Newbie to Cats

Eyup!

The names Reece and I recently bought my first Cat. Its a 2001 model in red and the PO's taste is questionable (sorry if they're on here! )... a half pink seat, pink handles on the rear, Tasmanian devil stickers everywhere, LOTS AND LOTS OF CARBON WRAP, a giant cat sticker on the windshield and to top it off metal spikes in the screw holes that hold the screen on! The good points are that they fitted a digital speedo and LED lights and heated grips (not sure if these work.

I bought the bike last week as a none runner with no MOT. It turns over, has good compression and seemed in good shape. Anyhow fast forward to yesterday where I took delivery of the Cat and I managed to get it started within 10 minutes with assistance from some easy start (I know, don't judge... I just wanted to see what the engine sounded like). It wouldn't stay running on its own and since it had been stood for 5 years (my assumption based on when it last had an MOT) I decided to pull it apart and have a go at the carbs. Other than a few strong words, a lot of grunting from me and rounded off screws from the PO, I managed to get them off - HOW MUCH OF A PAIN IN THE A**E ARE THEY TO REMOVE?!

I'm not a stranger to the inside of a carb body, my last bike was a 1982 Yamaha XJ650 Maxim US Import, also a none runner (I can see a theme starting here), which I broke apart from the rack and completely stripped down changing all seals & cleaned up the insides in an ultrasonic bath.

On the Cat I've not taken them from the rack. I've taken the tops and the bowls off, removed all screws/jets/needles including A/F mixture (counting the current setting they were at and setting back to it... all were 1 & 3/8ths out as they are at factory setting) and blasted with carb cleaner and sprayed all orifices that I could see. They weren't as gummed up as a I thought however they were coated in varnish and had oxidised after being stood for so long so I used the trusted boil in water with a splash (bottle) of lemon juice thrown in for good measure... they came up a right treat!

So that is where I'm at at the moment. I lost a lot of coolant when I took the carbs off even though the pipe was kept upright so I'll need to flush the system and replace that whilst the carbs are off.

My next steps are to give it a service: oil, oil filter, air filter, spark plugs and clean the chain up/check tension. I'll then rebuild the carbs once the new gasket seals arrive and then balance them using the Morgan carb tuner pro that I have - amazing piece of kit.

I do have a carb related question which I'll post in the fuelling section of The Workshop so if you read this please check that out for me!  

Here's a link to my Google Drive where I've added a few pictures that I've taken as I've gone along. They're not in any particular order and are mainly reference points for me to show me how it came apart as well as showing some before and after cleaning pictures.

Oh and if you made it this far, my favourite biscuit is a chocolate hobnob!

Happy riding!
Reece

Hi Reece, welcome. Sounds like you are doing quite well at sorting out your new 'Cat. Sorry can't help with the A/F settings. My second had carb issues and no one I took it to could sort it out - all telling me the carbs were fine. The dealer wanted more than the bike was worth to look at it and showed zero interest till one day I finally had enough and px'ed it. It spent about 4 months in the workshop - the problem? Carbs, a previous owner had turned screws randomly. Little wonder it was never right.

My bike before the 'Cats was also a 1982 XJ650, mine was the turbo, or in US parlance the Seca.

Thanks Steve.

I had read your story on some posts whilst doing my research prior to the bikes delivery. Very unfortunate. Especially with the mechanic not wanting to tell you!

I’m hoping that this won’t take more than a week to get fixed and an MOT slapped on. I’ve got a couple of bits on order including a new pump to tank fuel pipe as it had a kink in it.

The xj650 I had was naturally aspirated and air cooled. It’s final drive was shaft and it was soooo smooth. I regretted selling it but it needed work doing that wasn’t worth the price of it so I parted ways.

There’s always a satisfying feeling knowing your hard work pays off.

Hello and Welcome Reece. 

Glad to see you're hitting the ground running with the Cat. Sounds like you have things well in order. 
I'm no good on the mechanical bit of biking (in fact if you ever see me with a spanner in hand, take cover), so I'm afraid I won't be of any practical mechanical assistance.

Its nice to note you've made yerself  at home in the workshop section with your research.

Perhaps, one day, when this covid situation is under control, you'll be able to join the group socials from the "Something for the Weekend" section.

Good fortune sorting your Cat in the meantime. 

Stay Safe, Cheers 
Tel 
0c

Thanks 0c

I’m just on the hunt for some new carb inlet rubbers now, brand new are VERY expensive...

I hope to get out on some meets eventually, I’m in West Yorkshire and from what I’ve seen there’s a fair few people local on the forum. I only passed my bike test last year so have little experience/confidence that I need to build up. But I’ll get there one day!

Thanks

Hi & welcome, you sound to be making great progress, well done for bringing an unused unloved cat back to life & best of luck.

paul

Hi Reece

Welcome aboard.

Chocolate Hobnobs and Thundercats....winning combo.
I see what you mean about the pink seat/handles and screen "spikes".....not my cup of tea either.

Good luck with the carb strip/re-build. Hope it doesn't work out too expensive.
I've got a fuelling issue with my "spare" cat that is festering the garage so will be watching with interest.

Taste of Lincolnshire this year is hopefully still going to be going ahead in September if you are up and running and fancy a group ride out then.
Failing that Wee Mac 2021 will be in May and we normally have chocolate hobnobs.

Details of both are here.... https://www.yamaha-thundercats.org/f25-how-about

Cheers
Rosco

Hi Rosco

Indeed it is a winning combination! I’ve managed to reverse a lot of the cosmetic damages done by the PO... the covers come off with little resistance and the original seat cover is in excellent condition, the rear grab handles were just sown on. The stickers I peeled off with some heat and I’ve taken the carbon wrap off of the frame.

Cost wise I’m not in that deep... at least I wasn’t until I realised I needed new carb to engine inlet rubbers and @ £70 a set, they’re not cheap!

Have you done any detective work with your fuelling issue? Kinked pipe, split pipes? Have you opened up the carb bowls and had a look to see if it’s gummed up?

Out of interest, is it at low speeds or top end where you have the issue?

I’ll look at the link you posted, I’m tempted by the offer of biscuits!

Cheers
Reece

BiscuitLover wrote:
Have you done any detective work with your fuelling issue? Kinked pipe, split pipes? Have you opened up the carb bowls and had a look to see if it’s gummed up?

Out of interest, is it at low speeds or top end where you have the issue?

I’ll look at the link you posted, I’m tempted by the offer of biscuits!

It was only 10 months ago......I might have washed it since then but not much else.
I just wheeled out the spare thundercat and started using that one instead.

I'm sure the others that were there that might be a bit more technically minded (and / or have a better memory) will correct / add to the story but......

This was at Big Mac 2019 and we were way up north roughly in-between Inverness and John O'Groats.
It got me there without issue and over the course of the weekend there was a consensus of your bike smells of petrol by folks sat behind me.

Eventually it conked out and wouldn't start and it had run out of fuel (coz it was using so much).
Managed to bump start it and fill her up and limped it back to the digs and couldn't get it to start after that and had to get recovered home.

Battery wasn't strong enough to turn her over and couldn't bump start her but managed to borrow a jump starter from neighbours.
It couldn't turn the engine either.

Put it in a higher gear and managed to push the bike backwards and forwards and fuel would pish out the exhaust.

Took the oil cap off and it stunk of petrol too.

I "think" the general consensus from the local experts was that there was probably a cylinder that was full of fuel (which meant the engine couldn't turn) and this was likely caused by a problem with one of the carb's causing fuel to leak into the oil.

I don't normally go above 1.5 spanners on the Haynes so i've just been hoping it'll mend itself in the garage.

Maybe it's something like this.... https://www.youtube.com/watch?v=HrChrTOb3HY to blame.
It's on my to do list.

Cheers
Rosco

'The spare thundercat' - humble  

Joking aside,  I'm far from a mechanic - (I'm a pencil pusher in a mortgage department that enjoys tinkering about) I just took a quick peak online on how to clear a flooded engine/cylinder and found this link

Once you've done that, you should probably look into the carbs in more detail. Sounds like you're running mega rich, could be a number of things but I'd be cleaning it out first and checking A/F mixture screw settings. Oil will DEFINITELY need replacing before you try to restart the bike...

As for your battery situation, and I'm jumping the gun here so feel free to ignore this, if the battery is strong enough to turn the engine once the engine is drained then its happy days. If not and it isn't charging, there could well be an issue with your charging system but I remember seeing a YouTube video I'll see if I can find it... found it! where the guy was doing a track day and he found that his wire connector plug had melted and fused itself together preventing the battery from being able to charge. Watch from 5.06 to 8.54 to save watching the full thing. He basically cut the connector out and connected the wires up.

Edit:

I've only just realised that you've posted a link to a YouTube video... that's a good spot. May be worth checking that out alongside A/F mixture.

Thanks Reece.

Looks like your trying to flog me tyres with your first link.
Was that a test?

I’ll get to it all eventually and post something up with the hopefully positive outcome.

The battery is fine....it just drained with all the attempts.
Hopefully only having to change the oil / filter once.

Cheers
Rosco

Well I definitely posted the wrong link I was looking at some new tyres and copied the wrong one.

I have bad news and good news today.

Good news first (my favourite kind)... she runs!! I got her ticking over nicely.

This is short lived though... the bad news... I couldn’t get her to rev over 4K. She just kind burbled and died whenever I introduced throttle. During my excitement I forgot to check the cylinders to see if they were all running and then in my haste to fix the issue I started taking the carbs back off. I then realised the engine was hot and wasn’t a good idea so I’ve put it away for the night...

I’ve got the day off work tomorrow so will be toying with her again first thing. It’ll be a carbs off job, double check everything is seated correctly/still clean. Put them back on, fire it up, check the cylinders. And if that doesn’t work I’m stumped.

Wish me luck!

Good luck Reece.

Fingers crossed the “fix” will be in your grasp tomorrow and looking forward to hearing the next instalment.

Cheers
Rosco

Thanks Rosco, I feel like I need the luck!

I’m hoping it’s not electrically related, i.e. coils, spark caps etc. I know nothing of electrics.

So... I'm stumped guys.

I’ve had the carbs apart again and they're as clean as a whistle. I put everything back on, all air pipes, air box etc. Runs and idles but it sort of surges. I hooked up my Morgan carb tuner and got them close together. Revs a little but not a lot. Turning choke on kills the bike. I’m thinking maybe an electrical issue with the coils, I’ve bought a spare set and will fit them when they arrive. If that doesn’t fix it then I’m out of ideas.

I did the water test and cylinder 2 isn't as hot as the others. Its running but it surges. I've added a video of the bike hooked up to the carb tuner and you can see cylinder 2 is down.

Will give an update at the weekend once the coils turn up!

Thanks

Try swapping plugs 2 with 4, if that dont work

Try swapping HT leads over, if that dont work

Try swapping coils over, if that dont work

Put’s you back to the carb’s, or low compression on No2

I think.....

Davie..

PS: not a mechanic...

PPS: if anyone thinks of anything else pop it up...

EDIT:::: try spraying soapy water over the hoses looking for air leeeeeeeeks...

The coils do two cylinders, so less likely to be a coil, however the leads or the plug cap can go bad, so can a plug. I've had a coil go and you know all about it, the Thundercat makes a terrible twin No harm in getting a spare and testing/eliminating that.
As Furballs suggests, try changing the plug with another cylinder and see if the problem follows the plug. An outside chance, is the #2 plug in tight enough?

Thanks both

I've not swapped them out. Todays heat wiped me out!

i'll try again after work tomorrow and do as Furball suggested.

0c - I made sure they were firmly in place! I did do some testing on resistance and struggled to get a reading out of the sparks caps on 1 & 4. Here's a pic in my scruffy hand writing showing my readings.

One question I did have was that the Haynes manual says the caps should be 10k Ohms at 20 degrees... on the side of the caps it says 5k ohms and the readings that I could get were close to 5k. Does that make a difference?

Sorry those carb settings are way out of balance, check your throttle position sensor, difficult to tell from a recording but it still sounds like a carb fault, have you checked the float levels and fuel filter? Now you've got the carbs and coils off it might be a idea to check the compression readings if you've got a tester. Also check the valve clearances, I would be surprised if they're out of adjustment but it's worth checking now you've moved most of the crap out of the way.
The bike I've just SORN had a uneven idle when upright but was ok on its side stand, never bothered to adjust the float levels just lived with the uneven running till the MOT ran out then put the replacement bike on the road.

Hi past-it

Yes I noticed that earlier and I did manage to get them lined up equally however I still couldn’t get past 4K. So now I’m thinking about it clearly (instead of a sweaty mess stood next to a bike in 29 degrees) it could be carb related as you said. I didn’t check float heights as I couldn’t see how to check those, the only way I could see to check was using a fuel pipe alongside the carb body.

If I’ve managed to align the carb balance, surely that would suggest the compression is fine? It doesn’t explain why #2 is still not as hot as the others though.

Throttle position sensor was checked right at the beginning and was within spec... also has a new fuel filter.

I’ve not checked the valve clearances either, looking through the history of the bike it had a cam chain fit and I assumed the valves would would have been done at the same time.

As mentioned before I’m no mechanic so any help is appreciated!

Thanks

When it's running spray the inlet stubs with WD40 and see if the revs rise, could be a air leak between the carbs and head.

Fitted brand new rubbers last night mate. I’ll still spray to check though

Update:

Valves checked... in spec.
Float levels are spot on.
TPS is in spec.
Sprayed wd40 and no increase in RPMs.
Don't have a compression tester so can't rule that one out.

One thing did spring to mind though and that is that the bike feels as though it is being starved of fuel. I've checked for kinks and there is none. Tried with and without airbox on, still not able to get past 4k revs.

These leads me to believe the fuel pump may be at fault and isn't able to keep up with fuel demand post 4k revs. I've not taken it off to test however I've ordered a new one for £20 (aftermarket fleabay pump) so will fit that if it turns up at the weekend.

Will also test the resistance on the new (used) coils prior to installation on the bike and see if I can make 2 good ones out of the 4 that I'll have. If my issue still persists after new pump and coils, then I'll have to either invest in or find someone with a compression tester.

Coils turned up this morning. Much closer to spec than the ones on the bike. Will put them on today and see what happens. Failing that, fuel pump is due tomorrow.

Are you absoultely sure that all the jets are clear? The holes are quite tiny and can easily get clogged up with residue from old petrol, and even ultrasonic cleaning doesn't always shift it. I've found blasting through with carb cleaner from an aerosol usually does the trick.

Good luck - Bob