R and D racing ajustable leak jet AP cover

Greetings all,

I had considered attaching this onto Buzzards leak jet thread http://www.husaberg.org/index.php?name= ... pic&t=6754 , but, thought it would be better for clarities' sake to make it it's own separate thread.

Brief history, I had modified my float bowl to accept leak jets, like all the japanese bikes come with. Only the KTM and Husaberg's come with that casting not drilled and tapped for leak jets. I had already switched over to Buzzards Honda jetting set up http://www.husaberg.org/index.php?name= ... pic&t=5326 , before I had modified my float bowl for the leak jets. I posted the results of this in Buzzards leak jet thread. Even with the #35 leak jet, the smallest, I was still getting a bog. So I ended up wrapping an O ring around the ap arms to get the pressure up on the ap, and that worked out good.

However, recently I was out riding and out of no where I started getting a bog when I opened the throttle quickly, like you do in a bit of a panic to get the front end back up in the sand whoops. I thought for sure the O ring had broken. But to my surprise the O ring was still in tact. The short version of this story is that I think one of two things happened, I either got a piece of debris on top of the ball check valve that is the one valve in our float bowls that let's fuel into the ap, thus letting fuel flow back into the float bowl when the ap diaphragm was compressed. Or, a piece of debris got into the ap circuit and clogged the ap nozzle in the venturi. Of these two scenario's I think the first is more likely.

In any event, I was thinking of just putting a 4mm plug into the leak jet hole and getting rid of the whole O ring business as I didn't like the idea of the rubber band breaking at a really bad time.

However, I came across this web site and product: http://www.r1dean.com/cart/index.php?ma ... ducts_id=4
What intrigued me first was the spring that he sold, that took the place of the O ring, and initially was only interested in that part. I gave the place a call and spoke with the owner, a very nice man, and he was very forth coming with information and intelligent questions about my situation. After sleeping on it I decided to buy the power pump with the adjustable leak jet, the spring I was looking at before comes as part of the kit.

It was pretty easy to install http://www.r1dean.com/support.html, click on the power pump tab at the top of the page, and, this kit coverts the ap to the newer FCR style ball check valve that is located in the ap cover itself. This is supposed to keep air from getting into the ap chamber.

One thing that is nice about the power pump is that A-it's less than half the price of the power bowl, and B-it goes down to full cut off of the leak jet circuit, where as the power bowl, at least as advertised only goes down to a #35 leak jet.

So far I have only been able to check out it's operation on the stand, and it does work, you can dial in a bog, and dial it back out again. I will post later on real world testing as I go.

VIKING said:

DaleEO
what I have found out RE. Buzzards mod, if your accel rod pump start squirting before
5-6mm throttle opening and it don't matter what needle you are running a bog will happen
and it just get worse with altitude and it was the same on my 04 450 as my 07 450
just adjust accel pump rod to start squirting at 5-6 mm throttle opening
the honda accel pump diafram defiantly increases fuel economy by 10 miles per tank
in the tight woods
165MJ
40PLJ
Lineaweaver needle
emulsifying needle jet

happy trails VIKING

Click to expand...

So Viking,

You are saying that the slide should be open 5-6mm before the ap starts adding fuel or a bog will occur?

Does that mean that the ap squirt will then not hit the back of the slide and go straight into the venturi?

Just for your info and not contradicting you, Eric's mechanic Brett, had suggested to me to set the slide opening at 1.25mm for the ap start timing for the bigger motors, and 1.0mm slide opening for the smaller motors, 250XF.

I have set my ap gap @ .115", (that's 1/2 turn clockwise from stock setting which is .100"), don't know how that relates to the distance the slide is open and when the squirt starts. However, I did this to lessen the rich stutter, and it did delay the onset. The problem is that if you delay the start of squirt much further than this, you will get a lean bog when the engine temps are down, or elevations are lower. The only way to compensate would be to raise the needle, and I fear that would make it rich in the mid range.

I am hopeful that with the adjustable leak jet, and the stronger ap spring (stronger squirt when throttle opened quickly), I might be able to delay the ap timing a bit more, and then be able to tune the bleed off as necessary, and maintain a good mix in regards to the needle postion. I did not have these options in play the last time I was testing ap gap settings, so we'll have to wait and see.

Thanks a lot for your input, I'll keep this in mind when I'm doing my testing and will let you all know of my results.

Dale

VIKING said:

DaleEO
well it was a few tests to concluded this, to prove to my self that bog was caused by the
AP I disconnected AP, now I had a bog different from previous bog it was consistant at the same throttle opening (8-8,5mm) and altitude had no influence where as with the AP connected the severity of the bog got worse as you gained altitude
and no needle,ABJ or PJ could cure this bog with or without AP
so I was confident that AP was culprit so now it matter of adjusting AP to where it starts
to squirt before the bog (without AP) so the best adjustment was 5-6mm
if you adjusted AP 7-7,5 mm bog would return at low elevation and on cold days and it
improve with elevation
if you adjusted AP 3-4mm bog would return on a hot day and get worse with elevation
how this would work on a ktm 250 sxf I don't know but I can says this that my friends
honda 250x liked similar adjustments
I simply open up the slide and insert a drill bit then close the slide then adjust AP to zero
play
the stock needle root dia. is too large making the eng. run lean it have a nervous feel
to it at small throttle openings going with Buzzards mod cures that

VIKING

Click to expand...

I have a question.

What is the gap on the ap linkage that you are running with this ap timing based on the slide opening of 5-6mm? Knowing this would give a good ball park figure, and negate having to remove the carb.

Thanks Per and Dan,

I appreciate your contributions, and Per, that sounds easy enough. Unfortunately I won't be able to do much testing other than fiddling with the adjustable leak jet for a few weeks at least. I have my work weekend next weekend for our race, and the following weekend is our race weekend. So not too much time to mess about.

I will post on what adjustments I can make, and persue the other suggestions as soon as possible.

Dan, I tried the JD kit. And just about as you have yours set up, including the O ring. It makes good clean power. I had also installed the 65 leak jet with the kit he sent me. Like I said, good clean power. However, I found that with testing the Honda style jetting, including the HDJ emulsion tube back to back with the JD kit, the Honda stuff is quite a bit different, the Honda jetting set up is a lot more responsive. Don't get me wrong, I'm not knocking the JD set up at all it works great. Thanks again for your suggestions, all are welcome. Never can have too much information!!

Dale

An update:

My club HBMC (Huntington Beach M/C) had their team race/desert scrambles race last weekend, and the work weekend the prior weekend.

I didn't have a lot of time to mess about with my new toy on either weekend, but, I was able to make some adjustments.

I started with the recommended 1 & 1/4 turns out which is roughly equal to a #35 leak jet.

On the work weekend (temps in the low 70's or high 60's), towards the end of our 40 mile loop through some technical bits I started to experience some rich stuttering from closed throttle just as you opened the throttle. I stopped and opened the adjustable leak jet screw about 1/8 th of a turn, and this eliminated about 70% of the stutter, with no resulting quick opening bog. And that was the end of that day. On that day, I also tested a 158 main jet which I found to be too lean, as the motor struggled to gain upper revs in 5th and 6th gear. I had been running a 160mj before and it worked very good but wanted to test the 158.

Before heading out to the race weekend, I changed the mj to a 162 with which I had very good top end results with in the summer when temps were in the mid to upper 90's. I also checked the plug and it was a dark brown at the tip, as well as all the way down the insulator. I also changed the ap timing, by turning the adjustment screw in another 1/4 turn from the 1/2 turn I was already. This put the ap gap at .122" from the previous .115". I made this change to help erase any rich stutter at higher engine/carb temps, while not touching the adjustable leak jet. I also installed a much need new rear tire, Pirrelli MT 18 HD, 120/100X18.

On the way out to the race weekend on Thursday, I had a nice long chat with Taffy, and of course we chatted it up about jetting, and plug color. Based on this conversation, I developed a hunch. And on Friday morning before I went riding, I changed the NCVR needle @ #3, to the NCYR @ #2. This results in a 1/2 clip leaner position on the needle.

On Friday I ended up being assigned to putting up the finish for the team race on Saturday and spent a good deal of time on my feet pounding stakes and stringing banner. About the time my friend Jeff showed up later in the day, it had been decided that we needed to move the 1 mile long start or "bomb" as we call it a 1/4 mile to the west to prevent conflict with the experts coming round at the end of their first lap, and the starts of the other classes in the event we had a delay.

After finishing that task, and marking the start return loop, we were able to go out and ride the team race loop which was 20 miles in length. This loop had a lot of whoops, and I mean some really deep whoops, and a lot of tight technical sections, and it was a lot of fun. Some teams would ride 6 laps, and the others would ride 4. And of course the Iron men would ride 6, I cannot imagine riding that loop 6 times!

Anyway the bike ran flawless, power was crisp, roll on was excellent, and top end performance as near as I could tell was better than with the 158 main. No rich stutter, no bogs, and I could easily lift the front end up through 5th gear in rolling terrain. And hot starting on the button was quick. When the bike was not heat soaked, on the button, occasionally I would get a little pop out the exhaust as it started, but, when fully warmed up that didn't happen. I had the fms set at 1 & 3/4 turns out.

Saturday was the team race and I didn't ride, just drove my truck to the finish.

Sunday was the desert scrambles race and I was assigned to the furtherest check point out. My buddy and his wife and kids rode out in their truck on Bessimer mine road, and then another road out to the check. My friend Jeff and I followed later on our bikes. It was about 15 miles by road to the check. My bike started first kick with the choke. It was in the high 30's at night, and it was cool enough in the morning that I needed to wear my Monarch Pass riding jacket over the top of my gear to stay comfortable on the easy road ride out.

Our check was located at Galloway dry lake, and upon getting there I decided to make a couple of 6th gear pinned tests across the dry lake. There was a cross wind of about 10-15mph, and on my first run sitting up I got about 85-86mph. On the return, I got into the full tuck position and this raised my speed to 95mph (I wouldn't want to fall off at this speed!!!). Even in the full tuck I could feel the wind tugging at my jacket. The motor pulled pretty strong on top, but, took a bit to fully top out in 6th. Last summer, with the 162mj and no wind, I got 102mph max. Again, I didn't have time or resources to make any mj changes and test, but, I'm sure that had I turned and gone down wind, I would have easily exceeded 100mph.

The main difference this time was that I was running the lower oil level specified in the Husaberg tech bulletin, and thus, I didn't have any issues with excess oil blowing up into the air box. When I made my dry lake bed run in summer I was running a higher oil level and had to use 5/8" heater hose with a T fitting as the stock breather hose was cracked, and the new one hadn't come in yet. This resulted in a bunch of oil in the air box, and at the end of that run, the bike quit and I thought I had blown the motor until I figured out what had happened.

After the race we started pulling ribbon on the course, and there was a lot of it. The temp had come up to about 70 and there was a lot of stop and go pulling the ribbon. I left the motor running most of the time, unless I needed the motor to hold the bike still while I worked. The terrain was tight and technical and eventually I could feel the bike getting pretty warm. That's when the rich stutter just barely started to show up, but, it was slight. I didn't make any adjustments to the leak jet, and just waited until I got some air moving over the radiator and motor, shortly after doing that the slight stutter disappeared.

Viking had suggested setting the slide @ 5mm opening and then adjusting for zero clearance in the ap rod. I decided to take a slightly different approach, and just keep increasing the ap gap to a point where no rich stutter appears. If I start to get a bit of a lean bog in doing so, I can simply turn in the adjustable leak jet to get a bit more volume out of the ap.

When I got home I checked the plug, the same one I had been running (originally, as mentioned earlier, it was a dark brown at the tip and most if not all the way down the insulator). I found that the tip or end 30% of the plug was a lighter brown, and the lower 60% or so had cleaned up to a more vanilla, or very very light tan color. So, I consider the change I made to the needle a success. I may change back to the 160 later, but, for now I am going to leave it alone. In hindsight, I wish I would have put a new one in so I could compare it against the previous one, oh well, next time. I also noticed an decrease in subjective terms, in fuel consumption, will have to test this further.

The next change that I am going to make is to open the ap gap another 1/4 turn and see how that goes. This will mean that the ap gap is now at .130". In the past when I have done that it resulted in a lean bog upon quick opening of the throttle. But now, since I have the stiffer actuation spring that came with the R and D adjustable leak jet, it will give a much stronger ap squirt on quick opening, and I also have the ability to add volume by decreasing the leak jet size so to speak by turning the adjustment screw in.

Once I have achieved "nirvana" with the ap gap setting, and no lean bog, or rich stutter, I will reference the ap gap to the slide opening and zero ap rod clearance as Viking has mentioned.

So, right now these are my settings for 4000', temps high 30's to low 70's:

NCYR needle @ pos #2.
HDJ emulsion tube.
162 main jet
200 main air jet
40 pilot jet
100 paj
fms @ 1 & 3/4 turns out
Honda ap diaphragm
ap gap set @ .122" or 3/4 turns in (clockwise from stock)
R and D racing ap spring
R and D racing adjustable leak jet ap cover set at approx 1 & 3/8 turns out.

Conclusions from this test:

158 main jet was too lean.

NCVR @#3 was a bit too rich, by 1/2 clip.

Still need to increase ap gap a tiny bit to eliminate the slightest rich stutter when motor and carb are hot. This is a bit of a maybe actually, will have to test and balance this with increasing or decreasing effective leak jet size through the adjustable leak jet. My "hunch" is that the increase in ap gap will clean up the bottom, but, I will end having to decrease the leak jet size to eliminate a lean bog on quick opening,but, we'll have to wait and see.

Will keep you posted on any changes and their results.

Dale

Update 7-22-08:

Please see my thread: http://www.husaberg.org/index.php?name= ... pic&t=8638

After replacing the O ring in the above thread I changed the needle to a NCVS and dropped the pilot to a 38. And after racing a qualifier in May when it was hot, I opened the ap gap up a skosh more. So the follwing settings are what I am currently running, numbers in bold are a change from previous setting.

This setting is for 4400' 30-70 degree's.
NCVS needle @ pos #3.
HDJ emulsion tube.
162 main jet
200 main air jet
38 pilot jet
100 paj
fms @ 1 & 3/4 turns out
Honda ap diaphragm
ap gap set @ .130" or 1 turn in (clockwise from stock)
R and D racing ap spring
R and D racing adjustable leak jet ap cover set at approx 1 & 3/8 turns out.

Once I go up to the high sierra's this summer at 8500-10000', temps 55-80F, I will go to these settings.
NCVS needle @ pos #3, and try NCYS @ pos #2 (1/2 clip leaner).
HDJ emulsion tube.
158 main jet and maybe try a 155 or even a 153
200 main air jet
38 pilot jet and maybe try a 35 if conditions warrant.
100 paj
fms @ 1 & 3/4 turns out
Honda ap diaphragm
ap gap set @ .130" or 1 turn in (clockwise from stock)
R and D racing ap spring
R and D racing adjustable leak jet ap cover set at approx 1 & 3/8 turns out.