XL1200 need some advice

[yama-doo]

1998 yamaha xl1200 non-pv helping my buddy get get this basket case going it did run but ruff before course that could have been because it only had one engine mount and the couplers and rubber damper where eat up. The gauge cluster is bad and the by passed the start stop switch top run direct. something draws the battery down over night still???
I put new crabs its in replaced everything including low end high end set screws only exception was no new needle & seat , first time I used new 32psi springs and I just changed to lower 18psi springs,check with pop of gauge , I just open and reinspected everything and still have same issue. I do have vacuum form all three engine vacuum tubes I am pulling fuel through the lines (can see air-bubbles pass until it fills with fuel) . if I primer it will run on primer fuel if I keep easing primer fuel it will stay running but not dribbling and fuel through carbs ventral (sp?) form pumps ?????????

Fuel line in is connected rear of ski on lower rail and return is top rail front of ski


My first though is it is the carbs but I just can't find anything wrong with them so here I am looking for some Advice?

 

[Vumad]

Im not sure i comprehend the question from what seems like rambling.

No reason to bypass electrical things, leave it stock and disconnect the battery or add a disconnect.

Why are you lowering the popoff on a stock boat? Do you understand how any of it works? The 1200 is a big rough running motor that has tons of vibration. It has a stock psi of like 60 for a good reason. You cant just lower it to whatever you like because you read somethkng somwhre about a standup. Look into the carb throat and you will probably see fuel dripping from the venturi. Also the aftermarket needles are nkt as precise as mikuni parts so if you cut the corners on pzrtz you need to sack up and buy the good stuff. If it is a stock motor, put it to the stock settings. it is unlikely that 18 psi will tollerate that much vibration.

 

[yama-doo]

"what seems like rambling."
well wasn't meant as rambling but rather to try to pre answer all the questions "needing more information first"

"The 1200 is a big rough running motor that has tons of vibration."
well not really anymore then any other though they do have more torque then a smaller engine, maybe your just thinking of those fourstoke's ....LOL my 650's, 701, 1100, 1200 seem to have about the same vibration and all those seem smoother then the 951

"Why are you lowering the popoff on a stock boat? "
because it is not popping off "in" the ski at all but does with pop off gauge , and I have pulled off the air-intakes for now to allow access so it also has lower pressure (its normally for me to do skis way) and later I'll probably will throw on some ocean pro breathers I pulled off the blaster so it can breath better. By keep dropping to lower popoff it allows me to check an if it an if it will not popoff at 18,26, 32 there has to be another reason just thought maybe some KNOWLEDGEABLE mite have a suggestion for common vacuum/pulse leak spot to look for

"Do you understand how any of it works?"
yep .... not sure if that was question or insult

"You cant just lower it to whatever you like because you read somethkng somwhre about a standup."
I'm not sure what your issue is but I'm not reading anything on "standups" don't even know where you came up with that BS, I haven't even messed with standup for 15-20 years now though some of the guys who converted to 1100/1200 could probably give real answers instead of what you posted

"Look into the carb throat and you will probably see fuel dripping from the venturi."
If you go back and READ my post you will see that I already stated that fuel is NOT dribbling in the venturi , if it was dribbling it would also run , as it is it's dry (no fuel) unless I use primer to feed it though fuel pumps have fuel in them it isn't popping off "IN" the ski

"No reason to bypass electrical things, leave it stock and disconnect the battery or add a disconnect."
Yes several, there is something shorting in there and he had to run jumper wire to get it to run , by bypassing I can/did get rid of all that mess and I the electric cluster which is not needed or wanted . yes I already told him to get a disconnect but that isn't a fix just a band-aid . Again this was just background info to help pre answer questions about what has been done recently


Im not sure i comprehend the question
My question was if it isn't the carb what else to look for in this situation like any particular vacuum/pulse leaks that may cause it not to pop off

 

[Dartman]

most of the gp1200 non pv that I found after a seizure had bad creased fuel pump diaphrams in them
this caused weak fuel pressure
so always check those out on any non pv yamaha 1200

can you choke the top of the carbs wiith your hands to get it to prime fuel in the carb bores instead of relying on the primer?

 

[yama-doo]

My other two have that external fuel pump but this one is like smaller engines each carb has a vacuum/pulse line for case to fuel pump on carb , I just checked the diaphragms this afternoon and they where brand new few days ago

I haven't tried hand choking maybe I will try tomorrow , manual chokes are long gone .

 

[Vumad]

The ski idles on the low speed adjustment screw and the low speed jet. If you are having a no-idle issue, its not your popoff. The popoff pops around 1/4-1/3.

Did you test your fuel pumps for leaks. 10 psi for 10 minutes.

Are you running mikuni rebuild kits or something like sbt? Sbt kits for example have bad orings. A brand new carb kit can cause a leaking fuel pump which will prevent it from working correctly.

sorry about the rambling comment, but you are not being clear. It sounds like you said it was running rough, but later it sounds like its not idling at all. Youre going on and on about it not poping but popoff isnt related to the idle so your question is unclear. A leaking popoff causes rough idle but not poping shouldnt prevent idling.

 

[yama-doo]

Yes it holds pressure but I'll admit I only did each carb for about 4-5 minutes not 10, the kits are not Mikuni but not SBT either I'd say there somewhere in between quality wise the O-rings are a little thin (similar to SBT's) but they are not leaking

Ok that is a different understanding then I have always thought of for the carbs , to my understanding the round & square body Mikuni are the same principal, the vacuum/pulse moves the diaphragm in the fuel pump which pushes fuel through the filter screen form there it goes to opposite side to needle valve assembly where it must "popoff" to allow fuel into that side of the body where it can then travel to low & high end jet , then it can be adjusted at the low & high speed adjuster screws to tune carb, then fuel enters throttle body of the carb to feed engine .......... thus no popoff "in" ski means no fuel can get to the low end jet and prevents idling

I do (and redid yesterday) take out the low and high jets to clean with tip cleaner and use air pressure to blow out the carb body holes to be sure they are clear and have no blockage , so IF I can get fuel to the low end jet it will get to carb the problem is no fuel is passing needle assembly once carbs go back in ski

 

[Vumad]

I like to clean my jets and needles in chem-dip over night or several days if very dirty. This product is available at the auto parts stores.

Soak, then spray with carb cleaner.

Never push anything metal through a jet. If you do need to push out a hole, use nylon like on a scrub brush.

 

[Dartman]

to my understanding the round & square body Mikuni are the same principal, the vacuum/pulse moves the diaphragm in the fuel pump which pushes fuel through the filter screen form there it goes to opposite side to needle valve assembly where it must "popoff" to allow fuel into that side of the body where it can then travel to low & high end jet , then it can be adjusted at the low & high speed adjuster screws to tune carb, then fuel enters throttle body of the carb to feed engine .......... thus no popoff "in" ski means no fuel can get to the low end jet and prevents idling

you are correct sir
vumad has it wrong
if the needle valve never opens
fuel will never enter carb fuel cavity that feeds jets

vumad is correct that:
all fuel for low speed running and pilot (idle) feed all goes through low speed jet first
fuel then feeds the pilot hole in throttle body adjusted by the low speed needle screw

 

[yama-doo]

ok

 

[Vumad]

Sorry about that. i know the only path from the pump to the regulator is through the needle, so i dont know what i was thinking.

But on that note, did you check your internal fuel filters. They shouldnt be the issue, but i did once see one about 90% clogged.

 

[yama-doo]

yes they are brand new but did pull them and double check they where clean

 

[yama-doo]

Problem solved, I am chalking it up to my own stupidity I get so used to doing something one way I just kind of overlooked simple things . Carbs where fine the problem was the three vacuum / pulse tubes on the engine block I guess where to rough form previous owner using pliers to seal with zip ties , I reluctantly put some hose clamps on there and he's up and going now.