Question for an experienced spanner man. I mean person.

[The Other PaulG]

Hi all -

I am looking for a bit of wisdom, please.

I am overhauling the carbs on my GPz900R. Today I wrestled them out - it was a remarkably difficult job, given the very tight space between air filter box and the rear of the engine. The air box moves backwards, but only by maybe 20mm. The frame rails and other gubbins make accessing the carbs from above impossible. So the carbs are now out and being sorted (getting rid of varnish and hopefully sorting overflowing float bowls. The diaphragms / needles looked to be in good nick). The carb rubbers, by the way, were also OK - still pretty flexible.

Here's my question. There is no doubt that getting the carbs back into position is going to be an incredibly hard job. Lining up and properly seating 8 rubbers to the carbs simultaneously, with almost no access at all to carbs 2 and 3, will be a very significant challenge. So, please, for those with experience of doing this on any UJM, what are the tricks / techniques that will help me?

Cheers,

Paul

 

[Neil W]

How soft are the carb to airbox and engine rubbers , if they have gone hard it is nigh on impossible to refit the carbs .
They can be softened up with either a hairdryer or removing them and steeping them in a concoction of Oil of Wintergreen (look it up) .
On large older Suzuki fours you can also undo the airbox mounts which allows it to be pulled an inch or so backwards which gives you the space if the rubbers are pliable .
Best to get the carbs set on the engine mounts first and tighten the clamps and then you can usually if you need to access the airbox rubbers from inside box itself

 

[deangsadv]

As above really, have a look on YouTube for Ash Rowland, he’s just done the same thing on a gpz he’s in no way a professional but got it done. Good luck.

 

[The Other PaulG]

Best to get the carbs set on the engine mounts first and tighten the clamps and then you can usually if you need to access the airbox rubbers from inside box itself

Aha! Thats clever, I would never have thought of going through the air box.

The carb to engine rubbers are quite hard, the carb to airbox ones are quite pliable. The airbox is already pulled back it’s full 20mm or so.

Thanks Dean I will look up that video.

 

[The Other PaulG]

I will also lube the rubbers before reassembly.

Should I use silicon spray lubricant, or red rubber grease?

 

[Nin]

Make sure the rubbers are warm (ooer) and just a bit of wd40 will help them slip in (matron!). Cylinder head side on first, if they are thicker rubber.

 

[steve hughes]

I will also lube the rubbers before reassembly.

Should I use silicon spray lubricant, or red rubber grease?

Paul , pretty sure the lads on the Kr1s forum used wintergreen oil on the carb inlet rubbers to keep them soft and ease installation also prevent cracking on older less flexible rubber. I cant comment as mine were new from Z Power and I just used a bit of Vaseline

 

[DrFarkoff]

I will also lube the rubbers before reassembly.

Should I use silicon spray lubricant, or red rubber grease?

I am loathe to put WD40 near ANY rubber component on a motorcycle

What about MikeP's beloved Sonax Gummi Pflege actually helps make Rubber more pliable and doesn't cause any damage

I used two "sticks" on the roof seals of Madam's Megane convertible and no more leaks

 

[leadfarmer]

Just a thought, but whilst it’s all in bits would it be worth replacing the rubbers with new ones if they’re not too expensive ?

If they’re hardened off and you put them under stress when you put it back together they might crack in the near future

 

[Oldrat]

I’d agree with replacing the rubbers Paul if practical.
Imagine all that work only to find that you disturbing them has started a crack forming.

I don’t know about Wintergreen, but that or Gummi Pledge must be worth trying if keeping the originals.

 

[Santa-2512]

I bet the rubbers are as hard as nails , which will make them very unwilling to bend or compress

get some new ones and drop them in a pan of hot (off the boil) water for 10 mins, they will be like butter

 

[Mad Hatter]

Definitely get new inlet rubbers or you could end up with air leaks. Lube with silicone grease.

 

[squibb34]

I would have thought modern tyre mounting soap would be ideal. New rubbers will likely make things easier & avoid potential cracking/air leaks.

I have to confess, when I last played around with a top end job on the wife's ZXR, that had dropped a valve head, I seem to recall using a tiny smear of washing-up liquid as an expedient.
If you then take time balancing the 4 carbs accurately, it certainly pays dividends.

 

[theoneandonly]

take the inlets off , get the airbox ones on , then put the inlet rubbers on , dowse the rubbers with hot water , then push the carbs on .
take out plugs and crank engine , to expel any water that may have got into the cylinders .

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£29 each x4

as they are tubes , not bolted to the head , much easier to do .

 

[xsgraham]

Not sure if you're sorted yet Paul - have the same thing on my Z1000.

A forum for old Zeds recommended pushing the airbox rubbers into the box too far (there's a double flange in the rubber as I recall) and fitting carbs onto the inlet rubbers bolted into the head. You then need to pull / tease out the airbox rubbers whilst fitting them onto the carb mouths. Its not easy but I managed it a couple of times (don't ask) during the rebuild. You can't push them out by reaching inside my airbox as there's a mesh screen mounted in a frame inside it.

Tackling it soon for the third and hopefully the last time soon. Baldricks suggestion above sounds tempting though...... I may try that first. If you follow the way I've described be prepared for skinned knuckles

 

[The Other PaulG]

Thanks Graham. I am still at the stage of trying to eliminate the flooding of carb #2 on the bench, the last one giving me trouble, before I attempt the gynecology / re-fitting.

All advice hugely welcome though - I now have a range of ideas - a fortnight ago I had none!