Fuel & Carburetor

[Dannyralph86]

Ok seeker thanks.
I'll look at timing chain noise on youtube.

All the diaphragms were ok when I had the carbs apart but I will buy a seal kit and take them apart again.

I've literally run out of places to check for air leaks, also just wondering here, if it is an air leak why is the issue only when it's hot and ridden for more that 20 miles?

The mixture screws were set at 3 and 2.5 but the front carb had a leak before which I've now fixed, I'm almost certain it still wouldn't run at 2.5 turns so I had to put them back out to 3 and 2 3/4 when I changed the spark plugs the colour was perfect as they should be I'll get on it at the weekend and check everything again, I'll test the R/R, spark plugs, every single pipe hose diaphragm in the bike then
I'll set mixtures back to 2.5 turns and try to ride it.

If I find any issues I'll reply here for future reference.

Thanks again ��

[Seeker]

...digs out book entitled: "How I did things when I was a lad".

If you spray WD40 or carb cleaner on the inlet boots with the engine running it will change speed if there's an air leak from there. It isn't a totally reliable method admittedly but it's a starting point. 20 year old rubber components tend to get brittle and not seal as well with age. There was an old trick of spraying them with furniture polish (original Pledge) to soften them but that was when they were definitely rubber.

Is the tick over smooth or uneven?

Assuming you do have an air leak, I suppose you could try giving it a little choke when the engine is hot and see how it runs then. Beyond that, you might want to do a compression test.
What mpg are you getting, over the years I've had 2 curvys and would typically get mid 60s mpg (I'm a slow rider though).

[Biker Biggles]

You mentioned rust in the fuel filter. Could there be crud in the fuel tank that is intermittantly getting stirred up and blocking the line? Or------water in the fuel that is causing erratic running? A bit of a long shot with your symptoms but it is a common problem with old curvys as water gets into the fuel tank and settles to the bottom.

[Dannyralph86]

Thanks Seeker, I'll try WD40 on the intake boots, I had tried to remove them before but the bolts are well in there.

Idle is perfect, lovely and smooth, the ride itself has good power delivery as expected, nice and smooth all the way up to 100+ mph.

It really is faultless and then suddenly the symptoms appear, riding to and from work daily is no issue 10 miles each way, it's only when I ride further afield, originally I said about the lack of fuel because it almost seems like when you really pin the throttle the symptoms come on quickly upon slowing down.

Sure feels like it goes down to 1 cylinder intermittently and I had read on another forum the R/R caused these issues, perhaps I've got more than 1 problem as you have already said like an air leak on top of something else.

I was getting around 155 miles per tank, I'm not sure what that translates to in mpg but I accelerate hard to the national speed limit.

[Dannyralph86]

Hi Biker Biggles.

Yeah there was rust in the filter, I've tried to replace but the filter I bought is too big and sits on top of the engine whilst not letting the tank sit down.

I did run it down to the light and then some, drained the tank and refilled but I feel like it wouldn't hurt to take the tap off the tank and the fuel pump apart to ensure them diaphragms are intact and clean.

I will get a seal kit for the carbs and just strip them right down this time and replace everything.

The choke o rings are worn this could be causing the issue but the new ones are yet to turn up.

I sort of wanted as much info as possible from you lovely lot here before going crazy with buying parts I dont need.

[Dannyralph86]

Also I think there is 4.4 litres in a gallon so my tank is under 3 gallons, 155 miles per tank that's 4 miles with the light on works out at about 50 mpg

[Seeker]

Don't forget the screw heads are JIS not Philips, you'll need JIS screwdrivers. You don't need Suzuki o rings:
https://forums.sv650.org/showthread.php?t=230784
Bikes of that era were already being tuned for weak mixtures for pollution regulations, any air leak will make the bike run badly.