2001 Honda Shadow 750 carb issues

I have the beautiful old '01 American Classic Edition. Pretty stock...still has plugs over idle mixture screws on carbs....It doesn't get ridden much and I admit I get lazy and don't maintain it as well as I should...she always seems to start and run...was getting a little more difficult to start recently.

Went to start it yesterday and it took a bit of cranking for it to fire. I put in some fresh gas. Finally, got it started with the choke pulled all the way out...it would only idle on the fuel enrichment circuit and died instantly if I opened the throttle or closed the choke.

I figured the pilot jets were clogged...sure enough, after taking the carb off and pulling them, they were clogged...I was unfamiliar with these street carbs with the vacuum chamber and was in a hurry...so I replaced the jets, gambled and put it back together without inspecting anything else.

Sure enough...the bike starts and idles well with the new pilot jets but will die if I give it much more than 1/8 throttle...

What's with these carbs? there's some kind of vacuum chamber and bellows that moves the slide and needle? The slides did look gummed up a bit.IMG_2370.jpg

Pulled the carbs back out...checked the main jets...like I should have...one was mostly closed...the other clogged a little less...the tube the main jets screw into were gummed up and the little holes in the tubes were clogged.
Cleaned things up and got it back together...still starts easily and idles well...also seems to run off the pilot circuit now when I turn the throttle...I only got to ride it around the neighborhood slowly but got it to half throttle and it seems to be working well...I'll get it out tomorrow.
I'm trying to decide whether I should rebuild it with standard jets or get a JD Jetting kit.

Bike ran pretty well this morning...was feeling a bit of hesitation at about 1/4 throttle as I was rolling it on...rode for about 20 miles...filled up with fresh gas...hesitation seemed to be much reduced by the time I got home.

Are you running 91 octane in it? I have to ask because some people I know don't. Also try putting Sta-Bil in the gas in case you do let it sit for a while from time to time, it's keeps the gas fresh. I use it for my bikes and now chainsaws, seems to work well.

Yeah...been running 91 octane in it...also been using Stabil...that worked for a lot of years of neglect...
Its a 2001...I bought it back in 2009 from a friend with 10K miles on it...in the las 8 years I've only put 5K miles on it...I should ride it more regularly. The bike seemed to have more top end with the mains cleared out. Just has a slight hesitation before it transitions.
The bike has never had the carbs adjusted in 16 years! Those metal plugs are still blocking the idle mixture screws! I'm going to order some new jets, pull those idle mixture plugs, do a little rejetting, and a few minor repairs. Both carb insulators are pretty stiff and hard, don't seal the best, and may crack...
As you know I've been busy with some other fun bikes...
Always remember, "It's far easier to buy and collect motorcycles than it is to ride and maintain them regularly."

Yes it is! Seriously though that is a beautiful bike you got there. Really looks good I think. I've always liked those type of bikes, wouldn't mind one someday. You should ride it more!

It's fun to ride down to the hardware store or the 40 - 50 mph twisties on the local mountain road with this bike. But, the suspension is pretty primitive....Engine has gobs of low rpm torque, no top end...so I just naturally short shift it and lug it a lot when I am lazy.

Just changed the radiator fluid...my maintenance log said last change was 2009...ouch...fluid looked a little "off-color".

New pilot jets just arrived...I bought 2 of the stock #40's and a bit richer pair of #45's...I'm also going to pull out the idle mixture plugs so I can tweak the mixture screws. I ordered and need to replace the carb insulator boots...the insulators seem a bit hard and brittle...I've been lucky with them, so far.IMG_2388.thumb.jpg.f132873e6cec4e179bc0fcf83d5e5818.jpg


Quick question, how many bikes do you have? Just curious. As far as I know, you've got: '83 CR250, '83 CR480, '78 YZ250, '01 Shadow 750, and I recall a newer 4 stroke of some kind. You've got quite the collection! I aspire to have a collection like that someday, I'm working on it slowly. ;)

I only have 6 bikes...and I'm much much older than you, so you're doing fine...

You gotta be careful though, because all the maintenance takes time and the bikes need to be ridden. Its terrible feeling guilty when I see my stuff in disrepair and I'm feeling lazy...so...I cam't buy every bike I think is cool...it has to have a 'purpose' or 'reason' to be ridden before I buy it.

So...I have a street bike, the Shadow 750, I bought used.

An off-road trail bike, a 2005 Honda CRF450X, I bought used.

I kept my previous off-road bike, a 2006 Yamaha WR250F, so my girlfriend can use it. I bought it used.

When I retired, I decided to try racing Post-vintage MX and got the '83 CR250R. While I was repairing and setting it up, I saw the '78 YZ250E for sale, restored, ready to ride at a good price...it definitely serves a purpose as a practice bike and back up race bike. Then, I saw the '83 CR480R for sale...

I like that philosophy and that's kinda what I try to stick to. I had a reason for all my bikes, mostly lol. I bought my '83 xr200r as a bike to learn on when I was younger, and also was growing out of the quad a bit.

The '78 yz400 showed up kinda as a basket case and more so because I wanted a bigger bike as I wanted something more powerful than the xr. I then realized that where the YZ made up in power, it lacked in handling severely. I've been trying to get serious about being somewhat good at riding so I wanted a bike in the middle, something that handled good and had ample power and didn't feel like a big bore. This is where the CR showed up. I had been saving for a 250 2 stroke for some time, and was going to buy a much newer 250, early to mid 90s. Then I found the '86 for sale and really liked what I saw, a bike I could completely re-do and build with confidence, and eventually ride with confidence knowing I went through everything. I try to justify a bike before I buy it, but sometimes it's hard to do. I buy old bikes because, yes they are cool, but more so I want a bike I won't be in so much money wise. It seems like right now the CR is a money pit but if I had bought a newer bike I'd probably end up doing the same thing to it and paying more for it initially.

New pilot jets arrived...I pulled the carbs, again...getting faster at it...and replaced the stock size #40s with slightly richer #45s...I also pulled and cleaned the mains again



This time, I opened up the vacuum chambers...the diaphragms look really good...I cleaned the slide and the bore for it in the carb...The was also a little build up on needles I cleaned offIMG_2398.jpgIMG_2399.jpgIMG_2400.jpg

Got the bike out today and had fun with it...the throttle response and acceleration were much better from cracked open throttle through WOT compared to a couple weeks ago...I'm going to keep the larger Pilot jets in and install larger mains....when I get some of extra time.
I'm not a big fan of this vacuum chamber operated slide...I don't get why you would do it this way...looks more expensive, takes more room, and looks less reliable...

I saw a video of a guy with an older Harley twin, probably from the 70s, and it was running a vm38 Mikuni, similar to the stock carb on your '78 250. I wonder if there's an alternate carb for this bike that's similar to the carbs you and I are used to on dirt bikes.

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