jetting

[iancp5]

Originally Posted by stay_upright

Ian - what throttle opening did your bike seize at? 3/4 or WOT? or more like 1/4 to 1/2..

As you read from my post below I'm running my bike a lot leaner than yours and have eliminated the 4 stroking, have ran this jetting for a couple of years and it works great. Mine is lean at teh bottom end and gets richer - back to stock at the top end. I would not worry about seizing the bike at low throttle openings only 3/4 throttle onwards but it sounds as if you have had other problems... Were the rings definately welded to the cylinder?

It was running lean for half a season in tight woods enduros then I did the Welsh. Soon after the start there was a stretch down an fast road for several miles. I was cruising (after warming up) at 50 - 60 mph on very little throttle and it locked solid. Wouldn't kick over until it cooled down. Started and it sounded fine so I carried on a bit, then it started sounding laboured so I pulled the clutch and stopped. Cooled it down and limped home. End of enduro before even getting to the first forest.

I would say it was on no more than an 1/8 - 1/4 throttle. Had it been more I think it would've been ok.

I think it worked ok in the woods because you are either on tiny throttle at low revs or 1/4 - 1/2 accelerating on an open bit. When it seized I was at small throttle but high revs. I.e. very lean and revving. I had made it very lean off the bottom to keep it clean while tree hugging.

The piston was quite messy I was surprised it would still run at all. General smearing of metal and the rings had piston smeared over them. Barrel didn't look good either so it had a re-plate.

[ferguscawley]

Hi Ian

Are you sure your seizure was caused by jetting and not by running out of coolant or loose impeller etc ? How was your crank big end bearing ? - was this seized too or was it just piston seizure ?

Fergus

[iancp5]

Originally Posted by ferguscawley

Hi Ian

Are you sure your seizure was caused by jetting and not by running out of coolant or loose impeller etc ? How was your crank big end bearing ? - was this seized too or was it just piston seizure ?

Fergus

Just piston. Ran perfectly after rebore and richer jetting.
It's hard to be 100% certain of course but there was no other damage that's for sure.

[stay_upright]

Hmmm interesting, and slightly worrying.

My jetting at the bottom end is very similar to the homologation jetting, same slide and pilot jet, I don't think GG would sell the bike even with homlogation jetting that would seize... but there again yours did..

Was this the first time you had cruised at 50-60 for a while?

Had you recently had a new piston? What oil and % were you running - did you check after seizing the fuel did have oil in?

I've ran my bike like this for 2 years with no problems, have inspected the cylinder/piston in this time as well and could only see a few 'normal' very light score marks. I've done a lot of cruising on tarmac at 40-60 and some would have been after idling/blipping the bike for a few minutes to warm it up and to be honest that probably doesn't get it upto full working temperature though of course this is 'normal' as well.

I really don't want to change my jetting the bike runs so nice like this.

Could you describe what happened from when you started the bike - you mentioned you warmed the bike up are you allowed to do that before the start - how long for, was the radiator warm/hot? How long was the first off road section before the road?

Thanks for the info.

[iancp5]

Originally Posted by stay_upright

Hmmm interesting, and slightly worrying.

My jetting at the bottom end is very similar to the homologation jetting, same slide and pilot jet, I don't think GG would sell the bike even with homlogation jetting that would seize... but there again yours did..

Was this the first time you had cruised at 50-60 for a while?

Had you recently had a new piston? What oil and % were you running - did you check after seizing the fuel did have oil in?

I've ran my bike like this for 2 years with no problems, have inspected the cylinder/piston in this time as well and could only see a few 'normal' very light score marks. I've done a lot of cruising on tarmac at 40-60 and some would have been after idling/blipping the bike for a few minutes to warm it up and to be honest that probably doesn't get it upto full working temperature though of course this is 'normal' as well.

I really don't want to change my jetting the bike runs so nice like this.

Could you describe what happened from when you started the bike - you mentioned you warmed the bike up are you allowed to do that before the start - how long for, was the radiator warm/hot? How long was the first off road section before the road?

Thanks for the info.

It was the first time I had cruised on 35P, No. 1 clip N1EF, 178. Had done many times before with 38P, No. 2 clip N1EF, 178.

Running Putoline MX7 50:1. YES there was oil in the fuel!

Bike was warmed up by having to ride through town with 30 mph limits first. The start of the Welsh is in the middle of a town and you have to ride to a forest. I didn't get to do any off road!!!!

Maybe there was another problem I was not aware of.

[ferguscawley]

I reckon there was another problem Ian. Admittedly, a 35 pilot is a bit on the lean side, but at a 50 or 60 mph cruise your are well on the needle anyway and the pilot would/should have minimal effect there.

I have come across one 2006 EC300 that had identical jetting to yours with the exception of a 40 pilot, that began to run badly for no reason. After many checks it turned out to be the cylinder head had warped and what little coolant was left in the bike was entering the cylinder causing the bike to run poorly. Reason was eventually tracked down to a tiny pin hole in the left hand radiator that had gone un-noticed for enough time for the coolant level to drop significantly.

Luckily, we caught the problem before the bike got too hot and seized the piston to the barrel. We skimmed .08mm from the head, used a 0.3 mm and 0.15mm base gasket combined. Bike now runs like its on steroids

Fergus

[macho comacho]

Hi all
Thanks for all the replies and ideas, just one question is the CEK needle richer or leaner than a CCK ?
Cheers macho

[RBD]

The CCK needle is richer at the L1 length, the L1 is 36.35 mm and the CEK needle has a L1 of 38.15 mm. Both needles are the same diameter and they are both a taper of 1*34'. As you can see, you get onto the taper quicker with the CCK as apposed to the CEK needle.

Ron

[stay_upright]

Have a look at this http://home.att.net/~wbarrow/jd/download_jet.html

Put your set-up in and compare to some other set-up's.

In order to get the bike running very smooth with no spluttering and spooge I found I needed to lean out the jetting around the 1/8 to 1/4 throttle and slightly above , however for me a CCK does not work well as it leans out around 1/4 throttle but too quickly becomes rich again at slightly different throttle openings.
I use a 35p N1EF (put NOZI in the JD sheet as the needles are very similar I'm told and this demo does not have the N1EF needle in) on clip 2, 178 main and 9 slide - again you cannot put slides into this demo just bear in mind a 9 is leaner than a 7 at small throttle openings.
I suggest you put your curent settings, change the jetting and ride it for a couple of minutes and repeat until you understand what's going on. Also bear in mind if you go too lean you will get misfires which can feel like it's too rich though does have a slightly different feel, a bit harsher I think.

[fury1]

we had a rider around here seize his bike running a turkey run a few years back,he did some research I seem to remember he said he found out your not supposed to keep a two stroke engine at a steady pace for any length of time,it leans out very quickly,he was riding about 45 mph for a five or six miles when it happened