Ace 100 B+ Jetting Question

[cineburger]

There is no physical binding on the bike in neutral that i can feel; jacked up on the frame i can spin the rear wheel with my pinky and it keeps spinning with no unusual scraping sounds; as i have said before my top speed is 48-50 in 3rd gear; havent had the chance to find a downhill run yet; no further acceleration or speed in 4th or 5th gears; i will look into the cap issue in a day or so when i get home; thanks again to all who are trying to help me. David

[Al Harpster]

Well, ya kinda got me.

Max speed in spec book is 62. I always figured that was Japanese for 100 kilometers an hour and a guess rather than a rule.

Good compression, stock carb in okay condition, standard jetting, correct timing, stock clean exhaust, no intake air restrictions, no indication of ignition crapping out at high rpm, no indication of excessively lean condition.....

No exhaust port blocking from old school leaded gas.

No excessive smoking indicating leak of clutch side seal or failed crankcase sealant pulling trans oil into cylinder. This would be confirmed by pressure test.

Accelerates "hard" in first & second gears on demand.

I think this is the situation you report, more or less.

I don't get it, but full disclosure..... I felt my B+ was a dog even after throwing countless hours and counted money into it.

Cheap route: get a 13 toooth front sprocket & see how you go. Play a bit with stock type jetting.

Expensive and enormously time consuming route:... Also known as the one I took:

Reed valved, custom ported Super Rat top end, ( includes Rat head & single ring piston), Rat primary gears, 24mm carb, aftermarket duplicate Rat pipe, close ratio "racing" transmission gears, Ultimate Flow Optomizer carb slide modification and the Denso extremely fine electrode spark plug. I might have forgotten something, but that's about it

Now it's about fast enough.

[cineburger]

Al—you’ve summed it up nicely; i guess my question now is: is there anyone out there in the 155 lb range whose ace 100b+ is set up stock and gets 50-60 mph shifting thru all gears normally?

[dirty_rat]

After many people have mentioned that your bike might be over-geared, you are still asking what might be wrong??? What you keep describing sounds like a bike that is geared too high to properly use 4th and 5th gear.

As others have already mentioned, try a smaller counter-shaft sprocket and see what the results are. It is a cheap and easy change. My Ace 100, when brand new, would only do about 55-60mph top speed (and that was when I only weighted 135 lbs.).

A bike from the early 70's was not made (or expected) to run 60mph for any length of time.

[Bullfrog]

Uh-oh, my obsessive/compulsive issues are starting to kick in! Have a seat in a comfortable chair and get your beverage of choice. I've re-read the complete thread and taken notes . . . here goes:
-- Early posts gave info that you are near sea-level (Chesapeake Bay) high humidity, running the 95 main jet and that leaning out by dropping the needle seemed to help (I'm not sure I believe that last part about needle position - more on that later.) And that you have 150psi compression - which is just hunky-dory.

-- FIRST DIGRESSION - Compression range is listed in the Workshop Manual as 150 to 80. This reflects what is expected with a fresh engine, ranging down to the level where thangs are just plain worn out and it is time for some engine work.

-- Running 93 octane 10% ethanol car gas. While I don't think going to premium NON-ethanol car gas will fix the problem . . . It WILL help. That 10% of ethanol in your fuel simply is not as good at producing power as straight gas would be. So, in order to remove one KNOWN detriment to getting "original equipment" performance, I would HIGHLY recommend running only NON-ethanol premium in your Hodie. (But please run the jetting test listed at the end of this treatise before you go out searching for NON-ethanol fuel OK?)

-- It is nice to hear that your rear wheel spins freely with only a finger spin, but I still want to hear the result of the "whole machine" test. Can you grab the cross bar in the center with ONE hand and easily push the machine on flat pavement? (This confirms EASY rolling with all tires on ground and all bearings turning and all brakes in the test with machine weight on the suspension.) It is seeming more and more like some niggly little thing which we are all over-looking is either limiting the output of the engine OR absorbing wayeeee too much of the engine output.

-- 15X36 sprockets are indeed the stock "street" sprockets for the 100B. Following some scaling from photos (since I don't have a 3.00X18 tire to measure dia/circumference) - I've calculated that 8,000RPM in 3rd should give you about 46-48mph. Same RPM in 4th = about 53-56 and in 5th = about 63-66. EXCEPT the stock engine probably simply would not be able to actually do 65 in still air. Down hill and/or down wind . . . sure, but not on level ground in still air. As a double check, the owner's manual lists Max HP at 7,500RPM, which calculates out to 62mph (the max speed listed in the manual )

IT IS NOW TIME FOR the "more on that later" part - You reported that leaning the needle made things better very slightly. THEN you reported that switching from 32:1 mix to 50:1 mix made things very slightly better. Those two situations are exactly opposite (dropping the needle leaned out the gas/air ratio BUT switching to 50:1 richened the gas/air ratio) -- and BOTH improved things? We'll chalk both of those up to placebo effect (I tried my best guess and it worked . . . a teensy little bit.) I recommend that you install the 100 main jet and do one of your speed runs. Please change ONLY that ONE thing right now and test it. Better? Worse? (Data please - not impressions) NOTE: Testing a richer jet won't damage your engine . . . testing a leaner one might.

SUMMARY -- Yes, you should be able to go 50mph (maybe even 60 if conditions are right), but the 100B will never be a comfy cruiser at 50-60mph (note that 60mph is 20% faster than 50mph - that is a big jump). Clearly, something IS wrong . . . we just haven't found it yet. I don't remember anyone questioning the possibility of carbon build up in the silencer or elsewhere in the pipe. Should check that. I don't think that is it since it revs up quite well in third - and effects of plugged exhaust show up well with increasing revs. But we have to eliminate "suspects" right?

Are we having fun yet?
Ed

[matt glascock]

Excellent Captain. Very helpful.

[Al Harpster]

I did fail to try to answer a couple of the owner's questions.

These threads get so long it's hard to tell who said what when.

I don't know if anyone has run a "SOLID" B+ with 15/36 sprockets to their SATISFACTION.

I wasn't happy with my B+ & spent a load of time & money till I was satisfied.

The question about why Hodaka supplied 3 main jets with new bikes: I've always assumed it was a courtesy for owners to do fine tuning.

Those supplied jets are very close to one another.

Like the main jets, the jet needle position is fine tuning too. That's if you stay plus or minus one notch kind of a thing.

It takes a certain amount of power to overcome the force of friction and importantly the force of air against you to reach 50. You've got about that much power.

Getting to, say, 60 is going to require more than 20% more power because aerodynamic horsepower required is non linear above about 50.

I think the owner is left with the challenge of fine tuning fuel delivery to squeeze out a little more power & swap sprockets so he can work that power with all five gear ratios in the transmission.

If the engine, carb and ignition conditions conform to the Hodaka Workshop Manual (or real close to it) you're stuck with tuning in.

Then if you get the Hodaka obsession doing that, you can get out your wallet.

[cineburger]

Just returned home to the testing grounds and your above responses to my issues--many thanks again; to answer some recent comments: 1) dirty rat--I have the 13 sprocket approaching in the mail; will report back; but "What you keep describing sounds like a bike that is geared too high to properly use 4th and 5th gear." --are you saying that Hodaka's original stock gearing was too high to use 4th & 5th gear? Doesn't sound right to me....if somebody says that with a 155 lb +/- rider the stock setup pulled 50-60 mph using all 5 gears then something must be wrong with my tune or some other problem, which I am trying to figure out; if that top speed was meant to be achieved by a lighter rider and that's why all the other gears and jets were available then change away til yer happy is what I'll do; I love the bike and this problem for its learning experience as well as just the mystery solving aspects; so I happily persist; 2) Ed--thanks for the extended reply; I too have reread this thread a number of times and keep trying for clarification in my responses which I know is not always achieved; I just ran the one-hand walk around the yard test and the bike rolls easily with no noises (other than leaves crunching) and no apparent binding so that ain't it; as to jetting--"chalk up to the placebo effect" I would totally agree; my "impressions" were in response to previous requests for more description than just "fading in 4th gear" and not reliable data; I neglected to mention that when I changed fuel mix I went back to stock needle setting (middle position); my impressions were only a guess as to response not data; I will try the 100 jet and report back; ditto the non ethanol fuel. Assuming that you are right and as you say, " Clearly, something IS wrong . . . we just haven't found it yet." that is really my purpose in continuing this inquiry; if the answer is that the bike simply cannot perform close to historic book specs with my 155 lb body on it then I'll be happy to adjust tuning and gearing till I get close and roll on at 50 mph; I thought I mentioned the clean exhaust before but it is very clean inside...and yes we are having fun--wouldn't be right any other way....thanks agin to all for your time and help-d

[olddogs]

When I get a puzzle like this, consistent and unexplained, I like to eliminate the obvious. Remove the air cleaner and test ride. Remove the exhaust baffle and test ride. Remove the carb bowl and watch the fuel flow, push up the float to confirm where it stops. Check full cap vent and carb vents. Fuel needs to breath to flow. Use a flat file and confirm carb flange mount not warped, along with the plastic spacer. Is O ring sticking out far enough to seal to manifold. With carb off, twist the throttle, is slide being pulled all the way up? Cable right length?
What happens at in 5th gear? Load increases. Vacuum is lower, the pulling of air through the carb is slowed until rpms can increase. Any air leak is fuel not being pulled up from the bowl.
Rolling resistance. You have few horsepower to work with and none to spare. Are the tires the right size and at full pressure.

You dont have a problem, you have an opportunity for finding a solution.

[Al Harpster]

It sounds like the owner has what I call the Hodaka obsession.

I know what that's like.

Three words to guide you:

Hodaka Workshop Manual.

If you have it, study it well.

If you don't, get it. Then study it well.

This thing is an example of good technical writing.

Not to be missed.

[viclioce]

“15/36 were the stock sprocket configuration.”

I have my B+ running 14/56! And I am 220 lbs. & can get 47 mph out of her on asphal with an extended hold at that sprocket combo.

I haven’t considered a change because it’s my youngest Grandson’s bike who is just starting to ride & will be 14 in January. It sounds to me like he is still running the bike too lean. Richer, to a point, should give him a bigger “bang” for the buck, as they say & the bike shouldcrun just a little bit cooler as well, than when it’s lean.

Watching, reading and paying attention here. Captain Eddie is giving you good guidance here, so follow and report back. And remember to always check your plug by stopping immediately after a WOT test with an immediate stop to pull the plug. Victor

[cineburger]

reporting back--lotta rain yesterday no testing; cold and windy today; test #1--100 jet; needle in the middle notch; same 50-1 fresh fuel; B7s new plug; data--still cannot maintain 45 mph in 4th gear on flat road (of course nothing in 5th); impressions: seems to be "snappier" in feel and acceleration with the 95 jet in 1-3 gears; the sound is "crisper" with the 95 jet and lower (kinda boggier sounding) with the 100; my 13 tooth countershaft sprocket arrived so the next test will go back to the 95 jet and try the lower gearing. PS--to answer a few of the comments--I have original shop manual, 100-B supplement, owners handbook & parts manual and have read and read them; they are great pieces; I met you, Captain Ed, at Hodaka Days 2016 and enjoyed your conversation, advice, and speech at the "meeting." Your comment above about achieving 53-56 in 4th gear was what I was hoping for--at least some modest 4th gear continuing acceleration and speed maintenance above 50; there is non ethanol gas available here in podunk so I will eventually try that and report back; Al--your prior comments make good sense, thanks; the crank seals issue is starting to rear it's ugly head as a possibility and I will try to investigate further; I really appreciate all the expertise given to me in this forum and am definitely enjoying all of this. thanks again.

[cineburger]

PPS: plug color definitely shows too rich--sooty on the verge of oily

[cineburger]

test #2 data--90 jet--no other changes; much improved in crisp acceleration but still not quite there yet; will almost pull in 4th but still fades in rpm & speed after 5-10 seconds; but clearly leaner is better; plug color is gray

[cineburger]

a further test at a friend's suggestion--bike jacked up rear wheel off the ground; plug out; turn the rear wheel in 4th & 5th gears to see if there is binding or any weird sounds. Result--nada--spins relatively freely with no binding or sounds....

[cineburger]

Gentlemen: here's a late breaking question brought on as I begin looking into transmission issues; my official Hodaka Ace 100 B+ owners Handbook and parts list (from SH) shows 15T secondary sprocket and rear 36t or 50T; this has been the standard which I have been following; I just came across a Hodaka Ace 100 B+ brochure ad from one of Rick Mott's posts which shows stock sprockets to be 14T/56T---what is correct or is there such a thing???

[taber hodaka]

14T/56T 4.00:1 -----------Clarence

[cineburger]

Clarence--what about the "road" sprocket??

[taber hodaka]

Ace 100B model 92B+
The sprocket gearing 14T/56T and the primary drive ratio was different at 2.82:1. I believe this is how they came and you could always buy other sprockets.----------------Clarence

[taber hodaka]

can you post a picture of your manual. ---------------Clarence

[cineburger]

[cineburger]

[cineburger]

[cineburger]

Clarence--the last page pictured is from the left hand manual in the top pic; if you look at the orange literature it clearly shows a 14T countershaft sprocket as standard as you have said....

[cineburger]

This reference to 36t/50t rear sprocket as standard supplied with the machine is from the green Supplemental Manual