Every 650/660 I've dealt with on these NG BB kits wouldn't clear the 56mm piston when at BDC. Now that doesn't mean every 064/066/650/660 is that way. Almost every first gen. BB kit I used I didn't do any case notching.
MS650 won't start after BB kit
- Thread starter kraftyHD
- Start date
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Every 650/660 I've dealt with on these NG BB kits wouldn't clear the 56mm piston when at BDC. Now that doesn't mean every 064/066/650/660 is that way. Almost every first gen. BB kit I used I didn't do any case notching.
stihl only
ArboristSite Operative
I have yet to see a BB kit that was a "direct bolt on".
I have yet to see a BB kit with rings that I liked.
I have yet to see a BB kit with a cylinder wall finish that I liked.
Yes, OEM is not cheap, but neither was the saw to start with.
I know we all have opinions but I have looked closely at the current BB kits and putting one on my saws isn't going to happen.
Do some searching on them and you will see that most have to eliminate the base gasket to get the squish where it should be. A lot of folks don't like or use the rings that come with them, and the stock piston pin is a much better option on most of the kits because the supplied pin is much heavier. Not all of the after market kits have the same pin length,so the factory pin isn't always an option. I think with the BB kits, they will work though.
Most using them are very familiar with saws and are willing to go through all of the issues to come up with larger displacement. They are going to mod and port the cylinder no matter if it is OEM, or after market.
I would agree that since it has been an issue in the past, to take the thing back apart and make 100% sure you have no piston to case issues.
I have yet to see a BB kit with rings that I liked.
I have yet to see a BB kit with a cylinder wall finish that I liked.
Yes, OEM is not cheap, but neither was the saw to start with.
I know we all have opinions but I have looked closely at the current BB kits and putting one on my saws isn't going to happen.
Do some searching on them and you will see that most have to eliminate the base gasket to get the squish where it should be. A lot of folks don't like or use the rings that come with them, and the stock piston pin is a much better option on most of the kits because the supplied pin is much heavier. Not all of the after market kits have the same pin length,so the factory pin isn't always an option. I think with the BB kits, they will work though.
Most using them are very familiar with saws and are willing to go through all of the issues to come up with larger displacement. They are going to mod and port the cylinder no matter if it is OEM, or after market.
I would agree that since it has been an issue in the past, to take the thing back apart and make 100% sure you have no piston to case issues.
kraftyHD
ArboristSite Lurker
I am admittedly ingnorant about the ins and outs of saws...can someone describe exactly where the impulse line is. I'm guessing it's the 1/8" line that goes from the carb into the back of the crankcase...?
You are correct.
This is why I'm recommending he have a pro look his saw over.
The impulse fitting is directly under the intake boot. The impulse line goes from there to an opening in the airbox housing, and to the carburetor. It is also possible that you didn't get your intake boot sealed correctly.
excess650
Addicted to ArboristSite
"Do some searching on them and you will see that most have to eliminate the base gasket to get the squish where it should be."
I tried the old, well worn, P&C that came off another of my saws, and the squish was WIDER than with the P&C from the BB kit. To get the squish down to the theoretical optimum would have required a gasket not available OEM.
"A lot of folks don't like or use the rings that come with them, and the stock piston pin is a much better option on most of the kits because the supplied pin is much heavier. Not all of the after market kits have the same pin length,so the factory pin isn't always an option. I think with the BB kits, they will work though."QUOTE]
Jacob pointed out that the Husqvarna 395xp rings (56mm x 1.2mm) will work the the 066/660 BB.
As far as the pin goes, the stock pin is the same length and OD as the supplied BB pin, so again, not a problem. I agree that the lighter pin is the better option with the heavier piston.
With Bailey's standing behind these kits, and working to improve them, I don't see a problem with an optional topend.
I tried the old, well worn, P&C that came off another of my saws, and the squish was WIDER than with the P&C from the BB kit. To get the squish down to the theoretical optimum would have required a gasket not available OEM.
"A lot of folks don't like or use the rings that come with them, and the stock piston pin is a much better option on most of the kits because the supplied pin is much heavier. Not all of the after market kits have the same pin length,so the factory pin isn't always an option. I think with the BB kits, they will work though."QUOTE]
Jacob pointed out that the Husqvarna 395xp rings (56mm x 1.2mm) will work the the 066/660 BB.
As far as the pin goes, the stock pin is the same length and OD as the supplied BB pin, so again, not a problem. I agree that the lighter pin is the better option with the heavier piston.
With Bailey's standing behind these kits, and working to improve them, I don't see a problem with an optional topend.
jeeptj19992001
Addicted to ArboristSite
which way is the arrow pointing on the top of the piston? towards the intake or exhaust port?
It points towards the exhaust which puts the ring ends on the intake side.
jeeptj19992001
Addicted to ArboristSite
i know it does, just want to make sure his is pointed in the right direction
Wet1
Addicted to ArboristSite
Is this the general consensus? I was under the impression that w/o a gasket the squish is generally to low.
The squish on my 066BB was only .017 with a gasket. It hit and wouldn't turj over without it.
I haven't seen a BB kit yet that could run without a gasket.
excess650
Addicted to ArboristSite
the one I have right now would be .010" without gasket
1953greg
ArboristSite Guru
thats a little too close!!! like .010 too close
stihl only
ArboristSite Operative
Just what I had picked up reading some BB posts. May have been early design kits? I think it also varies with the different kits so what works for an 044 isn't the same as a 066, etc.
The problem is that these things must be checked, so it isn't a bolt it on and cut, kit.
With most things you buy today, instructions are lacking. If you frequent this site and do all the homework, it isn't an issue but not everyone who is going to buy a BB kit is on this site. I think it would be a big help if some instructions on what to look for as far as interference and squish were put in with the kits.
It would be easy to assume that you can just bolt it on, because you can with the OEM parts.
GASoline71
Mr. Nice Guy
You couldn't pay me to run any of the BB kits on any saws...
More hassle than they are worth...
Gary
More hassle than they are worth...
Gary
I got KraftyHDs MS650 in the mail today. The running issues was a simple fix but he wanted me to look it over. The 90* plastic elbow was not plugged into the fuel line in the top of the tank.
More importantly, here are some things I found with the BB kit. I put the saw back together using a new 660 gasket. The piston skirts were hitting the gasket, just b a r e l y. Luckily I had another, so back apart it came and the next one went in after I relieved the ID of the gasket a little. I still wasn't sure the piston wasn't touching the case. I put it back together and it's smooth as silk. I turned it over with my fingers on the flywheel back on forth past BDC and there's nothing there. It clears but not by much. That's why the skirts on this kit are .080 shorter than stock as Excess650 I think it was showed earlier today. The bottom of the piston does free port perhaps .020" at TDC, just like mine does. But it starts, idles, and accellerates great.
Here's another thing I found that I really don't like. The roof of the exhaust port is totally flat. I mean no curve to it at all. This flies in the face of everything I've learned about porting. I do not like to raise the roof of an exhaust port but I felt like I had no choice on this one. It's simply not worth the risk of leaving it flat. It only took raising it about the amount of the original bevel to get a little curve to it. Grant it, the original bevel was quite large. That's probably how they get away with such a flat roof. I can see why some ported saws break rings. Go ahead and widen that port and maybe loose a little of that factory bevel and you've got the recipe for a failure if you don't change the shape a little. It doesn't take a lot to make a difference. So builders beware. Fix that port shape when you port these things.
I've put it through a couple heat cycles and hope to get it in some wood tomorrow. After that it'll be back on its way back home.
More importantly, here are some things I found with the BB kit. I put the saw back together using a new 660 gasket. The piston skirts were hitting the gasket, just b a r e l y. Luckily I had another, so back apart it came and the next one went in after I relieved the ID of the gasket a little. I still wasn't sure the piston wasn't touching the case. I put it back together and it's smooth as silk. I turned it over with my fingers on the flywheel back on forth past BDC and there's nothing there. It clears but not by much. That's why the skirts on this kit are .080 shorter than stock as Excess650 I think it was showed earlier today. The bottom of the piston does free port perhaps .020" at TDC, just like mine does. But it starts, idles, and accellerates great.
Here's another thing I found that I really don't like. The roof of the exhaust port is totally flat. I mean no curve to it at all. This flies in the face of everything I've learned about porting. I do not like to raise the roof of an exhaust port but I felt like I had no choice on this one. It's simply not worth the risk of leaving it flat. It only took raising it about the amount of the original bevel to get a little curve to it. Grant it, the original bevel was quite large. That's probably how they get away with such a flat roof. I can see why some ported saws break rings. Go ahead and widen that port and maybe loose a little of that factory bevel and you've got the recipe for a failure if you don't change the shape a little. It doesn't take a lot to make a difference. So builders beware. Fix that port shape when you port these things.
I've put it through a couple heat cycles and hope to get it in some wood tomorrow. After that it'll be back on its way back home.
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Lakeside53
Stihl Wrenching
That's been my Bit?h... this is the third (?) generation of BB, and they still aren't right? I'll pay good money for OEM-like plug and play, but nothing for these..
Why don't they just make GREAT copies of the OEM... ???? Heck, make them right and sell them for $150.. or $200...
Why don't they just make GREAT copies of the OEM... ???? Heck, make them right and sell them for $150.. or $200...
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volks-man
Arboristsite.com Spooner
good man, snelling!
