Beta Xtrainer - Any cure to 1/4 blubber?

[drumiv]

On ‎7‎/‎16‎/‎2019 at 11:17 AM, redhurricane said:

Try the 38p and clip 2 on NECJ and let me know how things respond. air screw at 1.5 turns for a starting point. 

Got to finally try this set up, and it works well. I ended up turning the a.s. out to 1 3/4. So, with a 158 main, the airbox lid and o.i. removed plus rh's recommendation, definitely an improvement in response top to bottom.

[hawaiidirtrider]

On 8/6/2019 at 7:51 AM, Chas_M said:

Good luck with that.  I installed an RKTek head on my already good running 300RR and it led to lots of hesitations and 'pipe-banging' which no amount of rejetting could cure even after consulting with Kelsey.  A lower compression insert helped but pipe-banging still persisted.

Bummer. My RK head works great. Went to a 40 pilot.. nothing much other than that. 

[drumiv]

6 hours ago, hawaiidirtrider said:

Bummer. My RK head works great. Went to a 40 pilot.. nothing much other than that. 

No bummer, it's all good. I'd like to try that head, just not in the budget right now.

[firffighter]

3 hours ago, drumiv said:

No bummer, it's all good. I'd like to try that head, just not in the budget right now.

You can have him simply cut your stock head which is considerably less expensive than the full custom head and insert. 

My RK Tek head had yielded much smoother and linear power delivery, exceptional fuel economy (consistently 38 mpg), and a significantly cooler running motor. Great investment!

[Jakey]

Delayed reply here, But ive been busy. 

Stepped up to a 40 as suggested, It seems better. Still blubbers and rough at part throttle but this seems a characteristic of the xtrainer. 

I am still getting a closed throttle surge after high revs then letting off (Or down a hill for example). Improved from the 38 but still there, Considering stepping up to a 42 to cure this BUT bike starts with no choke currently, And it starts to 'load up' and will miss a bit when cold/4stroke til warmed a bit. Also a bit more spooge with the 40 

So thinking a 42 may be too rich, But the closed throttle surge after higher speed/revs is ANNOYING!

These bikes are so sensitive to jetting its a pain

[ToolmanJohn]

 I'm going to suggest it, but you may have already done it, but make double-triple certain your float level is correct. Maybe take the carb out and blow out the passages, and use a fishing line to see if they are clear.  Just one tiny bit of junk or trash can cause these kind of BS issues. The stock rubber fuel line WILL degrade and put black dust crumbs into the bowl. The 4th time I took it apart, and cleaned it right, it started working so much better. I was chasing jetting way too much.

[shrubitup]

3 hours ago, Jakey said:

Delayed reply here, But ive been busy. 

Stepped up to a 40 as suggested, It seems better. Still blubbers and rough at part throttle but this seems a characteristic of the xtrainer. 

I am still getting a closed throttle surge after high revs then letting off (Or down a hill for example). Improved from the 38 but still there, Considering stepping up to a 42 to cure this BUT bike starts with no choke currently, And it starts to 'load up' and will miss a bit when cold/4stroke til warmed a bit. Also a bit more spooge with the 40 

So thinking a 42 may be too rich, But the closed throttle surge after higher speed/revs is ANNOYING!

These bikes are so sensitive to jetting its a pain

Lower clip on the needle one notch and go back to 38 if temps above 40F. Lean main jet also contributes but many say it doesn’t. 

FYI, JD jet kits are super stable requiring only needle changes typically. 

Edited October 21, 2019 by shrubitup

[ohiodrz400sm]

I never found the XT to be difficult or particular about the brass. What you are describing could very easily be caused by an air leak.

[Jakey]

3 hours ago, ToolmanJohn said:

 I'm going to suggest it, but you may have already done it, but make double-triple certain your float level is correct. Maybe take the carb out and blow out the passages, and use a fishing line to see if they are clear.  Just one tiny bit of junk or trash can cause these kind of BS issues. The stock rubber fuel line WILL degrade and put black dust crumbs into the bowl. The 4th time I took it apart, and cleaned it right, it started working so much better. I was chasing jetting way too much.

The float level can not be set as per manual or it will almost constantly leak fuel. 
Its lowered slightly so it sometimes can be seen dripping very occasionally, any higher it would be leaking lots. So its as near to spec as can be!

Also running an inline fuel filter to catch all the junk, Bike only has 30hrs ish

 

I may try another clean but im OCD with cleaning it every time its been off (Lots)

9 minutes ago, ohiodrz400sm said:

I never found the XT to be difficult or particular about the brass. What you are describing could very easily be caused by an air leak.

Maybe I am being too fussy. 
Who knows, It doesn't work well that's for sure! 

 

No air leaks that's for sure

[lotus54]

I get only the very slightest ‘burble’ just off idle.  I can certainly adjust that out- but then too lean. (I’m on stock jets)  I rarely run very open throttle, for the ‘trails’ I like they are too tight/slow/obsticles. And with 3.5psi in a radial trials- going fast on connector roads is darn scary. (Not bad with 12-15psi, I carry a pump)

  Perhaps you needle is a bit lean on more open throttle, causing the lean symptoms when back at idle after higher speed. I’m running stock pipe with FMF spark arrestor muffler (I forget what you have).  Certainly check for air leaks- and perhaps pop your reeds out and make sure in good shape?  If they leak it can certainly cause burbling.

[ToolmanJohn]

5 hours ago, ohiodrz400sm said:

I never found the XT to be difficult or particular about the brass. What you are describing could very easily be caused by an air leak.

This is true. When I was going through my carb for the umpteenth time, I used some synthetic grease on the boots during reassembly. But because I had rechecked and cleaned EVERYTHING I didn't know what cured the issues I was having. I still have what some call pipe bang and a fluttery splutter at 1/4 throttle, but, meh, no big deal anymore. I ride.

[ohiodrz400sm]

This is true. When I was going through my carb for the umpteenth time, I used some synthetic grease on the boots during reassembly. But because I had rechecked and cleaned EVERYTHING I didn't know what cured the issues I was having. I still have what some call pipe bang and a fluttery splutter at 1/4 throttle, but, meh, no big deal anymore. I ride.

Yeah, I know the spot you're talking about. With the Suzuki needle it would ping on the 3rd clip and was a hair fat on the 4th. A splash of racegas was my ultimate solution.

Also keep in mind 2 strokes are a very crude design compared to a 4 stroke. They do not have the same seamless response at every throttle position at every rpm like a thumper.

[BV's]

I think all two strokes knock and clatter at part throttle.  that video doesn't show anything out of the ordinary.  

It will never feel anything like a 4 stroke at partial throttle, thats for sure.  

 

 

[pro101]

I disagree about 2 strokes not running good at all throttle positions.  I have a 2009 KTM 300 XC-W that runs fantastic all the way through the throttle range.  It's very crisp right off idle and pulls hard with no surges, bogs or dead spots anywhere.  It's actually so crisp it's tiring in tight woods where it's just too jumpy and responsive.  However ... my 2019 Xtrainer can't claim the same ... but I'm working on it.

I did not like the softness of the bike with the stock pipe so I replaced with a gnarly pipe (same as 300RR), turbine core spark arrestor, power valve about 3 turns in from flush, reset float level, removed the air box cover, went up to a 38 pilot, NECJ needle and JD needles, stock oil injection.

At roughly 2500 to 4000 ft elevation, 60 to 80 degrees ... I've tried JD needles and Suzuki NECJ at multiple positions ... and many different main jet sizes.  I am able to get the bike running very clean from 0 to 1/4 throttle with the 38 pilot / NECJ in 2nd or 3rd position / air Screw about 1.5 turns out / 162 to 168 main jet ... different settings as the temps went down in the fall.

However ... there was a serious bog when transitioning onto the pipe at 1/2 to full throttle ... then it rips like a motocross bike.  It's unrideable this way in the tight woods at higher rpms and 1/2 to full throttle.  I've found I can get rid of the bog though by going up to 170 or 172 main ... but then the NECJ needle feels a little too rich ... it's a very thin needle.  No matter what settings I've tried I've been going on reserve fuel at about 35 miles ... so it's not getting good mileage ... yet no sponge and doesn't feel overly rich.

It's been getting cold so I will return to jetting in the spring.  In colder temps though ... around 40 degrees and 3000 ft elevation ... it runs decent with 38 pilot / NECJ 4th position / 172 main.  The bog is nearly gone at 1/2 to full throttle but it doesn't feel as crisp at 0 to 1/4 throttle or when on the pipe.  I think the NECJ needle was very good with the smaller main jet but a bit too rich when running larger mains.

When it warms up again I plan to use whatever main jet size that can get rid of the bog at full throttle ... probably 168 or 170.  I think the JD blue needle may then be able to clean up the 0 to 1/4 throttle.

[Turboloader]

A freshly tuned 2 stroke "should" run nicely through out its running time. From idle up to hauling bootie, it should run crisply. I have observed folks with all kinds of gas powered hobbies having "issues" with running correctly. I notice the first thing they attack the carb. thinking a jetting change and adjusting the float bowl will solve their woes. Then its off to the ignition, and bam their bike is worse than it was say about a week ago? Folks always say "well it was running greatly last weekend but now its running poor." I put my noodle and past experience to it and found its the "gas" man, its the gas. All the goodies they add to it just wreck havoc to all petrol running vehicles and lawn equipment. I even heard fuel stabilizers could induce corrosion? Crazy. Some pleasant gent on here put up a website to find Ethynol free gas, I says go for it, its cheaper than VP gas, but VP racing gas is as sweet as honey...

[1gr8bldr]

I solved this problem on the KTM Freeride, assuming it's the same blurber????. After years of internet talk, theory's, parts, etc, it turned out to be simple.  May be the same, maybe not???. But it is the fix for the freeride. The Freeride main jet, due to high vacuum characteristics of low end marketed machines, is contributing when only the idle jet should be in play. I fixed it with a taller needle jet. The brass tube that protrudes into the ventri, metering  fuel via the needle clearance. The taller needle jet moved the blurber from lower to higher at the point the main was kicking in, thus made it insignificant. The freeride blurber, you could find, and magnify, if you rolled on throttle ever so slowly, and held it constant once you reached the blurber . It also stopped the hanging idle. And an occasional diesel run away . Jetting did not change. For the Freeride, I found  that the Kawasaki Jet needle 16017-1431 was perfect. Not sure about the Beta. It's worth a try because it's cheap and easy to change

[DirtJunkie69]

On 7/19/2019 at 6:44 AM, ToolmanJohn said:

Buy one of these.  Start here. If you get yours perfected, I want to know. But a little blubber has been my constant companion on my 2017 XT since new. And I have almost every jet and needle on the Xtrainer jetting chart. Tried it all. Plus the NECJ needle. Plug changes, carburetor cleaning, air filter swaps, reed checks, leak checks, silencer packing, you name it. I may have the cleanest Keihin  carb on the planet.

What the hell is this a penis measuring device? I dont need one that goes all the way to 4 inches.

[highmarker]

if you were wearing earplugs and couldn't hear it, would it be noticeable  : )

[ToolmanJohn]

7 hours ago, DirtJunkie69 said:

What the hell is this a penis measuring device? I dont need one that goes all the way to 4 inches.

How could you possibly think 4cm is inches???? 

[DirtJunkie69]

2 hours ago, ToolmanJohn said:

How could you possibly think 4cm is inches???? 

Ionno, wishful thinking?