First of all, please excuse my grammar/language... I am from Argentina and my english is little rusty.
I am having this problem since 2 years now and I am almost not riding any more
I will try to give some background about my bike, the problem detail is down in BOLD
I bought her 10 years ago... first bike and with her I learn to drive (yes its a big bike for first timer, I got my first inguinal hernia
(really) when I try to turn the corner like a if it were a bycicle), so... the problem began after taking the engine out for pistons/rings service because it used to consume some
oil, about 1 litre oil per 400km, anyway it didnt smoke black out the exausts.
(if I knew all the problems that came after I take it to the service... I would never opened the engine!!! for that f#cking 1 litre oil consumtion, I am regreting this everyday)
So, after taking out the engine, replacing piston rings and some other service the mechanic recommend like hidraulic tappets and cleaning every thing I could in the process like water tubes, etc... we put the engine back.
The carburator had got some problems while the bike was stopped (about a year searching parts), I bought the carburator rebuild kit from a reseller in UK... and change everything I could.
HERE THE PROBLEM
I went for a ride hoping no more oil consumtion but problems began, between 3000/4000 rpm the engine rattled if you accelerate fast... and it sound like "cla-cla-cla- cla" very quickly every time in that rpms, like something skipping. After that the engine accelerates like a beast, no problem at all. If I accelerate slowly, did not feel any problem at all.
The mechanic test it and told me that the new piston rings might need some time to settle... ok, I am no mechanic... so I went for about 1000km ride, trying not to accelerate hard to prevent the rattling, just to becareful with her.
Came back a week later, the problem still continues... the mechanic started to doubt, that it might be something in the carburator. There I bout the carburator rebuild kit and two brand new floats and rubber vacums (not the whole piston vacum, just the rubber diaphragm).
Nothing changed, only the mechanic
because mine had no more time and he is specialized with motocross bikes not custom like VT700. So the ratting continued, some time passed with no clue, but problem kind of change... now it is between 2000/4000rpm and sometimes even stopped and idle you hear one random rattle.
After that and a new mechanic specialized in old bikes suggested that it might be in the cross-shaft, that the spring damper (23732-MK7-670) with age it lost hardness.
So now I am completely lost:
1) I learnt a lot about bikes, carburators, engines
2) I learnt to NOT open your old bike engine
unless it is completely necesary... even if it consumes about 3 litres each 400km... take bottles of engine oil in your sidebags
1) there is no new spring damper to buy from a reseller (or cant find one)
2) the bike runs like s#it
3) I am starting not to trust mechanics
4) almost 2 years I cant enjoy riding my bike.
Hope anyone can give me some help, recommendations...
Thank you very much!
attached some pictures of my baby now and when the engine at service.
two links to videos with engine runing from start cold and second when hot... anyway, the rattling did not happen on these video, might be useless but hope it can help some trained ear :-p
(fuel light is on, because I have the tail light disconnected)