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Force-V4 Forum Index » RC30 Discussion » RC30 Recommissioning: Fuel Leak

 
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Boggie



Joined: 06 Jul 2021
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PostPosted: Wed Jul 07, 2021 12:05 am    Post subject: RC30 Recommissioning: Fuel Leak  


Evening All,

First Post Newbie here. On Sunday, I bought a 1989 RC30 at auction. It's the bike I have lusted after since my 20s, when they started cleaning up on the Superbike circuits. I was at the Stafford Classic Bike Show, looking for some parts for my 66 and 79 Bonnevilles, and spotted the RC in the auction. I started waving at the auctioneer and the next thing I knew, I had bought it.

The bike is in very good condition generally, but needs recommissioning after being in storage for a while (carbs and tank drained). I selected a high gear and rolled her forward to check the engine turned over freely. Then, after checking she had oil, coolant etc, I put in a half litre of fresh 97RON, turned on the fuel tap, pulled out the choke and hit the starter.

The oil light extinguished almost straight away and after a few short seconds, she coughed. So I tweaked the idle adjuster up a little and tried again. She burst into life with that familiar BigBangCrank sound. Lovely! I planned to let her get up to temperature, to look for any issues, but it didn't take long....

There was a strong smell of petrol, and a small puddle forming under the engine! So I shut her down and removed the tank and airbox. No sign of any obvious pipe issues and the tap seemed OK. So I took the lower fairing off and found that the LH side foam pad was soaking wet with fuel. Presumably from the LH carb area.

Any thoughts please? Sticking float or needle valve causing flooding and overflow? Lose drain plug? Float chamber gasket? I might strip the carbs and put them through my ultrasonic cleaner, then rebuild them with rebuild kits (assuming they are available), but would really appreciate any input first.

Thanks,
B
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Vfxdog



Joined: 12 Jun 2011
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Location: California

  

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PostPosted: Tue Jul 13, 2021 1:27 pm    Post subject:  


Sorry it's taken a while for you to get a response. A bit quiet here at the moment.

You almost certainly have at least one stuck float or a dirty float valve. It happens even if the fuel is drained down, although that's not a bad thing to do when a bike is being laid up.

There's no easy fix, really- you will have to pull the carbs off and go through them one by one. What you can do to save yourself some time before pulling the carbs, but after removing tank and fairings, is to push a 15" length of clear plastic tubing onto each of the floatbowl drains, then route the open ends up so they're higher than the carbs. Loosen the screw on the floatbowl drains, and put a fuel feed to the carbs. You'll see the fuel level appear in the clear tube and it should (from memory) stop at a point about halfway along the joint between floatbowl and carb body.
Level should be the same in all four tubes, but the level of the dodgy carb will go much higher than the others, and in fact will try and go to the level of your fuel feed.
Be very careful that you don't allow too much fuel to run out of that carb into the intake, as you could end up with a bent rod (hydraulic lock) which is far more troublesome to sort than a sticky float.
If you lay the bike up again, I'm a big believer in racing fuel (VP is my favourite) and also a product called Seafoam which sounds like snake oil but works amazingly well as a fuel preservative.
Hope this helps.
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Busy Little Shop
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PostPosted: Tue Jul 13, 2021 6:58 pm    Post subject:  


Is the Ron97 leaded???
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Andy
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PostPosted: Tue Jul 13, 2021 8:10 pm    Post subject:  


Busy Little Shop wrote:

Is the Ron97 leaded???

No leaded [pump] fuel in the UK any more, Larry. Can you still get pump unleaded in any form in the States?
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Boggie



Joined: 06 Jul 2021
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PostPosted: Thu Jul 22, 2021 12:09 am    Post subject:  


Thanks for the replies!
Yes, that's pretty much what I thought too. I have ordered 4 sets of genuine Honda gaskets and seals, plus 4 new rubber inlet pipes. As part of the recommissioning works, I could strip the carbs and clean them in my ultrasonic cleaner. Any tips on removing them please? I assume they cannot be removed together, so the top plate has to be taken off first, then each carb separately? When refitting, arebthey easy to balance?
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Vfxdog



Joined: 12 Jun 2011
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PostPosted: Fri Jul 23, 2021 12:50 pm    Post subject:  


Leave the carbs attached to the top plate otherwise you are letting yourself in for a world of pain getting the linkages all back in the right place.

It's not easy to get the carb assembly off (or on) but thats what you need to do. Make sure you undo all the clamps so they are really loose, and make a note of the orientation of the screws so you know how the clamps are located when you put the carbs back on.

You will find a nice piece of 2X1 timber can be used as a lever to help pop the assembly away from the head.

You then need to find an ultrasonic big enough to take the assembly, or even half the assembly.

Putting them back on will be easier, especially with new rubbers, but it is still useful to have a good collection of swear words. Balancing is not too hard as long as you have the correct screwdrivers to let you get at the adjusters. I use a Morgan Carbtune but most carb gauges will be fine. You will have to set up a temp fuel supply, as one of the vacuum stubs normally controls the fuel tap.
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Boggie



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PostPosted: Fri Jul 23, 2021 11:24 pm    Post subject:  


Sound like fun!
I happen to have the Morgan carb tune, so I will use that to balance them. Is it only the rubber inlet tubes that hold the carbs on?
Cheers Ian
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Vfxdog



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PostPosted: Mon Jul 26, 2021 11:17 am    Post subject:  


Yes, although they won't move very far unless you disconnect choke and throttle cables!
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Boggie



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PostPosted: Sat Jul 31, 2021 2:53 pm    Post subject:  


OK. Carbs are off. I fitted a gravity fuel supply and found all 4 carbs were leaking from the float bowl covers. Taking one off, I can see the rubber gasket is no longer sitting proud of the gasket channel, so not touching the carb body all the way around. New gaskets on order.

On question on synchronisation: the adjustment screws are on the underside. How easy will it be to sync the carbs on the bike? Is there a trick to it?

Thanks,
Ian
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Vfxdog



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PostPosted: Sun Aug 01, 2021 4:47 pm    Post subject:  


You'll need a right-angle screwdriver- preferably the bevel type. Motion Pro make a good one. Needs to be long enough to reach the adjusters with engine in the frame, but compact enough to fit in the limited space below the carbs.
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Boggie



Joined: 06 Jul 2021
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PostPosted: Mon Aug 02, 2021 9:08 am    Post subject:  


Oooh, I like that! Just ordered one. Thanks for the recommendation!

I have statically synchronised the carbs by using 4 lengths of 20SWG stainless wire, one in each carb and setting the throttle opening on each do that the butterfly only just grips the wire. Then carefully adjusting the balance screws so that the slightest touch of the main throttle spindle causes all four wires to simultaneously drop. I find this a good way to bench-set carbs before refitting. Sometimes they are spot on, and don't need any more adjustment. Rarely though...
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