Discussion in 'XJ Technical Chat' started by Metalliccurrent, Mar 17, 2017.
No.....were saying you're running lean because your sucking in too much air somwhere
With the jets you have the bike should be running rich, even with the pods (note Chacal's post and my response).
You have a vacuum leak.
I put color tune plug in tonight to see what I had. So determined that carbs 1 and 4 would never give me a (rich) yellow flame(at idle). Throttle shaft seals right. Soaked them with carb clean then starting fluid with no change in engine sound/rpm or flame color. Carbs 2-3 respond correctly when adjusting. These carbs are cursed.
The pilot circuits are partially blocked. Try the colortune on those cylinders again, but this time bump the choke on just a hair, see if you can get a yellow flame. The choke circuit is entirely separate from the pilot circuit and thus can be used to check whether it is a no-fuel-supply issue vs. an air leak.
Good thinking chacal.
Took off carburetors and disassembled carbs 1-4 for a look at pilot passages. Used a small piece of wire to fish around, clean air and fuel jet with torch tip cleaner. Blasted a whole can of brake clean through passages and then blew out with shop air. Tried to catch any debris on a white rag so that I could see the offender. Nothing visible on rag? Reassembled and adjusted carbs, found that they respond like they should with mix getting rich and then leaning as I turn them in. Took her for a run and she throws me back in the seat. Thanks for all the help guys.
Hey guys I got a set of carbs for a xj700 off ebay for cheap. When I recived them there a little different than carbs off the 650. they have a t fitting between 1-2 3-4 above bowl which I assume is a overflow?. Also have a hose barb on each carb LH side of throat,engine side, what is each of these connections for? I can post a picture if needed. Read a how to on xj forever (naked carb) that stated it's a xj700 California carb. Thanks guys
The will look like these. 4 hoses off bodies are vent to float chambers just hangs down between intake boots and yes 2 overflow tubes go down back of engine and stop just below rear frame cross member
Thanks for info. Those carbs you posted sure are clean,very nice.
You'll need to do some experimenting with the jetting on the XJ700 carbs. They are not only jetted differently than the carbs for the 650, they have a different throat size (33mm as opposed to 32mm). My recommendation is to sell them, and find a set for a XJ650 or Xj750 (all that needs swapped to use 750 carbs is the main jets). They can be made to work, but I don't think it's worth the amount of time that would be involved vs. rebuilding and swapping in a set of HSC32 carbs.
His motor is an XJ700 and he just got some carbs for an XJ700. Wouldn't that be the ideal situation to have? Shouldn't he just rebuild the XJ700 carbs to stock and use the stock airbox and he'd be good to go, right? Or am I missing something?
I missed that bit. My mind must be turning to mush. The last I remember he was swapping in a 750, but I see now that I missed a post.
k-moe, you help so many different people in so many different posts that I'm surprised you don't get mixed up more often! Thanks for helping everybody!
Right waldreps, the engine I thought was 750 is a 700 and the carbs I bought are from that exact engine. I am curious to see how she runs with stock carbs and air box. Did all the xj700 carbs have all these extra fuel vents or is this one 'special". What happens if I just put vacuum caps on them or leave hoses off?
I'm not real familiar with the XJ700 carbs so I'll let somebody who knows better get back to you.
The extra hoses are float bowl vents/overflows. If you cap them a low pressure area will form in the float bowls and the bike will eventually stall from fuel starvation. The hoses are a good thing to have. If a float needle should leak (or the bike lie down for a nap) fuel will spill onto the ground instead of into the crankcase.