Now then, here's a problem I am really stuck on.

My 2002 xjr was Ok one day but the next started to run very rough. I checked the plugs and I found that No. 1 plug was black with carbon so I changed the plug but this did not make any difference.

I put a new set of plug caps on. Again no difference. The spark wasn't bad but there was the possibility of a damaged HT lead. However the HT's from the coil are fixed I so couldn't just change them and had to buy a new coil. Hmm, lovely spark but still no difference. OK, strip the carbs and have a look.

HORROR!! No1 carb slide had a big burn hole in the back - the air filter side, not cylinder side, so I removed the cards and stripped the airfilter. Inside the inside of the air filter (on this side) was burned/melted and full of petrol. This was not good, so - carbs stripped right back, float chambers cleaned and checked, main and idle jets cleaned, chokes stripped and cleaned. A new piston, diaphram and needle purchased, petrol tank tap stripped and new kit fitted as this was leaking some petrol when the tank was removed and everything re-assembled.

Flippin' heck, same thing, misfiring (running on 3 cylinders) and plug still carbons badly up on No1. Also now I can see a small intermittant backfire on No 4 carb, but this plug colour is OK. Cylinders 2 and 3 fine, no probs. Soooo - any ideas please??

Thanks in advance

do a compression check jasper, seems like maybe the inlet valve isnt seated right , compare it to one of the good cylinders

Thanks Airhead, good idea, only problem is we retired to Brittany last year and although learning the language only have a basic working knowledge at the moment. This should make for a very interesting converation with the Yam Garage in St Brieuc hahahahaha.

All the best

use google translate and print out what the problem is and ask about a compression check

Hi buddy

Google translate - thanks for the suggestion and although it's Ok for the odd word or 2 its often nonsensical on sentences, eg "a la rigueur" means "or even, if need be, in a pinch, possibly" but if you translate it becomes "a discipline" Speaking isn't a major problem it's the listening that is difficult -very fast and they miss the ending off all words so "au revoir" ( goodbye) sounds like "avoir" (have/having). We're getting there but "passe compose" has me floundering " je me suis leve" - i me am lift (I got up) hahahaha

Again thanks for the advice on the valve. I have just read up on this idea and it seems likely this is the area for concern, but it may be a case of shipping to the UK to get sorted.

Thanks again, Safe riding

haha never experienced it, never really got further than junior school french! obviously youre way in front of me .

just a thought we have a new member 'cerd' he is french i wonder if he could help?

shipping it back seems a bit expensive??