EC300 losing power + rattle

[(F5)]

Yeah it isn't giving up easily. I would have to say that the more I learn the more I come up against tricky problems that stretch me. i've been tuning race bikes at the pointy end for 20+ years, but still something will get me stumped for a while.

The carb seemed easy & obvious. It could still be the float height is too low, but I doubt that, I have checked. It could be the float needle is sticking or the floats snagging, but they both look just fine. Carb swap would confirm that, but it is a major hassle when you think of what is involved & getting the carb off & back on my mates bike without compromising his riding.

Stator area looked dry when I had all that off doing the repiston. Vibration would tend to move a plate one direction, I've been there. But all looked in order. Stator issues just tend to go ok when cold & part & fail when hot.

yes it could be a fault in the ign box, but it would be a weird one.

The rattle in the pipe is a mystery. What is rattling. the change over of that pipe probably coincides with the appearance of the problem, or close enough. Enough to make me suspicious.

I have two race meets coming up so I won't ride the GG till end of month earliest. I might strip the carb & look again with an eye to changing the float needle, but it looked premo.

 

[Jakobi]

Exhaust mounts? Worn O-rings? Powervalve? They all rattle occassionally.

Nice tight springs on the pipe, fresh Viton o-rings and extra high temp silicone work well to keep it quite for the longest. PV is generally only a clack here and there at low rpm.

I have no doubt you'll work it out sooner or later and it'll probably be something so simple we'll all wonder how it stumped us so long. Good luck

 

[(F5)]

thanks mate.

Yeah spigot seals aren't that old but I'll fire new ones on. either way it seemed that one pipe makes the noise & the old beaten up original doesn't, same springs etc etc.

If I shake the pipe it makes no noise. I poked a clutch cable (remember those) up there & well there is a bit of an odd step at the middle of the baffle cone. But there is also one on the original pipe, seemingly less. Wish I could put on some x-ray specs.


Hmm, ok here's a difference. The old pipe is a stretch to get the rubber mounts aligned so they are stretched. The new pipe is a perfect fit. But resting weight against the pipe doesn't stop the rattle. it is quite noticeable, my other GG riding buddy noticed it straight off.

Just to add to my woes the g.box oil went totally milky again. Changed the impeller seal like 3 rides ago.

 

[Jakobi]

And the woes come in 3's.. Whats next? If it is vibing against the header it could be just a small difference in alignment. It could be something internal I guess.

The water in the oil scenario sux This bike sounds like my missus. Forever needing love and attention.. She makes weird noises and acts unpredicatably while riding too.. Hahah!

 

[(F5)]

OK so I rode again yesterday. I'd changed the impeller seal again & preloaded it with a couple of suspension shims which apparently is an LTR trick. I changed the rad cap to a KTM one as a precaution.

I flushed the g.box with diesel a couple of times & started the bike ont he stand to splash it around in gear for a few mins. Drained milky & then not so bad. Put some cheap g.box oil in & will drain after another ride once I'm happy it is fine.

First loop & I had lost a little water, but I hadn't run it so maybe there was a pocket, filled it from my backpack, didn't take that much. Checked again a couple of times & no water loss. Gearbox oil looks sweet.


Fitted the old original but slightly dented squashed pipe. Adjusted the carb so it leaks a bit on the sidestand so there can be no question of being too low.

Bike displayed no sign of konking out. There were some long steep uphills so it was a reasonable test. However there was no long open sections so I'm still not chalking up 100% result yet.

The bike did bog a little which I put down to flooding over bumps. I lowered the float closing height (you can measure the bend of the tang quite easily & we're talking another 0.5mm, so I'm being over cautious).

Bike ran better.

I want to try a more open ride & then put the other de-cat'd pipe back on & see if the problem re emerges.

Rattle from pipe gone. Still knocks oncee when throttle closes, guess that is PV, but my 200 never did it. Hmm, clutch didn't seem to have any play in it, maybe a drive lash thing Maybe I should try a higher octane gas just to see if not deto.

I do love this bike though.

 

[bchatt]

Still knocks oncee when throttle closes, guess that is PV, but my 200 never did it. Hmm, clutch didn't seem to have any play in it, maybe a drive lash thing Maybe I should try a higher octane gas just to see if not deto.

I do love this bike though.

So, you are running on 91? I find 96/98 much better. "knocks once when throttle closes" sounds like you are running just a fraction lean at wide throttle settings - raising the needle just one notch may well get rid of that (but may cause other issues lower down etc.) Mine will ping like that when I'm hard out on the pipe and close/open/close the throttle.

 

[(F5)]

I run it on 96, just thought I might splash in some Av to remove the possibility that the PV closes quickly being centrifugally operated raising the effective off the pipe compression quickly. maybe, easy experiment if I remember.

It does it from low throttle applications to sudden shut.

I had thought it was a tickle lean at low throttle applications when my float height was low. Now it is too rich & still does it.

Not as bad now I replaced the piston.

 

[(F5)]

Ahh bugger I forgot to try some Av gas in the tank. Bike ran with none of the stalling issues, but I still have the old pipe on. I intended to try the de cat'd one but thought I'd try lose the close throttle knock, so I raised the needle a clip. Well even with as much adjustment with the air screw it ran like a complete dog.

I might have to recind my thoughts on what I thought was a well jetted bike. It didn't want to pull through & would only run well if zinged back & forth in higher revs. Never had a bike change so much with one clip. So after that loop I went the other direction & it was mint. But knock back, but seemingly not as bad, which doesn't make much sense. I might start some other needles, 'cause clearly it is borderline somewhere in the range, perhaps the new piston & maybe the other pipe just pushes it too far.

G.box oil seems clean which is nice. Must reposition the PV outlet as it got spots on my trou. I had routed it up by the rad so it didn't get flooded, but now it spits oil at me.

 

[Jakobi]

Do you mean knock back as in pipe bang? Like a loud 'tang' noise? I found that being rich in the lower rpm has caused this on mine in the past. Like the fuel load is building up to a point where it ignites in the pipe. I found it most prominent when running a lean clip position and a burbly rich straight diameter and pilot.

The N1Ex and NOZx needles both have a really short straight section which then starts with a very rich first taper. I found the pilot circuit and needle diameter only has a very limited effect as before you know it you're on the first taper. Its richness on the taper that also causes the huge jumps in clip position. Myself and others have found that even lifting to the very top clip isn't enough to overcome the first taper. It makes it more ridable, but still far from clean or smooth off the bottom (more punchy), and for me the biggest killing was the lack of fuel economy.

 

[(F5)]

More like a Knang than a Tang, but that could be a local dialect thing.

Interesting, the Taper isn't supposed to affect things until after 1/4 throttle. . . unless it starts too early. From memory I have DEK, CEL (might be in my RZ) & BGNs in the jetbox, so I'll have to read up on what to try or order something different.

Thanks for the thoughts. I tells you, small capacity race bikes are so much easier to jet. WOF is all important & who cares what happens under 8000.

 

[Jakobi]

Could be..

The point at which the first taper starts depends on clip position and the particular needle.

For example, I just measured the NOZJ that I have here by the desk. Its a half clip leaner than N1EJ. Not counting the clip section. Just the effective part of the needle the full length is 50mm. The straight section is only 5mm before the taper starts. Now consider that you will have the slide lifted a little bit to allow for an idle, you only have a few mm of straight section to use before you're onto the taper. All in all for this needle the straight section is only 10% of the equation. By lifting the clip you lengthen it which is why it helps somewhat, but as always you then hit that rich first taper.

 

[bossmans kid]

I have an 09 ec 250 that had the exact same problem last weekend. When I was fueling the bike, I noticed the gas cap insert shrunk over the winter. I tried to stretch it out to make a good seal to the top of the tank and went riding. When the bike started acting up, I took that insert out and disconnected the vent line from the frame. Bike ran great the rest of the day.

 

[(F5)]

Well just as an update I thought I'd report.

Nothing much to report. Ran the bike a few times (not much riding in winter here), but with a combination of a few things & a CCL needle it seemed to run well. Had a ride in the weekend at reasonable altitude & cold day it seemed a little lean off closed so a 1/2 turn & seemed fine. Were a few uphills & under load sections.

Put my other non dented gutted pipe on & couldn't tell the difference. No problems so far. Although there wasn't much in the way of long up hills on this loop.

No smoking gun, but as long as it runs right I'll put it down to a combination of factors. Possibly the chromed pipe increased pipe temp a bit & required slightly richer jetting so went from borderline to over lean in some area.

Must do my planned head mod to reduce squish right down but retain compression as std (so I can kick it over easily). Its in the queue.