Valve question

[mark1914]

So today ragedigital came over to help me with my Fizz. We did the compression test and all of them were in the 160-180 range. We swapped out the coils with some from a YZF. Next tried to adjust the carbs. With an infrared heat gun we measured the temp of each header. Headers 1,2,4 were all around the same temp 500-600 degrees. Header #3 barely got to about 260. No matter how much adjusting he did it wouldnt get hotter. Valve job?

[reelrazor]

Was #3 the 160psi cylinder?

No matter what, that's still pretty good.
If you could get a leakdown tester involved, it would help.

What jumps intuitively to my mind is head gasket leak. #3 seems to be the prone one for coolant leaking into the cylinder. This would drop your cylinder temps down but not have any obvious sign.

How are the exhaust gaskets?

Has the exhaust been removed to check for obstruction in the #3 header pipe? Or for shininess in the port

[jax]

Pull the #3 spark plug. Does it look like its been cleaned? If so then your head gasket is allowing a small amount of coolant into the cylinder and steam cleaning your spark plug.

[mark1914]

Was #3 the 160psi cylinder?

No matter what, that's still pretty good.
If you could get a leakdown tester involved, it would help.

What jumps intuitively to my mind is head gasket leak. #3 seems to be the prone one for coolant leaking into the cylinder. This would drop your cylinder temps down but not have any obvious sign.

How are the exhaust gaskets?

Has the exhaust been removed to check for obstruction in the #3 header pipe? Or for shininess in the port

reel, I dont remember if #3 was the one at 160. I believe it was the lowest of the four. Rage will probably chime in here to confirm. Now there does seem to be an exhaust leak from #4 header. Its got some white stuff around it. I will remove the #3 header when the bike cools down in a few.

[yamaha_george]

So today ragedigital came over to help me with my Fizz. We did the compression test and all of them were in the 160-180 range. We swapped out the coils with some from a YZF. Next tried to adjust the carbs. With an infrared heat gun we measured the temp of each header. Headers 1,2,4 were all around the same temp 500-600 degrees. Header #3 barely got to about 260. No matter how much adjusting he did it wouldnt get hotter. Valve job?

Mark,
If the temp is well down is that cylinder actually firing every stoke?

Is that cylinder's plug wet TOO much fuel will cool the header ,

Coolant can cool that headr if you have a gasket leak but would normally (but I know for a fact not every time ) you should get white smoke

was this cooling at all rev ranges ? ie is it carb related

[mark1914]

George when I pulled the plugs #3 was black but that was due to the bike running rich. No white smoke coming from the exhaust. We let the bike warm up and tested the headers temp while reving the engine. The #3 header would rise in temp but not very far. The most it got up to was like 260. Like I said before the other three were well into the 600s.

[mszilves]

Mark,
If the temp is well down is that cylinder actually firing every stoke?

Is that cylinder's plug wet TOO much fuel will cool the header ,

Coolant can cool that headr if you have a gasket leak but would normally (but I know for a fact not every time ) you should get white smoke

was this cooling at all rev ranges ? ie is it carb related

Always check the easy things first... start with the plugs, then if those are in good condition, then more than likely it is carb related. Make sure the carbs (especially the float valves) are clean/in good condition, and are synced properly. Check the float levels, and idle mixture screws and get the carb sorted out. More often than not on these FZR's, it's carb related. These carbs can be very finicky. It's likely dumping a bunch of fuel into that cylinder...

[mark1914]

Mark,
If the temp is well down is that cylinder actually firing every stoke?

Is that cylinder's plug wet TOO much fuel will cool the header ,

Coolant can cool that headr if you have a gasket leak but would normally (but I know for a fact not every time ) you should get white smoke

was this cooling at all rev ranges ? ie is it carb related

Always check the easy things first... start with the plugs, then if those are in good condition, then more than likely it is carb related. Make sure the carbs (especially the float valves) are clean/in good condition, and are synced properly. Check the float levels, and idle mixture screws and get the carb sorted out. More often than not on these FZR's, it's carb related. These carbs can be very finicky. It's likely dumping a bunch of fuel into that cylinder...

I pulled the plugs and took a look at them before we did the compression test. Two were fine and two were black. That was from last weeks tuning we did. Darrin played around witht the adjustment screws while I monitored the temperature of each header. Now, my emulsion tubes are a tad worn but he dropped the needles down to compensate. I am going to get new tubes as soon as some come available for a decent price. I do have new plugs but yet to install them. Autolite 4303s. I didnt want to install them just to have them foul out. I burned out all the 91 octane gas I had in their and put in fresh regular gas. Seems to be running better. Still bogs though.

[mszilves]

I pulled the plugs and took a look at them before we did the compression test. Two were fine and two were black. That was from last weeks tuning we did. Darrin played around witht the adjustment screws while I monitored the temperature of each header. Now, my emulsion tubes are a tad worn but he dropped the needles down to compensate. I am going to get new tubes as soon as some come available for a decent price. I do have new plugs but yet to install them. Autolite 4303s. I didnt want to install them just to have them foul out. I burned out all the 91 octane gas I had in their and put in fresh regular gas. Seems to be running better. Still bogs though.

Well I can tell you from experience that adjusting the carbs is a royal PITA, but the results of having them well tuned are second to none. On a carbed bike, they are the most important, and often neglected area. Even minute wear and out of tune can make a big difference in how a bike runs. Just think of how precise the air/fuel ratios have to be to get proper ignition...

Good that you're going with the lower octane, higher octane than you require will theoretically give worse performance.

Adjusting the idle mixture screws will take a long time to show a reading at the header, and will not make significant changes in temperature. For some reason, it sounds like your carb(s) are dumping gas, and you need to get into them.

Really I would baseline the carbs and go from there:

1. Check the float valves carefully (their spring operation and seals) to make sure that they aren't overflowing
2. Check and set all the float levels to stock (should be about 21-22mm for stock needles, and I believe 24mm for dynojet needles)
3. Check all seals (including the choke valves at the bottom of each carb) to make sure they're ok. They tend to dry rot after so many years.

Depending on where your bog is in the RPM range and under what load conditions, will tell you roughly what carburetor circuit is dumping too much gas. I didn't see in the thread if you're running stock or aftermarket jets/needles, or what add-ons you have on the bike, but a lot of guys think putting a pipe and intake just requires you throw in some new jets and you're fine, where in reality, carb tuning can be a bit of an art.

[csofos]

So today ragedigital came over to help me with my Fizz. We did the compression test and all of them were in the 160-180 range. We swapped out the coils with some from a YZF. Next tried to adjust the carbs. With an infrared heat gun we measured the temp of each header. Headers 1,2,4 were all around the same temp 500-600 degrees. Header #3 barely got to about 260. No matter how much adjusting he did it wouldnt get hotter. Valve job?

I had the same problem with my R6. I checked the compression and it was ok. Before that i checked the valve gap and it waw ok too. When i went to dissasemple the carbs for cleaning (having in mind they are blocked somehow), i noticed that they were NOT properly tight on the rubbers. Damn!!!!!! That was the problem. My 3rd cylinder didn't working. I knew that by putting my hand on its header. It was warm, not hot like the other 3.
So buddy, check for leakage either by broken carb rubbers, either by non-tighten carb rubbers. Hope you solve the problem.

[ragedigital]

His carbs are flawless except for a small tear in one of the diaphragms - it moves that same as the others when given gas, so I assume that it is not affecting performance.

His floats are all the same height - roughly 24mm. I do believe that is the factory setting. They all move freely and look fantastic.

His emulsion tubes are enlarged, slightly egg-shaped, but more rounded, so I adjusted down the needles one step to compensate a bit. I still suggest a new set to remove them from the equation.

As far as adjusting the IMS (Idle Mixture Screws), I have always seen almost immediate resultswhen I do it. We will pull those screws again and shoot more carb cleaner in there.

I gave Mark a set of YZF600 colis that I had to make certain that it wasn't his coils. They produced the same result.

On header #4, the header is white/yellow on the outside and I can only assume that the header gasket is missing. I told Mark to pull them and check to see if they are still there.

It's nice to wrench on a FZR again... how familiar. Plus, the wife doesn't complain as much seeing as it's not mine.

MARK (homework):

- Pull the headers and see if the gaskets are still there and in good shape. Make sure the headers are tight.
- Pull the Idle Mixture Screws all the way out - don't lose the small washer and o-ring that are inside there (IIRC). Shoot carb cleaner in there real good. Insert the screws all the way in and back them out 3 full turns each (a good starting point).

I'LL BE BACK!!!

[mark1914]

Got it.