Well I'm stumped

[thatkid]

I have 3 bikes that all used to run fine. They all sat in my shop from anywhere from a day to month or so before being started again. Now all 3 will not run without choke. If the choke is turned to half, the bike will drop to about 400rpm and stumble for a bit and then die. When they are first started they jump to about 4-5k and then drop to about 2k. If you blip the throttle it jumps well beyond what the blip was and hangs for awhile before dropping back down.

Changed the plugs, cleaned the carbs, checked for spark, even went as far as to check the valves(they are within spec). I've tried to sync but it's not possible with how the bike is acting. I'm looking for options because I can't figure this one out.

[yamaha_george]

I have 3 bikes that all used to run fine. They all sat in my shop from anywhere from a day to month or so before being started again. Now all 3 will not run without choke. If the choke is turned to half, the bike will drop to about 400rpm and stumble for a bit and then die. When they are first started they jump to about 4-5k and then drop to about 2k. If you blip the throttle it jumps well beyond what the blip was and hangs for awhile before dropping back down.

Changed the plugs, cleaned the carbs, checked for spark, even went as far as to check the valves(they are within spec). I've tried to sync but it's not possible with how the bike is acting. I'm looking for options because I can't figure this one out.

TK,
they were stored in your work environment? which has a powder coat plant/ beadblaster near by.......................................

[cad600]

I've got the same problem with a friends bike I'm working on. It wouldn't idle for him or run for that matter, I cleaned the carbs and it cranked up and idled fine. One week later, it wouldn't hold and idle for anything. Sync will not work, and I've cleaned the carbs 2 more times and it still has issues.

Driving me nuts. If you figure anything out, I'd love to know as it will help me out too.

[yamaha_george]

I've got the same problem with a friends bike I'm working on. It wouldn't idle for him or run for that matter, I cleaned the carbs and it cranked up and idled fine. One week later, it wouldn't hold and idle for anything. Sync will not work, and I've cleaned the carbs 2 more times and it still has issues.

Driving me nuts. If you figure anything out, I'd love to know as it will help me out too.

Low RPM cct needs inspecting the jets and passages only need some VERY fine rubbish in to screw the whole shebang up.

Personally I would empty the tank ,wash out , fresh gas, new or VERY well cleaned filter, re -do the carbs, new plugs and go from there.

From personal experience it is very easy to get complacent when cleaning carbs for the ???teenth time and missing something obvious.

[cad600]

That's just it, I've looked at all those things. The gas is fine, the fuel filter is good, I've checked the plugs and triple checked the plug wires for proper order. I've even gone through the carbs to make sure everything is in place properly. It's got to just one of those "black art" carb things. I'll get is worked out, but it just seems to be the vein of my existence right now because it seems like no mater what I do it doesn't get any better.

[kilika2]

I agree with Geo, I know I'm way newer to bikes than you Nate, so take this for what it's worth . I had the same problem AFTER I synced my carbs for the first time. Razor told me I probably just missed something, even though I had went through everything throughly. But I got the fishing line out the second time just cause I didn't have any the first time. And while doing so I found a little junk in one of the pilots and then a little junk on the choke slide that I had missed. And the idle screws had gotten messed up a little when putting the carbs back in. (Don't know how this could have happened but oh well)

The fact that it's all 3 makes be believe it's carb or airbox related. Do you have the little vacuum hose connected to the airbox that is a drain for condensation?

Chris.

[yamaha_george]

That's just it, I've looked at all those things. The gas is fine, the fuel filter is good, I've checked the plugs and triple checked the plug wires for proper order. I've even gone through the carbs to make sure everything is in place properly. It's got to just one of those "black art" carb things. I'll get is worked out, but it just seems to be the bain of my existence right now because it seems like no matter what I do it doesn't get any better.

Ok take a break for a day or so & go thro it with a pal at your side , there is a saying abouts woods & trees.................................

[cad600]

Ok take a break for a day or so & go thro it with a pal at your side , there is a saying abouts woods & trees.................................

I'm a firm believer in the concept of - when you are not looking for the answer, it will present itself to you.

Worked for me many times in the past. The only bad part is when you wake up at 3 in the morning with the realization of he answer and can't get back to sleep.

Or the other method. Stop, have a beer, then use a hammer.

[thatkid]

I guess I'll just go back through everything VERY carefully. I'll start with the filters. two of the bikes have pod filters and the last is bone stock. All of them had all parts on while in the shop so it just seems odd that dust would be the cause of it on 3 bikes.

[zero9243]

I guess I'll just go back through everything VERY carefully. I'll start with the filters. two of the bikes have pod filters and the last is bone stock. All of them had all parts on while in the shop so it just seems odd that dust would be the cause of it on 3 bikes.

it would suck to have to pull the carbs again but maybe we'd better just do it and check everything thoroughly on all 3 sets of carbs

[reelrazor]

Okay,

The common element here is/are:

run condition of three units, and

environment and fuel

I would be checking airfilters first. As Geo mentioned.....powdercoat related dusts (and other shop dusts)-some of which can be very clingy


you say "one day to a month"

Modern pump gas loses 10 octane points in the first month of storage and 5 for each subsequent month. In one of my tech update classes a fuel industry guy told me that if you took a fuel chemist who died in the '60's and gave him a sample of what is now called gasoline, that he would be stumped..maybe suggesting it was a toxic solvent.

The gasoline chemists now work in conjunction with the auto manufacturers to achieve emissions goals..the fuel is tailored to burn clean on startup(cold engine parts) and to be quite easily 'lit' (volatile 'light ends') and the 'heavy ends' are there remaining to provide energy dense hydrocarbons for efficiency.

Since it is quite uncommon for a car to go more than a week without at least a top-off of the fuel tank, and the evaporative emissions controls in modern fuel systems stems much evap anyway, the light end volatility is not really a factor in that case.

Our bikes however....DO vent to atmosphere, and ALSO require good fuel..

(wow, bit of a ramble here by me)

Point being: "the gas is good" is hard to back up..drain it, throw it in your truck...put NEW fuel in the bikes

[yamaha_george]

Okay,

The common element here is/are:

run condition of three units, and

environment and fuel

I would be checking airfilters first. As Geo mentioned.....powdercoat related dusts (and other shop dusts)-some of which can be very clingy


you say "one day to a month"

Modern pump gas loses 10 octane points in the first month of storage and 5 for each subsequent month.

I fill my gas tank to the brim when put here up for the winters & bin the whole lot into the cleaning liquid bin or a gas can for pals old car and then wash out the tank with fresh fuel & then fill up with fresh. During riding season I leave the gas as is after the ride & when I leave to ride fil up then. RR thanks to why that works I just did it out of "hunch" rather than knowledge

[apsolus]

any air leaks? try the carb spray trick, see i idle changes

[Munzo]

any air leaks? try the carb spray trick, see i idle changes

+1

I'm new to FZR's but from working on other bikes this sounds like the issue. Hanging idle is often a sign of an air leak. Air Leak means lean mixture... which is why you need the choke to keep the bike running.

[yamaha_george]

any air leaks? try the carb spray trick, see i idle changes

+1

I'm new to FZR's but from working on other bikes this sounds like the issue. Hanging idle is often a sign of an air leak. Air Leak means lean mixture... which is why you need the choke to keep the bike running.

M,
+5 valid point in frustration fo doing the job many times getting the rubbers seated properly would be avalid mistake for the symptoms. Munzo nice to hear a new voice chipping in :-}