Okay I need some minds to come together to help me figure out the best way to vent the crank case. Many of you already know my 9'r is turbo charged. As I've begun to crank up the boost it has started pushing oil out of the clutch case cover. The only crank port is currently directly vented through a small K&N filter. That apparently isn't enough vent so what would be the neatest intrusive means of venting the positive pressure out?
I would suggest looking for the reason you now have excess pressure in the crankcases first.
Have you blocked off the PAIR passages. And by blocking off, I'm not referring to just adding block off plates to the valve cover. I mean REALLY blocking them off by machining inserts to press and/or weld into the passages.
My theory is that if you haven't done this, the extra exhaust back pressure (compared to normally aspirated) from the turbo is pushing past the seals between the passages in the head and the valve cover. This is creating the extra pressure in your crankcases.
If the above is the case, changing the crankcase vent may work for awhile, but as the seal deteriorates more, the problem will come back.
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The original vent and associated labyrinth air / oil separator in the valve cover is quite restrictive mainly due to the small inlet holes. Opening up the inlets and crossfeed passages and going with a larger breather filter may be enough, but if not there are two more places where breathers may be pretty simply added -- the PAIRS valve fittings. Just block off the feed drillings to the exhaust ports, drill through the bottom of the reed valve recesses into the cam cavity, probably near the front to avoid excessive oil splash, and plumb both outlets to a breather can located at a high point such as the original PAIRS valve location just behind the steering head, then to an inlet filter. Comparatively simple, and no exposed breater hoses to clutter things up any more than they already are.
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I will pm you the answer later whem im home as its a long winded answer.
Thanks Wood I'll be waiting to hear from you!
Quote:
Originally Posted by NealC
XRCajun,
I would suggest looking for the reason you now have excess pressure in the crankcases first.
Have you blocked off the PAIR passages. And by blocking off, I'm not referring to just adding block off plates to the valve cover. I mean REALLY blocking them off by machining inserts to press and/or weld into the passages.
My theory is that if you haven't done this, the extra exhaust back pressure (compared to normally aspirated) from the turbo is pushing past the seals between the passages in the head and the valve cover. This is creating the extra pressure in your crankcases.
If the above is the case, changing the crankcase vent may work for awhile, but as the seal deteriorates more, the problem will come back.
I do have the pairs blocked off but that's the only thing I've done. There shouldn't be any other restrictions. I have a feeling this motor just inherently doesn't breath well enough for that amount of boost.
Quote:
Originally Posted by robtharalson
The original vent and associated labyrinth air / oil separator in the valve cover is quite restrictive mainly due to the small inlet holes. Opening up the inlets and crossfeed passages and going with a larger breather filter may be enough, but if not there are two more places where breathers may be pretty simply added -- the PAIRS valve fittings. Just block off the feed drillings to the exhaust ports, drill through the bottom of the reed valve recesses into the cam cavity, probably near the front to avoid excessive oil splash, and plumb both outlets to a breather can located at a high point such as the original PAIRS valve location just behind the steering head, then to an inlet filter. Comparatively simple, and no exposed breater hoses to clutter things up any more than they already are.
Just spitballin'.
Rob
Rob that sounds like a good solution although I'm not quite getting the idea of drilling into the cam cavity through the valve recesses but I'm not very familiar with the actual structure of the valve covers. I do have a drawing of it (Page 1-36) but I just can't quite grasp the structure for drilling through there.
NEALC......It is interesting to hear your take on this, I have been plagued by my engine (also turbo charged) smoking on the over run.
I have done everything to it i can think of to cure it.
At first i thought it was a turbo oil drain issue, so i made many differant modifications and designs and fitted two differant oil scavenge pumps.
I thought it might be oil pressure to the turbo so i restricted that.
Turbo was new when i bought it, even so i fitted new seals in the turbo.
The engine was rebored and fitted with lower compression pistons and rings, with new valve stem seals at the same time.
Ive even fitted another cylinder head to rule that out.
During this time i also modified the breather system by putting one extra breather on top of the cam cover with k&N filter.
I had put one breather into the top of the clutch case and one extra into the top of the lockup clutch spacer.
In the end i took the turbo off and found it still smokes! so i will be stripping the motor down shortly and investigating.
Once the motor is stripped i think i will block up the pair passages just for piece of mind.
XRCAJUN....
I had a look at the spare head and cam cover i have to see how it can be modified.
I took a few pictures so i hope this helps.
Clutch and lockup breathers.
Once cam cover is removed you will see the little holes next to the spark plug holes...these would need blocking up.
Under the cam cover you have these dowels, if you block the holes up in the head dont forget to allow clearance for these dowels to fit into the opposing holes.
On top of the cam cover simply remove the pair valve cover, remove the reeds and drill holes underneath where the reeds were.
I think it best to do both pair valves and fit two K&N's.
Its probably best to drill lots of small holes than one big one to help stop oil fling.
Oh and as Columbo used to say....Just one more thing.
I think that the lockup clutch will create a bit of pressure due to the centrifugal force of the arms on the lockup!
That's exactly what I was referring to. Pictures are worth a 1000 words as they say.
A buddy of mine fought this problem with his turbo'ed bike. He had filled the PAIR ports in the head with epoxy. It worked for a while, but then returned. We capped the exhaust port and put 5psig of air in it, you could hear the air getting around the epoxy plug with a stethescope. We pulled the head, machined some inserts, then TIG'ed them in place.
Problem solved, he was happy. At least for awhile. He later found out the pitfalls of turbo's on street bikes. Re-rings, and valve guide seal replacement become part of your "standard" maintenance. But it's a helluva lot of fun to do!
That's exactly what I was referring to. Pictures are worth a 1000 words as they say.
A buddy of mine fought this problem with his turbo'ed bike. He had filled the PAIR ports in the head with epoxy. It worked for a while, but then returned. We capped the exhaust port and put 5psig of air in it, you could hear the air getting around the epoxy plug with a stethescope. We pulled the head, machined some inserts, then TIG'ed them in place.
Problem solved, he was happy. At least for awhile. He later found out the pitfalls of turbo's on street bikes. Re-rings, and valve guide seal replacement become part of your "standard" maintenance. But it's a helluva lot of fun to do!
I'd be a little shy about doing this but it sure seems to me if those ports were filled with JB Weld that they would surely seal off!
NEALC......
Once cam cover is removed you will see the little holes next to the spark plug holes...these would need blocking up.
Under the cam cover you have these dowels, if you block the holes up in the head dont forget to allow clearance for these dowels to fit into the opposing holes.
On top of the cam cover simply remove the pair valve cover, remove the reeds and drill holes underneath where the reeds were.
I think it best to do both pair valves and fit two K&N's.
Its probably best to drill lots of small holes than one big one to help stop oil fling.
Woody if you were to fill the head ports with JB Weld to seal them off what then would you think about just grinding off the dowels on the cover?
The dowels are made of steel so should pull out......but in all honesty i would be tempted to leave them in and just make sure the jb weld is low enough for them to fit, as the dowels are used for locating the position of the cam cover and gasket.
I would clean out the holes with a cotton bud and a tiny bit of petrol before filling with jb weld.
a tip when using jb weld......mix it in a corner of a plastic bag then snip off the corner and use like you would to decorate a cake!
The dowels are made of steel so should pull out......but in all honesty i would be tempted to leave them in and just make sure the jb weld is low enough for them to fit, as the dowels are used for locating the position of the cam cover and gasket.
I would clean out the holes with a cotton bud and a tiny bit of petrol before filling with jb weld.
a tip when using jb weld......mix it in a corner of a plastic bag then snip off the corner and use like you would to decorate a cake!
Yeah you know my biggest concern about applying the JB Weld is having it just flow down into the hole rather than sitting there and plugging it up.
i would suggest blocking the holes in the head.... as stated its VERY possbile that the junction between the valve cover and head for the pair ports is a spot where the extra exhaust backpressure is going into the crank case...
block it off in the head, then do what is described above by drilling some holes where stated....
I also might be inclined to leave the reads in but drill some holes in them to further aid in oil splash resistance.
what if it's just the spacer/gasket? what if you're taking it a step too far? or have i missed some info? the spacer is MUCH less accurate a fit than the stock clutch cover. no dowel pins for locating it (at least, with MY brand of lockup) and the holes for the clutch cover bolts are larger/sloppier than stock.
what if it's just the spacer/gasket? what if you're taking it a step too far? or have i missed some info? the spacer is MUCH less accurate a fit than the stock clutch cover. no dowel pins for locating it (at least, with MY brand of lockup) and the holes for the clutch cover bolts are larger/sloppier than stock.
Well yeah that is part of the problem because I didn't have oil leaking before I put the spacer on but I'm also having coolant pushed out of the reservoir so there's got to be some excess pressure coming from somewhere. Also if I never hit boost none of it ever happens.
if u have coolant pushed out of the rez ur having the head bolts stretching and creating a leak between the cylinder and cooling passages.... which could POSSIBLY be linked to the excess crank case pressure (same problem as cylinder to cooling passage, but instead cylinder to say cam chain valley, or oil passage)
maybe some aftermarket / stronger head bolts (if they are even made) or torqued down more? that would suck to have a sweet turbo setup and not even be able to get into the meat of the boost.
if u have coolant pushed out of the rez ur having the head bolts stretching and creating a leak between the cylinder and cooling passages.... which could POSSIBLY be linked to the excess crank case pressure (same problem as cylinder to cooling passage, but instead cylinder to say cam chain valley, or oil passage)
maybe some aftermarket / stronger head bolts (if they are even made) or torqued down more? that would suck to have a sweet turbo setup and not even be able to get into the meat of the boost.
Yeah unfortunately I don't think they make strong head bolts, I think I'd have to get bigger ones drill and tap the case and install the bigger ones. Man I just don't want to go through all that! I'm hoping if I can find the proper way to relieve some of the internal pressure that may cure it.
I'm thinking pulling the valve cover and doing the venting at the head is my best chance. I think I'm going to buy another valve cover to play with.
Yeah unfortunately I don't think they make strong head bolts, I think I'd have to get bigger ones drill and tap the case and install the bigger ones. Man I just don't want to go through all that! I'm hoping if I can find the proper way to relieve some of the internal pressure that may cure it.
I'm thinking pulling the valve cover and doing the venting at the head is my best chance. I think I'm going to buy another valve cover to play with.
unfortunately that isnt going to fix any real issues, it only goes around them... like stated your only real option is to go with bigger head bolts. IMO i think it will be worth the time. and while your at it, properly block off the pair ports IN THE HEAD... then ull be able to really get into the boost and play!
unfortunately that isnt going to fix any real issues, it only goes around them... like stated your only real option is to go with bigger head bolts. IMO i think it will be worth the time. and while your at it, properly block off the pair ports IN THE HEAD... then ull be able to really get into the boost and play!
Well this is exactly what I was just told by a guy over the phone who's running about 190hp CBR900RR turbo! He's also recommending I go with 40000 head gasket to lower compression a little more and it will be stiffer. I know I can get the larger stronger bolts. Man I really don't want to get into all of that. But come winter I might feel different about it.
6 psi seems quite low to be forcing coolant out the expansion tank, i have this problem running 9-10 psi of boost......i was running 8 psi today with no sign of any leaks.
Check your cylinder head torque settings, if your bolts have stretched.........then maybe new head bolts may help. I still think you would have to replace the head gasket though.
Ive spoken to a few people that have turbo'd fireblade engines and they have said they run more boost than us with standard head bolts!
Well this is exactly what I was just told by a guy over the phone who's running about 190hp CBR900RR turbo! He's also recommending I go with 40000 head gasket to lower compression a little more and it will be stiffer. I know I can get the larger stronger bolts. Man I really don't want to get into all of that. But come winter I might feel different about it.
hmm... dont know man. just cross referenced the CBR919RR (1996-1999) with the honda 919... for the head bolts and they do infact share the same part number. BUT we [honda 919's] do have a different headgasket / head and LOWER compression than the CBR919RR's ... but we also share the same intake and exhaust valves.
as far as a 190hp CBR900RR turbo... its more than likely a cbr954rr with its bigger bore and shorter stroke, along with bigger valves, more hp is had much easier.
Well I've just recently had a rebuild and went back with new head gasket and head bolts. I'll tell you I'm scared as hell to just try to torque the head bolts down more you know what happens if you go too far! He seems to think that just putting the thicker gasket may do the trick just because it's thicker but also it will lower the compression. I guess eventually the only way I'm going to know for sure what's going on is to tear it down.
Here's another question for you guys. I'm using what is suppose to be a very accurate digital boost gauge, but I have it connected directly to the airbox. Do you think this the right place to have it for a correct reading?
Yes, the boost gauge feed should be taken off the airbox. Interesting to note you used new head bolts and it still leaks coolant.....ive used the same ones so i can rule out that as a fix.
You may be correct about the thicker head gasket...it wont do it any harm to try and will help you to run more boost!
Yes, the boost gauge feed should be taken off the airbox. Interesting to note you used new head bolts and it still leaks coolant.....ive used the same ones so i can rule out that as a fix.
You may be correct about the thicker head gasket...it wont do it any harm to try and will help you to run more boost!
I've just bought another valve cover. I'm going to do the ventilation business then the thicker head gasket and I'm still considering the stronger head bolts but I really don't want to drill and tap the case.
Today i blocked up the pair valve channels in the cylinder head......
The pair valve channels in the exhaust port.
I used some alloy round bar and machined it down to just over 6mm, i then cut 4 lengths around 15mm long and knocked them into the channels next to the spark plug holes. I put the alloy bar into a drill to take a little off on some sand paper.
The fit is so tight i dont expect it to leak, however i also mixed up a little JB weld and put that on top of the alloy plugs i had knocked in.
Today i blocked up the pair valve channels in the cylinder head......
The pair valve channels in the exhaust port.
I used some alloy round bar and machined it down to just over 6mm, i then cut 4 lengths around 15mm long and knocked them into the channels next to the spark plug holes. I put the alloy bar into a drill to take a little off on some sand paper.
The fit is so tight i dont expect it to leak, however i also mixed up a little JB weld and put that on top of the alloy plugs i had knocked in.
Good job Wood! In the first pic the hole with the arrow pointing at it looks like it's broken? Is that the way it normally looks? In the second pic the plugs that are in the ports are they in at different depths? Are you now going to just put the pair valve covers back on and vent them to a filter?
You know now seeing this makes me think it might be a good idea to back off on boost when going out the first time because there was probably some pressure being lost through these channels.
XRCAJUN...The hole is not broken, thats just the way it is.
All the alloy plugs are the same size, all i did in that picture was knock it into place to show you how far down it has gone.
I know for a fact mine had been leaking from there as it had oil soot round the holes!
Yes i shall be drilling the cam cover under where the reeds are and fitting the pair valve standard covers back on with a k&n attached.
I will post it here when its done.
Just bite the big dollar bullet take the head to a good cyl head guy have him weld it and blend it you willalso get better exhaust flow out of that port.
XRCAJUN...The hole is not broken, thats just the way it is.
All the alloy plugs are the same size, all i did in that picture was knock it into place to show you how far down it has gone.
I know for a fact mine had been leaking from there as it had oil soot round the holes!
Yes i shall be drilling the cam cover under where the reeds are and fitting the pair valve standard covers back on with a k&n attached.
I will post it here when its done.
Okay good deal! I can't wait to see how this works. I've probably still got a few months before I tear mine down to do the same.
Today i blocked up the pair valve channels in the cylinder head......
I used some alloy round bar and machined it down to just over 6mm, i then cut 4 lengths around 15mm long and knocked them into the channels next to the spark plug holes. I put the alloy bar into a drill to take a little off on some sand paper.
The fit is so tight i dont expect it to leak, however i also mixed up a little JB weld and put that on top of the alloy plugs i had knocked in.
Nice write-up. That's almost exactly the mod my friend did to his bike. With the exception of welding the plugs in place.
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