Guys,
I just did a carb sync on the 92. Carb 4 did not register at all on the Carbtune. Knowing that No 2 is the non adjustable one I have got 1 and 3 pretty good ( they were out a fair bit ). I'm wondering what could be causing the problem with carb 4 being dead ? Is it a matter of pulling it apart and cleaning it up cause it may be full of **** or what would I be looking at ? Thanks in advance.

 

That's a little weird, was it running OK before you started?

 

Kiwi,
Yeah mate the bike was running fine, sounded fine and idled fine. I haven't ridden it since I've owned it cause its not registered. Its always started fine on choke then idles nicely when warmed up. Its got me stumped. Its still running fine now. Things is I don't know enough to know if it should be sounding different if the carb isnt actually doing anything or if it is actually working but there is a problem in the carbtune picking it up for some reason. Is there any sort of diagnostic test I can do to see if 1. The carb is working or 2 its just not working at all and the Carbtune is actually giving me the right info.

EDIT : Was just wondering if pulling the plug leads off 1, 2 and 3 cylinders and starting it only with number 4 attached that would tell me would it not if the carb is in fact working or not. Would it start on 1 cylinder ?

 

I only had that happen to me once Geoff and it was when my vacuum hose had not seated correctly on the "nipple" to give me vacuum pressure....
If not, maybe ..........some dirt in the vacuum point on the carb ?
If the carb wasn't working you'd def hear it running "lumpy" or only running on 3 cylinders....

 

Pete would it be worth taking the top of the carb off which that nipple is a part of and see if there is anything in there ? Would I need a new gasket or can I re use the old one. Sorry if I sound a bit dumb with regard to this. Carbs aren't my strong point....lol.

 

I'm with Shadow on this one Bordo.

If the bike was running fine (and you'd know if it was running on 3), it's got to be the vacuum nipple being blocked.

With it apart, swap over two leads say, 1 and 3 and see if '1' still doesn't register. That will narrow it down to the carbtune or the carb nipple.

Cheers, SB

 

Thanks guys,
I'll have another crack at it tmw after I get home from work and see how it goes. I just went out and did the plug wire thing. I started it on all 4 and progressively removed 1, 2 and 3 to see if it would run on 4 alone. It did for a little bit but then it stopped. I realise these engines wouldn't be happy running on one cylinder and I didn't expect it to stay running but it did rev a few times on number 4 only. Hopefully its just a blocked nipple. I'll poke something in the vacuum port and see if its blocked. If that doesn't work I'll take the top off and clean it out so if anything is in there that fell into the carb I'll be able to get it out. Cheers.

 

Should be able to use what's on there Geoff. Be careful with the membranes on top of the carb - if you tear one it's a bit of a disaster (unless you have some silicone and duct tape) You may even have a hole in one already.....??
I'd blow some air through the nipple if you can.
Switching leads 1 and 3 on the carbtune and getting the same "dead" carb - means the nipple is blocked or the carb has a vacuum leak.

Let us know what you find Geoff - always good to build up the info bank

 

So in simple terms for blokes like me......lol, Set it all back up after I blow some air through the nipple and while carrying out the sync swap over lines 1 and 3 on the Carbtune ? What will that tell me about the bad one though ? Sorry I'm a bit lost....lol.

 

Partially my fault Bordo, I was in a big hurry trying to get out to collect a gantry whilst it was still light, so rushed my answer.

Ok, between Shadow and myself you should have enough info to pin point the problem.

It doesn't sound as though your carb (number 4) is not working, It sounds as though the nipple is blocked on #4 or a small hole in the diaphragm.

You can hear (I assume) that the bike is running on 4 cylinders - a quick and dirty check is wet the fingertips and briefly touch the headers one by one. If one cylinder isn't firing (through lack of fuel or spark) it will be cool.

Now for me to pay attention and GET IT RIGHT



So, if (and I just looked back at your original mail) carb 4 is not registering on the carbtune, but we know that the engine is firing on all cylinders, it has to be either a problem with the carbtune lead or the nipple to carb 4 is possibly blocked. By swapping the carbtune tubes between 3 and 4 and still getting THE SAME reading on carb 4 we know that the nipple on carb 4 is the problem (or possibly the diaphragm). If carb 3 (after the swap) does not register, we know it is the carbtune lead itself.

Sheesh, I've got to stop sniffing Ajax.

Hope that is slightly clearer Bordo.

Let us know how you go.

Cheers, SB