Bent valves how?

So I wondered why the bike would not idle below 4 grand and just was not right at all

I felt maybe my carbs had poop in them, so I spent 12 hours farting around with them
super cleaning them and rebuilding them.

Checked the timing played with and tested the ignition ... no results :head bang:

This week I took the heads off to clean the carbon out of the ports then lap the valves
and i'll be 4 of the valves are bent however there was NOT a single mark on ANY of
the pistons. :shock: :shock:
How does one bend valves if they did not contact the pistons ???

I'm thinking that the P.O beat the tar out of it got it real hot and then put it away without letting it cool down. Any clues anyone??

I also found it does not have a thermostat, just an empty hole

id say it hit ....i dont know the story on it and the PO but ita hard for four valves to bend the way your talking but something happened tho .... its good that there isnt any piston damaged ....and its good that you found the problem im assuming that both heads have valves bent ....its a wonder it ran at all but they do ive herd tell before of it a lot......im assuming that the cylinderwalls look good ....seems to me time to fix the heads a little more than you planed to and pyt it back together .....riding season coming time to get-it-done... :rant: :head bang: :builder: :builder: :headscratch: :builder: :builder: :mrgreen:

If the bike is new to you could be the PO did belts wrong, bent the valves then sold it.
Just a guess but at least now you know what it is!

This is why I always advise checking compression first thing when it doesn't run right, especially one just bought.
Compression check would have revealed the bent valves and possibly saved all the futzing with the carbs.

Yeah I am kinda mad at my self for not doing a compression check on it first :rant:

the P.O is a coworker he bought a suzuki 1500 and started to lob it up then lost interest and I needed a project bad but 500$ for a ZERO rust bike seemed
pretty appealing.

the cylinder walls are perfect and still have the factory cross hatch. :good:

it has 64k or 40,000 miles on it.
I found 1 bent exh and 3 bent int

when you roll them on a flat surface you can't see the wobble but when
I tried to lap them only half of the seat would grind. :doh:

I ended up buying a new set of 8 with seals from Peak Moto on fleabay for 150$
Will probably end up lapping these ones in tomorrow and will also post pics in my build thread as well. :builder: :builder: :whip: :whip:

thanks for the input guys it's greatly appreciated
:salute:

One possibility. Someone may have tried an old trick we used in the 70s. Holding the throttle open a nd pour water through the carbs to clean out carbon. It works but on these motors the tolerances are so low that even minor hydraulic action could definitely do it.

OldGold":xvr8ysv4 said:

when you roll them on a flat surface you can't see the wobble but when
I tried to lap them only half of the seat would grind. :doh:
:salute:

Click to expand...

Just for clarity, are you talking about the face of the valve, or the seat in the head?
If the face of the valve will only lap half way around, then my guess would be burnt or bent. If the seat in the head will only lap half way around, then you might have guide problems or something like that.

Scdmarx, I'm talking about both the valve face and the valve seat.(head side)

I had to go into work to cover someone's shift and did not get a chance
to have a closer look, I really hope I don't have guide problems :beg:

when I first noticed bent valves I put a mag lite in the port and spun the valve in the closed position and could see light coming through at one spot

OldGold":3b5z37gh said:

Scdmarx, I'm talking about both the valve face and the valve seat.(head side)

I had to go into work to cover someone's shift and did not get a chance
to have a closer look, I really hope I don't have guide problems :beg:

when I first noticed bent valves I put a mag lite in the port and spun the valve in the closed position and could see light coming through at one spot

Click to expand...

If the light coming through turned when you turned the valve. Yes it is the bent valve.