance was 7k ohms..The rest were around 4.9k ohms.. CR9E or any NGK plugs with a "R" have a 5k ohm resistor inside. I just ordered 4 coils and a bunch of plug caps so I hope that fixes that issue.

"The plastic float holder has a rubber o-ring seal roughly 13mm diameter where it seats in the carb body, and will leak fuel if damaged. Ask me how i know "

Ha ha , how? I've checked all of them and they don't look bad but don't know. Was fuel leaking out of the 2 overflows on the carbs when you had the bad o-ring??


Waiting for parts ,blows!

[thatkid]

IF you have no leaks, them seals are fine, I only suggested you check for leaks, since you suspected to much fuel could be going into #3 carb, the possibly unseated float holder, and therefore possibly damaged o-ring.

I only had a leak out of one overflow, carbs #1 & #2. Carbs #3 & #4 share their own and separate overflow to #1 & #2. I.E. carbs #1 & #2 share the same overflow, which is not linked or connected to the overflow carbs #3 & #4 share.

Before buying anything else, Give the bike a good blast, to clear any excess carbon build up. I can only Guess at what your issue is by what you write.

As i said earlier "I wrongly assumed you jetted the carbs because of running/idling issues. My Bad." You have the problems after Jetting.

Please re-read my previous posts, if anything is unclear. Please ask before possibly wasting your hard earned cash.

[yamaha_george]

Also turns out that #3 spark plug resistance was 7k ohms..The rest were around 4.9k ohms.. CR9E or any NGK plugs with a "R" have a 5k ohm resistor inside. I just ordered 4 coils and a bunch of plug caps so I hope that fixes that issue. Waiting for parts ,blows!

Ok if you have been following the threads on this board you will see the total resistance of cap & R rated plugs will give you the 10K that yamaha specify as the "load" on the HT side of the HT coils.

and you wrote 4 coils you have ordered err why there are only two as the FZR uses wasted spark timing system.

[yamaboy]

Also turns out that #3 spark plug resistance was 7k ohms..The rest were around 4.9k ohms.. CR9E or any NGK plugs with a "R" have a 5k ohm resistor inside. I just ordered 4 coils and a bunch of plug caps so I hope that fixes that issue. Waiting for parts ,blows!

Ok if you have been following the threads on this board you will see the total resistance of cap & R rated plugs will give you the 10K that yamaha specify as the "load" on the HT side of the HT coils.

and you wrote 4 coils you have ordered err why there are only two as the FZR uses wasted spark timing system.

Yup , I managed to enlighten myself by finding out from NGK that R in their plugs means resistor. Also turns out that about all newer plugs have resistors in them ..

I meant 2 sets of coils. I've bought a used one from E-bay with a missing plug then an opportunity came over here and purchased another set just in case. Out of the plugs I hope to find at least 2-3 in great shape.

[yamaboy]

So I'm about to loose it because I spent a whole day trying to figure out the damn bike.

I've got my parts in and changed the coils and 3 of the plug caps. They are all within specs , so I have eliminated (or hope I did) my ignition system. Got new NGK CR9Es and spark looks blue for all cylinders. All plugs look ok (not to burned and not to dirty/black) . Have re-checked floats and they are at 23 mm with 4 turns out on the mixture screws , clip in the 3rd position and 110 Main.(starts without choke) I drove it and it seems to stumble a bit in 1st and 2nd untill over 2k rpms but seems responsive from 3k to 10k. No internal or fuel external leaks

I still don't know why in the world the #3 cylinder is at 170 degrees and the rest around 450-490. Also I turned the mixture screw all the way in and there is no change. For 1,2, and 4 I can feel a change when I turn them in for more then a turn..Runs rough..

So could the mixture screw hole for #3 be plugged or is it an indication of something else?



More Info :

at 24mm and 2nd needle position with 107.5 main jet , it does not want to start even with 4 turns out on the mix. screws. Starts with choke all the way up and runs good. Once choke is off , it runs rough

at 23mm and 3rd needle position with 110 main jet , it only starts at 4 turns out on the mix screws.

at 22 mm and 2nd clip position with 110 main jet , it starts at 2 turns out on the mix screws.

Should I go with a 105 main jet since my elevation is 4000 ft?

Out of ideas so appriciate any further ideas or help