Starter turns but no compression.

[AFazakerley]

Today I tried to get my idle to be less rough by tweaking the idle mixture screws. Then at one point the engine made strange noise, like if someone dropped a bolt into the carb/engine. Then it died. Tried starting it but it sounded like only the starter was turning and not engine. I pulled a plug and did comp test, got between 30-60psi. I am pretty stumped. I pulled the plate that covers stator/flywheel/starter gear and everything looked good. Something with the valves or…?

[csmith12]

Valves? Check em!

[lgk]

[FvnnyL3tt3r1ng]

Sounds like valves to me too but you could eliminate a few things by doing a compression check on the other side as well. A leak down tester helps a lot to pinpoint the leak as well.

[AFazakerley]

could this be my problem

haha NO luck with this bike. Any recomendations where to buy a new one? and any DIY to replace it?
I spend more time working on this bike then actually riding.

Also looks like there might be some fragments that were left behind.. do i just drain oil or more?

Thanks guys!!

[ninjamunky85]

Ouch, that's gonna hurt. That's your cam chain btw.

[AFazakerley]

Yah i could tell it was cam chain, hence going around the cam gears. Just not sure how to install new one as far as setting the cams to TDC, and getting the chain around the crankshaft sprokect. Does the chain seperate or stay as a whole?

[ninjamunky85]

As far as I know there is no easy fix for a broken cam chain. Replacing it would involve splitting the engine case.

[choneofakind]

paging @alex.s. He was talking about changing a cam chain earlier.

[alex.s]

Buy a new engine

[AFazakerley]

Ouch, damn really?! More worth it to buy a new engine then fix current one? it only has 2k on it.

[alex.s]

the problem is, that really is not supposed to break. finding out why it broke will tell you what needs to be done but the answer is more likely than not something you wont want to hear. maybe the CCT was installed incorrectly stretching the chain causing the break. maybe a valve bent jamming the cam snapping the chain, maybe something else broke in there and jammed inbetween the chain and the cam sprocket, snapping the chain. it could be a variety of things but the fact is, it is a serious engine failure that shouldn't be taken lightly.

supposing miraculously nothing else is broken here's whats involved in replacing the cam chain

engine out of the bike
split the case, top cover off
pull the crank out a little so you can fit the chain between the case and the crank sprocket and feed it down through the cylinder side slot and down into the head, then grab it and hold it with some safety wire or paper towel or something so it doesnt fall back down
reassemble

if you have no experience taking engines apart, it might take the whole weekend... maybe longer if you really dont know what you are doing.
if you are comfortable inside the engine it should take half a day

[flynjay]

I'd say you're in for a complete engine tear-down. You at the very least need to find all the parts that came off that chain. You don't want to leave any of that in the engine.

If you don't have a service manual, now is the time to get one.

Priority #1 is to find out why the chain broke. Without that you are doomed to unlimited problems.

A donor motor may be the way to go.

[alex.s]

i re-read the original post and here's my guess:

*something happened* now a valve is bent or broken, that resulted in the compression test fail and then the broken chain (broken valve got stuck jamming the cam, breaking the chain.

it would be a better idea as a whole to just replace the motor as a whole if that is really the case but you can't say for sure that's what happened without really tearing it apart and investigating. pulling the head off from the point you have it isn't much work and will tell you a lot

[alex.s]

oh hey here's an easy check, look at the backs of the valves with a flash light by taking off the intake/exhaust. you can do that in a couple minutes and will tell you a lot

[flynjay]

Originally Posted by alex.s

i re-read the original post and here's my guess:

*something happened* now a valve is bent or broken, that resulted in the compression test fail and then the broken chain (broken valve got stuck jamming the cam, breaking the chain.

it would be a better idea as a whole to just replace the motor as a whole if that is really the case but you can't say for sure that's what happened without really tearing it apart and investigating. pulling the head off from the point you have it isn't much work and will tell you a lot

Compression test is failing because the intake valves aren't opening. Leakdown test would show if the head is intact. But you are either going to have to tear-down the motor to fix it or just remove and replace.

Either way, my order of going forward would be:
1. Drain all fluids.
2. Remove engine from bike
3. Start engine tear-down. I would go all the way down to completely splitting the case so you can get a good look inside for any debris.
4. Re-assemble with new cam chain and gaskets (base and head).

Or skip 3 & 4 completely and install a new (used) engine.

[AFazakerley]

Alright so ive been neglecting the bike since my daily driver is having a few issues.
However i plan on drainning the fluids so that i can look at the backs of the valves. After ill pull the engine, pull off the head and try inspect as much as possible. I would like to get this engine fixed, but in the least i will take it apart and learn a bit more about it. Any advice where to search for an engine to buy? All i can think of is craigslist.