Factory Pro HDJ needle jet

[mik_str]

so got the bike running this evening and went for a short tide. It is surprisingly snappy and responsive at low and middle rpms (better than it's ever been in fact; no farting or loading up, just goes!). However, things go a bit sour above about @4.5K as it seems to load up, both at constant throttle and on acceleration. Definitely feels rich, so I will be going leaner on the mains (unfortunately, I have no leaner mains (DJ; was at 165F, 170R) so I will be switching to Keihin jets (from HRC jet kit), hope I get it close (158F, 162R) to avoid unnecessary jetting changes). Will keep you posted, but results are promising so far

[mik_str]

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)

[sirch345]

Micky, there's no rush as far as I'm concerned
I appreciate you keeping us up to date with what's going on.

A good job you found out when you did that the front carb was not seated properly. Good luck with it when you do get the HDJ carbs back on,

Chris.

[mik_str]

A good job you found out when you did that the front carb was not seated properly.

feel foolish about that... talk about a rookie error......

[MacV2]

A good job you found out when you did that the front carb was not seated properly.

feel foolish about that... talk about a rookie error......

This Rookie fellow takes a lot of stick but the question is why do we let the numptie work on our bikes ?

[sirch345]

A good job you found out when you did that the front carb was not seated properly.

feel foolish about that... talk about a rookie error......

At least you're man enough to admit it

Chris.

[mik_str]

A good job you found out when you did that the front carb was not seated properly.

feel foolish about that... talk about a rookie error......

At least you're man enough to admit it

Chris.

No sense hiding from the truth...

[mik_str]

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)...

[sirch345]

Keep up the good work Micky, I look forward to hearing more

Chris.

[mik_str]

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.

[VTRDark]

Wow you've been through the wars with this one Micky. FP service not too clever there which I am a little disappointed to hear. Anyway good to hear you happy. Lets hope you can get some riding time in now.

[mik_str]

Hi Carl,

nice to hear from you

Indeed, service was FP was a bit of a challenge at times but they came through in the end. 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. A frustrating ride (ie. getting it ready to install and use) to be sure, but worth it in the end

With practically all key elements virtually brand new (engine internals, carbs, electrical), I should be all set for a great summer!

cheers

[sirch345]

Hurray, I'm really pleased to hear it sounds like you're finally getting there Micky well done Good call on the carb balancing bit,

Chris.

[mik_str]

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....

[mik_str]

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