Carbs rejetted now wont start

[85Coupe]

Thanks guys,

Removed sparks, flamed them with blow torch, steel brushed them and replaced. Fires up 1st time.

Also, got the jetting right and she flies all though the rev range and is strong.

Now, as per Murphy's law i have a new problem.

Went for a ride, as i was pulling into the parking lot, slipped her into neutral i heard a klunk sound, followed by what i can only describe as a worn valve lifter or Tappet (on a car).

This sound now remains, it increases and decreases in tempo with the engine revs. It's like a tik tik tik sound, as said, just like a cars with worn lifters (tappets) sounds.

I think it might be a faulty valve spring, also it seems to be isolated to only the front cylinders, in terms of the sound.

The bike runs fine, no overheating, just this very loud noise.

Any ideas? I can't leave it like this, the tik tik tik noise is louder than the exhaust.

Thanks gents.

[Neosophist]

Lounder than the exhaust? Dont ride it with a noise that loud, something could be seriosuly wrong.

Nothing loose right? I had a loose exhaust collar that vibrated in time with the engine.. failling that get the rocker box cover off and have a look.

[85Coupe]

I guess that is prob a safe bet, would hate to drop a valve. Sucks as i just got the bike now it must stand whilst i diagnose.

I will check if exhaust is tight 1st.

Can you remove the front Tappet cover with the motor in the frame? Or must engine be removed?

[85Coupe]

P.s. i might have exaggerated how loud it is, a better explanation is i can clearly hear it over the exhaust note.

[85Coupe]

I read in the haynes manual that the valves need to be set at 24000km, the bike is currently sitting at 23800km...

Seems this is then the problem, is it normal for there to be zero ticking noise, then all of a sudden this massive noise?

[Dynamohum]

It's worthwhile doing the valve clearance check in any case if unsure about the bikes history but as you said the ticking noise has just appeared check the exhaust system for leaks at the joints as this can give a mechanical sounding tick . Yes the front cover can be removed in situ if you loosen the top radiator or better still drain coolant and remove completely for better access.

[Neosophist]

its never normal for there to be suddenly a loud ticking noise.

[85Coupe]

Hi Neosophist,

I agree, the thing is the bike never reved past 10500 in its life before. It hit 10500 then hit a flat spot and would not go over that.

This was a jetting problem, that I fixed with the carb rebuild.

Since refitting the carbs, the I rode the bike for like 25km, this is about 15miles. All the while enjoying the full rev range all the way up to 15000rpm. Then the sound started.

I think that due to it never doing these sorts of rev's it had a shim pop out or something.

Does this make sense?

[Neosophist]

Hi Neosophist,

I agree, the thing is the bike never reved past 10500 in its life before. It hit 10500 then hit a flat spot and would not go over that.

This was a jetting problem, that I fixed with the carb rebuild.

Since refitting the carbs, the I rode the bike for like 25km, this is about 15miles. All the while enjoying the full rev range all the way up to 15000rpm. Then the sound started.

I think that due to it never doing these sorts of rev's it had a shim pop out or something.

Does this make sense?

If a shim falls out theres a very high chance of the valve dropping out and destroying the engine (yes, you will need to buy a new one shoudl that happen while its running)

Im sure it revved to the end before when it was in Japan..

But yes perhaps not for a while... start with valve clearances and make sure everything looks ok in the top end.

[85Coupe]

I see,

I am rather scared I am very close to dropping a valve, so the bike is parked and will have the head off for investigation.

I think I am lucky as the valve has yet to drop...