EC300 still down on power

[19brendan81]

Hi Guys,

So I have this 2004 EC300 that was down on power when I bought it, which I knew but figured a fresh top end would bring it back. Since then, i have installed a brand new piston and ring, had the squish corrected, sent the carb to the states for boring and RB designs treatment. It goes heaps better than it used to, however compared to my mates 2008 EXC300 it is waaaaaay down on power, in all areas. I rode both machines back to back on the weekend and the difference is easily noticeable. My mates bike accelerates really hard, likes to get the front wheel up and is exhilerating to ride. My bike feels tame and pedestrian in comparison, with a weak transition to power and no real arm pulling power at all.

I am going to start playing with the jetting as per Ron Blacks suggestions however im worried that jetting alone isnt the issue.

My question is, should the power of this motor be broadly similar to the EXC300? If the answer is yes, what else could be giving me grief if I have done all of the following things:

1) brand new piston and ring (6 hours riding)
2) confirmed powervalve actuating correctly
3) squish corrected by head machining (RB designs)
4) Carb bored and improved and jetted to suit head and my specs (RB designs)
5) Clean air filter

Brendan

 

[djroggen]

What ignition do you have? Is it an MC ignition with a huge flywheel?

What kind does your plug look like?

What are you mixing your fuel at 32:1?

What kind of compression are you at?

Is your pipe crushed or blocked at the silencer?

You should be able to easily lift the front tire on a 300, there is definitely something causing the issue.

 

[19brendan81]

Hey DJ, thanks for the quick reply. In answer to your questions...

1) Ignition - no idea...think its stock. Its an Australian bike, identical to the one in this review... http://www.dirtbikeworld.net/Reviews/GasGas/2004_EC_250_300/GasGas_Text.html

2) Plug looks OK, a little rich I spose...but it idles well (really well in fact)...doesnt seem to fuel up, or blow smoke, nor is it particularly hard to start (4 or 5 kicks cold, 1 every time when hot)

3) Fuel mixed at 40 to 1.

4) compression is heaps better since rebuild will do a test when I get home to give you the numbers.

5) Pipe is stock and dent free

You dont spose its something like crank seals? They normally have other symptoms like oil coming in around the flywheel dont they?

 

[GMP]

If its all mechanically sound for sure, my $$ is on the CDI. Try and swap a different CDI. You can even use a KTM Kokusan CDI as they are electrically the same but in a different enclosure.

 

[PEB]

What do the reeds look like?

 

[stainlesscycle]

even with the heavy flywheel it should rip. is the slide opening all the way??? pv, ignition, or pipe restriction, or a reed issue is the only thing i can think of..



if it were crank seals, it would either race/climbing or hanging idle, or smoke bad.

 

[swazi_matt]

Same gearing?

 

[gasmonkey]

Pull the muffler apart and repack.

 

[19brendan81]

"is the slide opening all the way??? pv, ignition, or pipe restriction, or a reed issue is the only thing i can think of.."

Yep, slide functions perfectly. Will check out the reeds, I havent actually looked at them. If they arent shutting or are cracked they could definitely be the cause of the problem. The muffler could probably do with a repack...I think I will do that.

Its not gearing, the bike isnt running right...I can feel it. I'll be spewing if its the CDI...I thought when CDIs are broken the bike wont start at all, or will backfire and carry on...how would a CDI cause a general lack of power?

Brendan

 

[lonetree]

im pretty sure the cdi is responsable for all the advancing of the ignition so if its not working right, it could well be the problem. no idea how to test other than a swap with a working one.
you say its idling fine and starting good but also that its not running right.- whats it doing exactly? i presume its above idle where there is problems?
where in oz are ya? i have a 04 too...

 

[19brendan81]

Im in Canberra mate. F*ck I hope its not a CDI...getting hold of one to test is going to be extremely difficult or expensive. Ive never had a CDI fail on me, but I am lead to believe that they either work properly...or not at all. I could be wrong though.

Re what its doing...its very hard to describe the power issue through a forum post however I guess the best way to describe it is 'its not powerful'. If you rode it back to back with the KTM like I did you would agree theres something amiss.

 

[lonetree]

Re what its doing...its very hard to describe the power issue through a forum post however I guess the best way to describe it is 'its not powerful'. If you rode it back to back with the KTM like I did you would agree theres something amiss.

hmm. mine will give any ktm300 a run for its money, so somthing wrong for sure...
trouble is it sounds like you've checked everything....
mine runs like shit when the muffler falls apart inside.....
i once had the ignition lead at coil end come loose......
the reeds in the older bikes can curl up a little, i flipped mine over....
sorry, out of ideas...

 

[19brendan81]

OK, I think (hope) I have found the problem. I pulled the reed block out and the reeds arent sealing. As you can see from the photos attached, the bike has boysen dual stage reeds (are these stock?) and they arent sealing in numerous places. The outer reeds sit about .75mm proud on one side and .35mm on the other. The inner reeds sit about .15mm proud on one side and sit flat on the other. The reeds wont seal either...if I suck on the round part where the carby goes the reeds will pull in but wont seal...they leak a lot.

I also did a compression test with and without oil, 3 times for each. Without oil the reading was 120-125psi each time. With oil added it was about 130psi. I think that is low from what I have read, but the piston and ring are brand new (well, they have done 6 hours now) and the bore is in mint condition. I am hoping the non sealing reeds are causing that low reading.

I also pulled the muffler apart and checked the packing. Its a little messy as you can see, but not falling apart. Its not oily either. The inner core is also free from soot or blockages as you can see. The muffler is a pro circuit factory muffler...is this stock?

So, from the photos..what do you reckon? Do you think some new reeds will fix the problem?

Brendan

 

[19brendan81]

More attachments....some super close ups of the reed block and reeds, and a view through where the carby goes to the crankcase...you can clearly see the air gap there where the outer reed isnt sealing.

 

[lonetree]

your reeds look exactly like mine did, i flipped mine over and they then re sealed....
the muffler is not stock...

 

[stainlesscycle]

get a new set of reeds. or flip/mix and match those reeds till they seal, while you wait for new reeds...- but with that inner reed damage (last pic of first set of pics) you may not be able to get a seal..make sure the sealing surfaces of the cage doesn't have any dings in it - if it does, they won't seal even with new reeds.... usually when they don't seal the throttle response gets unpredictable, bike gets hard to start, and all kinds of strange power issues..

 

[(F5)]

ok I have your answer. . . maybe. Bikes in NZ & presumably Auss were often supplied with the nickel plated pipe but often sent along the matt black Euro street legal pipe (not to be confused with the 6 day pipe also Matt). This has a plate welded in it with a catalytic doffie about the size of a dust mask filter about 1/3 way up the fat part of the pipe. If your pipe is black then likely someone has munched the original & put this pipe on.

I tried mine as it measured up the same, but boy it was uninspiring, gutless compared to my 200 & it misfired. Cut out the plate & it rips as well as my mates with the std pipe. Hope this is it. Took some poking with a wire to find it, actually missed it first time we looked for it.

 

[19brendan81]

Am going to order some new reeds...these ones are cactus. in the photo called 'overview' you can see a black mark I have highlighted...upon closer inspection this area of the reeds is all chipped away. They are too far gone to turn over in my opinion.

What about the compression test though? 120-130psi is a little low isnt it? I was expection something up around 160?

Re the exhaust - my bike has a nickel plate exhaust on it, which is badged gas gas. It sounds heavy when you tap it though...I suspect there is some sort of baffling in there, like what my old KDX used to have. The pipes straight, but pretty rusty. I think I could justify getting a new one in the pursuit of more power.

 

[stainlesscycle]

nothing wrong with stock gg pipe (as long as it's not the catalytic one..) - believe the catalytic one has obvious welds where the cat is - dunno never seen one.

check your compression tester on something else. sometimes the calibration is way off. mine reads 120 or so for 180... so some simple math and i can get accurate readings.. should buy another one - but afraid it'll be all wonky like this one...

 

[(F5)]

ok well your pipe should be ok if it is the nickel one, worth a guess as they (cat ones) really knock the power out of the ring. Std or cat pipe don't have baffles or double skins - or mesh like I pulled out of old KDX. Keep the std pipe if it isn't squashed or twisted at the header bend which happens.

Cat pipes don't have obvious welds at all. Fooled our local pipe manufacturer & when I rode it I thought 'some-thing's wrong', - way wrong & my old squashed pipe back on & RIP the power comes back.
So I had another poke with a wire & found a clunk. So I got him to cut the pipe. He missed as there was no obvious spot, but cut it out & welded it back up as new (& then I got it chromed as easier to clean).