Good news so far :D

Yep :) They do mention that the HDJ, because it atomizes fuel better, requires leaner jetting (thus more power and better fuel economy)... seems to be that way so far (though I suspect the streamlined butterflies, by improving airflow, and hence the vacuum signal for the jets, are possibly also partially responsible for the need for leaner mains).

Looking forward to tomorrow...

so, bike was very hard to start, was backfiring and farting through intake...... typical lean conditions. I decided to temporarily ditch the HDJ experiment to stick with a "known quantity" (ie. former carbs), thereby allowing me to chase down an electrical problem (which I think/hope I have solved). In the process of swapping the HDJ carbs, I noticed that the front carb was not properly sitting on the rubber boot (perfect recipe for an air leak.....!!!!!!!). So, I elected to put the old carbs back in in order to ensure all is well. Once I am confident the electrical gremlin is dealt with, I will put the HDJ carbs back in (BTW, I ground the butterfly bolts and did a partial streamlining to the butterflies on my old carbs, similar to what I have on my HDJ carbs, which will allow me to isolate any changes in performance to the HDJ needle jets). Sorry for the delay folks, but I jumped the gun in doing too many things at once and am now having to backtrack. On the positive side, once I get the HDJs back in, I will be better positioned to make a valid comparison. Will post results ASAP (possibly in two weeks time as I will be on vacation; great time to get some tuning done, lol)

Me again :)

so, after having run the bike with the previous/stock carbs to verify that all is well (went for a 150 km ride; bike ran great and electrical system seems to be top-notch... well, after replacing the battery with one on loan from my friend Mr. Flash). With that in hand and an idea as to ballpark figures to use, I re-jetted the HDJ carbs (38 pilots, Keihin mains: 158F, 162R) and put them in. I had to lean the fuel screws slightly (1/2 turn, now at 1.25 turns out F and 1.375 R) as well as the Flo-Commander for the mains. It ran well at cruising speeds but seems to be loading up slightly as the revs rose (as I am running identical stacks from and back I will reduce the rear cylinder main to 160). Oh yes, and my idle speed will not dip below about 1500 rpm. Now, this may be remedied after a good synchronizing or it may be traceable to my streamlining of the butterflies.

Technical babble aside, the response is quite impressive, the improvement at low speeds being noticeably improved (and it was pretty good to start with). Will report back tomorrow after I get more miles in (only rode about 20 miles with new carbs, so more to follow)...

Sweet! Are you going to swap out the butterflies for stock ones, or are you going to sync the carbs first?

definitely synch first....

more fine-tuning and riding, and the verdict is in: awesome!!!! I cannot yet comment on fuel mileage as I have not a chance to put any significant mileage since my last jetting change (leaned out needles half a clip position). Bike fires right up as soon as you hit the starter button, hot or cold, and responds instantly to throttle, regardless of rpm. The pull from low rpm is noticeably smoother than before (ie. pre-HDJ carbs). Hard to quantify the extent of the improvement, but I have no regrets and would do it again. In truth, there are other less expensive mods that I would recommend first (billet velocity stacks, FIL mod, X-wing, and cheapest of all, grinding the rear of the butterfly retaining screws and rounding/streamlining the leading edge of the butterflies) but for those who have done this, the HDJ is the next logical step... the cherry on the sundae if you will. For those of you wishing to go ahead with this, remind the boys at Factory Pro to use the correct o-rings and to ream the HDJ out to the proper size before returning the carbs to you.

There it's done... and I am smiling :)

P.S. to those going this route, expect to have to lean out the low-speed circuit slightly (fuel screws should suffice) and to go down a few steps on the mains.

Was out riding again today (am on vacation this week, and one of my objectives for the week was to get this thing sorted, lol) and did some additional fine tuning (gotta love the Flo-Commanders). Also, after having given the matter some thought, I figured out that my high idle speed problem was likely caused by a lack of synching of the carbs (tried to do it manually/mechanically using two 6mm tubes) and, lo and behold, I was right! I adjusted the synch screw slightly and my idle is now back down to normal levels. I will get it properly synched shortly but for now it runs fabulously (starts as soon as you hit the starter button, hot or cold) and responds in a very lively manner at all speeds and throttle openings.

woohoo!

Great news and thanks for the journey!

Good to see a positive outcome of a trying project.

What will you do next?

Quickly running out of options as I have pretty well reached the end of the road for mods...

Possibilities include:
- I still have a Graves aluminum fairing stay that I would like to have modded to use with a stock fairing and a 900RR aluminum rear subframe that could be modded to replace the stock steel item
- Now that I have seemingly cured my electrical woes (traced to a bad ground it would seem), I may give a lithium battery another go.
- Also, I noticed that Spiegler make a carbon handlebar (with aluminum core) which seems interesting, though swapping the top bridge and all would cost a few dollars (of course, I could recoup some $$$ from selling the Apex 4" riser clip-ons I am currently running).

I would like to get it up on a scale too. I have been doing my best to keep track of the weight loss over the years and suspect it will be at or below 400 lbs wet.....

Most importantly, I plan to do some riding... and smiling :)

BTW, while out riding yesterday, I noticed my fuel consumption was still a bit higher than my best pre-HDJ numbers. That, along with a sneaking suspicion that it was still a tad rich in the mids, led me to drop the needles slightly (about 0.014") and, lo and behold, it's better yet again... definitely runs cleaner now. I will continue to monitor my fuel mileage to see if any further tweaks need to be done but I am pretty darn close now....

another update: fuel economy improved after my last needle change but still not back up to pre-HDJ level... so I leaned both needles another 0.010" (FWIW, one needle clip position on HRC needles is 0.037" as measured on digital caliper). Bike is running extremely well (though I suspect it will run better yet after latest needle change). I have to say that the HDJ needle jets are doing an amazing job in the low-end and mids (better than I would have hoped to be honest). The bike has never pulled so cleanly and with so much authority at lower revs. I can now roll on it as low as 2500 rpm (in 6th!) and it just pulls, no bucking, farting or anything. A bit further up the revs, it has instant response and just charge ahead at the slightest provocation. If anyone is giving this (HDJs) some thought, I say go for it, you will not be disappointed. Besides, the development legwork (so to speak) has already been done (as trying as it was, I have no regrets now that I see how well the bike runs)

cheers

Just got back in from a short ride to Jack Flash's place to visit with him and have him help me to synch the carbs. The slight leaning of the needles helped clean things up yet again (can't believe how insanely responsive it is!). Now with a perfect synch thrown in, the engine is now smoother and more even to boot.

My work here is now done, I don't see how I can make it any better :)

A long and sometime eventful ride has been the HDJ experiment, but it was all worth it.

cheers

Would love to see an AFR charted run on the Dyno..Idle, mid and full throttle positions, and mid throttle to full roll on.

Had the bike on the dyno many times in the past but don't really feel a need to do so again. Of course, that may change at some point, but nothing planned for the foreseeable future.... sorry

That's a bold statement mikstr,

Aren't you curious?

I know I am!

You mean this one, Right?

" My work here is now done, I don't see how I can make it any better "

We need a snickering smiley!

well, considering :
- I have had the bike on the dyno numerous times in the past, including after 2 (yes, two) Stage 1 rebuilds (including one which saw it get 77 lb-ft and 122 bhp).
- I have over 150,000 miles travelled on said bike
- I have tried more mods than probably many here combined (airbox, air filters, exhaust, carb, frame reinforcements, suspension, brakes, wheels, steering dampers, cams, cam timing, velocity stacks, "X-wing" diffusers, and much, much more....)

So, I think I am well positioned to know what works and what "it works" feels like on my bike. Bold, sure,... arrogant, perhaps, but I know what I know, and what I feel. My past experiments and experience with my VTR have also earned me a well-deserved right to an opinion, and a very objective and credible one at that. And right now, it is spot-on everywhere. Feel free to disagree, it's a free world.

carry on.

"I don't know why, but I believe him yo." Half Baked

I am seriously thinking of doing this to my carbs over this coming winter. Micky, thank you for forging the way for us!

I think it would accentuate very well the sum of your other efforts

I don´t recommend to go dynoed. With my last setup, I had similar feeling as you write, and after dyno I felt a bit dissapointed :D Of course it is only full throttle number, but I am sure I will go to carbs again.


On the other hand, altough you are trustworthy, I cannot celebrate your progress because from my personal experience, I know only hard data shows the truth.
Another thing is that most of the behaviour you describe can be hardly catch by dyno numbers ...

Mikstr,

There is no doubt or insinuation that you don't know what is right and what is wrong.

Like you and many on here I have tinkered with my bike and gone by my butt as to what is right and what is wrong.

I am curious as to what difference this mod has made and as you have numerous Dyno reference points I thought that you would Dyno her again to see what this mod had done.

The most important thing is that you have validated that it is a worthy mod and succeeded in getting a great result by persisting where others would of given up!

Thank you for that, however I can't help thinking what you are going to do next other than ride and enjoy her.

I may get it on the dyno at some point (I am curious too, of course), it's just not in my immediate plans. Perhaps that is a better summary of where I am at....

I get what you mean on the dyno, but I was looking for AFR numbers, not HP and TQ...

Anyway..why did I bring up such an old thread???

Two things.. How are those carbs running now that you have had a bunch of hours on them? Did you every get AFR numbers post HDJ install?
And lastly...I noticed today, FP no longer is marketing the HDJ for any carb other then the screw in type, emulsion jet of the FCR39 MX carb, and only the OEM ones at that, not the aftermarket ones...
mikstr I think you broke Factory Pro...lol

carbs are running great (or, they were last fall anyhow). I never had the bike on a dyno again and truthfully don't know if I ever will. My apologies if I put FP out of business, lol

Than I challenge you to install dual AF meters with graphing and test for us.....:evillaugh:
I think your good...still in biz, I'll call the engineering guy I spoke to last month on the shifter parts and see what's up with the needle jets.