Carb Boot Issues?

[TonimusMaximus]

Allright fellahs. I'm so close to having this beast running properly. She idles with the choke out and warms up to 2600 RPM with it all the way out. Put it in, it dies. I have tried every screw setting imaginable. Where I currently have it set, when you slowly rotate the throttle it will climb to 3000, drop to about 800-1000 and struggle, you continue to rotate the throttle and it will speed up slightly to about 1200, then it will shoot up to 4000 and continue on normally from there. I suspect the carb boots for that reason, and I did try to put my hand over the airbox intake. It started to develop a vacuum, but the engine speed didn't change AT ALL. I tried the WD-40 boot trick with no sucess. I should just replace the boots because they are old, but it's kinda hard when the money has elsewhere to go. Suggestions? TIA.

[ratbyk]

Carb Mounts

Do not waste money on replacing your carb boots. Unless it has been in a major accident where they were physically damaged they will be OK.
Sounds more like you should increase your idle speed a bit. (large knob between the two center carbs). Hard to reach but duable with a long shafted screw driver from the right side. Turn the screw clockwise.
If that does not solve the problem open up the idle mixture screws a 1/2 turn at a time until it will idle.
Either the throttle plates are not open enough to provide enough air for it to idle or it is not getting enough fuel to allow the engine to run without the choke on.
Ken/Sooke
78E Ratbyk
82 FT500" lilRat"

[mitch]

Carbs

I agree with Ken, also did you bench sync your carbs? If not that needs to be done before u start adjusting the idle screw and idel jets. ......MITCH

[fusionking]

As stupid as this may sound......it sounds like yer gettin' close, Keep on pluggin' at it!

[Robert Haller]

I would check the idle jets. My bike idled and ran fine until I ran out of gas on the way home this weekend. Now my bike doesn't want to idle but still runs fine with the throttle open or with the choke on. I'm thinking that some crud got sucked into the idle jet restricting it (I'm sure it must be a fuel supply issue).

[nashville_bill]

Could be the carb boots. I had bad ones on my XS650 and the idle was all over the place. It would range from barely running to 3000 rpm.

Probably the carbs though. Clean the pilot jets, look at the idle mixture screws and the chamber they screw into.

Good luck.

[TonimusMaximus]

Let's say it is my carb boots. (I've resigned to the fact I need to take the carbs back off and clean them again) Is there a temporary fix? Maybe Bondo's Spray on rubber undercoat?

[mitch]

Liquid plastic

In Canada its called GOOP dont know what they have in the states a good auto parts store should be able to help i coated mine. But i think u need to clean and sync your carbs then adjust the idle jets and main idle screw
...MITCH

[TonimusMaximus]

I believe I cleaned them really well, but we all know what that can do to you. I am going to take them off and clean them again, but I'm still looking for some sort of preventative coat for the boots. As for Goop, I work at Checker Auto out here and I haven't seen any.

[buffalo]

Go to your local hardware store and get some brush-on liquid electrical tape, works like a charm. It is also the same stuff sold as plastic dip for tools handles. I used spray carb cleaner to make sure all oily residue was off the boots before coating them.

[Dragonrider]

By all means, coat the boots with the liquid electrical tape, or use that dip coating that you put on tool handles and such, but also check the "o"-ring between the engine and carb boot.

More importantly, have you synced the carbs?

[scalded dog]

If the engine dosn't change tempo, when you spray the boots. it doesn't sound like the boots, when is the last time you adjusted the cam chain, changed spark plugs, adjusted timing, checked diaphrams. just some things to try, with out spending a lot of money. Later 'Dog

[MartyA]

I'll vote carbs, you said you have trouble up to 4000 RPM, which sounds like the idle circuit.

But I would definitly check the timing. A few years ago my timing plate came loose, but I did not realize it. I had adjusted the timing with the plate loose, then after seating it correctly and bolting it back in place, turns out I was 25 or 30 degrees off. When the engine was cold it would start with only a little trouble, fully choked, but I had a heck of a time getting the thing to start and idle and run at the lower RPM when the engine was warm, without the choke. Revved well at 4000-6000 in the driveway, but had reduced power on the road. The way I noticed it was the sunny day I was changing the plugs, hunting down this ugliness. I noticed the #1 piston nearly at TDC and the timing plate said I was 25 degrees or so late (wrong side of "0.")

Also be sure the vacuum advance and the centrifugal advance are working. My centrifugal advance was gummed up and would not advance till late in the RPM's, then hold the revs up off throttle a bit till it relaxed. Also the vacuum advance should move freely, and look for any leaks in your vacuum hose. Been there too.

[TonimusMaximus]

Let's see. Lots of suggestions.

Timing: On the Mark
Carbs: Synched
Plugs: Fresh
Diaphragms: Suprisingly goof condition
Chain Tension: Umm... Sure?
Advances: I know I have one.

So, I've got a couple things to check... It'll have to wait a little while. Work has me pulling oddball hours. Thanks for the help so far, fellahs.

[skids]

I didn't hear you say anything about the manifold boots here, but, I strongly agree that your idle circuits are fouled. Remove the pilot jets and clean each one with a guitar string or similar. Then you need to make sure that, with the pilot jets removed, spray carb cleader into the exit holes (three holles near where the throttle plate rests on the top of the ventouri bore) and make sure that it runs out of the pilot jet bores.

Originally posted by TonimusMaximus
Let's see. Lots of suggestions.

Timing: On the Mark
Carbs: Synched
Plugs: Fresh
Diaphragms: Suprisingly goof condition
Chain Tension: Umm... Sure?
Advances: I know I have one.

So, I've got a couple things to check... It'll have to wait a little while. Work has me pulling oddball hours. Thanks for the help so far, fellahs.