'84 vsx1200 popping out carbs

[garyS-NJ]

wow, I typed the title carbs popping and I see there's similar threads. I'll look at them but in the meantime, let me post here hoping I have some guidance to mount another attack in the morning.. long story short - I recently bought an '84 venture royale complete with bags and plastic.. it looks stock. electrics work but it was seized. I got the pistons moving and it ran just adding gas. but it was spitting fuel out the top of one carb and wouldn't rev without spitting popping and bogging. and the carb drains were clogged. I flushed the tank and installed a new fuel filter and blew out the bowl drains (crap, I blew one hose off the front right carb and can't get that sucker back on..). one slider was completely stuck and a few of the sliders seemed real sticky.. so I cleaned up the sliders and sprayed carb cleaner and air through the ports under the diaphragms.. then I sent a mixture of gas, carb cleaner (B-12 chemtool) and seafoam through the carbs (I let it sit for a bit) and then flushed with fresh gas. she fired again but took a while to warm up and get off choke. I didn't have fuel coming out the overflow (I had that before, oh yes, and I rapped on the carb bodies with a ratchet handle) nor did I have gas squirting up out that air jet on top of one carb.. so much better now but she won't rev without bogging down (idles OK) and also when I rev it, she pops fire out the carb throats. one of the sliders still seems sticky as it isn't fluttering like the others but they are all popping.

 

I tried to yank the carb set but even with all the boot clamps loose she wasn't budging. I read something about a clogged pilot circuit causing popping out the carb throats and also read that stock the main jets are oversized and the pilot jets are undersized - and this makes them pop, But I have a gross problem as she wont even rev. Is there something I can do without pulling the carb set? (seems they are stuck on there good and I bet difficult to get out and back in and I was even having trouble getting the throttle cables off!)

[garyS-NJ]

test to reply

[Vonwolf]

Backfiring like that can be caused by a lot of problems, it might be running lean check the pilot screws make sure you can turn the mine were welded in place and wrecked my Carburetors, you can have a vacuum leak or it might be electrical. I'm not sure on your experience with these Ventures so forgive me if this is well known to you, but Ventures do not like to run with the air box off it will idle on choke but won't pull any RPM's. I hope this helps Good Luck

[Great White]

From your description; I'd stop messing about, pull the carbs and do a proper cleaning and rebuild on them.

 

Then a proper install and adjustments (air screws, idle, balance, etc) iaw the service manual.

 

Its actually what should be done with all carbs that are a little "mungy". I've never been a fan of "tune in a can" solutions. They usually just limp you along until you have to tear them down anyways and the bike doesn't run to its potential while your limping along.

 

I learned long ago that you actually save time, reduce frustration and end up with a better result by just yanking the carbs and doing it right the first time. This implies, of course, that someone has the proper tools and knowledge to do a proper rebuild.

 

To get the carbs out of the boots you have to work each a little at a time. Theses are easy, try getting a Honda vf750 v4 carb set out!

 

Edited May 13, 2015 by Great White

[OrlinEngh]

If you are running it with the air filter and box off it will not run like it should and pop out of the carbs. And syncing the carbs maybe of help too.

[garyS-NJ]

Backfiring like that can be caused by a lot of problems, it might be running lean check the pilot screws make sure you can turn the mine were welded in place and wrecked my Carburetors, you can have a vacuum leak or it might be electrical. I'm not sure on your experience with these Ventures so forgive me if this is well known to you, but Ventures do not like to run with the air box off it will idle on choke but won't pull any RPM's. I hope this helps Good Luck

 

OK, everyone is saying try it with the airbox back on... but to be clear, when I rev the throttle (even bringing it up slowly), it starts to backfire and pop (flames) out the carb throats. it also self limits and refuses to rev as it starts to bog and pop. I used to work in a small engine shop and whenever a motor acted like this we would fix it by cleaning and rebuilding the carb (they were a lot simplier but I guess the same!). as for the Pilot screws Von Wolf, do mean the capped (but adjustable) pilot screw (idle mixture I think) or the Pilot Air Jet 2 under the diaphragm (I squirted carb cleaner throught here and it came out top the carbs), or one of the purge jets 1&2 beneath the diaphragm at the bottom near the mixture jet?? or are you talking the Pilot Air Jet 1 or the Main Air Jet near the throat. What about the diaphragm on top of the carbs?? popping out carbs usually means way lean so maybe I just have to slick up the one sticky slider (yes, one looked sticky after all four were done) and try it with the airbox on to restrict the air in. I kinda remember I was working on a newer inline 4 sportbike thaty wouldn't rev without the airbox... (gone are the days of wide open anything).

[flyday58]

Hey Gary. Your cryptic statement "...it was seized..." implies a whole bunch of issues to look at. Think of it this way: your '84 is like Frankenstein and you are its Reanimator. You're bringing it back from the dead, so take it slow, a little at a time. It's on life support right now, but the right meds and surgery can bring it all the way back.

 

Since it was seized there could be any number of reasons - you work with small engines, you know them. But I agree, get the carbs off. I used a 12" long 1/2" extension and GENTLY pried on the carbs to get them to pop out. Like you said, lots of posts here to help you take em apart once they are out.

 

You will also have to take a peak inside your TCI. Mine had been full of water so much there was practically no electronics left, but it still ran on 2 cylinders.

 

'Fool, Dingy, skydoc, and Prairiehammer() and others will surely weigh in soon, but this gets you started. All the stuff that applies to working on small engines applies here, too. Valves, air leaks, leaky head gaskets, yattayattayatta. You'll get there. It won't take too much, it'll just take money!

[garyS-NJ]

The pistons/rings were sized to cylinders. I broke them free with penetrating oil and Evaporust. Rocking the bike in gear and finally rocking while tapping on the pistons with a rod thru the rear spark plug holes.. I'd think the TV I would either work or not work. Yours was half dead. I have spark on all for cylinders. What about the diaphrams on top??

[Prairiehammer]

and blew out the bowl drains (crap, I blew one hose off the front right carb and can't get that sucker back on..).

one of the sliders still seems sticky as it isn't fluttering like the others but they are all popping. Bad things can happen inside the carbs if compressed air is used: diaphragms ruptured, floats bent out of shape, sludge catapulted into heretofore open orifices and circuits, slides cracked. Since you applied enough air to blow a bowl vent hose off, there is no telling what may have been disrupted. Carb removal and disassemble appears to be in order.

 

I tried to yank the carb set but even with all the boot clamps loose she wasn't budging.

There is a groove around the circumference of the lower carb throat. As age takes its toll, the rubber carb boots conform to this groove and develop a set. Judicious use of heat to soften the rubber boot, combined with WD40 sprayed around the boot where it meets the carb and finally gingerly pry the carbs from the boots. Use a length of broom handle or a suitable hammer handle and be cautious about where you pry.

 

I read something about a clogged pilot circuit causing popping out the carb throats

Definitely the primary reason for such behaviour. If the sludge and varnish was sufficiently bad to plug the bowl drains, the same sludge and varnish will have plugged the pilot jets.

 

Is there something I can do without pulling the carb set? (seems they are stuck on there good and I bet difficult to get out and back in and I was even having trouble getting the throttle cables off!)

Perhaps, but from your description, I doubt that any attempts at cleaning the carbs short of removal, complete disassembly and soaking in Chem Dip will remedy your symptoms. Most find that the cables are easiest to remove after the carb set is removed from the boots and slid out toward the left side of the bike. Then remove the cable ends. Back off all the adjusters to gain some much needed slack.

 

OK, everyone is saying try it with the airbox back on... but to be clear, when I rev the throttle (even bringing it up slowly), it starts to backfire and pop (flames) out the carb throats. it also self limits and refuses to rev as it starts to bog and pop.

That is precisely what will happen with the airbox off.

as for the Pilot screws ..., do mean the capped (but adjustable) pilot screw (idle mixture I think)

Yes, the pilot screws (idle mixture screws) are below the diaphragm covers and are capped (if someone hasn't removed the caps yet). If yours are still capped, that means the you have not cleaned or adjusted the first thing to be cleaned and/or adjusted. Not saying that removing the pilot screws and attempting a cleaning of the pilot circuit via the now empty pilot screw ports will remedy your problems, but that should have been the first thing to attempt.

 

What about the diaphrams on top??

I don't what you are referring to when you ask about "the diaphragms on top". Perhaps you mean the coasting enrichment valve diaphragms? Those are not on "top" but along the side of each carb. The coasting enrichment diaphragms can go bad, primarily because of carb spray deteriorating the rubber. The coasting enrichment diaphragms cannot be replaced until the carbs are removed and separated. Well, two of the coasting enrichment valves are not accessible without separating the carbs.

 

Three characters. HA!

[garyS-NJ]

now that I think of it, I saw a youtube video of a guy shooting a carb cleaner into the throat jets with the idle mixture screw turned two turns out (pea shooter carb clean), but this video shows a guy running his venture with the airbox off and he's not having any issue with popping or bogging. I'll try it with the box on today but looks like dems carbs need to be pulled off and gone through.. would a compression gauge while cranking the engine check the valve seating well enough? (hate to do the carbs and find it was intake valves not closing well).

 

runs without airbox:

[garyS-NJ]

big thanks Prairiehammer!!

[Prairiehammer]

IF the engine is warmed up AND the pilot jets and pilot circuitry are clean, then it will idle and take some throttle but the throttle has to be applied slowly until you get into the midrange where the main jets are starting to feed. Notice that it died after he quit giving it gas? Trust me, it will run like crap without the airbox. It doesn't even run well (lots of bogging and stumbling) without the air filter installed but the air box buttoned up.

[Vonwolf]

OK, everyone is saying try it with the airbox back on... but to be clear, when I rev the throttle (even bringing it up slowly), it starts to backfire and pop (flames) out the carb throats. it also self limits and refuses to rev as it starts to bog and pop. I used to work in a small engine shop and whenever a motor acted like this we would fix it by cleaning and rebuilding the carb (they were a lot simplier but I guess the same!). as for the Pilot screws Von Wolf, do mean the capped (but adjustable) pilot screw (idle mixture I think) or the Pilot Air Jet 2 under the diaphragm (I squirted carb cleaner throught here and it came out top the carbs), or one of the purge jets 1&2 beneath the diaphragm at the bottom near the mixture jet?? or are you talking the Pilot Air Jet 1 or the Main Air Jet near the throat. What about the diaphragm on top of the carbs?? popping out carbs usually means way lean so maybe I just have to slick up the one sticky slider (yes, one looked sticky after all four were done) and try it with the airbox on to restrict the air in. I kinda remember I was working on a newer inline 4 sportbike thaty wouldn't rev without the airbox... (gone are the days of wide open anything).

 

I am talking about the caped off Idel mixture screws they can create a lean condition that can cause the motor to backfire and the bike will not run well without the air box, it took me while to figure that one out how else are you going to know the slides are working right? I still haven't figured that one out. Good luck with your build

[garyS-NJ]

reaching into the throats, one slide was seized and the rest reacted different when I pushed them in and let them spring back out. so I used a plastic abrasive pad to scour the slides and the slide tubes using PB blaster as a lube/cleaner - careful to keep the throat pluged with paper towels. this smoothed out the sliders and then running I could see them all pulsing the same with vacuum except for number 3. I just took that slider out again but it was moving freely so I'm guessing the vacume to the diaphragm isn't working properly. can't see/understand that vacuum path from the carb cross section in the manual. Oh and the mixture screws were unplugged already. gonna count the turns in on them and then remove them and spray them out and then set them an extra two turns out to try the "peashooter cleaning method" (see below) and try with assembled airbox before yanking the carbs for a real cleaning.. you know they always say don't fix what aint broke so I don't want to pull these carbs and taka a chance screwing them up if I'll be able to ride it (as least for a week or so to check it out and while my other bike is down waiting for parts...)

[Prairiehammer]

Examine the slide diaphragms carefully for tears and pinholes. Lightly stretch and straighten each diaphragm along with a strong backlight to reveal perforations.

Closely examine each slide for cracks. Hold the slide upright (diaphragm up), plug the vacuum port (at the now bottom of the slide) with a finger tip and pour gasoline into the slide interior. Cracks will manifest as gasoline leaking (seeping) out the slide side.

Clean the bore of carb body where the slide is supposed to, um, slide.

Check all the diaphragm/slide return springs for identical at rest length.

The vacuum path is fairly short and simple. Air passing through the venturi creates a negative pressure (vacuum). The vacuum port on the end of the slide allows vacuum to be applied to the outer diaphragm chamber. This raises the slide. Any leakage due to a perforated diaphragm or a cracked slide or misplaced diaphragm lip (allowing leakage to atmospheric pressure around the diaphragm cap) will mean there is not enough vacuum generated to overcome the return spring force.

 

Since you mentioned the "pea shooter" method of cleaning, you are probably aware that there is a more thorough, but similar method, variously called "the shotgun" or "shotgunning". You apparently haven't tried the shotgun yet. There is a 50/50 chance that you may get the pilot jet (the real culprit) clean enough with the "shotgun".

Edited May 13, 2015 by Prairiehammer

[garyS-NJ]

well today could have went better. I did the shotgun and even shot some chemtool through. I did the squirt/blow three times and also polished one slider that was a little slower than the others to snap back. It ran better with the airbox and filter on but was slow to warm and didn't want to come off choke or rev. It popped a little less and reved better but not good enough. I'm also seeing that after it warms, it cranks slow really loading down my spare battery (with a charger and 50amp start boost).

 

I'm going to run it a few times with seafoam in the gas hoping that clears things up some. and I just read about another tune up in a bottle called Liquid Performance fuel system cleaner. I know this stuff rarely works and may well eat the rubber parts but I'll be replacing the rubber parts anyway in the rebuild if I have to tear them down.

 

And I'm hoping the slow cranking when hot is due to "sticky" rings from the seized engine and this will loosen up as I run the engine. I used diesel oil (because it has zinc) and added some STP (with zinc) and a bottle of ZZDP Max (zinc!!!) hoping this lubes up everything. maybe I need some marvel mystery oil or seafoam in the oil (that's OK as I bought more oil to purge the crank case again...... Could my starter brushes be tired?? I read somewhere that the first gen starters are lame and should be replaced with second gen starters (or brush sets?) but that starter under the from exhaust pipes will suck! (I sprayed the studs figuring I'll have to do that sucky job..).

[Vonwolf]

And I'm hoping the slow cranking when hot is due to "sticky" rings from the seized engine and this will loosen up as I run the engine. I used diesel oil (because it has zinc) and added some STP (with zinc) and a bottle of ZZDP Max (zinc!!!) hoping this lubes up everything. maybe I need some marvel mystery oil or seafoam in the oil (that's OK as I bought more oil to purge the crank case again...... Could my starter brushes be tired?? I read somewhere that the first gen starters are lame and should be replaced with second gen starters (or brush sets?) but that starter under the from exhaust pipes will suck! (I sprayed the studs figuring I'll have to do that sucky job..).

 

I promise you the slow cranking is the result of the 1st Gen's use of 2 brush starters mine would hardly turn the motor over when cold, but when hot I had one shot at it then it was, sit let things cool down for a while and hope like hell . The second gen's and the VMax's use 4 brush starters and beleave me there is no comparison Hot, Cold it doesn't matter my motor spins and spins. It is no longer a concern for me, this bike will turn over when asked to.

[garyS-NJ]

Holy **** my little '83 xj550 has 4 brush starter. The starter has to cool? So when the motor is hot it makes the starter hot and it don't crank? How the hell did that design pass?

[bongobobny]

NEVER use antifriction additives in your bike unless you want to ruin the clutch!!! You have a "wet" clutch and the STP will make it slip!

 

To fix the hot start issue there are two things to do, replace the starter motor with a 4 brush from either later VMax or from a 2nd gen Venture. The swecond thing is to replace your battery cables with heavier cables. Member Dingy makes up sets using 4 gauge wire...

[Vonwolf]

Holy **** my little '83 xj550 has 4 brush starter. The starter has to cool? So when the motor is hot it makes the starter hot and it don't crank? How the hell did that design pass?

 

I thought the same thing, but it takes the problem a long time to raise its ugly head. There is a way to repair the 2 brush starters by improving the ground, they have a thread on the mod. It appears to work, but if I'm going to dig out the starter I'd just as soon get the best thing I can find and the 4 brush starters work great and Dingy's heavier battery cables work great as well.

[garyS-NJ]

Good point on the stp. Will see how it grabs. Was runnjng a lot better today. After she's road worthy I'll do the starter. Might only mean a bottom hose. Does a 4 brush plate fit in the old starter?

[Vonwolf]

Good point on the stp. Will see how it grabs. Was runnjng a lot better today. After she's road worthy I'll do the starter. Might only mean a bottom hose. Does a 4 brush plate fit in the old starter?

I'm not sure if the 4 brush plate will fit, but if you search for "First Gen Starter Mod" you'll find a great way to improve grounding the starter, many have tried this fix and swear by it and you'll save money

[Prairiehammer]

Good point on the stp. Will see how it grabs. Was runnjng a lot better today. After she's road worthy I'll do the starter. Might only mean a bottom hose. Does a 4 brush plate fit in the old starter?

 

The four brush PLATE will physically fit, but your starter won't work. There are four 'poles', meaning four field coils on a four brush starter. Entirely non compatible electrical theory. There are only two poles and two field coils on a two brush starter.

If you go to all the trouble to remove the starter to mod the brush plate, you are more than half way toward installing a four brush starter. The four brush are not expensive used. Keep an eye on eBay. Often sold for $50 or so.

[flyday58]

The four brush PLATE will physically fit, but your starter won't work. There are four 'poles', meaning four field coils on a four brush starter. Entirely non compatible electrical theory. There are only two poles and two field coils on a two brush starter.

If you go to all the trouble to remove the starter to mod the brush plate, you are more than half way toward installing a four brush starter. The four brush are not expensive used. Keep an eye on eBay. Often sold for $50 or so.

Got mine for $80 a year and a half ago, and did the battery cable upgrade. Money well spent.

[Patch]

So carbs a side as we know they have to come off and gone through.

Get a can of Deep Creep and spary some around the carb/intake mating area, wait an hour, remove the small plate on top of the carbs left side, you can now see the linkage and cables, remove the black tube completely between the carbs, running from the PCV ( mine was too stiff to bend and move, presto!

 

What you describe is valve seats! The intake seats are leaking, the valves rusted, like the rings did, and it is wrong to force rings to free them, they should soak free, forcing them is like picking at a scab!

 

The seats are not sealing pressure on the intake side, so -as the pressure builds during combustion it is slipping past and up through the carbs. 2 choices soak them as I mentioned in my post or remove the heads! You could also prove me wrong and do a, compression test, but and also, a leak down test would be the correct test for this!

 

I seem to never have the right English to explain the air box, so I try to explain it this way: It serves as an air spring, it balances the air velocity and stream, it falls under tuning. Although different the exhaust system has a similar feature -we usually don't fallow or see it in the same light though, and that being back pressure! When I tune, with each step I add to the intake side of the carb, I look for a note that shows positive change, for example, extensions leading to the air box, the air box, the filter, the lid so on. It is harder to understand this then having a part number for a re jet, likely because it is not visible to us, so we don't see the importance of it.

 

 

If I have popping on a warm engine, I missed somethin!

 

Patch