Advice needed please!

[Craig J]

I'm having a couple of problems with my TJ and wonder if any of you guys can offer any solutions?

It doesn't want to rev on full throttle, when it gets passed about 7k. It struggles to pull up the revs in a kind of spluttery jerky way, if I back of the throttle a bit it pulls fine.

I've had the carbs off, the slides are all fine. One of the main jets was blocked, which I've cured - thought this was the problem, but pissed off to find that it didn't cure it! If you spray carb cleaner down the main jet, should it squirt out one of the holes on the air inlet?

Gonna put some new plugs in this afternoon, see if that sorts it, but not holding my breath...

The other problem I'm having, is when I'm in traffic and the bike starts to get hot - about half way up the temp gauge - it doesn't idle well and sometimes cuts out and really struggles to start. Could these two issues be related?

Any ideas would be much appreciated...

[castrol101]

If it dies at idle when hot this indicates a very rich fuel mixture. Take the A/F screws back to standard and take it from there.

I think your carbs just need sorting, check you float levels too if you know how.. Is the end of the exhaust full of very thick black soot?

Carb cleaner is meant to be sprayed down the body of the carb while the engine is running. But yes the jet does feed into the main body of the carb, when the bike is running the fuel is sucked out of that hole due to the air flowing through it, that is why carbs are thinner at one end (venturi) to create the pressure difference to suck fuel.

Also with regards to carb cleaning I find those small 'shots' of redex that you can get from halfords for about £1.60 do a great job!

Hope this helps.

[Evilchicken0]

Could you have put the main and idle jets in the wrong way round or still have dirty main jets ???
Does sound like the carbs are all over the place though. Maybe the emulsions tubes are ovalled ... personally I think I'd look for a set of second hand ones and see if they run the bike better it would be cheaper than a dyno run and easier than chasing the problem round the various adjustments

[Craig J]

Cheers for the suggestions...

Plugs didn't solve the problem, but the old ones were quite corroded at the top so it needed some new ones anyhow!

I did have 100 and 102.5 main jets in, which I've returned 97.5 and 100, which had no effect. All the other settings on the carbs are standard. Next job is to check the float heights I reckon, any ideas how I would go about doing this?

Getting some second hand carbs would probably be a good shout, if not just to eliminate the carbs as the problem! Anyone near to Sheffield want to sell or lend me a set?

Could the coils breaking down maybe cause this?

...again cheers for the help, this is really starting to proper do my nut in!!

[plodder]

When mine did this it was the coils.

I stuck FZR1000EXUP coils in 'cos I had some lying around (you need to make connectors) and no probs ever since.

[CMSMJ1]

Sounds like a plan.. I have ridden it and it is a strange one for sure.

It just starts to mess about as you hit the meat of the revs and just cannot pull through 9k when on full throttle. Blding off the throttle slightly sees it try to come through..

The carbs have been on and off and have got to be right..

Are the FZR coils fairly generic across the 400, 600 and 1000?

[KIYOSHI]

Sounds like it could be an air turbulance fault. Are you sure the carb rubbers are not perished and split? Its a common fault on the yams. If they looked perished coat them in silicone and have a test ride, might just locate your fault.

[Evilchicken0]

Coils are fairly generic not just across the FZR range but across bikes in general. A pair for an across the frame four from just about any manuafacturer will work.

[plodder]

It is more difficult to form a spark as there is more load on the engine, so the backing off and it gets better thing ties in with that.

[CMSMJ1]

How stressed are you now Craig?



I reckon you want some carbs off a known working moto to try and eliminate that....