EN450 dying at 2k-3k RPM

[Pepito]

Hi, i.ve been ghosting around here as a guest, and i decided to register. Saw more posts like this but i need some help, a very good friend of mine has an 89 EN450, bought it from my dad. The bike ran great, no problems whatsoever. Now it has been sitting for more than 1 year. I got her prepped for this season, everything seems fine, but when it reaches around 2500-3000 rpm its just wants to die, if i pull the throttle slowly and need to rev it hard to jump 3 k rpm, after that it shoots me like a rocket ( this with me riding it, in first gear ). 

I did the following and need some assistance since i dont know anyone who has one of these and am clueless to her temper :

1. carbs cleaned about 4 times (tried soaked, carb cleaner, break cleaner, compressed air ) and in sync

2. new spark plugs + and new wires ( the ones from the coil to the spark plug )
-> got a good spark

3. Cleaned the tank and rebuilt the petcock ( got a repair kit for it ) + secured vacuum line
-> got fuel

4. New fuel line hoses and filter, secured

5. Idle screws are set to 2 and 1/2 ( tried everything from 1 1/2 to 4 turns out)
-> oddly enough, nothing seems to change even the idle kinda remains the same, wich i find weird

6. Measured the fuel level in the carbs with a transparent tube and both carbs have the same fuel level, if i measured corectly the fuel stops below the 0 line, roughly 2 mm

7. Valves are good, my dad did them before he sold it. 

8. Air filter changed (stock)
-> tried with filters on and off, no change on the problem


I still suspect the carbs... somehow... since every time i check the spark plugs, they are black, but never wet. Seems that whatever i do, it gives the same feedback. More fuel, less fuel, filters on, filters off, tried giving fuel from a plastic bottle... Any ideas would help, cause im out of them atm

thanks 

Forgot to say, i tried seeing if she has power and tried easing of the clutch, its starting to move without problems, if this helps :-? 

[Blaine]

If your not getting change when you adjust A/F screws that is your problem....You either still have blockage or needles not assembled properly.....Washer spring than o-ring.

[Pepito]

Hello Blaine,
i`m almost done taking the carbs out, will check asap. 

EDIT:
the needles look fine, a bit blackened at the tip, placement was spring, washer then o-ring.  The washer from the left carb seems a bit rusty, or corroded of some sort. Sprayed some carb cleaner and some compressed air. Ill put them back and see how it runs, didnt find any junk inside.

EDIT 2 : i put everything back. 2 1/2 turns, it wont start, and did one really loud bang out the exhaust, spark plugs are just a bit black

[Blaine]

Sorry..your placement was correct....spring washer o ring......The washer just keeps the spring from ripping the oring.....Sounds like your flooded now...Clean up plugs & spin her over with the plugs out should clear things up.

[Pepito]

I got it started today, same issue, i measured the fuel level in both carbs, is the same, a bit lower than the 0 line from the manual ; at 2500-3000 rpm its kinda sounds like starting to run in one piston, then after 3000 rpm, bam ! goes up with no problems, but still sounds a bit different than the normal tempo of the pistons, if you know what i mean. WIll try adding a video, maybe you can hear something i dont since you are more aquainted with this model than me.

EDIT: Found out something new, if i rev up slowly, it will get stuck at around 2300-2500 rpm and as soon as i let off the gas, it dies. Cant rev over 3000, alternatevly, If i rev up fast it goes over the chocking point and just rolls on. In deceleration, engine break, sounds the same on all rpm range, no popping or backfire.

It bothers me a lot cause it was running fine before sitting, cant wrap my head around this one

[eaglerider]

Did you remove the jet seat tubes and make sure all the little holes were open? That sounds like your problem...many forget they are removable and the holes are all gunked up.

[Pepito]

Yeah, i did remove them 2 days ago, just to be certain i clean them properly, blasted them with some carb cleaner fluid and compressed air. Clean as a whistle.

My initial tought was the pilot jet clogged, cause the problem is at 1/3 throttle, but they clean, all jets, needles, the membranes are in good condition, there are some minor diferences on the float needles, but it ran like this before so i avoided doing any modifications or adjustments.

[Pepito]

Done with the video. warmed up the engine, and this is how she acts. This is one of the more aggressive dying techniques xD

[Pepito]

OK, so... i did a bit of research and would like some opinions:
Might it be that the slow running fuel passage be  clogged so it wont allow enough fuel to go as i gas it in low revs? but that would mean i couldnt get idle speed aswell, would it ? even though i sprayed it with compressed air, could it be still obstructed ? ( i could feel the air coming on the small butterfly orifice), or the pilot jet... but the pilot jet along with all the others are thoroughly cleaned... 

Since it needs spark, air and fuel to run... i have spark, i have air ( getting the filters on and off did almost nothing, i could feel that it is sucking more air while the filters were off, less power, but thats it ) logically, the only thing in my mind is the fuel, i.m asking myself about which one of the fuel delivery passages and only pilot and idle come to mind, since it idles, only the pilot jet and passage remains. HIgh RPM is ok, which means the main jet doing its job.

But if i gas it slowly, as you see in the vid, it doesnt want to rev, even though the main jet delivers fuel, could it be that its leaking air somewhere ( even though i checked the intake, vacuum, and airbox rubbers hoses, they are fine and on spot) and not sucking enough fuel ?

Thoughts?

[Blaine]

To me it sounds like a lot of the time your only running on one cylinder....Like one carb is starving for fuel.

[Pepito]

Sometimes the right piston isnt running. So it might mean the right carb; 
Fiddling with the idle screw still has no influence on how it runs;
Could it be that one inducion coil is shot and its not working when recieving more impulses from the ignition unit ?

[eaglerider]

Coils wired right??

[Pepito]

Hi again, found a thing with a guy that put his IC igniter in the freezer, so i did that to check if it does anything and after about 30 mins, got it out and plugged it back in, worked as a charm... for about 10-15 min, after i did that for about 4 times, i didn`t get any spark at all. Checked everything from the signal generator to the final electrical connector at the IC igniter. Found a similar igniter from a `87 GPZ. Got a good feeling about this 

Waiting for it to come and will test it out.

[Pepito]

Apr 12, 2020 5:05:22 GMT -6 eaglerider said:

Coils wired right??

Yeah, checked them 

[Blaine]

Normaly thats when they fail..When they get hot....Your on the right track.

[Pepito]

I changed the Igniter, runs well, but same problem, not as persistent though. When it gets hot, its starts running wierd in some rpm now, the rev range is between 4k and 7 k, as soon as it goes past 7 k runs and sounds great. Changed he ignition coils with new ones, just in case, has very good white spark.

New discovery: As i turn the mixture screws to lean, the rev range with problems drops - > at 1 1/2 problem is at 1k-4k ; at 3 1/4 problem is at 5k - 7k . 


Last igniter was faulty, thats for sure, but now... hmmm .... Carb issue, one of my firends who owns a LTD told me he had similar problems and did not solve them but he seems sure that the slides are worn for him, what do you guys think, could it be the slides are worn out ?

[Blaine]

Never heard tell of that..If the diphrams are sealing well & not leaking & slides are moving smoothly than you problem is elsewere......That being said when I added aftermarket filters & rejetted I still had a slght bog......I cut 2 coils of the diaphram springs......No more bog & crisper/faster response.....With less vacuum Less spring pressure lets the slides move quicker.

[Pepito]

Hi again,

Found another guy, and went to him with the bike, we took the carbs off and he took a look at them, he also said that the sliders are worn out and because of that they dont go up when i gas it easily, and goes ok when i do it harder. I just let him do his thing without saying any of my opinions on the matter, guess thats the only thing left to change, found new ones with 124 $ a piece. I`ll see what does the owner decide and if he`ll change them, i`ll keep posting if it works.

[Pepito]

Found some carbs from a GPZ 500, will try to switch them whole, see if that does something

[Pepito]

The GPZ carbs have arrived, everything runs smoothly, guess the sliders were the issue after all. They had a lot of play compared to the ones from the GPZ carbs.
Seems this was it, Fixed, finally, Thanks a lot for the input and advice, guys.

Ride safe !