3TJ Carb balancing problem

[quality]

Hi Guys and Gals,

I have had a go at balancing my mikuni carbs on my 3tj today but couldn't work out where to connect the hoses for the carb balancer. I might be being really thick but don't want to undo something I shouldn't! If anyone can let me know if there are spigots to push the hoses onto or screws to undo to screw adaptors into and where these are, please let me know. If you could also put up a piccy that would be brill!!

Cheers.

[buntz]

i think mine has screws/ bolts in and they are below the carbs on the rubber inlet, cant help with a pic mines at the dyno.
buntz

[Evilchicken0]

Yup they're on the inlet manifolds. You'll have to take the carbs off to get the pipes on so you might as well give them a clean up first.

[quality]

Cheers guys,

Fathomed it out and then realised that I needed 6mm adaptors for the carbtune! Got them sent for and set about it tonight. Cylinders 1 and 2 were perfectly balanced but 3 and 4 were way out, although 4 was close to the readngs for cylinders 1 and 2. This explains my lack of top end at Cadwell a couple of weeks ago a little. Tried balancing 3 and 4 and just about managed it before trying to bring 1 and 2 in line with 3 and 4 and found it impossible to do as cylinder 3 reading would not alter and it ran like a bag of spanners. No amount of fettling would alter the gauge reading for 3. Lots of service manual checking later I'm hoping its the valve clearances that are out, especially on cylinder 3, causing the problem. The carbs are in good nick, plug gaps checked and adjusted etc. Valve clearances are getting done next week and then I'll try balancing the carbs again hopefully with success this time. I'm hoping its nothing more serious, what does anyone else think, does this make sense?

[Evilchicken0]

When I had mine done I think I had them set up as 2 and 2 matched I think it was inner and outers.

[quality]

Hi Evilchicken,

Great name by the way! You've lost me a little on your last post, could you post again? I understand that you set up 1 and 2 together, then 3 and 4 together, and finally 1/2 against 3/4. Do you think the valve clearances could affect balancing, ie my cyclinder 3 reading not coming into line?

[Evilchicken0]

But your name's quality.

I didn't set the carbs I did a great job of watching
They were set 1 to 2 and 3 to 4 ... only. The guy said that he'd try to get all 4 the same but it's wasn't pracitable. That's not to say it couldn't be done but you might have to have the engine completely dialed in. checking the valves is a good move especially if you use it at high revs, it's one of the things that wear.

If you run an exup check it's adjusted properly and maybe compression test (wet and dry) will help too.

[quality]

Yep, a compression test will help I agree. Should tell me if there is a problem with rings or valve seats etc. I'm not getting any smoke on start up and not on running which hopefully might mean its just the valve clearances. Its in for the valve clearances next week so will get a compression test done at the same time, once the valves have been done. If this comes back clear and the valves were way off, problem solved, if not I reckon a carb strip down would be my next option. Here's hoping its just valve clearances, track day looming and all!

[quality]

Hi Guys,
Great news!! Bike now fully sorted. Had a compression test done, dry and wet. Valve clearances checked and all slap bang in the middle of the right range so not that causing my problem but peace of mind. A full carb strip down and clean, blow out jets with compressed air etc followed by checking float chamber levels and mixture and reassembly sorted the problem. Carbs then balanced up a treat! All 4 carbs were full of crap and well choked up. It now pulls like a train, starts easy, idles great and sounds all round fantastic. I am just going to drain and flush the tank now and fit a new fuel filter just to complete the job.

Bring on the next track day, should get round a good bit quicker now!

[Evilchicken0]

Cool - jobs a good one then :)