ESE's works engine tuner

[Frits Overmars]

... I am on 125 main and the needle on the top clip, I ran out of jets at 125 but am I right in thinking it's still too lean?

A bit more information couldn't hurt. There are numbers on needles and needle jets, you know...
But checking if the main jet is too small is easy: leave it out. If things improve, it was too small.

[TZ350]

Kx100 ignition set by the suck it and see method

KX 80/100 ignitions like this one have timing marks that line up with a pointer cast into the GP engine case for 20 deg BTDC. Which is a pretty handy place to start with. The ESE bikes running KX ignitions all had final settings somewhere in the range of +-5deg from there, my engine with a squish band liked 16, others with the original open chamber, 20 or 25.

[cotswold]

A bit more information couldn't hurt. There are numbers on needles and needle jets, You know...
But checking if the main jet is still too small is easy: leave it out. If things improve, it was too small.

Thanks Frits,

The main is a 125
The pilot is a 40
the needle is 4 ej14

I removed the main and the bike will start and tick over but will not rev

[cotswold]

KX 80/100 ignitions like this one have timing marks that line up with a pointer cast into the GP engine case for 20 deg BTDC. Which is a pretty handy place to start from and the final setting will be +-5deg from there.

Thanks Rob,

I was thinking it was a carb issue due to it revving freely with the choke on but back firing with the choke off, I was sort of hoping someone could point me in the right direction as I will need to order some more jets. I have from 97.5 up to 125, not all of them are original and after our experience with the pattern parts I would be looking at original part jets.

[speedpro]

It runs with the choke on but fluffs about with the choke off - reasonably obvious to me. I'd put the needle clip in the middle just as a place to start and start with BIG jets and work down until it runs. Rob should be able to tell you what is a big jet for your engine. Testing with no main jet fitted at all is good but only confirms that the needle jet is not a restriction to fuel flow. I've drilled jets out to see what happens and soldered them back up and redrilled them. It's a good way of getting in the ballpark without buying a box of jets most of which you don't need after you've tuned it. I then buy a small range of the correct size jets once I know what is needed. Plus the last dyno session nobody had jets big enough and the actual size was a surprise, to me anyway.

[cotswold]

It runs with the choke on but fluffs about with the choke off - reasonably obvious to me. I'd put the needle clip in the middle just as a place to start and start with BIG jets and work down until it runs. Rob should be able to tell you what is a big jet for your engine. Testing with no main jet fitted at all is good but only confirms that the needle jet is not a restriction to fuel flow. I've drilled jets out to see what happens and soldered them back up and redrilled them. It's a good way of getting in the ballpark without buying a box of jets most of which you don't need after you've tuned it. I then buy a small range of the correct size jets once I know what is needed. Plus the last dyno session nobody had jets big enough and the actual size was a surprise, to me anyway.

Thanks Mike,

I have played with the clip position and it made no difference but the idea of drilling out one of the pattern jets sounds like a plan......

[TZ350]

If its a Mikuni round head main jet 125 sounds bigish, but a Kehien 125 would be to small, drills and spare jets at work, pop around tomorrow and borrow them, quickest way to find what you need.

[cotswold]

125 sounds big, drill and spare jets at work, pop around and borrow them, quickest way to find what you need.

You are right, I drilled one of the TM jets and it was like having no main, so put the clip down 2 and put in a proper 100 main and it is much better, it still pops if I hold it half open but revs freely on the stand, I'll take it to work tomorrow and try it up the road.
I am saving for an ignitech so may just flick off the kx one and wait.

[F5 Dave]

I think the "Trick" was the bike shop reliving Tim of $29 ??? ....



Wob ... will deto cause the same problem with the R7376 too? am I better of using gold pladium and/or std electrode plugs untill I have the over rev deto thing sorted.

Sweet $207 ea (R7376 at bottom of page)
http://www.bits4bikes.co.nz/accessor...gine/1667.aspx

or I've just now bought a couple off Amazon for $45ea landed. My they do vary in price somewhat.

[wobbly]

The old BR10EGV isnt prone to ceramic cracking at all, and the 7376 at 4 times the price of those is virtually indestructible.
I get the plugs off Amazon as well when a good deal comes up occasionally - best i have done was 52nzd landed.
One retailer i saw wanted 300nzd for the genuine shorty NGK plug cap for RS125, that is why I went searching and contacted NGK in USA who told me about the
exact same configuration plug with a normal body shape.

[cotswold]

Sweet $207 ea (R7376 at bottom of page)
http://www.bits4bikes.co.nz/accessor...gine/1667.aspx

or I've just now bought a couple off Amazon for $45ea landed. My they do vary in price somewhat.

http://www.ebay.com/itm/NGK-R7376-10...50e6fb&vxp=mtr

[TZ350]

The old BR10EGV isnt prone to ceramic cracking at all, and the 7376 at 4 times the price of those is virtually indestructible.

Thanks ...

[F5 Dave]

http://www.ebay.com/itm/NGK-R7376-10...50e6fb&vxp=mtr

yes I saw those. $47ea landed + I didn't want to spring for 4 just at the moment. Much better shipping rate than the $18 I paid. But end cost is similar.

[chrisc]

Another of Tim (Fixer) but this time on the RS GP125 bike during the 'borrowed bike race' on Sunday.



And Cully's FZR GP (not the beast which looks very similar). The exhaust looked like it was getting very close to the ground at times! Was it rubbing the floor?

[bucketracer]

Another of Tim (Fixer) but this time on the RS GP125 bike during the 'borrowed bike race' on Sunday.

I heard he came second in the first leg of the borrowed bike race and lead the second for most of the race to take the win.