mikstr

So, got the carbs in today. It took some effort to get it started but fire away it eventually did. I tried to do a mechanical synchronisation (using 6mm aluminum tubes) prior to installing them in order to not have their effect clouded by being out of synch. Unfortunately, I have my daughter this week and so was unable to take it for a test ride (that will have to wait until next weekend) to get a real good sense of their performance. First impressions from running it at standstill are (that it needs a synch, lol) that it seems to snap more quickly on throttle than it did before.

I set the carbs up with exactly the same settings as the original carbs I took out (38 (yes, 38) pilots with fuel screws out 2.5 turns, 165F/170R DJ mains, HRC rich needles, DJ springs, modded lift holes, TPS set at 500 ohms (vs 430 in old carbs)). I am hoping the fine-tuning will be minor, but will keep you posted once I have saddle time in.

FWIW, in addition to the HDJ needle jets, I also streamlined the butterflies (only on side opposite end which seals against venturi) as well as the screws (are now flush and held in place with red Locitite). Carbs also have carbon side plates (0.8 lb lighter). I also took advantage of the swap to put in a set of Jack Flash's brass choke nuts.

cheers

CruxGNZ

Dangit! I clicked on this link thinking this must have had your first impressions of the carbs. I and all the Superhawk Forum members say, throw your daughter on the back and take 'er for a spin. We won't tell her mother :wink:

mikstr

I took the day off work with the intention of getting the carbs in early on in the day and getting some miles (or km) on in the afternoon but the bike was stubborn to start and I ran the battery dead trying to get it going. I finally got it going after dinner and, unfortunately, I am Mr. Mom for the weekend..... Believe me, no one is more disappointed to not have seat time impressions than I..... but, I have waiting over a year (through numerous delays) for this, so one more weekend won't kill me, lol If it's any consolation, it did feel snappier when giving the throttle a quick twist (which is quite quick given that I am running a 1/6 turn throttle tube), impressive considering it was already quite responsive before

Besides, it really feels like it needs a synch, so I will have to head to Jack Flash's house shortly to have him help me with this....

thedeatons

Enjoy the weekend. Time with your kids is precious, and the one thing you can't buy or get back...

The motorcycle can wait.


James

mikstr

very well put

mikstr

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

CruxGNZ

Good news so far

mikstr

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...

mikstr

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)

mikstr

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)...

CruxGNZ

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

mikstr

definitely synch first....

mikstr

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.

mikstr

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!

kenmoore

Great news and thanks for the journey!

Good to see a positive outcome of a trying project.

What will you do next?

mikstr

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....