One of these carbs is not like the others...

KZ250LTD wrote:

As best I can see on the parts diagram, there isn't an accel pump on them.

I didn't see an accelerator pump in that diagram either, but, a couple pages down from that is the exploded diagram of the accelerator pump.

It looks like the 650SR has two different part numbers for the D2 model: 16001-1069 and 16001-1084. God only know what the difference between them is.

Patton wrote:

Perhaps the pump has been rendered non-functional, but does twisting the throttle grip cause any fuel to squirt from the nipples?

Good Fortune!

Nothing squirts, but it isn't dry either. I doubt anything would squirt anyway considering the pump appears to be missing and only the flanges are left.

Looking at the parts diagram, the US model had the pump. I would think this would be to offset a leaner jetting for emissions. This way they could burn cleaner but when you grab a handful it doesn't lag.
Not enough stuff there to put it back, right? So making sure that there is no pump function, and ports/ nipples are plugged you may have to raise the needle a clip to keep it from lagging. Just possibilities.

sparkn wrote:

...Nothing squirts, but it isn't dry either. I doubt anything would squirt anyway considering the pump appears to be missing and only the flanges are left.

Wondering exactly where fuel is escaping. Nipple? Gasket area? Other specific location?

Thinking it might be from a float bowl overflow circuit due to a leaking float valve.

Good Fortune!

Might fuel leak be from a float bowl gasket or drain screw?

If from an overflow circuit nipple, would not be a good idea to cap off the nipple.

All overflow nipples should be routed through attached hoses to exit underneath the bike.

Good Fortune!

The PO is dead and the bike was from an estate sale so there's pretty much no going back to find out if the missing parts are around. This maybe does explain the lean look of the plugs and why I had to turn the air screws 1/4 turn clockwise to get the bike to stop hesitating from idle to 1/4 throttle.

The engine seems to be running much smoother now and the plugs are clean and on the good side of lean now (with an occasional miss at cruising speed). I haven't ran this tank enough to see if the mileage has changed any. Was getting 41-44 mpg before in mixed driving, but even that doesn't mean much considering this is the fourth tank of fuel I've had in it since I bought it last month.

Normally, I just don't trust POs and buy everything new, but I went against that judgment because I hadn't owned a bike in nearly 20 years and didn't want to test my skills on a new machine. I do enjoy this bike immensely, but because I don't fully trust it yet, I can't really push it to the limit. There's just too many unknowns this early in the game. So, I'm stuck atm with the thought of dumping $2k into a 31 year old bike, or saving my money and buying a new bike come next season. I don't have to dump $2k, but if I decide to keep it, I want to make it mine and not just a scrap heap I putt around town in. I'm certainly not going to drive more than a tank of gas from home with this bike before I've broken it down to parade rest and put my mark in every corner.

A new KLR650 is starting to sound pretty good.

sparkn wrote:

...had to turn the air screws 1/4 turn clockwise to get the bike to stop hesitating from idle to 1/4 throttle....

Do the carbs at hand have side-located pilot air screws or bottom-located pilot mixture screws?

Or maybe both?

(See also pilot circuit diagrams in the following post.)

Good Fortune!

[Click on image to enlarge view.]

[Click on image to enlarge view.]

If this is a US model bike (I'm assuming it is), then the accelerator pump was probably functional at one point in time but someone has disabled it. If the bike runs fine, but there's definitely a little fuel dribbling from the nipples, simply install new tubing between the carbs & forget about it... use zip ties to secure the tubing.

If you want to investigate further, check to see if the accelerator pump rod & spring are still in place. If it is, I'd go ahead & remove it... the stuff that connects the throttle pulley to the pump.

So, if I'm getting everything correctly and the PO disabled things right, I should be able to cap off the ports inline with each other in the accelerator pump circuit or just create another drain circuit like the overflow circuit and run a tube down for a little peace of mind in case of a malfunction of sorts? Honestly, after adjusting the pilot airs, it's running strong. I'd like to say the engine is adequate and move on to shocks, chain, forks, ignition, etc. (omg, the shocks have GOT to go).

And since I haven't been doing you guys any favors and I know you're all pic happy, this is what the bike looked like the day I bought it. I have removed the fairing since.

It looks like the two inner carbs have drain screws on the wrong sides... just more evidence that the bowls were swapped at some point.

You would be correct. This is my learner bike (it's been 20 years nearly since the last one I drove). The only thing missing is the training wheels. I think in the three weeks I've been on this site I now know more about this bike than all my biking friends know about theirs combined (chrome and saddlebags don't count imho).

It's OK, though. I'm in the last stage of acceptance about it. The decision I have to make is whether to take a craftman's approach and treat this as a resto, or ride it out and save for a new bike. If this bike were perfect it would still be hit or miss in what I want in a motorcycle, but, then again, I may not have known what I wanted without owning it. I'm guessing I'll put some cold hard cash into it from a hobbyist perspective, but it won't be my daily driver.