The beast on bike carbs

[360beast]

God damn it that's brilliant, please post a video of it in action!

My first instict with the vibration would be down to the engine mounts. My brother fitted heavy duty mounts to his 309 GTI and at idle the whole car shook like a sh@@@ing dog.

[andythepandy]

Yes classicsweded I wouldn't have thought it would be the mounts as they are solid. And yes video soon to follow I just need to work out how to do it. It didn't sound great on the gopro.

I think I may have worked out what it is. There seems to be a small air leak around the silicone tubing on the carbs. A quick fix has made a difference so it seems that has something to do with it. I'll do a proper job later and see what I can do

[360beast]

You can check if it is an air leak by spraying wd40 around the inlet manifold and any leaks the wd40 will seal for a second or two and will stop the shaking.

[andythepandy]

Cheers for the advice yes there was definitely an air leak around the silicone hoses which I think is sealed now but I'll probably wack some more sealant on it when I get time. But doing that has smoothed out the ride a hell of a lot more but now its running even richer and it stinks of fuel. I've spoken to Steve (the guy who tuned it) and he said he'll have a look at it and probably adjust the timing and fueling. He did originally tune it to be rich probably because of this problem but now its sorted he can lean it off a bit

[Maskinmester]

Well done!

I am planning to attempt the same setup.
But using cv-carburators from an yamaha R1.

How does / did it drive?
Did you ever get around to shoot a video of it beeing alive?

[Othen]

Wonderful.

The vibration at low revs sounds like the the pilot jets are probably too large. Tuning bike multi-carburettors from scratch is a process of going round the loop:

tick-over adjustment>pilot jets>main jets>needle jets>mixture fine adjusters>balance...

... quite a few times as changing one of them will impinge upon the others, and you have four of them. That may well be the reason the fuel consumption is very high as well.

It is a bit of a painstaking task (particularly with 4), one just has to be methodical and change one thing at a time, also make note about how each change affects the motor's running. If you have not done so already you will need to get (4 sets of) spare pilot and main jets (a couple either side of those fitted). It is a bit hit and miss with a multi carburettor set up because there are so many variables, I'd suggest dropping two sizes with the pilot jets first, getting the tick-over right, and only then moving to the main jets (which will probably be too large as well, but only change one thing at a time ... as above).

Good fortune, I'll look forward to hearing about it.

Alan

PS. I've just realised this thread is 4 years old. It suddenly ended, so I rather suspect the OP found tuning bike carburettors difficult (it is) - but I hope I'm wrong and the motor car is driving around somewhere, does anyone know if it is?

[Othen]

Originally Posted by Maskinmester

Well done!

I am planning to attempt the same setup.
But using cv-carburators from an yamaha R1.

How does / did it drive?
Did you ever get around to shoot a video of it beeing alive?

... the GSXR ones will be the CV type also.

Alan

[andythepandy]

Haha crikey. Been a while since I've posted on here. Glad to see there was a bit of interest on this project. Quite a bit has happened since I posted this originally!

And yes your assumption was correct. They are a bit of a bugged to setup

I started to do some jobs on the car before lock down. Mostly chasing a few gremlins and getting it to run a bit better but as I had more time during lockdown I thought I would take a few more bits off and before I knew it I found a whole host of ROT everywhere.

Much to my agony I decided to try my best to do it all properly. This involved taking all the underseal off treating the rust and retreating it all. This took a lifetime to sort! And I'm sure there are some bits I missed. There aren't many parts that haven't been taken out stripped back and redone. The two rear arches were completely redone. Parts of sills and soak aways. The petrol tank looked like it had been left under the sea for a few decades. The thing was not in good shape 😂

I also decided to do a load of jobs I've always wanted to do. I upgraded the audio system in the car, fitted alfa seats, rewired and tucked all the wires in the engine bay, repainted the engine bay, fitted a lumpier cam, fitted a through sill side exit exhaust and a load of other things I've forgotten about.

It needs to go back on the rolling road to get the carbs setup again but since all this I've gotten married, moved home twice, started renovating a house and are expect a little one. So at the moment it's near the bottom of the priority list.

HOWEVER! I have been thinking about getting stuck into this old girl again as there isn't a hell of a lot to do. I'm sure I've got some videos of it somewhere so I'll try and find them. Hopefully at some point I can actually stick some photos up of it and post a better update!

[Othen]

Originally Posted by andythepandy

Haha crikey. Been a while since I've posted on here. Glad to see there was a bit of interest on this project. Quite a bit has happened since I posted this originally!

And yes your assumption was correct. They are a bit of a bugged to setup

I started to do some jobs on the car before lock down. Mostly chasing a few gremlins and getting it to run a bit better but as I had more time during lockdown I thought I would take a few more bits off and before I knew it I found a whole host of ROT everywhere.

Much to my agony I decided to try my best to do it all properly. This involved taking all the underseal off treating the rust and retreating it all. This took a lifetime to sort! And I'm sure there are some bits I missed. There aren't many parts that haven't been taken out stripped back and redone. The two rear arches were completely redone. Parts of sills and soak aways. The petrol tank looked like it had been left under the sea for a few decades. The thing was not in good shape 😂

I also decided to do a load of jobs I've always wanted to do. I upgraded the audio system in the car, fitted alfa seats, rewired and tucked all the wires in the engine bay, repainted the engine bay, fitted a lumpier cam, fitted a through sill side exit exhaust and a load of other things I've forgotten about.

It needs to go back on the rolling road to get the carbs setup again but since all this I've gotten married, moved home twice, started renovating a house and are expect a little one. So at the moment it's near the bottom of the priority list.

HOWEVER! I have been thinking about getting stuck into this old girl again as there isn't a hell of a lot to do. I'm sure I've got some videos of it somewhere so I'll try and find them. Hopefully at some point I can actually stick some photos up of it and post a better update!

Wonderful! Not only is this thread now 7 years old, but you have responded to my posts about carburettor tuning which are 3 years old. Thank you.

I wonder, did you ever get the motor running properly on 4 CV carburettors? I'm fascinated by this, I've balanced and tuned many motorcycle multi-carburettor motors, but never tried to do it from scratch. I've always had the manufacturer's settings that were more of less right for a particular motor - if you have managed it from scratch then Chapeau!

[andythepandy]

No worries. I usually take much longer to reply to messages 😂

I can't take any credit for the tuning fo the carbs as it was done by a guy called Steve Walton near Sutton Coldfield. Does brilliant work. He got it running really well and asked me to bring it back after running it for a few months to tune out any issues and finesse it a bit more

Just before I put it in the garage to work on it I think of injectors may have gotten clogged up as it sounded like it was only running on 3 cylinders

Hopefully when I get a chance I'll a look at it get it back on the road