My XJ600n wont accelerate

[trancer]

Hi all im new to the forum, im just about to get my first big bike on the road since passing my test in December but i have one major problem, the bike starts fine and runs well and even revs up nice when stationery but as soon as i take it down the road for a spin, it seems to bog under badly after 2.5k revs, if i run the throttle wide open, it gradually gets better then comes alive around 5-6k revs but soon drops off again when i slow down, hill climbs are almost impossible

[Deleted]

Clutch slipping?

[trancer]

Clutch is very good on the bike and looked fine when i sorted the oil drive rattle last week, it seems the mid range power band is effected, if i go lightly with the throttle and stay below 2.5k revs everything seems normal

[rowlf]

Sounds a bit like icing in the carbs. I used to get that in my 900 although I am not sure if the 600 is as prone to the problem. Check the carb heating system which is by engine oil in up to 1995 models or by electric heaters 1996 on.

It could also be fuel supply problems. Clogged fuel filter, fuel lines or even low float levels in the carbs. The fuel pump (vacuum up to 1995) or (electric 1996 on) is another candidate. Especially the vacuum pump. They can lose vacuum if the pipes are loose or split or if they just get old.

I would start by checking the fuel filter and fuel lines, then the carb heating system, considering the weather. After that it gets a bit harder.

[trancer]

thanks for the reply, i have the 1998 XJ 600, this morning i went out and checked the float levels which seem fine, i noticed that cylinder 1 and 2 weren't doing very well, C1 was clean with no deposits and C2 was white (Lean) C3 and C4 was a nice tanned colour which is normal, i stripped down the failing carbs and cleaned out all the jets and reassembled everything, the bike was no different, all the header pipes are getting hot at the same time though, it's driving me mad!

[m40man]

If you're happy with the carb clean it would point to either breaking-down ignition leads/caps, or a coil on the way out. Are your C1 & C2 on the same coil ?? (I think C1 & C3 should share, but it's worth checking).

[trancer]

I have been thinking about the coils, left coil is 1&4 and right coil is 2&3, with the bike running i can hold on to C1 plug and i get a small amount of currant but its the same when i give it some revs, im wondering if replacing the coils might help, the bike has been sitting for 2 years before i bought it

[trancer]

I have been thinking about the coils, left coil is 1&4 and right coil is 2&3, with the bike running i can hold on to C1 plug and i get a small amount of currant but its the same when i give it some revs, im wondering if replacing the coils might help, the bike has been sitting for 2 years before i bought it

[m40man]

As they'e on separate coils, C1 & C2, consider replacing their plug caps first. A cheap thing to do.

[trancer]

Thanks for the reply's, just grabbed a bargain on ebay and bought nice clean carbs, rubbers and coils for £40, the guy is also throwing in a load of free parts, just hope it solves my problem,

I was just wondering if the TPS would give the same trouble without giving any fault code on the clock

[CD]

Has it still got the restrictors in place?

How do you know the clutch is ok?

[trancer]

There's no restrictors and the clutch is great, you can hear the bike running on 2 cylinders under load, but as soon as its idling again its perfect, its definitely a strange one, iv cleaned the carbs out and put a new fuel filter

[bobh]

I had a somewhat similar problem with my Thundercat after it had been standing for a few weeks. I turned out the pilot jets were partially clogged up with a sort of gel that was left after the petrol (95 octane from Asda) evaporated. At first glance they appeared to be clear, but in the end squirting them through with carb cleaner solvent from an aerosol did the job.

Now I always try to put 97/98 octane fuel in if I know it'll be standing for more than a week or so.

[CD]

The sparks are the easiest to diagnose then move to the carbs. Fit new plugs (unless already new) then swap the coils over and see if the miss-fire moves.

Posh petrol from such as Shell will help keep things clean but on a carb fed Diversion wont do anything for performance.

[trancer]

Iv got fresh petrol in the tank and new plugs, next im trying a set of known working coils, after that il move onto the carbs, il keep you all posted, thanks for the reply's everyone

[trancer]

Problem solved! after replacing the carbs the problem has gone completely, very odd because the original ones were spotlessly clean, the only small problem i have now is a bit of popping from the exhaust when cold, i think the carbs need synchronizing

[rowlf]

Wow, well done with solving that one trancer. That sounded like a real nightmare to deal with.

It is a good idea to synchronize the carbs regularly. The bike always runs so much better when that is done, better mpg usually as well as smoothing out that mid range vibration.

I use a set of these, which make it a really easy job.


Ebay 180998500558

Funny but every time I have used them one carb is always a bit out. I just used them on my new XJ600 and again, one was a bit out. It sounds really smooth now and next to no vibrations at 3000 to 4000 revs, which is where it normally happens.

Good luck with it all now.

Rowlf

[trancer]

Thanks for the info Rowlf, went and bought myself a Morgan carbtune pro, iv heard some good things about them and always handy to have, im looking forward to seeing the results too

[rowlf]

Indeed an excellent bit of kit the Morgan Carbtune. A fair bit more sophisticated than 4 dial gauges screwed to a bit of aluminum and a lot more compact too. A good choice!

Be interested to hear how you get on and how well it runs after you synched (sank? ) it.

Rowlf

[CD]

The cards are balanced in pairs so you don't need 4 gauges.

This simply compares the suction. Do one pair, then the other pair, finally do the 2 pairs.
www.twinmax.co.uk/

A rubber listening hose also also works to compare the bellmouth pop pop sounds and costs 2p.

[trancer]

If i can il get a video of the bike running before and after the tune up, im hoping to see some good results

[Deleted]

You won't regret buying the Morgan Carbtune. They make a tricky job easy.

Oh, and well done with the fault-finding and spannering

[trancer]

Apr 2, 2013 11:38:21 GMT @jimoz said:

You won't regret buying the Morgan Carbtune. They make a tricky job easy.

Oh, and well done with the fault-finding and spannering

Thanks matey

I heard that the Morgan carbtune was the best and that they no longer use mercury, instead they now use rods which can also be cleaned if any dirt gets inside the device

[CD]

Morgan a good 4 lead tool, but the Twinmax is more accurate. It compares two signals when they are the same it's balanced. As all carbs are done on pairs it doesn't matter if the bike had two, four or six.