Back from a ball of flames - only 1 problem remains

[Arkan Eller]

Well not quite a ball of flames. I crashed my 96 B6 3 years ago. I've just finished rebuilding it / streetfightering it and it looks pretty good (pics to follow).

I tested the engine a month ago and all was well. Fired up almost straight away and idled almost perfectly. RPM would rise without stutter from idle to about 7 or 8k (didn't go any higher cos the engine had only been idling for about ten mins and hadn't been used for three years!!) All is well I thought, so I switched her off and carried on with the cosmetics.

So I've now finished the bike. I fire it up again for a test ride but this time, it revs to 4k without a problem. From 4k, if you twist the throttle quickly it will just cut out. If you SLOWLY turn it, it remains at 4k but burbles and splutters, then suddenly rises to about 7k and appears to rev relatively freely after that. Again, I didn't go past 8k cos the engine had only idled for about ten mins. It does this when the engine is hot or cold.

It's got fresh oil and plugs in and a new air filter. It's had NO engine mods at all and I've made no changes to the carbs or anything since the first time I fired it up. Any ideas?

One possibility maybe, is that because it's got an R1 2005 back end on it now, I've had to re-route some of the wiring. Some of the wires pass in front of the hole for the airbox. Would this make such a difference if a few thin wires are obstructing the hole (say 25% of the opening is now blocked)?

Many thanks for any help or hints you can give.

[Red01]

If you're blocking that much air, yes, it could make a difference.

Has it had old gas sitting in the carbs during this down-time? If so, time to clean the carbs.

[Arkan Eller]

Ok, So I changed the petrol and synched the carbs. It wasn't possible to re-route the wires so I've drilled several additional holes in the airbox - air starvation is no longer a problem!!

However, the problem remains. I took it for a test ride, over about 10 miles. Every time, it pulls clean to 4k, then bogs down badly. I have to open the choke fully, then it pulls much better (but still not perfectly). Do I need to pull the carbs (I really don't wanna cos they're a complete nightmare to get back on) and clean them?

I think I already know the answer, but I'm hoping someone can come up with some other way!?!?

[PitterB4]

I think you already know the answer too.

However, have you seen the other recent threads in this very forum about gummed up carbs????  Chevron Techron and whatever that seafoam stuff is might be worth a shot first...

Good luck.