[RudulfHucker]

This is today's plug colour. Better but not quite there.

 

[Ship]

Not far off.

No needles here anymore, otherwise l'd lend you.

 

[RudulfHucker]

Thanks anyway.

Whichever needle I end up with could do with being flexible enough to allow adjustment for the winter when it needs a bit more fuel.

 

[Ship]

Once the jetting is right, you should be ok messing with airscrew alone - unless you ride somewhere with a marked elevation change.

 

[Ship]

P.S - your copy pilot might well be an issue ......

 

[RudulfHucker]

I looked at the pilot jet earlier. It's not a genuine Keihin jet but an EBC branded job I bought from a Beta dealer. I've only just put it in so I can't be sure if it's kosher or not.

I reckon I'll replace it just to be sure. No point chasing round and round with needles for the price of a pilot jet.

 

[Pindie]

100%. Mine came with a so called 40 pilot. It was a ****** shitter. I took it out. No Keihin genuine markings. Changed it for the real deal. No problem since. 250s like a 40.

Retailers will buy jets as they see fit but my bike had monkey jets not real jets. Jet quality can be very different. It has to be genuine Keihin or don’t bother.

 

[steveman]

100%. Mine came with a so called 40 pilot. It was a ** shitter. I took it out. No Keihin genuine markings. Changed it for the real deal. No problem since. 250s like a 40.

Retailers will buy jets as they see fit but my bike had monkey jets not real jets. Jet quality can be very different. It has to be genuine Keihin or don’t bother.

Over the years I have seen quite some issues with aftermarket jets. Since I had a problem with one myself I never use anything else than a genuine Keihin jet, wether pilot or main jet.

@RudulfHucker 14 mls per liter is unusually much. Normally it should be around 9 or 10 miles per litre. I would try a richer needle and use a genuine Keihin 40 or 42.

The N2ZJ and NECJ have the same diameter.
The difference is the taper profile, which defines the needle family, or "NE". The NECJ holds this dia longer where the N2ZJ tapers faster, making it richer sooner off idle, then it leans out quick, enhancing the "hit" feel all else being equal. The NECJ starts later, tapers more through the mid so it ends up richer in the upper mid and to the tip. Its more linear.

The N1EI has compared to the others a very short straight sector. The N1Ex needles normally give a burbly/blubbery response from closed throttle up to 1/4 throttle as they are very rich down low, but the N1EI is the leanest of the N1Ex needles. From rich to low they are N1EG, N1EF, N1EH, N1EI.

NOZI and NOZJ should work well on the Beta if in clip #2. In clip #3 and #4 they create a lot of spooge but you know that already.
N8Rx is 1/2 clip leaner than N2Zx otherwise identical.

I know it might be wasted money but try to get a NECW, NEDW (1/2 clip richer than NECW) and a NECH. maybe someone can lend you these needles.

The Suzuki needles (NECx/NEDx) are the easiest to understand, have a very logical numbering system and give a very linear feeling due to their tapers from lean to moderate to rich. They normally require a smaller main jet that the N2Zx as their last third is significantly thinner.

 

[RudulfHucker]

Thanks Steve! That's really detailed and I shall have to read it a few more times to understand the detail.

I've been out again today with fresh E5 fuel and the same jetting as last time. The jetting has been completely bizarre and all over the place. One minute it's been running really well with good smooth power. The next it was blubbering and stuttering. Spooge has been running out of both the silencer and the PV breather. The breather has pissed oil all over the bottom of the engine and frame. As the same time, the engine has swung from boiling hot to stone cold.

It's almost making me think of buying a TPI! I think I need therapy...

Off 1st thing to see a man about a genuine Keihin pilot....

 

[Pindie]

Forget the spooge….it will just disappear. Just how a 2t works means there’s no sudden change. The spooge migrates through the entire pipe- there is a lot of surface area in there that gets coated and slowly migrates out.

Genuine jets are a must as are good quality needles. Anything else is guess work.

Do consider the S3 power head.Its no huge difference but it does help.

The one thing we do know is the Beta 250 is superb. Brad Freeman won the world enduro championship on one. It’s a great bike. For me personally, I’d take the 250 every time over the 300.

 

[Silvefhades]

I do run an S3 high comp head and lower gearing though. 12/51 for hill work. 13/51 for everything else. I also run Exol at 60-1 on Tesco 99. No issues on this oil in 8 different 2t bikes from small bores to 250 enduro and 200-300 trials bikes.

 

[steveman]

Thanks Steve! That's really detailed and I shall have to read it a few more times to understand the detail.

I've been out again today with fresh E5 fuel and the same jetting as last time. The jetting has been completely bizarre and all over the place. One minute it's been running really well with good smooth power. The next it was blubbering and stuttering. Spooge has been running out of both the silencer and the PV breather. The breather has pissed oil all over the bottom of the engine and frame. As the same time, the engine has swung from boiling hot to stone cold.

It's almost making me think of buying a TPI! I think I need therapy...

Off 1st thing to see a man about a genuine Keihin pilot....

No worries!

I wonder why your jetting gives such different results. Is the carburetor you have installed the OEM 36 Keihin?
Remote analysis is always fishing in muddy waters, unfortunately. After re-jetting the bike needs a while to "react" on the changes, so I really second what Pindie says. But it should not change its behaviour like you described. Something may be wrong. I just don't know what. When did the bike start to make problems? What changes have been made before th problem appeared? Do you have th possibility to get the carb and all of its components ultrasonic cleaned?

It may sound a bit boring but only genuine jets work as intended. People think they save 7 quid buying a Pollini or other aftermarket jets, but those aftermarket jets can be a pain. Some work fine, others don't. Especially when trouble shooting you only can rule faulty jets out if you use genuine ones.
Many riders think that the numbers stamped on the jets are the diameter and use strange jet gauges to measure them. The truth is, the jets are tested on a flow bench and the numbers indicate how much air they let through in a certain time. Cheap jets aren't tested for correct flow and sometimes lead to problems.

 

[RudulfHucker]

I picked up a genuine Keihin pilot jet today. Visually, they are identical but the genuine one is much tighter in the threads.

I was suspicious that the pattern jet was loose when I took it out but I can't be sure. However, the difference in thread fit makes me wonder if it was unscrewing as I was riding.

It is the OEM carb and it has always been running rich, as they normally do. I have re-checked the float height today and it is still 7mm, which is in the zone.

I have fully stripped, cleaned and rebuilt the carb today and have put the NECJ needle back to clip #3 for a repeat of testing. I have an ultrasonic bath and everything is nice and shiny.

 

[Pindie]

The insides of copy pilot jets are not the same shape. That’s the biggest difference. Copy ones just drill a hole. Genuine has a machined shape inside hence they just don’t work the same.

I set my floats with the carb off the bike and blow through the fuel pipe. I check the shut off occurs just as the floats moulding mid line come level with the mating surface of the carbs float bowl joint. If it’s parallel with the mating surface I find too much fuel can come through. I’ve no idea what the measurement would be unfortunately.

Hopefully the genuine jet will be a big difference. It could have been drawing fuel through the threads as well as the jet itself.

 

[steveman]

The insides of copy pilot jets are not the same shape. That’s the biggest difference. Copy ones just drill a hole. Genuine has a machined shape inside hence they just don’t work the same.

I set my floats with the carb off the bike and blow through the fuel pipe. I check the shut off occurs just as the floats moulding mid line come level with the mating surface of the carbs float bowl joint. If it’s parallel with the mating surface I find too much fuel can come through. I’ve no idea what the measurement would be unfortunately.

Hopefully the genuine jet will be a big difference. It could have been drawing fuel through the threads as well as the jet itself.

I too set my float exactly the same way. The blow job method has a significant advantages over the common method. First you don't need to pay attention to the little plunger in the float needle cause you can hold the carb in its normal position and not upside down. But more importantly you can see that the float needle does not just shut off but has a certain range where it reduces fuel flow till it fully shuts off. I started to set the float height that way that the seam (you call it moulding mid line) of the float is parallel to the sealing edge. That was way too high and since I set it that it shuts off when the seam is about 50% visible and at an angle. So I never can tell the figures in millimeters but as I have done it like that several times I know it works. At least on all my bikes.

Whatever, I am pretty sure that RudlufHucker's problem is not the float height. And after reading he has the carb u/s cleaned and well maintained I really hope that it was the aftermarket jet. If not I am running out of ideas...

 

[RudulfHucker]

Me too!!

 

[RudulfHucker]

Been out briefly this afternoon and I'm now 99% sure that the pattern pilot jet was the culprit.

I started back at clip #3 and it was pretty near. Easy start, regular tickover, zero smoke and spooge but the plug was a bit pale still.

To avoid a disaster by losing the needle clip whilst out on the trail, I just added a couple of shims to move to the equivalent of clip #4. That really added a lot of power and torque at the expense of a bit of spooge but I can live with it for the meantime. I'm going to try moving to 60:1 to address that once I've done a few more hours.

I shall give it another go before heading off to Northumberland for the weekend next week.

Thanks for all the accumulated knowledge so far!

 

[Pindie]

I hope your spooge issue slowly dries up with more use. I’m glad you’ve found the benefits of going to clip 4 but I still think it’s diameter you need to change also. I’m on the same machine and running a G diameter without issues. The Beta seems to handle a wide range of settings really well.