750 brute force

[Garryese]

That is more good info.

Yes, if one cylinder fired it would run, but really rough.

No, I do not think the key sheared off. If the key sheared off the engine would likely not have restarted as I do believe the poor running and then the no compression are directly related. If the poor running was cause by dirty carbs and then the key sheared it would be quite a coincidence, but it is possible.

As both cylinders have no compression it is very likely that there is one part failure that caused the problem. Very few parts affect compression on both cylinder but here is a list of some of the possiblities:

1. Drive sprocket and key for the timing chains
2. Lower timing chain (broken or skipped on the sprockets)
3. Crankshaft (not likely broken, but remotely possible)
4. Idler shaft or sprockets (broken)

If I remember correctly there are three timing chains. One from the crank to an intermediate shaft and one from the intermidiate shaft to each cam shaft. Any problems between the intermidiate shaft and the crankshaft will cause the valve train to go out of time on both cylinders. If I am recalling the right engine, I have replace a broken lower chain a few years back.

If the valving timing is out there is a very good chance there is a bent intake valve (explains the fuel spitting back through the carbs) and if the valve is bent it is possible a piston is broken (explaining the oil at the crankcase breather). A leak down test will help determine where this secondary damage might be. If the front cylinder head needs to come off, I suggest pulling the motor out of the frame to do the work.

With the info you have provided this is what I believe has happened: The lower chain jumped a cog causing the engine to run poorly. When you started it with the carb clean the lower chain either broke or jumped another cog, causing the piston to contact an intake valve on each cylinder. The valve contact bent the valve at the base of the stem and possibly broke a piston. This is a scenerio that explains all your symtoms, but it is also the worse case scenerio.

As stated above the sheared key scenerio is possible but doesn't explain the oil at the breather when it last ran. The key is also easier to check, so that is why I suggest checking the key first. If the oil at the breather is not that bad or the engine backfired recently then a sheared key is much more likely. Other than a backfire the most likely time to shear the key is when hitting the starter button. If the key sheared when starting then the chance of top end damage is significantly lower.

Check the key first, then the lower timing chain.

 

[twinpeaks3]

So why not pull one valve cover and make sure the valves are moving. Then check valve lash. If its in the ballpark and you haven't set them since this all started they are fine. Now slowly pull it overwatching when the intake valve closes stlop pull a plug and see where that cylinders piston is. it should be near the bottom of its stroke. and as you keep pulling it over come to the top of its stroke. If that all seems good your key and valve train should be fine.
Have you checked/replaced your plugs. With a dry set of plugs spin it over not spraying anything anywhere. pull a plug and check it. It should be damp but not dripping whith fuel. If it is dry or soaking wet pull your carbs and figure out what went wrong when doing the carbs.
Check your oil and make sure there is no fuel in your oil.

So is the kill switch on the handle bars on. My wife turned mine off after going for a ride and getting the bike really hot. It took me 1/2 an hour to figure out why it wouldn't start. I've never used it and never thought to look. Talk about feeling dumb.

 

[STEVIE D]

I cked timing on cam this weekend an it is on the money i did not perform leak down test i am this week i have to get tool , i am at point where to me if chain jumped on inter shaft timing would be out on cams but they are ok so i will do leak down test an go from there , never had one whip on me like this ,

 

[STEVIE D]

I cked timin on cams yesterday that was on money so it cant be chain jumped if so timing would be off up top to ,correct , i will ck carbs again

 

[twinpeaks3]

So did you check the plugs? Is there fuel in the oil? Have you checked spark. When your spinning it over can you feel pulses out of the exaust. Don't know about 750s but some 700s have leaked fuel past the needle and seat and flood out to the point of getting gas in the oil and depending if an exaust valve is open filling the exaust. its worth a check.

 

[Garryese]

Twinpeaks3, please read the entire thread. It has been established there is zero compression.

Stevie, if cam timing is dead on, then chains and key should be good. I just can't imagine what would take out the compression on both cylinders at the same time. Very strange! Leak down test will at least tell you were the compression problem is on each cylinder. Fire alarm testing companies have smoke in an areasol can; I spary the liquid smoke into the leak down tester just before I plug in the air hose so I have a visual indication of leakage (listening for small leaks can be tough).

Keep in mind if chain did jump in the retarded direction the intake valves could coming to contact with a pistons and jump the chain back to it's proper location. I don't know how likely this is, but it is possible.

 

[STEVIE D]

So do you think it is worth pulling head on front cylinder cause i pulled rear already an it is fine , i did pull cover an ck valves i did not pull head on front an ck for bent valve i can see valves movin as i spin over with wrench on pull rope bolt they seem to be open an closing as normal not to say=though one is not bent at base of stem an cant tell ,

 

[STEVIE D]

No i have not but i will this weekend i had to charge battery over night it was weak so no help there , but after i ck front cylinder to see if valve bent at stem i will go back to beginning if all is ok , an then i will ck comp again with good hot battery,,,,,,,,,,,,, dont have pull rope for me to pull an ck ,,,,,

 

[twinpeaks3]

Garryese I did read the entire thread. Just wasn't sure if he actually had a compression tester on it, is there an issue with the compression tester. Other than bending valves it seems unlikely to loose compression on both cylinders at once.Checking valve lash should tell you if you bent a valve. I was just asking seeing as he was still trying to get it running.

 

[STEVIE D]

I used another comp tester just to ck an same thing , but like i said i am trying a few things this weekend , it is really hard when i work till 6 every nite an dark when get home , i have just weekend time an inbetween honey does for wife i test things , i tell you if my son would have not bought that bike i dont thing i would have another bruteforce , but that is alot of frustration i guess once i figure it out i ll be ok , honda is so much easier to work on . I just rebuilt a 500 foreman runs excellent that is easy stuff this brute is a different animal are i am just overlooking somthing in frustration an letting it whip me ,

 

[Garryese]

Honestly, I am not sure how bad of a job it is to remove the front head without removing the engine. Anytime I have had to remove the front head on these kawi v-twins I did it on the bench cause a rebuild was needed.

You have the rear head off and found nothing? Something is up if you had no compression in that cylinder. Damaged/bent valve or piston or cylinder wall.. Place the head on the bench with the combustion chamber facing up and level. Fill the combustion chamber with varesel and check valve stem through the port for leakage; If there is no leakage the valves are seating. Somewhere the is a reason for no compression.

 

[Bruteskeg]

do you go the kawi service manual ??? your saying you dont have any compression and there was lots of crap in your carbs right ?? allmost sounds like it could have been sunk once.... but have you tryed pouring some oil down the cylinders and trying to fire it up, iv read that for some reson on the brute the rings sieze in the piston and just need some lube to un stick emm............... but if you dont got the link to the kawi service manuale hear it is , also read the if you sink the brutes you can streach the timeing chain really bad ........ if you havent all ready would still check on High Lifter bunch of yankees but there are lots of guys that could probaly help you out gettin that brute goin way more people on that site then on hear.

 

[STEVIE D]

Hey gary i took carbs off again an recleaned put back on after cked timing again an sprayed alil carb cleaner on plugs an in cyllinders an tryed to start again an it popped over for sec an then would not again so i am thinking possible carbs not synced correct are fuel issue , what you think

 

[Garryese]

Are you sure you don't have compression?

Carb for the rear cyclinder is jetted fatter than the front cylinder, but even if you got the jets in the wrong carb, it should still start.

Do you have the means to check fuel pressure from the pump?

 

[STEVIE D]

hey gary i reset valves this weekend an recleaned carbs an put back together poored alil oil in each cylinder an it fired off but blowing oil an what lookes like fuel through vent hose from crankcase to airfilter housing , so what is up wiht that

 

[Bruteskeg]

Its common on the Kawis, you gotta drain the oil and crap out of that airbox drian hose or you could get sprayed with oil, happen to a buddy of mine once we wear crusing down the road and all of a sudden he stoped was covered in oil lol .. hopefully thats your problem with that .

 

[Garryese]

If it blowing fuel up from the crankcase then one or both floats leaked at some point and partially filled the crankcase with fuel. Do an oil change and run it. Keep an eye on the oil level, if it rises above the full mark one of the carb floats is still leaking.

Kawis are bad for puking oil into the air box if the oil level is even slightly too high, especially if you wind the RPMs up. Never go above the full line.

 

[STEVIE D]

hey gary just wanted to thank you for all info i got that beast running yesterday between valves out an carb i put alil oil in cylinders an it cranked off after got hot stopped blowing oil an then changed oil an recranked an runs great so just wanted to tell you thanks for info ,,,,,,,,,,,,,,,,,,

 

[doobest]

check your valves if spitting through carbs the valves are either out of time or not sealing

 

[munhoez]

check your valves if spitting through carbs the valves are either out of time or not sealing

If intake valve clearances to tight valve will stay open a bit, youwill lose comp., comp. of the air/fuel mix will be spit back out through carbs.