Carb Problems ??

[amatco]

I am asking for support once again. I am still having a problem getting my carbs working the way they should. I have disassembled the carbs and soaked them in a carb solution and cleaned them very carefully. I adjusted the float with a depth mike and tested the fuel level with a plastic see thru hose. I took my time and I think it was set as precise as possible. I did not install new needles and seats. I think I should have. I reinstalled the carbs on the bike. The bike started OK and seemed like everything was working well however for some reason the RPM's started increase rapidly and erratic. It did idle OK long enough for me to synk the carbs with mercury. I am getting to be an expert who doesnt know what hes doing. I am thinking the needle valve (float) is staying open.
If anyone can steer me in a direction that will help solve this problem I would appreciate it.

My bike is XS1100H Venture.

[crunchbird]

Some people have had a leaky float that would fill with gas ergo not float so good, and this might be consistent with your problem. (Carbs would be synched and bike would start fine but then idle deteriorates.) Check it by dunking in hot water and looking for a stream of bubbles from a pinhole, etc. I haven't had this problem, be advised, just a thought.

[slick]

You may want to check your vacuume advance system, make sure that the hose is sealing good on the fittings. Try unhooking the hose from the canister and start the bike. If the RPMs are no longer eratic the hose may be bad.

[amatco]

Good morning guys,

Thanks for the replies. I will try your suggestions and see what happens. Unless I find some simple I will start over and rebuild the carbs with new needle and seats and check the floats for leaks. I hate to spend another 50 to 100 bucks for carb parts.
Basically I have a very similiar problem (SNOW tread) with the RPM"s racing to 4k and higher until you kill the engine. I will keep trying.

Thanks again, Allen

[wildbill]

carb problems

That sounds like a vacum leak.Will have to do some tinkering later myself.If one or more speed up might be in diaphrams on top of carb(s). Good luck

[skids]

If the fuel valve (float/needle/seat) is leaking, you will know it if you set the petcock on PRI and she starts making a mess. And yet, with later models, the oring around the fuel valves can also leak and overflow the bowls.

Originally posted by amatco
Good morning guys,
Unless I find some simple I will start over and rebuild the carbs with new needle and seats and check the floats for leaks. I hate to spend another 50 to 100 bucks for carb parts.
Basically I have a very similiar problem (SNOW tread) with the RPM"s racing to 4k and higher until you kill the engine. I will keep trying.

Thanks again, Allen

[amatco]

Vacuum lines / blowoff

Hi , I am still trying to get this carb set right and running smooth.
I noticed that the vacuum lines are building up with pressure and blowing off. Could it be that the intake valves are not closing completely or I have a leaky intake valve or the valve shims are set to tight. This could cause all kinds of problems.

Any input on this would be appreciated. Thanks, Allen

[Snow]

I am pretty sure my float needle/seats are not leaking, as I replaced them a couple years ago and also I can leave my petcocks on prime without any problems.

I don't remember who mentioned it (think it was DennyZ), but his idea about the idle mixture is starting to make sense to me (could be the migraine medicine taking effect), especially now that I think how my bike has always seemed to idle just a little roughly - now I am just waiting on my new colortune to find out for sure.

If your intake valves weren't closing completely, wouldn't the pistons be hitting them - I definately don't know as I am just a padawan to these Jedis of the XSsive force...

Also, something I did notice due to my other brother's inquisitveness, is that if I try to run the bike without the full airbox, it won't even start - does that mean I am running waay too lean or is that normal? If that is a "waay too lean sign" then maybe amatco could check on his bike too to see if we truly have a similar situation?

[strom]

In my case, valves of #2 cyl were hitting eachother and bending... ergo no compression and some air was blown back to the carbs, filling the airbox with gas, and the bike ran way too rich. Check if your cams are in sync and do a compression test.

My bike wouldn't start without the airbox as well... good thing a friend had his carbs in my garage with some K&Ns on... borrowed them LOL... had my pants soaked with gas. Gotta stop smoking. lol

LP

[Snow]

Well, got her running again today with the 78E carbs - found out something quite odd, if I disconnect the float vent hose from the air box, no spewback problem, and she runs pretty much ok - on my test right, she stuttered between 1/4 and 3/4 throttle between 4250 and about 7500 rpm, fine before and after that range though.

My pops suggests that since it is a freshly rebuilt motor (39 miles at the moment), that it may just be do to not being broke in yet, but I have my doubts. Another thing that the stuttering may be, apparently in my attempts to get it running, I managed to retard the timing while thinking I was advancing it...DOH! Well, guess I can check that tommorow.

The thing that puzzles me though, is why do #3 and #4 pour gas out the intakes and #1 and #2 are perfectly fine? I let the #3 and #4 carbs sit overnight in carb dip, not much effect....

[Ken Talbot]

Ah, yes, the old "I already cleaned my carbs" or "I soaked my carbs in carb dip overnight" scenario. Then "she runs real good except...." I hate to be the one to break the bad news but you're going to have to clean the carbs again. The old 'triple clean' handle is not just a myth, and there are a few XSives out there who couldn't count on two hands the number of times they cleaned their carbs before they finally got it right. Don't get discouraged - just think of it as a character building exercise!

BTW - check the airbox nipple that you had the float vent hose connected to. Later model carbs were vented differently, so the airbox nipples were not drilled. If you run the vent hose from an early carb to a plugged-off nipple on a later airbox, you'll have problems.

[Snow]

...I think I may be an idiot - a while ago, I had noticed that it looked like the 2 nipples had bin plugged with some brass nails or similiar things and shrugged it off b/c at the time, I was using later model carbs.... I will remove those plugs tonight if I can... Heh heh, thanks Ken